The BSA Workshop > Twins

A65T Fork Slider Length

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    Just looked at my bikes, I have the 1969 sliders  97-3641 and 97-3645.

The image shows a set without the counter bore (not for 650 twins), everything about them is the same as the counter-bore type except for the spindle clamp dimension.

The clamp material is solid not hollow and is 5/8" long, the counter bore sliders clamp material is 3/4" long.

The counter-bore and the ones shown are 10 1/2" long.

Best wishes...

Wow - thanks for all of the information.
I checked on the weekend and my spindle caps also have the counterbore - so it seems that everything is correct. The bike is original in every other way and shows less than 10k miles so I can't imagine why one of the slider legs would have been changed.
The different leg lengths might also explain why the manual says to tighten the thicker RHS cap first. This leads to the question - why? Maybe it does have something to do with the brake forces as suggested by Charles - who knows. Unfortunately after nearly 50 years, tightening the caps (even with some preload (my wife) on the forks), does not fully align the spindle by compressing the longer LHS leg, but rather cock's the wheel off centre - the reason I first started this investigation. The only way I can get the wheel vertical is to shim the bottom of the RHS fork leg a few mm, hence my original thought of simply filing down the longer LHS leg.
I've now played around with the various seals and spacers and think that I can 'extend' the operating length of the RHS leg by placing an additional washer above and below the oil seal. I might even skim a mm off the LHS upper bush flange too. Less drastic and permanent than attacking the leg itself. I have some parts on order and will let you know how it goes.
If anyone can see an obvious flaw in my logic, please let me know.

Charles R:

Before I dismantled the forks I didn't notice any wheel misalignment.  My A65L had done 18,000 miles, but I have no history as to why it was off the road for a number of years before I got it (who knows, it could have been pranged) and reassembled with whatever was to hand.

Unfortunately the dismantling process involved destroying the stanchions as they were so badly corroded!  This means I don't have the stanchions to quickly reassemble the forks to check whether the wheel spindle really does clamp up properly (at right angles to the forks).

Please forgive me asking the obvious, but have you checked the spindle is true?  Is there distortion or looseness in the clamps?  Are the clamping nuts really pulling down fully onto the clamps?  Could a very thin metal shim be placed around the spindle ends to create a better clamp?  The thought of modifying other parts would worry me.

It looks as if a job I've scheduled for later may need to be brought forward - I'm going to have to buy a pair of stanchions and do a "dry" assembly to see what happens to my front end!

Cheers, Charles

    To put your mind at rest the spindle hole in the sliders is not bored at 90 degrees. See attached images, the angle I have been told is 89 degrees (thank-you, John Phelan).

I was going to buy a set with a shallow counter-bore but was told the normal fork sliders were also used on some "A" group twins before the change (97-3641 & 97-3645, 1969 and before shown in the attached images and 97-3933 & 97-3934, 1969 and after, shown in your images). So I won't be changing mine, saving some cash for other projects.

This angle will bring the sliders inline when the wheel is fitted. No need to add shims or alter the arrangement, it is as BSA intended. It also tilts the fork slider brake lug into the brake plate.

The poor chap in the photos actually machind his sliders to 90 degrees and fitted caps of equal length.

Best wishes...

I have had the chance this weekend to investigate further and have identified that the spindle bore in the fork sliders and end caps is not 90 degrees. I had assumed that the metal had 'creeped' over the years causing the misalignment, until I read the post above.
Now I have a dilemma. My forks seem correct, the spindle is true, but when I fit the wheel and bolt them up the wheel remains cocked off 90 degrees to the spindle.
I was going to rework the bores to 90 degrees but am now not sure - is there something that I am missing?
Any suggestions on how I can rectify the problem would be appreciated.


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