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Re: My A70 [Re: Servodyne] #726092
02/18/18 11:39 pm
02/18/18 11:39 pm
Joined: Aug 2016
Posts: 87
UK - Bucks
Steve Wilson Offline
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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
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Re: My A70 [Re: Ray Elliott] #726192
02/19/18 11:11 pm
02/19/18 11:11 pm
Joined: Apr 2005
Posts: 2,458
Bega NSW Australia
Mark Parker Offline
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Bega NSW Australia
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
02/19/18 11:33 pm
Joined: Aug 2014
Posts: 1,851
OZ
Triless Offline
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OZ
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
02/20/18 11:48 pm
Joined: Aug 2016
Posts: 87
UK - Bucks
Steve Wilson Offline
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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] #726298
02/21/18 2:35 am
02/21/18 2:35 am
Joined: Jan 2004
Posts: 4,075
ca, us
D
DMadigan Offline
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D

Joined: Jan 2004
Posts: 4,075
ca, us
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
02/21/18 6:13 am
Joined: Apr 2005
Posts: 2,458
Bega NSW Australia
Mark Parker Offline
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Bega NSW Australia
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
02/21/18 1:21 pm
Joined: Aug 2016
Posts: 87
UK - Bucks
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
Joined: Aug 2001
Posts: 4,601
argyll. scotland, uk
gavin eisler Offline
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argyll. scotland, uk
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
02/21/18 11:50 pm
Joined: Jan 2004
Posts: 4,075
ca, us
D
DMadigan Offline
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D

Joined: Jan 2004
Posts: 4,075
ca, us
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: NickL] #726644
02/24/18 10:34 am
02/24/18 10:34 am
Joined: Aug 2014
Posts: 1,851
OZ
Triless Offline
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OZ
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
02/24/18 10:05 pm
Joined: Aug 2016
Posts: 87
UK - Bucks
Steve Wilson Offline
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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: Ray Elliott] #726847
02/26/18 11:47 am
02/26/18 11:47 am
Joined: Aug 2016
Posts: 87
UK - Bucks
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
Joined: Aug 2016
Posts: 87
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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
Joined: Jun 2013
Posts: 111
Texas, USA
R
Ray Elliott Offline OP
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Posts: 111
Texas, USA
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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Posts: 87
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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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Posts: 87
UK - Bucks
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] #729625
03/22/18 10:16 pm
03/22/18 10:16 pm
Joined: Mar 2011
Posts: 839
derby england
wak Offline
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derby england
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?????


BSA lightning
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TRIUMPH TR6C
BSA BUSHMAN
BSA Gold Star Daytona
BSA Gold Star Scrambler
BSA Rocket Gold Star
BSA C15S
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Cheney 560 TT
Re: My A70 [Re: Ray Elliott] #729660
03/23/18 9:13 am
03/23/18 9:13 am
Joined: Aug 2013
Posts: 52
England
Servodyne Offline
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England
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: NickL] #729968
03/26/18 8:50 am
03/26/18 8:50 am
Joined: Aug 2016
Posts: 87
UK - Bucks
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
Joined: Mar 2011
Posts: 839
derby england
wak Offline
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derby england
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.


BSA lightning
BSA B50MX
TRIUMPH TR6C
BSA BUSHMAN
BSA Gold Star Daytona
BSA Gold Star Scrambler
BSA Rocket Gold Star
BSA C15S
BSA Cyclone
Triumph T120
Triumph T100 Daytona
Triumph 5TA Trials
Triumph T100 Scrambles
Cheney 560 TT
Re: My A70 [Re: NickL] #730497
03/31/18 10:54 pm
03/31/18 10:54 pm
Joined: Aug 2016
Posts: 87
UK - Bucks
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
Joined: Aug 2016
Posts: 87
UK - Bucks
Steve Wilson Offline
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Steve Wilson  Offline
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UK - Bucks
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: NickL] #735044
05/12/18 8:57 pm
05/12/18 8:57 pm
Joined: Aug 2016
Posts: 87
UK - Bucks
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
Joined: Aug 2016
Posts: 87
UK - Bucks
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
Joined: Aug 2013
Posts: 52
England
Servodyne Offline
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England
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
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