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Sticky Forks

Started by jvb_ca, August 12, 2010, 01:59:56 PM

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jvb_ca

Not sure if this in the right section or not. Oops...should be in the "running prblems" catagory... :bad:
I seem to have a sticky fork leg. Fork legs are from an 89 and have been rebuilt,bushings,seals, emulators, springs etc. I noticed one of the legs seems to be stickier than the other, as in not sliding in and out as smooth as I think it should. I rebuilt these forks a couple of years ago, but did not do the bushings. Seeing as it was raining on Sunday I thought good time to tear into the forks again. (I just put seals in earlier this summer) I installed a set of RaceTech bushings  thinking that this was my problem. Apparently it isn't. They are still sticky.
When I ride a constant speed around town and hit a small bump or seam in asphalt I get a small sort of rhythmic hopping form the front end it feels like. Disappears shortly, then comes back after the next bump. Feels like my rebound is not reacting fast enough? Do not feel this when up to speed and accelerating hard. Is not tires as I just mounted and balanced new Pilot Road 2's.

Racetech 1.0kg springs
RaceTech bushings
15 wt BelRay for oil
Emulators 2 turns out
New bearings in 88FZR wheel straight and true.
New Pilot Road 2's
Steering head bearings feel good, no slop, nice and smooth and pass the flop from side to side test. (I have never changed them)
Fork legs are not bent, as best as I can see, and only thing I can think it could possibly be is a fork lower out of round.
Any one ever had a fork leg out of round?
Anyone thoughts?

Cheers...Jake
Cheers...Jake
86FJ1200
Ontario

the fan

pull the tubes and make sure they are straight. It does not take much to cause binding. I shoot for .003 runout when straightening. As little as .01 can cause binding which is not readily visible.

racerman_27410

or the forks could be binding up when the axle is torqued..... lift the front wheel off the ground and see if the wheel turns freely.

i have had to loosen the axle pinch bolts and bounce the front end up and down a few times to get everything seated correctly... then re torque the axle


Kookaloo!

jvb_ca

Frank.
That's one of the first thing I thought of. I loosened axle and bounced front end, still the same. I also removed the superbrace to make sure it wasn't binding. Checked axle\fork alignment at triples and at wheel...seems ok.


Quote from: racerman_27410 on August 12, 2010, 04:41:24 PM
or the forks could be binding up when the axle is torqued..... lift the front wheel off the ground and see if the wheel turns freely.

i have had to loosen the axle pinch bolts and bounce the front end up and down a few times to get everything seated correctly... then re torque the axle


Kookaloo!

Bill.
Whats best way to check straightness? I don't have a dial indicator. I do have a couple of sets of 1st gen fork tubes that I could try. They should work in the 89 legs no? At least to see if that's the cause.

Quote from: the fan on August 12, 2010, 03:56:49 PM
pull the tubes and make sure they are straight. It does not take much to cause binding. I shoot for .003 runout when straightening. As little as .01 can cause binding which is not readily visible.

Cheers...Jake
Cheers...Jake
86FJ1200
Ontario

the fan

all year tubes will work. The simplest way to check for straight is to remove the front wheel and fork brace, loosen 1 of the legs in the triple clamp and slowly rotate the tube in the clamp. Measure the distance between the lower castings at the axle mounting point. If the tube is bent this measurement will change as you rotate the upper tube. In most cases it helps to leave the axle in place loosely.

You can also roll the tube across a known flat surface like a plate glass table and check by feel.