Fox fork help

[Scarfacexxx08]

I have 2 fox forks one is an F100 and other F120, the F120 lowers look awful. Would the lowers of the F100 fit the F120 uppers?

Cheers

 

[ishaw]

Yes is the short answer. I would measure the bushing locations in both and compare just to be sure but that's just belt and braces.

 

[muddytreker]

In the respective stanchion and wheel size yes, though be aware that stanchion and bushings
wear together, so fitting a different CSU into different lowers may require bunishing the bushings
if the stanchions are tight,
or the bushings may be a loose fit so then new bushings fitted and burnished to size,
you may find all match up nicely but something to be aware of.

 

[ishaw]

That's a fair point. I have transplanted a few fork lowers and uppers over time, and replaced bushings. Most have been absolutely fine, the only time I had an issue was when replacing bushings which on one occasion were tight. Didn't know there was a term, so burnishing it is. My reality was using some very fine sandpaper and going round the bushing very carefully until I got them to a point they allowed the uppers to move nicely without any play. Slow and steady, frequently checking until they were just right.

Is there a better way, no idea but it worked.

 

[muddytreker]

I believe the surface of the bushing that slides against the Fox fork stanchion is PTFE,
these are stuck to an aluminium ring, to size them your forcing a smooth slightly larger
round stock through the bushing, this kinda compresses, squashes the PTFE to the size needed
to fit the stanchion.

This link shows the tool set to give you an idea.

Suspension Fork Bushing Sizing Tool​

Suspension Fork Bushing Sizing Tool PRO Kit - SICD Ltd

If your forks feel harsh with poor small bump sensitivity the culprit could be tight bushings. Our suspension bushing resizing tool can be used to resize your bushings to ensure optimum performance and better oil flow by allowing the lower leg lubricating oil to effectively coat the bushings...

sicd.co.uk

And this guy who runs liquid labs gives a very insightful rundown of the whole process
of removing, fitting and sizing fork bushings, see youtube link below.

Enjoy : )