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Kevin E Offline OP
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Hi all,

During the rebuild of my 1966 A65 Lightning I have been paying a lot of attention to the geometric detail and wheel alignment etc.

I have come across a little bit of confusion over the wheel rim offsets, more so on the rear wheel.

According to information I have gained on here, specifically a BSA document that Beach posted, I have a conflict between what the factory says and what I have measured on the rear wheel before I stripped it down.

The document that Beach posted says that the quick release 8" half width type brake drum front wheel rim should have an offset of 1-15/16” from the edge of the brake drum to the centre of the rim. My wheel was within 40 thou of that, so I am happy with that one.

The document says that for the Q/D rear wheel the rim should be central to the Q/D hub spoke flanges. That would give an offset from the edge of the speedo drive side hub spoke flange to the wheel rim of about 3mm. My original Wheel measured 7.5mm. Unfortunately, I did not check how central the original wheel was in the swinging arm and frame before I stripped the bike down.

If I was to aim for the factory offset dimensions, then the complete wheel assembly would need to move over to the final drive side by about 3.5mm.

I have checked the dimensions of all the spacers and associated parts and brand-new wheel bearings have been fitted. The only thing I am not sure about is the 68-6067 dummy wheel spindle dimensions, as I have nothing to reference this with.

With the rear brake assembly mounted in the frame, when I fit the bare Q/D hub assembly (without the rim and spokes) into the brake drum it does not seem to go in far enough and it also ‘wobbles’ a little when I press it home. Suggesting that the end face of the 68-6067 dummy spindle is not square to the wheel bearing inner race that it bears against? This also ties up with what I believe about the rear wheel needing to move over more that way.

Would it be possible for someone to measure the gap between the rear Q/D crinkle hub spoke flange and the rear brake drum as shown in the attached image. This may help to confirm what I think that the rear wheel does need to move over a little more that way.

My rear brake has the steel brake plate, not the later alloy one and I am not sure if this is important, or not for this dimension?

Thank you

Kev E

A65 QD Detail.JPG (64.36 KB, 222 downloads)
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My experience is that the original specs were never that accurate. When I lace a rim I mount it in the swing arm without the fender or tank to make sure the centerline of the rim lines up with frame spine and steering head


Rich
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I agree with Richrd.

Do it his way with both wheels and you will know where center alignment really is.

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That's fine if all the parts are correct.


Bill
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Kevin E Offline OP
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As far as I am aware, using all the data I can find the parts are all dimensionally correct. The only one I can’t verify is the dummy spindle in the brake drum assembly. The brake drum, when fitted to the frame looks as though it is correct. I intend to verify this with laser alignment on the final drive sprocket when I have the engine in place. When the Q/D crinkle hub is fitted it bears up against the dummy spindle and this is what determines its final position in the frame. If I fit the crinkle hub in, as it is now, the hub is not central with the centre line of the frame. This means that I will need to apply an offset. If I was to mount the rim centrally to the spoke flanges it won’t be aligned correctly. It will be off the centre line by about 4 mm to the right side. That’s why I asked about the dimension of that gap between the spoke flange and the hub. It would help me verify if the dummy spindle is dimensionally correct. Also on the subject of the crinkle hub, on the spline side the bearing is held in place with the LH threaded retainer and behind the bearing is a thrust washer (65-5884). What is the purpose of this thrust washer? As there is only the one part number for it I assume they are all the same thickness. In which case why is it needed, as the bearing could have been simply fitted in against the shoulder of the bore in the crinkle hub? If it was available in different thicknesses, like a shim for alignment purposes, it would make more sense to me. I just can’t figure out why it has to be used. It’s thickness has a direct bearing on the position of the crinkle hub in the frame.

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I'll get that measurement for you after bit. Mine isn't on the bike yet. Pretty sure though that the crinkle hub should be close to center of the frame, according to Manual. But yours isn't off by much.


Bill
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re the spline side bearing spacer washer, if you look closely at the drawing you will see the bearing inner locates against a shoulder on the spindle, it looks to me like the washer is needed to prevent excess side load on the bearing, if it is tightened in with the screwed retainer ring the OD of the bearing would have nothing behind it should the washer be left out. This would not be good for the bearing.


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Kevin E Offline OP
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Originally Posted by Beach
I'll get that measurement for you after bit. Mine isn't on the bike yet. Pretty sure though that the crinkle hub should be close to center of the frame, according to manual. But yours isn't off by much.
Thanks Beach, much appreciated.

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Kevin E Offline OP
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Originally Posted by gavin eisler
re the spline side bearing spacer washer, if you look closely at the drawing you will see the bearing inner locates against a shoulder on the spindle, it looks to me like the washer is needed to prevent excess side load on the bearing, if it is tightened in with the screwed retainer ring the OD of the bearing would have nothing behind it should the washer be left out. This would not be good for the bearing.
I would accept that if the bearing on the other side of the hub was positively located but it isn't. As long as the bearings were fitted properly by pressing them in on the correct faces, so that you don't cause any damage to them the right hand bearing can move to its final position (dependant on the thickness of the thrust washer). This position is determined by the shoulders on the inner sleeve. As far as I can see this inner sleeve stops the bearings having any axial load applied to them when tightening up the wheel spindle as it bears on the inner races. The fact that the splined side hub bearing butts up against the dummy spindle in the brake drum ultimately determines the crinkle hub's position (and wheel) in the frame. I just wonder why the hub wasn't made more accurately with the correctly dimensioned shoulder for the bearing to locate on and fix the position, without the need for this thrust washer? If it's always the same thickness then why have it?

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Haven't had mine together in frame yet but looks like 3/16" to me.


Bill
1974 Norton Commando
1966 Lightning
1965 Lightning Rocket
1966 Norton Atlas
1967 Norton Atlas
1948 Panhead
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