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Rating: 4
That weird A65 lower shock mount shoulder nut.... #724326
02/05/18 3:46 am
02/05/18 3:46 am
Joined: Aug 2001
Posts: 4,177
Santa Barbara, California
KC in S.B. Online content OP

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Santa Barbara, California
Ran into a question today. The '60s A65 bikes use a shoulder nut on the lower shock 3/8" bolt. That shoulder nut fits into a larger hole on the inner swing arm shock lug, (why this design I have no idea....) Then, if you have a '69 A65, the chain guard has an extra support at the rear. It is attached by the lower shock mount, and fits between the nut and the inner lug. That means the shoulder needs to be longer than the earlier bikes. That would also mean it should have a different Part Number. Looking at the '67, '69, and '70 parts books, that nut has the same part number, and is simply called 3/8 nut. No mention of anything odd about it, and the illustration does not bother to show a shoulder on the nut. Does nut P/N 68-4235 have a shoulder, or is it a common Ace Hardware nut? I've got 6 of the earlier nuts, and have seen and used the longer shoulder nut on 2 '69 A65s. What am I missing here ??????
(Sure wish I could post a photo saved on this iPad .......... Lots of people use iPads...... )
------------------------------------------------------------------------------------------------------------------------------
OK, fired up the old faithful, just for this purpose.

Attached Files Nut IPC.jpgShock bolt.Nuts.JPG
Last edited by KC in S.B.; 02/05/18 4:25 am.

Down to 1 BSA, 2 Triumphs, 1 '56 Chevy
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Re: That weird A65 lower shock mount shoulder nut.... [Re: KC in S.B.] #724506
02/06/18 4:29 pm
02/06/18 4:29 pm
Joined: Feb 2014
Posts: 971
Lancaster, California
C.B.S Online content

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Lancaster, California
I've been trying to find this nut with no luck. It's almost like every replacement part is just a regular nut..

Re: That weird A65 lower shock mount shoulder nut.... [Re: C.B.S] #724515
02/06/18 5:13 pm
02/06/18 5:13 pm
Joined: Nov 2009
Posts: 249
UK
V
VicCyclone Online content
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VicCyclone  Online Content
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V
Joined: Nov 2009
Posts: 249
UK
Google BSA 68-4235 They're available in UK at a number of outlets including Draganfly and BBB. Someone is also listing stainless ones on UK *-Bay. Looks like Klempf and Baxter have them too.

Last edited by VicCyclone; 02/06/18 5:14 pm.

VicCyclone

1965 A50 Cyclone Clubman
1966 Victor GP
1967 Victor Special
1968 Victor Special
1968 A65L

2009 HD FXDC
Re: That weird A65 lower shock mount shoulder nut.... [Re: KC in S.B.] #724563
02/06/18 10:27 pm
02/06/18 10:27 pm
Joined: Oct 2006
Posts: 2,427
Elburn, Ill. USA
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Irish Swede Online content
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I have bought a lot of BSA and Triumph used hardware over the years. In it all I have found several of these nuts.

NOW I know what they are for.

Re: That weird A65 lower shock mount shoulder nut.... [Re: KC in S.B.] #724593
02/07/18 3:22 am
02/07/18 3:22 am
Joined: Aug 2001
Posts: 4,177
Santa Barbara, California
KC in S.B. Online content OP

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Santa Barbara, California
Mr. Swede.........
Would any of those happen to have a shoulder section that is +/- 3/8" long? That's the best guess for a '69 chain guard bracket under the nut head, and still leaving enough to engage the bottom shock mount inner lug.


Down to 1 BSA, 2 Triumphs, 1 '56 Chevy
Re: That weird A65 lower shock mount shoulder nut.... [Re: KC in S.B.] #724594
02/07/18 3:27 am
02/07/18 3:27 am
Joined: Aug 2001
Posts: 4,177
Santa Barbara, California
KC in S.B. Online content OP

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Santa Barbara, California
had-a-thought! If a guy found one of those All-Thread hex connector nuts in 3/8 SAE fine thread, it would be a perfect starting point to make one. Chuck up the hex in a lathe, turn down the shoulder, face it off to shoulder length (3/8" long). Reverse the part in the lathe chuck, and face off the hex until thin enough to work in the available space. Bob's yer uncle........


Down to 1 BSA, 2 Triumphs, 1 '56 Chevy
Re: That weird A65 lower shock mount shoulder nut.... [Re: KC in S.B.] #724609
02/07/18 6:32 am
02/07/18 6:32 am
Joined: Jan 2004
Posts: 3,599
ca, us
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DMadigan Online content
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KC, I have a couple of those coupling nuts. Appear to be galvanized or zinc plated so turning the section round will eventually rust. I have 1/2", 9/16" and 5/8" inoxidable hex rod. I you give me the length of the hex and diameter of the cylinder section I can pop out a couple for you.

Re: That weird A65 lower shock mount shoulder nut.... [Re: KC in S.B.] #724715
02/08/18 1:44 am
02/08/18 1:44 am
Joined: Aug 2001
Posts: 4,279
Owego, NY, USA
Mark Z Online content
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Mark Z  Online Content
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KC, DM, I have those measurements:

Bolt diameter: 3/8". Any thread density will do. Fine thread would be better, but I'm guessing those couplers don't come in fine thread.

Desired length of round part of nut: 3/8".

Outer diameter of round part of nut: The fifty-year-old nut I measured is actually tapered. I don't know if the taper is original or due to wear, but it ranges from .537" at the end to .550" right under the head.

Thickness of the head: This one is .20", but there's about 3/4" clearance between the swingarm and the rear brake plate, so the head could be a little thicker without hurting anything.


Mark Z

'65(lower)/'66(upper, wheels, front end, controls)/'67(seat, exhaust, fuel tank, headlamp)/'70(frame) A65 Bitsa.
Re: That weird A65 lower shock mount shoulder nut.... [Re: KC in S.B.] #724724
02/08/18 5:41 am
02/08/18 5:41 am
Joined: Aug 2001
Posts: 4,177
Santa Barbara, California
KC in S.B. Online content OP

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I know it was my idea to make them, but before bothering DMadigan, have you tried the suppliers mentioned above by VicCyclone? If they in fact do have the long items, that would be the way to go. I may try calling them tomorrow.
The eBay search did have a result, but I would still have to ask the seller a question regarding the length of the round part:

https://www.eBay.com/itm/BSA-A65-TOP-YOKE-PINCH-BOLT-REAR-SHOCKER-DAMPER-BOTTOM-BOLT-FIXING-NUT-68-4235/112780698093?hash=item1a4240e1ed:g:pfkAAOSwEK9ULnnw&vxp=mtr


Last edited by KC in S.B.; 02/08/18 5:55 am.

Down to 1 BSA, 2 Triumphs, 1 '56 Chevy
Re: That weird A65 lower shock mount shoulder nut.... [Re: KC in S.B.] #724745
02/08/18 1:40 pm
02/08/18 1:40 pm
Joined: May 2013
Posts: 4,731
Rotherham - S. Yorkshire
Allan Gill Online happy
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KC, if you have the standard size, what are you hoping to gain by using ones with a longer narrowed portion? I doubt that the nut actually bottoms in the frame with or without the chain guard confused


beerchug
Re: That weird A65 lower shock mount shoulder nut.... [Re: Allan Gill] #724833
02/09/18 2:14 am
02/09/18 2:14 am
Joined: Aug 2001
Posts: 4,279
Owego, NY, USA
Mark Z Online content
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Mark Z  Online Content
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Originally Posted by Allan Gill
KC, if you have the standard size, what are you hoping to gain by using ones with a longer narrowed portion? I doubt that the nut actually bottoms in the frame with or without the chain guard confused


I should chime in here, since I'm the one who got KC started on this. I just bought a used chain guard for my '70-frame bitsa, and this guard has the bracket that mounts to the lower shock mount, which as far as we can tell, started in 1969. My existing shock mount hardware is older than that, probably '66 or '67.

The round part of my shouldered shock mount nut is just a hair over 1/4" long. The chain guard bracket is 1/8" thick. So with the bracket under the head of the nut, it will protrude into the swingarm lug only 1/8". The end of the bolt is now about flush with the face of the nut, so 1/8" of thread is also lost with the bracket in place. (Although that part is easily remedied with a longer bolt.)

I think the existing nut will probably suffice as is, but it does give up a bit of strength, and KC thought he had seen longer shock mount nuts, so here we are. I haven't yet tried to source one of these longer bolts because I have other issues (dents, a split at the front) to deal with on this chain guard.


Mark Z

'65(lower)/'66(upper, wheels, front end, controls)/'67(seat, exhaust, fuel tank, headlamp)/'70(frame) A65 Bitsa.
Re: That weird A65 lower shock mount shoulder nut.... [Re: KC in S.B.] #724841
02/09/18 3:12 am
02/09/18 3:12 am
Joined: Aug 2001
Posts: 4,177
Santa Barbara, California
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Well, FWIW, today at the lunch table, I called JRC, Klemphs, Britiish only, Baxter's, and Raber's. If they had them at all, they were the shorter version. That 1 on eBay LOOKS like it's the short version, but not positive on that. I'd suggest using what you have, and putting this item on your "things to be on the look out for" List.
That is how some things finally turn up, often when I'm looking for something else. Nice offer from DMadigan, but My feeling is I wouldn't ask him to bother unless it was a critical part. You can count on I'll be on the look out too!


Down to 1 BSA, 2 Triumphs, 1 '56 Chevy
Re: That weird A65 lower shock mount shoulder nut.... [Re: KC in S.B.] #724857
02/09/18 7:59 am
02/09/18 7:59 am
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Posts: 3,599
ca, us
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DMadigan Online content
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The bolt listed on eBay has a taper under the head. I thought it would be square. The ones that KC shows appear to be square under the head. Are there two different nuts, one with and one without the taper?
I think you need a 9/16" hex, 1/4" long with a .545" diameter shank 3/8" long. Right?
The coupling nuts that I have are fine thread but it would be about as easy to make it from stainless hex rod.

Re: That weird A65 lower shock mount shoulder nut.... [Re: DMadigan] #724957
02/10/18 12:09 am
02/10/18 12:09 am
Joined: Aug 2001
Posts: 4,279
Owego, NY, USA
Mark Z Online content
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Mark Z  Online Content
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Owego, NY, USA
Originally Posted by DMadigan
The bolt listed on eBay has a taper under the head. I thought it would be square. The ones that KC shows appear to be square under the head. Are there two different nuts, one with and one without the taper?
I think you need a 9/16" hex, 1/4" long with a .545" diameter shank 3/8" long. Right?
The coupling nuts that I have are fine thread but it would be about as easy to make it from stainless hex rod.


Right. "1/4 long" being the thickness of the head, right? The wrench size on the stock bolt is larger, but 9/16" should suffice.

The nut I measured is tapered under the head, but not noticeably so; that is, I didn't notice until I measured it. As I wrote above, the taper is .537" to .550" over 1/4" of length (not very much). But .545" all the way should do the trick.

Fine thread is preferred. SS would be even better (no rust). Of course I'll gladly pay for one.

Thanks,


Mark Z

'65(lower)/'66(upper, wheels, front end, controls)/'67(seat, exhaust, fuel tank, headlamp)/'70(frame) A65 Bitsa.
Re: That weird A65 lower shock mount shoulder nut.... [Re: KC in S.B.] #724973
02/10/18 5:22 am
02/10/18 5:22 am
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Posts: 3,599
ca, us
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DMadigan Online content
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I have 5/8" hex SS also. The taper that I mentioned is from the hex to the round shank, not a taper of the round section. The one on eBay appears to have a taper, maybe 30 degrees, between the hex and round shank as if it sits in a countersink recess.
1/4" head length. Of course 3/8-24 thread.

Re: That weird A65 lower shock mount shoulder nut.... [Re: KC in S.B.] #724987
02/10/18 10:03 am
02/10/18 10:03 am
Joined: Feb 2010
Posts: 410
Au
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markoz Online content
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I think this thread is proof that this forum has covered every conceivable aspect of a65s.

Re: That weird A65 lower shock mount shoulder nut.... [Re: markoz] #725038
02/10/18 5:21 pm
02/10/18 5:21 pm
Joined: Aug 2001
Posts: 4,279
Owego, NY, USA
Mark Z Online content
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Mark Z  Online Content
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Originally Posted by markoz
I think this thread is proof that this forum has covered every conceivable aspect of a65s.


Hmm, can you spell "OCD"? Wait, there's more:

DM, as far as I can tell, there is no countersink area on the swingarm lug. Can't really see or measure back there without removing the wheel, but I can kind of feel with the nut. One thing I did notice is that there's a fair amount of slop between the nut and the hole. So it would not hurt to err on the plus side of the diameter.

ANOTHER thing I noticed: The half-inch-or-so hole does not go all the way through the swingarm lug. The inner side of the lug (toward the shock) has a 3/8" hole! So the bolt is actually supported in the inner swingarm lug, and not just by the nut. It's making me wonder now if this re-engineering is really necessary.


Mark Z

'65(lower)/'66(upper, wheels, front end, controls)/'67(seat, exhaust, fuel tank, headlamp)/'70(frame) A65 Bitsa.
Re: That weird A65 lower shock mount shoulder nut.... [Re: KC in S.B.] #725125
02/11/18 1:24 am
02/11/18 1:24 am
Joined: Aug 2001
Posts: 4,279
Owego, NY, USA
Mark Z Online content
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Ok, it's clear to me now. The shock bolt goes through a 3/8" hole in the inner swingarm lug. The shouldered nut is not there to support the bolt. If it were, it would have to be a very snug fit in the swingarm lug, which it's not. I reckon the only reason for the shouldered nut is that they wanted a goodly length of thread in the nut, and they didn't want the nut and bolt to protrude 1/2" out from the swingarm toward the wheel. (There may have been an element of aesthetics at work here too.)

Anyway, the bottom line is, the existing nut and bolt will work. I'll lose 1/8" of thread in the nut, but I don't think that's a big deal. Sorry for leading you all down the garden path. Next time I'll study the subject more thoroughly before posting.

"The optimist says, the glass is half-full. The pessimist says, the glass is half-empty. The engineer says, the glass is twice as large as it needs to be."


Mark Z

'65(lower)/'66(upper, wheels, front end, controls)/'67(seat, exhaust, fuel tank, headlamp)/'70(frame) A65 Bitsa.
Re: That weird A65 lower shock mount shoulder nut.... [Re: KC in S.B.] #725141
02/11/18 4:32 am
02/11/18 4:32 am
Joined: Apr 2007
Posts: 768
Brisbane, Australia
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Late to the party as usual, but this is informative.

I've been running standard 3/8 bolts with nylocks for this for 15 years and this has worked fine. I was always concerned that the load on the inner side shock mount was not properly distributed if I wasnt using the shouldered nut. In my last order from British Only about a month ago I ordered 2. 68-4235 # based on 1970 parts book. They are as described. 0.2" shoulder (turned down section) with a taper (~60o or 30o depending on the reference point). After fitting the spring washer shown in the parts book, not a lot is going to be in the rebated hole anyway. And then, as noted, with the late chain guard none?

I think I'll just stick with my existing system. With the late '69-on chain guard as noted, there is little room between the nut and the brake backing plate on that side.

Ray


BSA 1969 A65F
BSA 1966 A65H
Triumph 1968 T120
Kawasaki A1R
& too many projects!

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