57 twin forks

Dave Walker · Post by **Dave Walker** » Sat Apr 29, 2006 1:00 am

Got my MOT last weekend & thanks to all who've helped me get it this far over the last few years.

the forks bounced up & down long enough for the guy at the MOT station to pronounce them roadworthy and then stuck gently at full compression after I'd ridden over a few mendip roads. When I put it on the centre stand & kick the front mudguard hard they drop down again ready for the next assault.

To ride it feels a bit like riding a horse when you haven't got the hang of rising to the trot .... not good for the kidneys & lower back.

Technical info is as follows ...

I built the bike from a box of bits in 1978 supposedly comprising a 57 G9 and 56 model 30 and have never got the forks right. This time around I replaced one heavily corroded tele tube from the spares scheme, bushes & all wearing bits & made sure I put in everything shown on the drawings in the right place as far as I could tell. I checked that the movement was completely free over the full travel before assembing them finally & I thought I'd done everything right.

The only thing I can think of is that the fork springs are wrong - would this be enough on it's own to account for the symptoms?

Once again I'd be grateful for any thoughts on the subject ...

Don Madden · Post by **Don Madden** » Sat Apr 29, 2006 4:16 am

In my experience the most common cause of your problem is the tubes not being parallel. It's a little late now for you but I clamp the stem in my vice & insert the bare stantion tubes & tighten the fastners. Then using two straight edges spanning the tubes check the alignment. Any misalignment is due to bent tubes and/or twisted lower clamp, which must be corrected. When the forks are fully assembled on the bike, loosen the slider to axle clamps & the lower clamp fastners. While holding the front brake firmly, plunge the front end a few times as far as possible. Them re-tighten everything. Cheers, Don.

Dave Walker · Post by **Dave Walker** » Sat Apr 29, 2006 1:15 pm

Thanks - that makes a lot of sense.

The lower bridge could well be a candidate as the mudguard was seriously distorted many years ago when I suffered the classic front brake anchor failure. (fortunately without personal injury ).

I think everything is going to have to come off again sooner rather than later so your tips are very welcome .... as will be any more from any source.

Thanks again.

Biscuit · Post by **Biscuit** » Sat Apr 29, 2006 1:35 pm

I would suggest not slackening the lower clamp on the left hand side, the one that locates the wheel via the spindle nut, just let the right hand one float as you pump the forks up and down.

Dave Walker · Post by **Dave Walker** » Sun May 07, 2006 12:37 am

That has certainly improved it - they don't seem to stick any more, over gentle bumps at least - I'll keep my fingers crossed for a few more miles yet.

I loosened off everything down the right hand side - pinch bolt, mudguard bridge bolts, axle clamp bolts, and also the spindle nut on the left hand side then worked the forks up & down very vigorously a dozen or so times, propped the bike upright on its wheels with a block under the footrest & then tightened everything up again.

.... and I'm back from a thrub along the lanes to Littleton on Severn of an evening for a shandy with the forks going up & down nicely all the way..

Thanks gents - I don't know what I'd do without you!

Don Madden · Post by **Don Madden** » Mon May 08, 2006 5:47 pm

Thanks for the de-briefing. We try to find solutions to problems but if people don't give us feed-back we don't know if the advice was sound.
Cheers, Don.