Concourier
Well-known member
I was lucky enough to participate in a recent Tech Day (I use "participate" loosely-I kinda just watched) when I remembered a long forgotten tip for reducing stiction at the front end as we were working on forks. I was first shown this technique in the pits when a friend of mine was WERA racing in the 1990's.
Now, I did do a search for "fork tuning" and "stiction" across the forum and didn't see this tip specifically, so forgive me if this is redundant, but at least its here if you want to try this the next time you have your forks out. Not trusting my memory (and you shouldn't) I found these specific instructions by a Mike Nixon online and adapted them here to closely match what I've done in the past:
Assemble the fork, leaving out the oil and springs and the wheel and fender.
Very lightly snug the triple clamps.
Bolt in the axle, tightening it in its clamps without the wheel.
Now raise this axle /slider assembly all the way to the top of its travel and let it go. It should drop to the bottom of its travel unaided.
If it doesn't budge, you've got some serious binding somewhere. If it's just a little slow, tap the top of one of the fork tubes with a soft mallet to move the tube downward in its clamps a smidge (0.010"-0.020") and try the drop test again.
If there's no change, tap some more. If still no change, raise the slider/axle assembly all the way to the top of its travel and tap on the bottom of the leg upward, which will move the tube upward in its clamp, and check with the drop test again. Try with the other leg also. You're hunting for the best alignment.
Because of manufacturing tolerances, the best internal alignment may very well occur when one of the fork tubes is incrementally higher than the other. Say 0.050"-0.080".
It's far more important to align the fork's parts internally, than it is to worry about what they look like on the outside.
Just remember to fully tighten the triple clamp bolts when finished.
Install the front fender and try the drop test again.
Don't let the fender influence fork movement. Reshape its inner bracket, shim between the fender and the sliders--whatever it takes to get the same drop speed with and without it.
You could also try sourcing fork seals with fewer sealing lips and sanding the upper wipers, but I never went to these lengths.
Now, I did do a search for "fork tuning" and "stiction" across the forum and didn't see this tip specifically, so forgive me if this is redundant, but at least its here if you want to try this the next time you have your forks out. Not trusting my memory (and you shouldn't) I found these specific instructions by a Mike Nixon online and adapted them here to closely match what I've done in the past:
Assemble the fork, leaving out the oil and springs and the wheel and fender.
Very lightly snug the triple clamps.
Bolt in the axle, tightening it in its clamps without the wheel.
Now raise this axle /slider assembly all the way to the top of its travel and let it go. It should drop to the bottom of its travel unaided.
If it doesn't budge, you've got some serious binding somewhere. If it's just a little slow, tap the top of one of the fork tubes with a soft mallet to move the tube downward in its clamps a smidge (0.010"-0.020") and try the drop test again.
If there's no change, tap some more. If still no change, raise the slider/axle assembly all the way to the top of its travel and tap on the bottom of the leg upward, which will move the tube upward in its clamp, and check with the drop test again. Try with the other leg also. You're hunting for the best alignment.
Because of manufacturing tolerances, the best internal alignment may very well occur when one of the fork tubes is incrementally higher than the other. Say 0.050"-0.080".
It's far more important to align the fork's parts internally, than it is to worry about what they look like on the outside.
Just remember to fully tighten the triple clamp bolts when finished.
Install the front fender and try the drop test again.
Don't let the fender influence fork movement. Reshape its inner bracket, shim between the fender and the sliders--whatever it takes to get the same drop speed with and without it.
You could also try sourcing fork seals with fewer sealing lips and sanding the upper wipers, but I never went to these lengths.