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Older Fox 40 oil leak question

freshwire

Monkey
May 24, 2007
105
0
Roanoke Virginia
I have an '06 Fox 40 RC2...I completely rebuilt the internals with the kit from Fox, I've resurrected the rebound...it had quit working, changed the seals and dust wipers, everything seems to be working just fine...but...even tho I've replaced the crush washer at the bottom of the adjustment knobs on the rebound side, there is still a tiny bit of oil in the black protective cap that covers the knobs when I remove it? I didn't think there was a rubber o ring required here...and none is shown in the exploded schematic...but the rebuild kit came with literally 10 0r 12 rings that I can't find a home for??? The kit is for the FIT system I guess, and mine is pre FIT...I don't think the oil is coming from within the adjustment knobs/rebound shaft...anyone else had this prob, and fixed it???
 

Udi

RM Chief Ornithologist
Mar 14, 2005
4,915
1,200
I've had the same thing happen on the older style 40, chances are it actually is coming from the adjustment knobs especially if you've replaced the crush washer (personally I haven't found leaks from the crush washers very common).

A good way to check is to remove the black cap and both blue compression adjusters (don't lose the balls), and then clean the area thoroughly with isopropyl alcohol or similar. Then cycle the fork a heap of times, and inspect the area for oil to see where it's coming from -

If it is from the adjusters, chances are it's a small internal o-ring that needs replacing. Good news is it's part of the kit that you bought (one of the smallest ones), bad news is that it's difficult to get to. You have to disassemble the compression base valve assembly (removing bladder, and unscrewing the larger silver bladder housing if I remember correctly, which may require some clamps).

http://service.foxracingshox.com/consumers/Content/Service/Forks/40/40RC2.htm
That'll get most of the way, but it stops at removing the bladder, getting to that small internal o-ring (if that is the culprit) takes further disassembly. If you don't have the right tools it might be best to give it to someone who does.