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My A70 #616744
09/09/15 9:12 pm
09/09/15 9:12 pm
Joined: Jun 2013
Posts: 97
Texas, USA
R
Ray Elliott Offline OP
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Ray Elliott  Offline OP
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R

Joined: Jun 2013
Posts: 97
Texas, USA
About a year ago I bought an A70 on eBay. I had wanted one for 40+ years. I tried to buy one about '78 from a fellow who rode into the Honda shop where I was working. He had no idea what he had. I guess I was too eager & he figured it out: he rode off & never returned.

This one was in pieces (though the engine not disassembled) & quite a few pieces were missing (no big deal as I have NOS or very good used parts for most).

Frankly I was fearful when I bought it as it was located 1600 miles from me: I had to go by pictures & conversations with the owner. It had a Triumph gas tank & the frame looked 'odd'. The space between the oil filler & rear frame looked like a '74+ T140 not an early OIF. The serial # was confirmed valid & I jumped in. I arranged for a company to pick it up & deliver it to me. I just couldn't bring myself to drive that far.

After it arrived I stuck a pencil in a spark plug hole & 'checked the stroke'. It was longer. The 7 stamp on the cases above the gearbox was there. Then I pulled off the timing covers & could see the thrust washer over the bushing. I finally quit panicking over what I'd bought.

It was the first time I had seen inside an A70. Then I had thoughts: I really don't know anything about the differences in an A70 engine & there was no way to pull the timing side gear without a puller as there is no clearance between the thrust washer, case & gear.

My original 'factory' puller was stolen with all my tools in the late 70s. So it was off to my buddy's mill & we made a gizmo to slide over the gear & fit a puller. It worked fine.

The cylinder base nuts were painted pink. No idea about that story. The oil was burned goo. The bushing clearance with 0.006". I found a NOS 0.010 bush on eBay.

I turned my attention to the frame & stripped it bare. What I found is interesting: someone had grafted a T140 subframe onto the original frame. I do not know the history of this machine so I have no idea who did it or when. But the work is good. And the subframe is straight. I found no cracks.

Pictures of the frame and timing side thrust washer are here. Some may find it interesting. Maybe someone will know the history of this frame.

My painter in Vietnam (where I usually work) painted a tank I had on the shelf for $40. I cannot paint & there's no use torturing myself trying. Since the frame isn't original I've decided not to worry about original colors & all that hysteria.

The frame has been coated with KBS & painted with black top coat. It looks quite nice.

When it cools here in Houston I'll turn back to the engine & will post quite a few questions before reassembly! I don't care if I hose an A65, but this one needs to be right the first time.

Thanks folks!



Ray Elliott
---
A65, A70, A75, T120, T140, T150, T160
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Re: My A70 [Re: Ray Elliott] #616756
09/09/15 10:28 pm
09/09/15 10:28 pm
Joined: Aug 2001
Posts: 4,420
Santa Barbara, California
KC in S.B. Offline

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Posts: 4,420
Santa Barbara, California
Very interesting! Thanks for posting. I expect you will get more questions than answers on an A70. I for one have never seen that timing side Thrust Washer you mentioned. Since the timeing side has the inner Thrust Washer between the crank check and the case, having a way the limit travel in the opossite direction on the outer timeing side case makes alot of sense. It certainly has to be better than the stack-up of shim washers !! Please do post more as you get it apart!


Down to 1 BSA, 2 Triumphs, 1 '56 Chevy
Oops,.. add 1 '65 XLCH
Re: My A70 [Re: Ray Elliott] #616785
09/10/15 3:31 am
09/10/15 3:31 am
Joined: Apr 2005
Posts: 2,443
Bega NSW Australia
Mark Parker Offline
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Mark Parker  Offline
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Bega NSW Australia
EdV has A70 pistons.


mark
Re: My A70 [Re: Ray Elliott] #616832
09/10/15 2:04 pm
09/10/15 2:04 pm
Joined: Jul 2012
Posts: 345
Forfar, Scotland
J
JER.Hill Offline
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J

Joined: Jul 2012
Posts: 345
Forfar, Scotland
Hi Ray

Long time no speak. Personally never been inside an A70. But as Mark P said get into touch with Ed Valiket he know the motors. Also as Nick L said having that bearing set-up has benefits over the original.

We'll all be looking forward to seeing your future posts on the rebuild.

John

Re: My A70 [Re: JER.Hill] #616872
09/10/15 8:17 pm
09/10/15 8:17 pm
Joined: Aug 2014
Posts: 313
Bowral NSW Australia
John Goodwin Offline
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John Goodwin  Offline
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Posts: 313
Bowral NSW Australia
There's a good cross section drawing of the crank and cases clearly showing the double thrust washers either side of the timing side bearing in the 1970 A70 parts supplement which is on Kims the CD man BSA manual set.
I'd post a copy of it but not sure if that would be ethically correct?
Doesn't look like it would be a major hassle to incorporate the idea in standard A65's if they didn't change the width of the bearing housing in the crankcase casting. It would need some machining and I suppose if you're going to do that you may as well go the whole hog and do the needle roller conversion while you're at it.

Here's a bit of the cross section, I'll remove it if it's considered bad form

[Linked Image]


Current: 2 x 1966 A65S, 1 x 1967 A65SA, 1 x 69/70? A65LA space Y, 1 X D14/4 & 1 x B175
Past: 4 x 1976 T160V, 1 74/5 T150V, 83 model GSX 750 ESD, Z650, Katana 1100(Bathurst Model), 79 T140V, 70's TR6, 2 x 1971 BSA 250 Gold Stars, 50's 350 Goldie, A65 Spitfire semi basket case, 1965/6? A65 LC, Tiger 21 350 & a D14/4 Bantam, 175 Bridgestone Twin with Zimmerman discs!
Re: My A70 [Re: Ray Elliott] #718501
12/12/17 8:45 am
12/12/17 8:45 am
Joined: Aug 2016
Posts: 87
UK - Bucks
Steve Wilson Offline

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Steve Wilson  Offline

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Posts: 87
UK - Bucks
Ray - or anyone else who knows...
Can you tell me how thick the thrust washer is? (No 9 in the parts list) looks like about 1/8"
Also - the shims (Number 10) In the picture they look like they are the same diameter as the thrust washer but that doesn't make sense?
I'm in the process of converting my A65 to this arrangement.
Cheers
Steve


SJW
Re: My A70 [Re: Ray Elliott] #718556
12/12/17 9:04 pm
12/12/17 9:04 pm
Joined: Sep 2004
Posts: 900
Farnham, Surrey, UK
gunner Offline
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gunner  Offline
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Posts: 900
Farnham, Surrey, UK
Nice find and from your description the engine seems to be original so that's a bonus.

Not sure why someone would try and graft a T140 sub-frame onto an OIF A65/A70 frame, I can only guess it was because of previous accident damage.

If it was my bike, I would get the frame checked for alignment, distortion and integrity by a company using a moto-liner type jig. Very often bike frames over 40 years old have suffered all kinds of incidents and although the frame may appear straight some of the critical measurements such as head rake & twist, swinging arm alignment etc. may well be out of spec.

I would also be a bit worried about the large amount of brazing around the frame and oil filler hole. This may well be sound and perfectly usable and I don't know how much strength is needed in this area, others may chime in with advise.



1968 A65 Firebird
1967 B44 Shooting Star
1972 Norton Commando
Re: My A70 [Re: Steve Wilson] #718559
12/12/17 9:36 pm
12/12/17 9:36 pm
Joined: May 2013
Posts: 5,128
Rotherham - S. Yorkshire
Allan Gill Offline

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Allan Gill  Offline

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Posts: 5,128
Rotherham - S. Yorkshire
Originally Posted by Steve Wilson
Ray - or anyone else who knows...
Can you tell me how thick the thrust washer is? (No 9 in the parts list) looks like about 1/8"
Also - the shims (Number 10) In the picture they look like they are the same diameter as the thrust washer but that doesn't make sense?
I'm in the process of converting my A65 to this arrangement.
Cheers
Steve


Why convert an A65 to this when you can fit a ball end DS, I’ve already got more miles out of my RHP Ball bearing DS than I had out of a RHP roller, also the crank end float is locked. The bike is used for touring and “scratching” and sees some punishment, so a good candidate in my opinion.


beerchug
Re: My A70 [Re: NickL] #718608
12/13/17 8:34 am
12/13/17 8:34 am
Joined: Dec 2017
Posts: 211
England
F
ferretjuggler Offline
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F

Joined: Dec 2017
Posts: 211
England
+1 for the thrust washer conversion on my A65.
I'm not keen on the end feed conversion or that needle roller main bearing.

But I could possibly be persuaded to go for the DS ball race instead.
I'm not sure about it's durability on a lightning spec engine.
The roller appeared shortly after BSA started to tune up these engines.
Were the ball races failing early, or was it just a precaution ?

Re: My A70 [Re: Steve Wilson] #718641
12/13/17 3:32 pm
12/13/17 3:32 pm
Joined: Jun 2013
Posts: 97
Texas, USA
R
Ray Elliott Offline OP
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Ray Elliott  Offline OP
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R

Joined: Jun 2013
Posts: 97
Texas, USA

Steve - I know I wrote this down somewhere because I was so paranoid about losing the one I have. The engine is on my workbench. I only need to pull off the pinion. I'll measure the shim & thrust washer sizes. IIRC I found an appropriate shim @ McMaster but didn't need to buy any.

Originally Posted by Steve Wilson
Ray - or anyone else who knows...




Ray Elliott
---
A65, A70, A75, T120, T140, T150, T160
Re: My A70 [Re: JER.Hill] #718642
12/13/17 3:45 pm
12/13/17 3:45 pm
Joined: Jun 2013
Posts: 97
Texas, USA
R
Ray Elliott Offline OP
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Ray Elliott  Offline OP
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R

Joined: Jun 2013
Posts: 97
Texas, USA
John - now that that work project from Hell is done I look forward to having a life again & being able to complete it (as well as any other projects).

Ray

Originally Posted by JER.Hill
Hi Ray

Long time no speak. Personally never been inside an A70. But as Mark P said get into touch with Ed Valiket he know the motors. Also as Nick L said having that bearing set-up has benefits over the original.

We'll all be looking forward to seeing your future posts on the rebuild.

John


Ray Elliott
---
A65, A70, A75, T120, T140, T150, T160
Re: My A70 [Re: Ray Elliott] #718685
12/13/17 11:15 pm
12/13/17 11:15 pm
Joined: Jun 2013
Posts: 97
Texas, USA
R
Ray Elliott Offline OP
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Ray Elliott  Offline OP
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R

Joined: Jun 2013
Posts: 97
Texas, USA
I ran into an issue. Can't find my pinion puller. It's necessary on the A70 as the pinion is flat against the thrust washer. But I have some measurements that should solve the problem. I measured in mm for some odd reason.

Thrust washer recess is 54.5 mm wide & 3.37 mm deep. The washer is a reasonably tight fit, but I was able to slip in a piece of wire to get the depth.

The bushing is about 2.2 mm shorter than the A65 bush. I bought a 0.010" bush for use but ended up milling a bronze bush to the correct width bec I only wanted to make the crank round instead of taking to -0.010".

I'll make a serious search for my pinion puller so I actually can measure the washer.

The pinion is wider. Some seller on eBay has 10+ so they'll be available for a while.

All things considered, for an A65 I would do a bearing conversion. The right outer case has to be setup on a mill, find center & mill out the washer recess. It is no more work to fit a bearing. The crank has to be turned in either case. It is likely less work to turn to fit a bearing race. That only leaves drilling the end feed hole, fitting a quill, blocking the bush feed hole & fitting which ever type feed you want, internal or external.


Ray Elliott
---
A65, A70, A75, T120, T140, T150, T160
Re: My A70 [Re: gunner] #718686
12/13/17 11:21 pm
12/13/17 11:21 pm
Joined: Jun 2013
Posts: 97
Texas, USA
R
Ray Elliott Offline OP
BritBike Forum member
Ray Elliott  Offline OP
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R

Joined: Jun 2013
Posts: 97
Texas, USA
The seller knew nothing of the history. He'd bought it off CL. The fit is excellent & from my measurements is straight. I have thought about sending it & a spare frame to Framecrafters to make it original. But that's too much money.

Originally Posted by gunner
Not sure why someone would try and graft a T140 sub-frame onto an OIF A65/A70 frame, I can only guess it was because of previous accident damage.



Ray Elliott
---
A65, A70, A75, T120, T140, T150, T160
Re: My A70 [Re: NickL] #718687
12/13/17 11:24 pm
12/13/17 11:24 pm
Joined: Jun 2013
Posts: 97
Texas, USA
R
Ray Elliott Offline OP
BritBike Forum member
Ray Elliott  Offline OP
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R

Joined: Jun 2013
Posts: 97
Texas, USA
I wish I'd read this earlier. This would work exactly right.

Originally Posted by NickL
The shims are the same od as the crank.

I'm also going to have to do this mod to a damaged engine i have in at the moment. (Drive side bearing pushed out through cases.)
I'm going to make the thrust washer 2.4mm thick and have 2.5 machined into the case and 2.4 off the crank, i may have to shim it another thou or 2, we'll see.
The new ts bush will be formed/machined as the opposite thrust.

The od of the thrust looks like about 52mm. You can't go much bigger due to the pump stud. It doesn't need much anyway.
It will be cheaper and easier than end feeding it.

I think Danny at Burtons has the original ts bushes in stock, (well he did 35 years ago anyway.......)



Ray Elliott
---
A65, A70, A75, T120, T140, T150, T160
Re: My A70 [Re: Ray Elliott] #718690
12/13/17 11:33 pm
12/13/17 11:33 pm
Joined: May 2013
Posts: 5,128
Rotherham - S. Yorkshire
Allan Gill Offline

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Allan Gill  Offline

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Posts: 5,128
Rotherham - S. Yorkshire
I can only go by my own experiences as you do Nick, I found a new bearing was a close fit in the outer race when new and was a firm fit on the crank, any slight tilt in the rollers when fitting the complete lot meant that the cases wouldn’t go together. The engine also started to show more vibes after a few thousand miles than when the bearing was new. The ball race was employed (after taking advice from a well respected friend, who has been to many internationals on his A65 and not known for dawdling has had good service out of his DS ball race. I eventually took his advice and been happy with it. To boot the CR of my bike is around 10:1

Not denying that the specs of the roller outweigh the ball, but they were also never designed to assist with end float control. Granted the A70 style bush conversion takes the issue of end float away from the DS side and placed onto the timing side, leaving the issue of the bearing no longer taking side thrust from end float.


Another thing to note is most owners bikes will never see enough miles to wear out any of the original style components.


beerchug
Re: My A70 [Re: Allan Gill] #718723
12/14/17 7:03 am
12/14/17 7:03 am
Joined: May 2004
Posts: 3,892
Sydney Australia
B
BSA_WM20 Offline
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BSA_WM20  Offline
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B

Joined: May 2004
Posts: 3,892
Sydney Australia
Originally Posted by Allan Gill
I can only go by my own experiences as you do Nick, I found a new bearing was a close fit in the outer race when new and was a firm fit on the crank, any slight tilt in the rollers when fitting the complete lot meant that the cases wouldn’t go together. The engine also started to show more vibes after a few thousand miles than when the bearing was new. The ball race was employed (after taking advice from a well respected friend, who has been to many internationals on his A65 and not known for dawdling has had good service out of his DS ball race. I eventually took his advice and been happy with it. To boot the CR of my bike is around 10:1

Not denying that the specs of the roller outweigh the ball, but they were also never designed to assist with end float control. Granted the A70 style bush conversion takes the issue of end float away from the DS side and placed onto the timing side, leaving the issue of the bearing no longer taking side thrust from end float.


Another thing to note is most owners bikes will never see enough miles to wear out any of the original style components.


Too true.
They were just adequate when the bikes war ridden to wok every day then taken out and thrashed on the weekend oft two up.
Now days when they might get a run 2 hours a month, rusting away is a bigger problem hence all the psts about sticking clutches, Carb stiction & wet sumping, three things I never knew existed till I turned 40


Bike Beesa
Trevor
Re: My A70 [Re: Ray Elliott] #718732
12/14/17 10:07 am
12/14/17 10:07 am
Joined: Aug 2016
Posts: 87
UK - Bucks
Steve Wilson Offline

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Steve Wilson  Offline

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Joined: Aug 2016
Posts: 87
UK - Bucks
Thanks for that - I don't need to exactly replicate the A70 but would like to be close as someone would have made some effort to get it right back in the day - No sense in ignoring their efforts.


SJW
Re: My A70 [Re: Ray Elliott] #718733
12/14/17 10:08 am
12/14/17 10:08 am
Joined: Aug 2016
Posts: 87
UK - Bucks
Steve Wilson Offline

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Steve Wilson  Offline

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Joined: Aug 2016
Posts: 87
UK - Bucks
Thanks. That's useful


SJW
Re: My A70 [Re: Allan Gill] #718735
12/14/17 10:21 am
12/14/17 10:21 am
Joined: Aug 2016
Posts: 87
UK - Bucks
Steve Wilson Offline

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Steve Wilson  Offline

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Joined: Aug 2016
Posts: 87
UK - Bucks
Alan - I see your logic but What I am trying to fix Is the oil pressure issue - fixing the end float at the timing side doesn't do that. I'm happy with the Roller bearing. If I use the A70 method it reduces clearance at the edges of the timing side bush and so prevents oil spilling out the sides - Which is claimed to be the reason for oil starvation on the big ends when the bush wears. The Devimead combined roller conversion appears to me to be a lot more work in comparison. (And a lot more cost)
Cheers
Steve


SJW
Re: My A70 [Re: Ray Elliott] #718736
12/14/17 10:23 am
12/14/17 10:23 am
Joined: Aug 2016
Posts: 87
UK - Bucks
Steve Wilson Offline

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Steve Wilson  Offline

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Posts: 87
UK - Bucks
Ray - Interested in that crank pinion - not sure what would be different - do you have a link to that eBay vendor?
Cheers
Steve


SJW
Re: My A70 [Re: NickL] #718757
12/14/17 4:11 pm
12/14/17 4:11 pm
Joined: Jun 2013
Posts: 97
Texas, USA
R
Ray Elliott Offline OP
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Ray Elliott  Offline OP
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R

Joined: Jun 2013
Posts: 97
Texas, USA
Steve - I agree w NickL. The A70 gear is wider so that it has a flat surface against the thrust washer. It makes removing the gear without a puller that slides into the gear slots impossible. I took a piece of 1/4" x 2" x 1" steel & milled a slot for the gear. Then I use a 2 jaw puller against that gizmo (that I cannot find). If you're making a thrust washer it'd be easy to make it appropriate for the A65 gear.

Originally Posted by NickL
https://www.eBay.com.au/itm/71-2689-NOS-Crankshaft-Timing-Pinion-Gear-BSA-750-Twin-A70-S192/312017437241?hash=item48a5b04239:g:XMAAAOSwpdpVZmrl

You don't have to use this pinion, it depends on how you do the thrust washer and turn the crank.



Ray Elliott
---
A65, A70, A75, T120, T140, T150, T160
Re: My A70 [Re: Ray Elliott] #718814
12/15/17 1:11 am
12/15/17 1:11 am
Joined: Jun 2013
Posts: 97
Texas, USA
R
Ray Elliott Offline OP
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Ray Elliott  Offline OP
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R

Joined: Jun 2013
Posts: 97
Texas, USA
I have pictures of the bush side before & after disassembly. PM me & I'll gladly share them.


Ray Elliott
---
A65, A70, A75, T120, T140, T150, T160
Re: My A70 [Re: Steve Wilson] #718833
12/15/17 1:37 pm
12/15/17 1:37 pm
Joined: May 2013
Posts: 5,128
Rotherham - S. Yorkshire
Allan Gill Offline

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Allan Gill  Offline

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Posts: 5,128
Rotherham - S. Yorkshire
Originally Posted by Steve Wilson
Alan - I see your logic but What I am trying to fix Is the oil pressure issue - fixing the end float at the timing side doesn't do that. I'm happy with the Roller bearing. If I use the A70 method it reduces clearance at the edges of the timing side bush and so prevents oil spilling out the sides - Which is claimed to be the reason for oil starvation on the big ends when the bush wears. The Devimead combined roller conversion appears to me to be a lot more work in comparison. (And a lot more cost)
Cheers
Steve



Even with the standard bush it should be a long time before you reach any surveer wear on the bush for it to cause pressure problems, a friends bike has covered over 20k with no problems, and Push Rod Tom's Hornet uses (or did use) the bush arrangement on his LSR bike, my 650 race motor will also get trialled with the bush arrangement too. However I completely agree that if your going to use a roller then the end float should be controlled at the timing side, which will limit the side thrust on the DS bearing lip.


beerchug
Re: My A70 [Re: Ray Elliott] #719058
12/17/17 12:02 am
12/17/17 12:02 am
Joined: Jun 2013
Posts: 97
Texas, USA
R
Ray Elliott Offline OP
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Ray Elliott  Offline OP
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R

Joined: Jun 2013
Posts: 97
Texas, USA
I found my puller, so here's some dims on the machined thrust washer recess, thrust washer & pinion.

Recess
----------
OD = 2.144" or 54.55mm
Depth = 0.124" or 3.11mm

Thrust Washer
-------------------
OD = 2.123" or 53.97mm
ID = 0.75" or 19.05mm
Thickness = 0.096" or 2.45mm

Thrust Washer Shims
-----------------------------
I didn't measure, but they're slightly larger on ID than the washer and fit only over the end of the crank, not crank & crankcase. So they're much smaller than drive side shims.

Pinion
---------------
A65 - Side to side at highest point = 0.678" or 17.23mm
A70 - Side to side at highest point = 0.684" or 17.37mm

The A70 pinion as flat on the thrust washer side unlike the A65.



Ray Elliott
---
A65, A70, A75, T120, T140, T150, T160
Re: My A70 [Re: Ray Elliott] #719090
12/17/17 12:58 pm
12/17/17 12:58 pm
Joined: May 2013
Posts: 5,128
Rotherham - S. Yorkshire
Allan Gill Offline

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Allan Gill  Offline

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Rotherham - S. Yorkshire
Great information Ray! What are the chances that you have any photos to accompany this? All I have seen is the data sheet/diagram showing what parts are different and a set of crank cases.


beerchug
Re: My A70 [Re: Ray Elliott] #719156
12/17/17 9:31 pm
12/17/17 9:31 pm
Joined: Jun 2013
Posts: 97
Texas, USA
R
Ray Elliott Offline OP
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Ray Elliott  Offline OP
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R

Joined: Jun 2013
Posts: 97
Texas, USA
I have assembled pictures on Google of the crankcase recess, thrust washer, shims, crank, bushing, pinion, some before & after disassembly.

Anyone wanting me to share them please PM with an email address & I'll share them. All in all it's rather simple. Another of those "why didn't they do this earlier?" issues.

Before I assemble again I'm going to turn a spacer the width of the pinion. Not having to install, remove the pinion a few times will making shimming a quick, simple job.


Ray Elliott
---
A65, A70, A75, T120, T140, T150, T160
Re: My A70 [Re: Ray Elliott] #719158
12/17/17 9:38 pm
12/17/17 9:38 pm
Joined: Jun 2013
Posts: 97
Texas, USA
R
Ray Elliott Offline OP
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Texas, USA
Or just click this link. Login with any Google account & request a share. I'll approve right away.

https://drive.google.com/drive/folders/1bOUpStLgNLkD1AFkDuF89NuM6zjBR68l?usp=sharing


Ray Elliott
---
A65, A70, A75, T120, T140, T150, T160
Re: My A70 [Re: Ray Elliott] #719166
12/17/17 10:28 pm
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Allan Gill Offline

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Sent a request Ray.


beerchug
Re: My A70 [Re: Steve Wilson] #719225
12/18/17 1:20 pm
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Steve Wilson Offline

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OK - Think I found it and ordered one. Should be a late christmas present :-)


SJW
Re: My A70 [Re: Steve Wilson] #719232
12/18/17 1:45 pm
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Ray Elliott Offline OP
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Pinion, thrust washer or both? I'd like a spare thrust washer should you find a stock!

Originally Posted by Steve Wilson
OK - Think I found it and ordered one. Should be a late christmas present :-)



Ray Elliott
---
A65, A70, A75, T120, T140, T150, T160
Re: My A70 [Re: Ray Elliott] #719310
12/18/17 11:22 pm
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Steve Wilson Offline

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Just the Pinion. I'm having a thrust washer made - could get a price for another but I think it was about 50 quid to make harden and grind.


SJW
Re: My A70 [Re: Ray Elliott] #719313
12/18/17 11:31 pm
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Allan Gill Offline

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Thanks for the viewing of the photos, the shims look interesting, as though they are bigger than the OD of the shaft and also smaller than the ID of the bush, so I’m assuming these self centre? Or is it an optical illusion?


beerchug
Re: My A70 [Re: Allan Gill] #719325
12/19/17 1:21 am
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Ray Elliott Offline OP
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Allan, you're right, it's not an optical illusion. The shim ID is about 20.5mm, larger than the washer ID. The OD 36.5mm so smaller than the the diameter of the crankshaft bush journal. I assume that the shims turn with the crank as the inside of the washer shines brightly in the shape of the shim. The inner of the washer has a ground finish where the outside has machining marks. If accidentally reversed the shims would likely disappear quickly.

Originally Posted by Allan Gill
Thanks for the viewing of the photos, the shims look interesting, as though they are bigger than the OD of the shaft and also smaller than the ID of the bush, so I’m assuming these self centre? Or is it an optical illusion?


Ray Elliott
---
A65, A70, A75, T120, T140, T150, T160
Re: My A70 [Re: Ray Elliott] #723725
01/30/18 9:44 am
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That looks like about the same size as Classic Mini balljoint shims

Last edited by Steve Wilson; 01/30/18 9:45 am. Reason: Spelling mistake

SJW
Re: My A70 [Re: ferretjuggler] #723812
01/31/18 3:43 am
01/31/18 3:43 am
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Mark Z Offline
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Originally Posted by ferretjuggler
The roller appeared shortly after BSA started to tune up these engines.
Were the ball races failing early, or was it just a precaution ?


Just one man's half-educated opinion: I think much of the engine development at that time was largely driven by the competition market. In the States, the predominance of competition for A65s centered around flattrack racing, where you would take an A65, stroke it to 750cc, install a racing cam and hardened or aftermarket crank, port and polish the head, install high-comp pistons and 32mm carbs, etc. etc. and then take it out on the track and beat the bejesus out of it.

Like Alan, I'm of the opinion that the DS ball bearing main is adequate for "normal road use".






Mark Z

'65(lower)/'66(upper, wheels, front end, controls)/'67(seat, exhaust, fuel tank, headlamp)/'70(frame) A65 Bitsa.
Re: My A70 [Re: Ray Elliott] #725544
02/14/18 10:44 am
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Ray. Do you have any idea what the thrust washer is made of? I'm wondering if it is Hardened or if a plain steel would do the job. If it didn't need hardening and subsequent grinding flat it would be a lot cheaper to make
Cheers
Steve


SJW
Re: My A70 [Re: Steve Wilson] #725545
02/14/18 10:45 am
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Unfortunately I've checked and Mini Balljoint shims are just too big - about 38mm OD


SJW
Re: My A70 [Re: Ray Elliott] #725546
02/14/18 10:47 am
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Crank and Crankcases are back with the machinist for the A70 conversion mods. Likely to be a couple of weeks before he can get onto it but looking forward to the results.


SJW
Re: My A70 [Re: Ray Elliott] #725554
02/14/18 1:28 pm
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[Linked Image]
Trial post - The BSA before open heart surgery!

Last edited by Steve Wilson; 02/14/18 1:30 pm.

SJW
Re: My A70 [Re: Ray Elliott] #725646
02/15/18 12:48 am
02/15/18 12:48 am
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Looks nice although that front tyre looks a little wide?

The thrust washer can be just steel, i used a large stainless washer which was bored out to suit, it was 3mm thick.
I ran it over an oil stone for a while and it's good.
As for shims, buy some stock and make them, or buy a shim kit from an engineers suppliers they are not mystical items.


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Re: My A70 [Re: NickL] #725696
02/15/18 3:02 pm
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Well the front tyre is stock size I think - probably just the photo perspective. If I can get away with a non hardened washer that's good - will be cheaper (Or I can make it myself) shims not sure about making them neatly Just bought some online at huge expense! (£6 for a thin washer!!)
Cheers
Steve


SJW
Re: My A70 [Re: Ray Elliott] #725712
02/15/18 5:20 pm
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You can probably find a needle thrust race the right size. Already hardened and ground.

Re: My A70 [Re: DMadigan] #725742
02/15/18 10:15 pm
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NickL Offline
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Originally Posted by DMadigan
You can probably find a needle thrust race the right size. Already hardened and ground.


Not do-able in this case, They all came with very large ID's. Plus it's only the thrust washer that's needed, the radial race would be too thick with it's associated thrust washers.



To make a neat circular shim up to about 5 thou i just use a couple of washers to clamp the stock and cut the ID with a small Stanley knife.
The OD can be trimmed up with either tin snips or scissors. Time and patience is all that's needed. They are not visible items so some leeway is allowed.


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Re: My A70 [Re: Ray Elliott] #725811
02/16/18 3:47 pm
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Torrington has just thrust washers. What dimensions are needed? From above, I.D. > 20.5mm, O.D. < 36.5mm. The TR(A/B/C/D)-1423 are 22.22mm I.D., 36.5mm O.D., A: 0.031", B:0.062", C:0.093", D:0.125" thick.

Re: My A70 [Re: Ray Elliott] #725868
02/17/18 12:57 am
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The shimming would be between say 5-20 thou.



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Re: My A70 [Re: Ray Elliott] #725884
02/17/18 5:16 am
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There is also valve seat shims, come in 0.005" increments from 0.010". I am not familiar with the setup so advice might be wildly off the mark.

Re: My A70 [Re: Ray Elliott] #725887
02/17/18 6:14 am
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The shims go between the thrust washer and the crank to set the end float approx ID 20mm OD 35mm

See the drawing on the first page.

This mob have something suitable by the look of it.
http://www.depcom.sg/index.php?route=product/category&path=59_1191_130_131_886_897

Last edited by NickL; 02/17/18 6:18 am.

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Re: My A70 [Re: Ray Elliott] #725924
02/17/18 6:49 pm
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DMadigan Offline
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The whole arrangement looks a bit out of wack. I would not put the shims between the thrust washer and crank because the thrust washer should take the thrust, not the shim. The A65 arrangement has the shims clamped between the crank and inner roller race. I would put the shim between the pinion gear and thrust washer or thrust washer and crank as appropriate.
Then, I would make two half bushes with flange thrust faces inserted from each side with an appropriate gap in between to feed the oil into the bushes and crank. The current arrangement has the shim wearing against the edge of the timing bush and a plain steel shim will wear quicker. A thin shim is more prone to tearing than a thrust washer.

Re: My A70 [Re: Ray Elliott] #725938
02/17/18 10:41 pm
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OK There seems to be some misunderstanding of what's going on here.
Talking specifically about the A70 arrangement. The shim(s) are trapped between the thrust washer and crank and do not touch the timing side bush.
Crank, shims and thrust washer all revolve together. The shims just adjust the gap/float available across the timing side bush
Did that make sense?
The shims NickL is showing are very similar to the ones I have purchased. In my case I am aiming to make the crank 0.25mm shorter than the Bush and use a 0.3mm shim to give 0.05mm float
I've drawn the stuff up in 3D cad When I have reassembled the engine and proved it works I can publish the 'recipe' for others to follow as they see fit.
Cheers
Steve


SJW
Re: My A70 [Re: Ray Elliott] #725940
02/17/18 10:50 pm
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Yes, except it appears that there is no thrust face on the outside other than the end of the steel backed bronze bush, correct?

Re: My A70 [Re: Ray Elliott] #725941
02/17/18 10:51 pm
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I think you are mis-construing it Dave, The Timing side bush is narrower and the thrust is effected by the washer running on the machined recess in the case
it's about 54mm dia. the shims only set the distance that thrust washer sits off the end of the crank, they are effectively a spacer to set the distance the thrust
washer sits on it's shoulder they do not act as a thrust. This set-up also uses drive side shimming as per the A65 as well, you set that first then the timing side.

The set-up i have done on the broken cases differs from this in as much as i have had a TS bush made as a single item which forms the inner thrust as well,
rather than using the inner thrust ring that sits in the cases, as the mounting pips for that ring were trashed. As the bush is a solid leaded bronze item, my outer
thrust washer recess is smaller and uses the face of the bush as well as the recess, it's 50mm rather than the a70's 54mm.


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Re: My A70 [Re: Ray Elliott] #725945
02/17/18 11:05 pm
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Interesting thread.
I'm current in the process of having an A10 crank modified to fit into my A70 cases, (unless someone out there has got a spare A70 crank). I want to retain the timing side bush as I feel that the combination of having an outboard thrust washer helping to maintain oil pressure coupled with a cartridge oil filter, I should get decent longevity out of the engine. Also it's one of the defining differences to the A65.

I'm using the inner race of a needle roller bearing (IRB2014 Imperial Inner Race 1-1/4x1-1/2x22.475) as a sleeve to bring the A10 timing side journal up to the 1.5" dia of the A70 bush. Due to the A10 journal being longer than the A70, my thrust washer will fit over the end of the the journal and effectively clamp the new sleeve bearing onto the crankshaft by the worm drive pinion nut. I don't envisage using any shims if I can get the machining of the bang on, or I'll make a bespoke inner thrust bearing to accommodate the difference.

The question is what is the factory recommend end float for the A70 configuration? I would have thought it may be covered in a service bulletin, but I have yet to find it mentioned anywhere.

With a standard late A65, the 1.5 to 3 thou float would increase as the engine gets up to temp and the crankcases expand. With an A70 set up, I would envisage that the end float would actually decrease and the material around the timing side bush expands, therefore 1.5 thou might not be enough.



1957 BSA A10 Spitfire
1971 BSA A65 Firebird
1971 BSA A70 Lightning
1975 Norton Commando
1961 Norton 99
Re: My A70 [Re: Ray Elliott] #725954
02/18/18 12:53 am
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3-4 thou on the timing side 1.5-3 drive side. (if you are using a roller drive side.


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Re: My A70 [Re: Ray Elliott] #725974
02/18/18 5:02 am
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I got that the timing bush is shorter and recessed into the case. So the outer thrust washer is running on the aluminum case (and maybe the end of the timing bush)? That was what I objected to. If two flanged bushes were used for the crank (with the outer flange in the case recess), all the shimming would be on the outer thrust washer and it would run against a proper bearing (meaning replaceable if needed).
I am not clear on why the drive side shimming is needed. That controls the crank movement to the left and the thrust flange of the timing bush controls the right.

Re: My A70 [Re: NickL] #726007
02/18/18 10:11 am
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Originally Posted by NickL
3-4 thou on the timing side 1.5-3 drive side. (if you are using a roller drive side.


I'm with you on the 3 - 4 thou on the timing side, but what's the point of shimming the drive side also to 1.5 - 3 thou? The sectional view in the parts catalogue doesn't show any shims on the drive side.



1957 BSA A10 Spitfire
1971 BSA A65 Firebird
1971 BSA A70 Lightning
1975 Norton Commando
1961 Norton 99
Re: My A70 [Re: Ray Elliott] #726060
02/18/18 7:33 pm
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DMadigan
Yes you are correct and that's what BSA did. In my case I am having a solid bronze bush made up so the thrust washer will bear against that - Its quite thick so I'm OK with that. I know it will touch the Aluminium casing as well but I don't think that will cause a problem. It's certainly better than using the main roller bearing as the end stop in that direction which is what happens normally :-)


SJW
Re: My A70 [Re: DMadigan] #726077
02/18/18 10:03 pm
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Originally Posted by DMadigan
I got that the timing bush is shorter and recessed into the case. So the outer thrust washer is running on the aluminum case (and maybe the end of the timing bush)? That was what I objected to. If two flanged bushes were used for the crank (with the outer flange in the case recess), all the shimming would be on the outer thrust washer and it would run against a proper bearing (meaning replaceable if needed).
I am not clear on why the drive side shimming is needed. That controls the crank movement to the left and the thrust flange of the timing bush controls the right.



It was probably just done as a matter of course. ie They had always done it.
It does stop any chance of the bearing rotating on the shaft , which isn't a bad thing.


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Re: My A70 [Re: Servodyne] #726092
02/18/18 11:39 pm
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To my mind the shimming on the drive side becomes redundant EXCEPT to align the two halves of the roller bearing SKF bearings claim they can be up to 1.5mm out (in one direction obviously!) But I'm aiming to stay the right side of 0.25mm. With my setup I can do that with just the shim bucket between the inner bearing race and the crank


SJW
Re: My A70 [Re: Ray Elliott] #726192
02/19/18 11:11 pm
02/19/18 11:11 pm
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I don't know why the factory didn't just put a heavy series needle roller in there, with a bearing plate outside the alternator to control end float. And the bonus is it also prevents shaft deflection and primary misalignment.

This bearing carrier is one piece, rather than using spacers into the alternator.

[Linked Image]

The dimples are to clear the inspection plate screw lugs on the chain case. The hole is for timing, with a drilled dimple into the alternator rotor.

[Linked Image]


mark
Re: My A70 [Re: Mark Parker] #726194
02/19/18 11:33 pm
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What a simple, yet elegant solution ! It is a wonder why BSA didn't do this. After all, it is a sort of extrapolation of what was done with their B31, 33, etc singles. Using the outer ball bearing drive side main to locate the crank.
That bearing carrier is a neat job, Mark.

Last edited by Triless; 02/19/18 11:37 pm.
Re: My A70 [Re: Mark Parker] #726291
02/20/18 11:48 pm
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Hi. Is that another bearing you have fitted to the plate behind the clutch as well?
Steve.


SJW
Re: My A70 [Re: Ray Elliott] #726295
02/21/18 12:04 am
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I did have a similar arrangement on my outfit at one time but when i ran a 36 tooth engine sprocket i had to machine the alternator carrier off.
I never got around to re-engineering it. Just used a duplex chain as they are more forgiving to the deflection in the crank.
The clutch outrigger is a must on performance a65's. Racers were doing that since the 60's in the UK.

I was told by a couple of guys out of the competition shop that it was the redesign of the timing cover and subsequent re-drilling/sealing
the cases that stopped the whole end feed thing as a production item. MONEY! Les Mason got out and did it. Devimead, he sold dozens
then SRM bought Devimead and sold hundreds. There was a guy who was casting the timing covers with an end feed in as well, years ago.
They looked more square than the originals, saw a few at race meetings.
If i was going down that path i'd make the timing cover as a separable item from the box cover, just to complete the picture and make things
more convenient.


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Re: My A70 [Re: Ray Elliott] #726296
02/21/18 12:19 am
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I've just put the modified bottom end together on this damaged engine, all worked out quite well. The thrust on the timing side works well.
The shimming on the drive side main, although not really necessary does mean you don't need so much shimming on the drive sprocket to get the chain alignment correct.

Steve, if you are going to make a gearbox outrigger, the traditional way is to use a sealed bearing and machine the inner to 20.5mm (a tight fit on the mainshaft) Then cut
the projecting bush off. Various 20mm ID bearings are around but you'll have to watch the width of them. You can make up a new plate or machine the original as Mark has done.


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Re: My A70 [Re: Ray Elliott] #726298
02/21/18 2:35 am
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I made a gearbox outrigger this way:
[Linked Image]
The nut was an extension shaft into a ball bearing in the primary cover. A three arm lifter in the shaft and triple lift plate in the cover pulled out the pressure plate. Talk about light lever force, I had to add a spring to return the lift plate because the friction in the lifter bearing was adding so much torque the lifter would not return.
The bearing in the sprocket door is less noticeable.

Re: My A70 [Re: Ray Elliott] #726303
02/21/18 6:13 am
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The other thing the bearing outside the alternator does is make it much more difficult for the crank to flex in the middle. If you get a plastic ruler and sit it on a couple of blocks with an overhang on one end, when you push it between the blocks the end of the overhang flexes up. If you secure the end of it, its harder to flex the middle.

What a wild looking mod Nick. I got the longest alloy bar lever I could find to get some mechanical advantage on the clutch. I was thinking of extending the lift lever in the case but it's not that bad, even with the heavy 4 spring unit I use.


mark
Re: My A70 [Re: Ray Elliott] #726325
02/21/18 1:21 pm
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Steve Wilson Offline

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Too many interesting ideas!! I need to put mine back together before I get carried away!


SJW
Re: My A70 [Re: Ray Elliott] #726333
02/21/18 3:35 pm
02/21/18 3:35 pm
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Posts: 4,244
argyll. scotland, uk
gavin eisler Offline
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https://www.ccm-britain.co.uk/?xhtm...m.html&category=&xsl=diagram.xsl

item 5 on the diagram, Mark Cook of PES makes a bearing / clutch back plate for B50s, fits A65s too, although the one I got was a slack fit, my motor was not typical.


71 Devimead A65 750
56 Norbsa 68 Longstroke A65
Cagiva Raptor 650
MZ TS 250
The poster formerly known as Pod
Re: My A70 [Re: Ray Elliott] #726367
02/21/18 11:50 pm
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DMadigan Offline
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This is another way that I did it:
[Linked Image]
The bell housing sits over the clutch basket and the short spud on the outside runs on rollers (same as the clutch hub). A boss was welded into the primary cover and a steel race was pressed into it. Unlike the other one this used the stock lifter.

Re: My A70 [Re: Ray Elliott] #726384
02/22/18 2:18 am
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Nice one Dave, outside the box again.


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Re: My A70 [Re: Ray Elliott] #726641
02/24/18 8:33 am
02/24/18 8:33 am
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Re: My A70 [Re: NickL] #726644
02/24/18 10:34 am
02/24/18 10:34 am
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Nick, this is impressive stuff ! Why do you tell me not to believe all you say ? Is a weird mental anomoly why you were transported to Botany Bay ?
Incidentally, will you be going to the International BSA Rally this year at HallsGap. It is near where I live !

Re: My A70 [Re: NickL] #726696
02/24/18 10:05 pm
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Nick. Thanx for that - There appears to be an extra step in the crankshaft I wouldn't expect - The A70 uses a thrust washer with a 3/4" ID - are you using something bigger?
Steve


SJW
Re: My A70 [Re: Steve Wilson] #726706
02/24/18 11:07 pm
02/24/18 11:07 pm
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NickL Offline
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Originally Posted by Steve Wilson
Nick. Thanx for that - There appears to be an extra step in the crankshaft I wouldn't expect - The A70 uses a thrust washer with a 3/4" ID - are you using something bigger?
Steve


The thrust ID is 22mm, it is a convenient size for shims, (i had some). I am using the standard timing pinion with it.
The washer sits 10 thou below the 'face' as otherwise it would foul on the oil pump body in a couple of spots.
As i said, i used a 3mm thick 50mm od stainless washer for the thrust, nothing fancy. It ended up 2.8mm thick after flatting on a stone.
The bush is 660 Leaded bronze, i don't like PB1 or hard gear for these. The inner flange is 3.6mm thick so does not use the old thrust ring.
As you can see, the locating lugs for that ring were trashed well and truly by the previous builder's mistakes.
I normally don't use one piece bushes and prefer the original steel housed type, but as i needed the two thrust areas it was the easiest way.

Stephen, i don't know if i will be at the rally as i may be moving house later in the year, i will do my best to get there though.
They only sent me to Botany because Port Arthur didn't allow sidecar racers! (they reckoned there were limits to the nutters they would take)


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Re: My A70 [Re: Ray Elliott] #726847
02/26/18 11:47 am
02/26/18 11:47 am
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Steve Wilson Offline

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Nick - My locating lugs are trashed as well and I had also aimed to do without the thrust ring - I think its better without anyway. Mine works out about 4.4mm thick. (Whats left of the locating lugs is 3.9m deep on mine) I'm going to change to your design for the step in the crank as it locates the shims properly.
Incidently I have both types of Cam gear pinions and mine are almost Identical width - the ones measured earlier in this thread were about 0.5mm different.
Steve


SJW
Re: My A70 [Re: Ray Elliott] #729038
03/18/18 4:33 pm
03/18/18 4:33 pm
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Steve Wilson Offline

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OK - Parts are machined now and crank balanced so its all back in the shed awaiting rebuild. Spent this afternoon fitting Helicoils to all the barrel stud positions.
Crankcase was line bored and Bush was specially made. They also re-cut the anti rotation flats a bit deeper as they had been trashed.
Rebate for the thrust washer is about 50mm x 3mm a bit smaller diameter than the actual A70 version.
I'm quite pleased so far - What does the panel think?


Attached Files P1060956.JPGP1060962.JPGP1060964.JPG

SJW
Re: My A70 [Re: Ray Elliott] #729206
03/19/18 8:37 pm
03/19/18 8:37 pm
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Texas, USA
R
Ray Elliott Offline OP
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Looks might fine to me. Turning that crank must have been tedious.


Ray Elliott
---
A65, A70, A75, T120, T140, T150, T160
Re: My A70 [Re: NickL] #729213
03/19/18 9:15 pm
03/19/18 9:15 pm
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Steve Wilson Offline

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Its just a small step - I left the job to the professionals - they definitely turn not grind. I guess with the right tip tool and a big lathe its no problem
Steve

Last edited by Steve Wilson; 03/19/18 9:17 pm. Reason: Answered wrong comment!

SJW
Re: My A70 [Re: NickL] #729215
03/19/18 9:18 pm
03/19/18 9:18 pm
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Steve Wilson Offline

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Originally Posted by NickL
All looks tickety boo to me. Bloody copy cat!!!!!! smile


Imitation is the sincerest form of flattery :-)


SJW
Re: My A70 [Re: Ray Elliott] #729224
03/19/18 10:18 pm
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NickL Offline
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Turning the crank journal is not that bad, just go easy 75-100rpm or so.
Easier without the flywheel on.

Tipped tools???? not required, just good/well made ones.

Last edited by NickL; 03/19/18 11:29 pm.

No-one expects the Spanish Inquisition................
Bring in the 'Comfy Chair'
Re: My A70 [Re: Ray Elliott] #729625
03/22/18 10:16 pm
03/22/18 10:16 pm
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derby england
wak Offline
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Is there a reason you lot are replacing composite VP3 bearings with lumps of brass, sorry "bronze" ,it seems crazy , would you consider making big ends out of bronze ??? I guess the answer would be no , so why do in to the main bearing?????


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Re: My A70 [Re: Ray Elliott] #729640
03/23/18 1:12 am
03/23/18 1:12 am
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NickL Offline
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First up, 660 bronze is not in any way 'brass' look at the specs.
Normally i would use the steel backed shell type whenever i can, i do prefer them. (previous post)
I needed to create this arrangement as i needed a thrust face on the timing end of the bearing. (see the previous posts)
Many people use the one piece bronze type bearings nowadays even people like SRM sell them, admitedly they are PB1
but i have found in the past that material is a bit hard and wears the crank journal over time in these motors.
If in were to use it, i would have the journal hardened or hard chrome plated. I have used it when using a needle race inner
as a sleeve, with an A10 crank or with a badly damaged A65 one. One of the things about the standard bearing is the
lining has an embed-ability which PB1 does not, 660 is a very good alternative.
As for a comparison of big ends with the timing side main, loadings are totally different, many engines used bronze
bearings on the timing side over the years.
One of the problems with the steel shell type is they are made with a standard OD, as you probably know, when the bearing
is worn it tends to flog the case and this then needs to have a few thou removed to ensure the aperture is round again.
This means the standard bearing OD is too small so re-lining or fitting a standard bearing is not an option, a complete
two piece bearing must be made up as a special, this is a much more difficult and expensive route than a one piece bronze one.

I hope this answers your question.
Any sensible alternative path for a future application in this situation would be appreciated.
The customer was not prepared to go to the expensive of an end-fed needle arrangement.


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Bring in the 'Comfy Chair'
Re: My A70 [Re: Ray Elliott] #729643
03/23/18 1:36 am
03/23/18 1:36 am
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Specs from Vandervell on the used lining material, it is also a leaded bronze not brass.

'VP2 is a lead bronze material which is continuously cast onto steel strip. Casting and quenching conditions are controlled in order to produce a microstructure with vertically orientated
bronze columns. This gives the bearing material its superior strength increasing its compressive load capacity. When plated with lead indium it has become the favoured material for
racing engines. The combination of a lead tin alumina overlay with VP2 improves wear resistance by a factor of two when compared with a lead tin copper overlay. In addition
the shaft conditioning properties are enhanced and fatigue resistance is improved.'

'VP3 is similar to VP2. It is supplied with either a lead tin copper or lead indium overlay.'

Last edited by NickL; 03/23/18 1:39 am.

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Bring in the 'Comfy Chair'
Re: My A70 [Re: Ray Elliott] #729660
03/23/18 9:13 am
03/23/18 9:13 am
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Servodyne Offline
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Hi there.

On a similar subject of bearing material, SRM have informed me that the only difference between the A70 big end shells and ones for the A65 is a higher spec of material.

Could anybody out there please confirm this as pictorially the A70 shells appear slightly wider in the sectional view in the parts catalogue and A65 shells do appear to be too narrow for the A70 rods.

Cheers



1957 BSA A10 Spitfire
1971 BSA A65 Firebird
1971 BSA A70 Lightning
1975 Norton Commando
1961 Norton 99
Re: My A70 [Re: Ray Elliott] #729753
03/23/18 10:57 pm
03/23/18 10:57 pm
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NickL Offline
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As far as i know, the A65 and A70 big end shells are identical. The A70 did use steel capped rods, but so did very late A65's.

The timing side main on the A70 is narrower due to the thrust arrangement.


No-one expects the Spanish Inquisition................
Bring in the 'Comfy Chair'
Re: My A70 [Re: NickL] #729968
03/26/18 8:50 am
03/26/18 8:50 am
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Steve Wilson Offline

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I agree with Nick - and its really a heck of a lot cheaper and less complicated in comparison with the roller bearing conversion.
For what its worth I can recommend T&L engineering in Bedford for the work if you are in the UK
Steve


SJW
Re: My A70 [Re: NickL] #730002
03/26/18 6:08 pm
03/26/18 6:08 pm
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derby england
wak Offline
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well I'm not sure how the 2 compare , VP3 is listed as"being suitable for racing applications" were 660 is listed as "being suitable for valve and pump bodies and medium load and medium speed bearings". The fact SRM use it says it all , I'm surprised they don't anodize them blue for good measure lol. Anyway I guess if the housing and crank are worn its a way out.


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BSA B50MX
TRIUMPH TR6C
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BSA Gold Star Scrambler
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BSA C15S
BSA Cyclone
Triumph T120
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Triumph 5TA Trials
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Cheney 560 TT
Re: My A70 [Re: NickL] #730497
03/31/18 10:54 pm
03/31/18 10:54 pm
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Steve Wilson Offline

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Just an idiot grade question but - the shells are narrower than the conrod big end right? May be obvious to seasoned rebuilders but I'm used to cars where the shell is the same width as the conrod !!
Steve


SJW
Re: My A70 [Re: Ray Elliott] #734889
05/11/18 1:51 pm
05/11/18 1:51 pm
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Steve Wilson Offline

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Bikes now back together and running. so the conversion works - at least short term. Time will tell. I should be able to produce a drawing and memo detailing the specifics if anyone's interested. The basic principal is simple but there's some subtleties in the fine tuning.


SJW
Re: My A70 [Re: Ray Elliott] #734929
05/11/18 10:40 pm
05/11/18 10:40 pm
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NickL Offline
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Nice one Steve, how's the oil pressure?
The engine i converted is still sitting on my bench waiting for me to fit back into the frame.
The owner just dropped the bike over as he now wants me to rebuild the forks etc.
He has been too busy at work to get on with the bike.
It'll be a couple of weeks before i fire that one up. It's a nice cafe' racer 1970 (converted from a Royal Star Police bike)
Pukka rear sets, big alley tank, single seat etc


No-one expects the Spanish Inquisition................
Bring in the 'Comfy Chair'
Re: My A70 [Re: NickL] #735044
05/12/18 8:57 pm
05/12/18 8:57 pm
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Steve Wilson Offline

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Haven't hooked up a pressure gauge - I'm busy with a charging problem at the moment. I had one about somewhere - will see if I can find it


SJW
Re: My A70 [Re: Ray Elliott] #743238
07/26/18 3:19 pm
07/26/18 3:19 pm
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Steve Wilson Offline

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Still haven't checked the oil pressure but its done about 2000 miles now and is still in one piece:-)


SJW
Re: My A70 [Re: Steve Wilson] #757216
11/26/18 8:33 pm
11/26/18 8:33 pm
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Servodyne Offline
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Hello again.
After finishing my A10 crank conversion for my A70, which turned out rather better than expected, Typically I've now found a modified A70 crank less flywheel. The timing side journal appears to have been machined down to fit the A10 bush (1.375") and the end of the timing side shaft reduced to just under 12mm presumably to fit an end feed oil seal. The trouble is, the timing side left hand thread is now no longer long enough for the lock nut and washer. As I want to return the crank to something like standard the two options I've come up with, involve either welding up the reduced shaft and restoring the left hand thread or drill and tap the end of the crank with a left hand thread to provide a locking bolt. I would then sleeve the timing side journal using a needle roller inner sleeve 1.5" x 1.25" x 1" long as I did with the A10 crank. This would enable the use of a standard bush which I prefer to the needle roller conversion.

Two questions spring to mind;

Does anyone know why the section of the timing side shaft with the left hand thread is 1/4" longer on the A70 compared with an A65 or A10?

Is it possible to modify a late A65 flywheel with the big end cutaways to fit an A70?


1957 BSA A10 Spitfire
1971 BSA A65 Firebird
1971 BSA A70 Lightning
1975 Norton Commando
1961 Norton 99
Re: My A70 [Re: Ray Elliott] #757310
11/27/18 4:19 pm
11/27/18 4:19 pm
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Rotherham - S. Yorkshire
Allan Gill Offline

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Some A65's had the same cutaways on the flywheel so I would say yes, providing it fits on the crank, it can be machined.

I'd be interested to see your photos of the A10 crank conversion, Im going to fit an A10 crank to one of the A65 motors (79mm pistons for 830cc) I'd like to see how you worked around being able to fit the alternator, Im also looking at using another Bob Newby Belt drive (which in turn pushes the alternator outboard a little)


beerchug
Re: My A70 [Re: Ray Elliott] #757350
11/27/18 11:50 pm
11/27/18 11:50 pm
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NickL Offline
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I found the most awkward part of sleeving the crank main with a needle inner was cutting the anulus.
The a10 crank also has a larger drive side journal i think, which has to be turned to 1-1/8in.
The current a10 one i'm doing is going to be an end fed needle job as there's not too much difference in work involved.

The a65 that had the funny/a70 main conversion is going very well, just did the 500 mile service on it. Very quiet engine, runs like an a10, lovely.

Last edited by NickL; 11/27/18 11:55 pm.

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Re: My A70 [Re: Ray Elliott] #757404
11/28/18 11:42 am
11/28/18 11:42 am
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England
Servodyne Offline
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The late A65 flywheel cutaways or 40mm whereas the A70 is guesstimated at around 33mm looking at various pictures I've seen of them. My A10 flywheel was slimmed down to 35mm to get me in the right ball park when I had the crank balanced at SRM. They 'only' drilled two holes in it so it couldn't have been far out.
My latest problem with fitting a late A65 flywheel to an A70 crank is that the A65 ID is around 122mm and the A70 OD is around 131mm. I don't really want to start machining only to make it unusable for both cranks. I would imagine the relief on the flywheel to allow it to slip over the big ends will require deepening as well.

Cutting the annulus groove on the bearing sleeve required a bit of lateral thinking as my local machine shops wouldn't do it. I simply attached two jubilee clamps leaving the desired gap in the correct position and rotated it slowly while attacking it with a high speed disc cutter with two discs fitted in stead of one. I then punched through the wall of the sleeve using a carbide burr.

I'll post some photos of the A10/A70 crank conversion is a new thread


1957 BSA A10 Spitfire
1971 BSA A65 Firebird
1971 BSA A70 Lightning
1975 Norton Commando
1961 Norton 99
Re: My A70 [Re: Ray Elliott] #757407
11/28/18 12:08 pm
11/28/18 12:08 pm
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NickL Offline
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We put the sleeve in a lathe and mounted an air grinder in the tool post to do the groove, once the stone was dressed it worked ok.
Also used a burr for the oil hole.
I suppose a ceramic tipped tool would be ok too, but we hadn't got one................

The very late A65 flywheels are fully scalloped more like a triumph. I hadn't thought about the ID though, that's a bit of a pain.


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Bring in the 'Comfy Chair'
Re: My A70 [Re: Ray Elliott] #757433
11/28/18 5:10 pm
11/28/18 5:10 pm
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DMadigan Offline
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A body grinder in the tool post works well also. I used it to cut a needle bearing inner sleeve to size. Handy for removing the chrome from discs, especially ones with holes in them.
EDM works very well for drilling holes in hardened steel.

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