Front wheel Alignment,centering

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lemonjelly

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At my recent MOT found my four pot calipers were rubbing on the disc and weren"t central,I was with Norman and he put on some washers onto similar mounting brackets to Reds which was ok to pass,bike rides well but its still slightly over to one side with the speedo drive hard up against the fork leg.There seems to be a larger than normal gap between the speedo hub and drive cog.
Whipped the wheel off at Normans but couldn t see anything wrong,as its a mod on the brakes and with CMA wheels its obviuosly not easy to know but its had new wheel bearings and there is a funny hexagonal spacer inside the speedo drive.I m waiting for Alan to be back from hols  as he may have taken some pics whilst in for the resto.

It needs to move about 1/2mm to the right if looking from the front,rides well but didn t need the washers on the mounting plates before.

Any obvious ideas chaps?

Shaun

I ll post a pic when my wife returns from Spain with the camera!
 
Shaun, sounds like all was well previously?
What changed? Wheel off and back on again?
As it is a non-standard wheel and brakes there will likely be more than one spacer involved. Any chance these were transposed?
 
Shaun, echoing what Grant said I'd also check that the new wheel bearings have been seated properly. If anything is a midge's dick out it can create the sort of problems you are experiencing. I'm not a fan of using shims on brake calipers, sometimes it can't be avoided but often it's done to mask the fact that something fundamental is out of kilter.

If you can't find the source of the problem my advice would be to go back to basics; get the front of the bike in the air,remove the calipers and measure the distance between each disc and the fork leg and then start looking at spacers etc
 
Thanks guys no not like it before,no need for shims but I hope Alans got some pics let you know.

Shaun
 
Hi Shaun, sorry if I'm stating the bleedin' obvious, but assuming that the wheel bearings are correctly seated and everything is in it's correct order, have you tried centralising everything with the nuts loose? (oo, err)

Loosen the spindle and clamp nuts a little, as well as the mudguard stays, but with the calipers fully home. Then hold  the brakes hard on, I use a zip tie, retighten everything again in their current positions and see how that looks once you cut the tie. Usually does the job.

HTH

A tutto gas!

Paul
 
Shaun,

There is normally a slight gap between RH fork leg and speedo drive.

The axle clamps the speedo drive and wheel assembly to the LH fork leg.  Is the wheel rim central to the fork?

I suggest propping up the bike so the front wheel is free to rotate, remove the mudguard and the brake pads from both calipers, loosen the RH axle clamping bolts, make sure the axle clamps the wheel assembly and LH spacer hard to the LH fork leg and eyeball over the LH caliper centre line to start off.  This should be centred over the LH (of course) disc.  If it isn't, the LH axle spacer or the caliper mount is at fault.  If all is OK, turn your attention to the RH fork leg.  Loosen the RH stanchion clamping bolts at the yokes (and handlebar if of clip-on type) and turn the stanchion in the yoke, watching for movement of the fork slider on the axle.  If it does, the stanchion is bent, chances are the other one is too!  If the slider remains stationary while turning the stanchion, try nudging it in or out a bit to get the RH caliper centred over the disc.  If you cannot get it to line up properly without putting pressure side-ways on the fork leg, you will need to review your caliper mounts....

With the pads replaced and the RH axle clamp loose, compressing the forks a couple of times allows the RH fork leg to find its own position on the axle, it can then be tightened.

HTH,
piet
 
Just to put an end to this thread Alan and I took off the calipers and discovered three pistons sticking on the left and one on the right ,they weren"t part of the restoration and they are now booked in for a  overhaul,

Cheers Shaun
 
When I fitted 4 pots to my 180 Jota I swopped the fork legs over so that the caliper mounts were behind the forks,
I had to make up a 40 thou spacer to centralise the wheel and get an RGS speedo cable as the sopeedo drive required a longer one due to the rear possitioning of the calipers, if that's any help!
 
Cheers Bob my caliper mounts are behind the forks and shimmed up a little but its the calipers fault,been on the bike since 94.

Lemon
 
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