Fork stiction - need to shim wheel spacers??

[ReidMcT]

For some time, I've felt that my forks have more stiction than they should. I've now confirmed that the reason is that there is a small amount of play - perhaps 0.3 mm - between the for legs and the wheel bearing spacers. So, when I tighten the axle screw on the left side, the fork legs are pulled inward just enough to cause some binding during operation.

I wonder, has anyone else found this problem? Is the solution to add a shim between the spacer and the fork leg? If so, where to get such shims? Or some other solution?

Thanks for input.

 

[ReidMcT]

OK, I've found a source for the shims I might try: https://www.fastenal.com/products/details/11511063

Still, I'd like to hear thoughts on this topic.

With no tension of the axle screw, the forks operate very smoothly. It seems to me that shimming won't do any harm, even if it is not getting at the root of the problem.

Though I bought my RC390 used, it had less than 600 miles on it and no evidence of having been crashed; so I am pretty confident that the fork tubes aren't bent... unless they came that way from the factory. I am reluctant to completely disassemble my forks again in order to check the tubes for straightness, though I will do that next time I have them off to change the fork oil.

I wonder if there may be a small machining error on the wheel that has one or both bearings seating just a hair deeper than they should. Having read of some problems with brake rotors out of true due to machining errors, this seems at least plausible to me.

 

[ReidMcT]

Problem solved. It was caused by a Tyga slider, whose design does not impress me.

 

[Berto585]

Problem solved. It was caused by a Tyga slider, whose design does not impress me.

Was it caused by the front axle sliders? The Allen bolt that replaces the brake side axle nut? I’m having the same issue and that’s the only thing I added and now I can’t find the axle nut !

 

[ReidMcT]

Was it caused by the front axle sliders? The Allen bolt that replaces the brake side axle nut?

Not exactly. The solution is to:
First, install and tighten the left-side slider and screw. Do not over-tighten it.
Second, tighten the right-side pinch screws to the specified torque.
Finally, install the right-side slider.

 

[avs]

For me, the slider was an issue (on clamping side, rider’s right). It needed a chamfer so it would only bear on the axle. The mating face OD was so big it pressed the fork leg.

 

[rideontt]

For some time, I've felt that my forks have more stiction than they should. I've now confirmed that the reason is that there is a small amount of play - perhaps 0.3 mm - between the for legs and the wheel bearing spacers. So, when I tighten the axle screw on the left side, the fork legs are pulled inward just enough to cause some binding during operation.

I wonder, has anyone else found this problem? Is the solution to add a shim between the spacer and the fork leg? If so, where to get such shims? Or some other solution?

Thanks for input.

fork stiction here is a video I have tried it and it works.

for the axel

some times this (highlighted ) is a hair oversized so it won't slide into "Right side fork leg" easy(axel pinch bolt side) to resolve it I used sandpaper 300-600 grit, I sand it enough so it can slide easily. this allows the Right side fork leg to be free and recenter itself.

(first image left side) the axel is flush with a fork; that is bad

(second image right side) when axel is recessed inside the fork; that's correct

Hope this helps resolve the binding.