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Girder fork dampers

Submitted by david_cooper on Sat, 20/07/2013
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Singles

Grease from the lower front spindle has emerged right round the damper discs (looks inevitable). Is it possible to remove the lower outer links (one at a time maybe) with the forks still on the bike so I can wash the bits in petrol - or do I end up in a shower of abruptly released springs? I'm not even sure if the bike should be on the back stand plus front wheel or on blocks under the crank case.

Or maybe slacken it all and try to wash it in-situ - or just tighten the adjuster regardless of the grease?

Thanks..

Submitted by simon_amos on Mon, 22/07/2013

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Hi David,

I have had my girders apart several times while insitu. What a pain in the arse !! I've tried with side springs both detached and in place, front wheel off the ground/stand and on. I found the easiest way was to try and keep everything in place and compressed using a combination of ratchet straps and G clamps. I have tried to do one piece at a time whether it was an outer link off or spindle out. When I removed spindles I withdrew spindle while similtaneously pushing a rod through of same diameter to try and keep everything in place. It took time with quite a few choice words thrown in. Be careful not to damage threads on end of spindles or within the link. If someone has a better way of doing it please share it with us.

Glenn

P.S. David could you check my last post on the Pre-war ES2 restoration thread.

Submitted by simon_amos on Mon, 22/07/2013

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While we are on this subject does anyone else have trouble with the nuts on the end of the spindles and the spindles themselves working their way loose over time while riding. Mine come that loose after a while, say 100km or so, that I have to stop and adjust the spindles again and tighten nuts. The movement of the forks going up and down just un-does them. I've tried locktight to no avail. Any suggestions ?

Submitted by david_cooper on Mon, 22/07/2013

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It took me a while to work out how the girder spindles operated since the forks aren't well explained in any Norton literature I've seen. I'm sorry if this isn't the issue but anyway -

On the plain end (the one without the square peg) the spindle passes through the plain unthreaded link and the nut tightens the link hard up against the shoulder on the spindle. Butwhen adjusting, this nut must be slackened back just enough to allow the spindle to turn so that the other, threaded, end can wind its way in and out of the other link which is threaded to match. When the width is correct (the indicator discs free to turn) thenut on the plain end is tightened solid again and the lock nut done up against the link at the 'peg' end. So the spindle should be solidly fixed to the links and free in the inner cross pieces. So there is in theory no reason for the nuts to come loose - and they haven't done so on mine even though there is grease everywhere at present.

I can't see how the nuts couldcome loose unless the nut on the shouldered end of the spindle is not fully hard tight against the link.

Now to wash the dampers in petrol - without taking it all apart...but thanks for the comments re: ratchet straps to hold the main spring..if I feel inspired. After a hot day out on Surrey roads I'm beginning to understand exactlty what the term 'featherbed' frame meant at the time!

Submitted by simon_amos on Thu, 25/07/2013

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Thanks for that precise procedure David. I am sure that is how I have been doing it but when I return home in a couple of weeks I will have another look. I seem to find that when I have the spindle tightened to the point that the indicator discs are just free to move, and then I go and tighten the plain side and the peg side of spindle it just locks everything up so I have to slacken the nuts slightly. There is my problem I think. You say yours are done up tight but forks are still free to operate.

When you say "On the plain end (the one without the square peg) the spindle passes through the plain unthreaded link and the nut tightens the link hard up against the shoulder on the spindle." Do you mean the nut tightens against the shoulder on the link ? I don't recall my spindles having a shoulder.

Submitted by david_cooper on Thu, 25/07/2013

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I found this the other day:

The damper arrangement is different from ours but the spindle arrangement seems to be otherwise the same. Each one illustrated has a shoulder butting against the link. I searched for ages to find this nut I was getting hopelessly confused running nuts backwards and forwards whithout understanding why links were or were not getting tighter or looser.

Attachments web-forks-jpg

Submitted by david_cooper on Tue, 13/08/2013

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Glenn

After you said it could be done I bit the bullet and just changed the girder fork friction discs. Too dark and wet to test ride it tonight but in the shed it doesn't bounce up and down as much as it did when I sit on it. The discs that came out were like black greasy iron washers. No wonder the forks joggled up and down so much on the road.

As you suggested, I used a short ratchet strap round the front frame down tube and through the back of the front wheel - to stop the whole thing from 'doing the splits' when the bottom links were both off. It would have been easier to re-assemble if I'd lifted the bike up by its crank case to relieve the check springs more but it wasn't too bad. Careful use of a screwdriver lever covered with rubber tube to protect the paint helped to line up the bottom threaded spindle.

It took about an hour from start to finish. Threading the front lower spindle was hardest. Now I must make sure I don't over-grease the spindles - or undergrease - or whatever. They are bound to be just as black and greasy in a year or two.

I'm guessing that the handling of girder forked racing Nortons (with much the same frame) would have always been better than road bikes because presumably the racers would keep their dampers clean? I'm sure this one handled much better on day 1 after its 40 year retirement (before the forks spindle grease warmed up) than it did last weekend. Maybe it'll now be transformed.

David Cooper

 


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