New front end wobble

[luvmy40]

This winter I delinked the brakes and installed Progressive springs in the front. I also got a new custom seat. All of which necessitated adjusting the rear suspension. So I am running no air in the front and 40psi in the rear. The ride is at least 2" higher than with the old springs @ 12psi in the front and the rear shock air maxed out.

 

When I installed the progressives, I did a non technical check of the head bearings. They felt fine. No hitches and good motion from stop to stop when pushed. The front wheel bearings also felt and sounded good.

 

The bike now has a distinct front wobble at 40mph. Not uncontrollable but worse than I'm comfortable with. She always had a slight wobble when decelerating through 35mph. Very slight, almost unnoticeable.

 

Oh, the trials and tribulations of riding vintage scooters!

[bongobobny]

Well, there are multiple things that can cause this! The most obvious is improper torque on the head bearings, or bad head bearings. But, a bad tire can also do this as well as a bent rotor that is intermittently scraping against the brake pad, bad wheel bearings, etc, etc, etc!

 

You state that you are running zero air pressure on the front forks. You really need to have one or two psi of air in the forks to prevent the shock oil from foaming. That's all it takes is just a psi or two and it will keep the oil from foaming and keep the suspension working at peak performance. And speaking of front forks, if one is just slightly out of alignment with the other that too can cause oscillations...

 

Hope you get it all sorted out, start with the steering neck first.

[SpencerPJ]

I ride mine with 0 in front, 40 in rear. I'm a bit bigger than you (275, lol) You might try 35 in rear. I think I dropped my front tire pressure as well. But my wobble I had at 40 went away.

[Marcarl]

Be mindful of putting the front end together, so here is what I mean just in case you dropped the forks.

Push the forks all the way into the triple tree until they stop on the snap ring. Forks must be seated in the triple tree, on the rings. Then tighten the lower pinch bolts to spec, only about 12ft lbs if I remember correctly. Now check to make sure that both forks are the same in the upper triple tree, if not, redo the lower one to get it where it belongs. If you are going to play with the steering head, now is the time, before you snug up the upper pinch bolts. Once you are done fooling with the steering head and have it tightened into place, then snug up the upper pinch bolts. Until then, they should be totally loose. Do not, repeat. do not over tighten the pinch bolts, it can and will do lots of funny things, including causing a wobble. If you are thinking that all that stuff needs to be real tight to keep it together, then think about what those pinch bolts actually do, they just keep the forks in line, more or less. You won't loose anything by them not being super tight, the forks are held in place by the weight of the bike and can't go anywhere but up and they can't do that because of the snap rings. The forks also will not drop out because the recommended torque on the bolts is plenty enough to hold them there.

[luvmy40]

I did not drop the front end for anything. I didn't even remove the fork brace at the fender. Just pulled the calipers, fender and wheel.

 

I added a pump (small hand pump) probably 4-5psi to the forks at Bob's urging. The wobble seemed to be diminished greatly on the ride home from work yesterday. I doubt that little bit of air pressure made the difference. It's more likely, in my view that I either exaggerated the wobble in my mind.

 

I'm putting close to 100 mi./day on her so I'll see how it goes today.

[Marcarl]

Knowing what you know now,, and if I were you or you were me,, so meaning that if that bike were in my garage and I had the getup and go to getter done, I might just for the fun of it take a few minutes to check the torque on those pinch bolts. You never know who did the work on them the last time and what was in his head.

[luvmy40]

Well, I could not even instigate a wobble on the ride in to work this morning. Maybe I imagined it?

 

I did, however find a seeping leak from the left anti dive/fork seal. Not dripping but definitely seeping.

[BlueSky]

If you haven't watched it, you may want to watch the attached video that covers adjusting the front forks.

 

[luvmy40]

I ordered the o-rings for the anti dive unit yesterday. They are on back order everywhere. Hopefully they don't take too long to get here.

 

I probably have the right o-rings in one of my several o-ring kits, but I'd hate to tear it apart and not have the right size.

 

When I get them, I'll take another look at all the front end stuff.