Triumphrat

McQueen · 08-03-2006

OK, first...the basics:

bike: 1979 Triumph Bonneville Special (T140D)
problem area: forks

desc: My forks stick, and I mean REALLY stick. Grab the front brake and push down, and the front end just stays there. I have to grab the brake and yank the forks back up to the height of their travel.

I'm not the original owner, so I can't say if it's ever been hit or dropped. But it doesn't look like it.

I changed the fork oil (just because it needed it). Then in desperation, I replaced the fork tubes and seals.

Now, with the wheel off and the mudguard detached, I can grab each fork tube and move them up and down, no binding or sticking. When I put the front wheel back on...no go. Stick city.

I put the front wheel on with the fork caps (that clamp the spindle) only finger tight. I rolled the bike around a bit to get it all seated, and before tightening the caps checked again. Still sticking. It's bad...to the point I can't even ride it.

Any ideas?

Could the front wheel spindle be bent? It sure doesn't look like it using my Eye Gauge.

I did NOT replace the dampening units or the springs. Could these play a part?

help me Obi Won Kenobi...

cheers,
paul

LukeMac · 08-03-2006

I've got the same bike and had the same problem. Your front springs are shot. I took all the same steps you have, but I also replaced the fork springs. Nothing helped until I put in new coils. Really easy to do and cheap to buy.

I got a set of progressive fork springs for about $45. You can get them lots of places at varying prices.

When I unscrewed the top of my fork tubes to remove the old springs, the old ones didn't even pop the cap off. They were about 3"-4" shorter than my new ones.

Drop in the new springs and you'll be good to go! Putting those caps back on while compressing the new springs is a little tricky, you might ask one of these guys about a good way to get that done.

McQueen · 08-03-2006

Luke,

Thanks for the reply. New springs are my next step. Glad to hear it solved your problem. Let's hope it solves mine.

cheers,
paul

Bonnevillian · 08-03-2006

You didn't state if the fork tubes were new or not.

Try turning the tubes 45 degrees and try it again.... then 45 more if that doesn't work.

I'm not exactly sure if the forks have bushings or not but most do. If those are worn it can cause stiction.

daveforty · 08-04-2006

It is possible that it is just a matter of adjusting the assembly, especially if you have had the forks dismantled.

From a Triumph factory manual;

After replacing the fork legs, mudguard and wheel, it may be found that the fork is incorrectly aligned.

To rectify this, the fork wheel spindle cap nuts must first be screwed up tight on the right-hand leg and the spindle cap on the left leg slackened off. Also loosen the top caps and the pinch bolts in both the bottom and top yokes. The forks should now be pumped up and down several times to line them up and then tightened up from bottom to top, that is, wheel spindle, bottom yoke pinch bolts, top caps and finally, the steering stem pinch bolt in the top yoke.

If, after this treatment, the forks still do not function satifactorily, then either the fork stanchions are bent or one of the yokes is twisted.

The top of the stanchion is tapered into the top yoke, so the stanchions wont push up through the top yoke.

There are no bushes in the alloy fork sliders, they are machined internally over their whole length.

McQueen · 08-04-2006

Thanks for the advice. You know, I feel like I've tried every possible combination of tighten this, slacken that and pump the forks. But I'll give it another whirl.

I will prevail! :-D