Hi guys.
I have stripped down my old Boxxer Race forks, replaced the wipers, and oil seals. I stripped most of it down and also ordered replacement o-rings.
Everything is back together OK however I noticed that on the right (rebound and compression) side the new oil leaks past the rebound shaft sealhead. Here is a picture of the rebound shaft with seal head..
The seal head is the white plastic with o-ring on outside. It also has an internal o-ring to glide up and down the rebound shaft. It is this internal o-ring where the oil in the cartridge is escaping and draining into the lowers. I measured up the original internal o-ring to be 18mm OD, 12mm ID and 3mm cross section. It only passes oil when rebound shaft is in motion, doesn't leak statically just sitting there. I have tried 2 other o-rings with very similar sizes but the original one (from 2008) seems to do the best job of holding the oil in.
Any advice? I could try a thicker o-ring cross section or will I have to pay up and buy the rebuild kit? I just feel that with 20hour service intervals even the smallest passing of oil will quickly drain that 150mL damping oil volume
Also noticed on the top of the rebound/compression leg, there was air escaping from underneath the blue knob and I could see some oil building up over there as the rebound shaft moves up/down. So I opened up the motion control unit and replaced 2 o-rings in there - it seems to have improved a lot but I need to put it underwater to see if leak is still there. Other than dirt getting in, will a small air leak compromise the rebound or compression behaviour?
BTW this is my first time ever stripping down forks... it's been a good learning experience even if these forks are toast...
I have stripped down my old Boxxer Race forks, replaced the wipers, and oil seals. I stripped most of it down and also ordered replacement o-rings.
Everything is back together OK however I noticed that on the right (rebound and compression) side the new oil leaks past the rebound shaft sealhead. Here is a picture of the rebound shaft with seal head..
The seal head is the white plastic with o-ring on outside. It also has an internal o-ring to glide up and down the rebound shaft. It is this internal o-ring where the oil in the cartridge is escaping and draining into the lowers. I measured up the original internal o-ring to be 18mm OD, 12mm ID and 3mm cross section. It only passes oil when rebound shaft is in motion, doesn't leak statically just sitting there. I have tried 2 other o-rings with very similar sizes but the original one (from 2008) seems to do the best job of holding the oil in.
Any advice? I could try a thicker o-ring cross section or will I have to pay up and buy the rebuild kit? I just feel that with 20hour service intervals even the smallest passing of oil will quickly drain that 150mL damping oil volume
Also noticed on the top of the rebound/compression leg, there was air escaping from underneath the blue knob and I could see some oil building up over there as the rebound shaft moves up/down. So I opened up the motion control unit and replaced 2 o-rings in there - it seems to have improved a lot but I need to put it underwater to see if leak is still there. Other than dirt getting in, will a small air leak compromise the rebound or compression behaviour?
BTW this is my first time ever stripping down forks... it's been a good learning experience even if these forks are toast...
Last edited:
