A65 Rear Q/D Crinkle Hub Thrust Washer

[Kevev]

Hi all,

On the A65 rear wheel crinkle hub from 1966-1970 there is a component that is described as a thrust washer in the parts book. It is part number 65-5884 and fits in the crinkle hub on the brake drum side. It goes in first then the wheel bearing and then the threaded retainer.

Is there anything that needs to be done to this thrust washer when assembling the rear end?

I have bought a new 65-5884 thrust washer from Draganfly, which looks like a pretty crudely pressed out metal ring. I can't remember the exact width measurement of this new thrust washer but it is thicker than the one already in there, which looks like it has been on a surface grinder and is thinner than the new one.

I would have thought that the distance between the inside of the bearings in the crinkle hub wants to be exactly the same as the distance between the shoulders of the sleeve that fits in between them. Otherwise you are going to be applying some axial load on the wheel bearings when you tighten everything up?

Am I missing something, or does this thrust washer need to be ground to suit the job before it is fitted?

[AWJDThumper]

I'm not sure why it's called a thrust washer - it's basically a spacer or shim as far as I can see. When the wheel is bolted to the swinging arm, the wheel bearings will be tightened hard against the internal sleeve (67-6027). Assuming the crinkle hub has internal shoulders on both sides for the bearings, the thrust washer is there to take out potential free play of the bearings between these two shoulders.

To check on the correct thickness, I would try to measure the distance between the shoulders on the internal sleeve and compare it with the spacing of the internal shoulders in the hub. The thrust washer should take out much of the difference but leave a bit of free play (10 thou) to avoid unnecessary axial loading of the bearings.

If the crinkle hub has only one internal shoulder then the precise thickness of the thrust will not be that critical.

[AWJDThumper]

I've just looked at a Crinkle hub I had lying around and basically it has a shoulder for the bearing on only one side. Therefore, the thrust washer is just a spacer under the brake side bearing allowing the retaining ring to end up flush with the outside of the hub tunnel. Its thickness is not that critical.

[Kevev]

Thanks for that Thumper.

I think I get it but I'm still a little mystified with the set up.

I think I'll get my depth mic and slip gauges on it all, while it's in bits and see if I can make full sense of it all.

It will all fall into place and become clear once I've got it all drawn up and on the screen.

I have found out, during my re-build on my bike that it is quite a mix of bits and pieces from different years. Most of the BSA A65's I've seen have the cast alloy rear brake plate but mine is a chromed pressed steel brake plate, which I think is from 1966 (the year the bike was registered). The frame however seems to be a 1968 item.

I'm not sure if the different brake plate makes a lot of difference but I have noticed a few combinations of spacers and distance pieces with different part numbers, although I am finding out that a different part number does not necessarily mean a different part.

It's all good fun anyway, we wouldn't do it otherwise would we?  

[AWJDThumper]

I know what you mean - my A65 was a nightmare to sort out when I restored it and is still a bit of a mongrel!

In terms of the crinkle hub, you need to understand how it all tightens up when you do up the wheel nut and bolt. If you ignore the hub itself, then the bearings are held in place between the swinging arm by the hub internal sleeve and the separate brake drum spindle. Basically everything gets clamped solidly together when you do up the brake drum nut and the wheel bolt.

Quite separately, the hub is held axially in place via the LH bearing because that is retained by the internal shoulder/thrust washer on the LH side of the hub and the bearing retaining ring. Essentially, the hub is held in place on teh wheel spindle by the LH bearing.