Leaky MTB forks

[J4CKO]

Hi, I have an old Trek 8000 hardtail I use with slick tyres and panniers as a local errand bike.

It works well but noticed the forks seem a bit slack, they are Fox alps air/oil ones, it’s never done any real hard stuff but think through age the seals are leaking, is it possible to refurbish them, it’s fine but I like thinks to work properly and it’s annoying me a bit, plus might be an interesting mini project. There is oil near the air filling valve.

Anyone done a fork rebuild, is it diy able ? Or does it need fancy tools etc ?

[Barchettaman]

Hi Jacko.

I have successfully rebuilt a cheap pair of Suntour forks, there are rebuild guides on YouTube to diy this sort of job.

I understand that you like to have stuff working properly, but as it’s just an errand/pub bike, why not just lock the forks out and leave it at that?

Cheers

[bobbo89]

Should be pretty easy as it sounds like you just need to do a lower leg service with a seal change. Not knowing exactly what fork it is, model and year, I don't know exactly what it'll need but it should just be a case of....

- Undo the foot bolts/nuts at the bottom of the fork leaving them a few turns in
- Knock the foot bolts/nuts with a mallet to release the spring and damper
- Take bolts/nuts off
- Slide the lowers down slightly and let any fork oil drain out
- Slide the lowers all the way down to remove them from the fork completely
- Pop the old seals and foam rings off with an open ended spanner
- Clean the inside of the lowers with some shop towel
- Pop the new seals on along with new foam rings (people say you'll need a seal tool but I've always managed without)
- Lube up the seals with some suspension grease
- Slide the lowers back onto the fork but not all the way
- Top up both sides with the correct amount of the right fork oil (probs 20wt)
- Slide the lowers all the way back on
- Put foot nuts/bolts back on and tighten to the correct torque (I just do it to what I know feels right)

You'll have to do a bit of research as to what seals you'll need but I'd guess they'll be standard Fox 32mm. Same with fork oil and levels but it'll likely be 20wt.

Tool wise it's nothing special. If they're bolts they'll likely be allen as they are on RockShox, I've only worked on Fox 36's which use nuts and so require a socket set. You'll then need a mallet/hammer to break the spring and damper away from the lowers and an open ended spanner to pop the seals out.

There's loads of videos on YouTube that'll show you what to do, it's dead easy really.

Edited by bobbo89 on Saturday 30th September 14:25

[J4CKO]

Barchettaman said:

Hi Jacko.

I have successfully rebuilt a cheap pair of Suntour forks, there are rebuild guides on YouTube to diy this sort of job.

I understand that you like to have stuff working properly, but as it’s just an errand/pub bike, why not just lock the forks out and leave it at that?

Cheers

May well not bother, but kind of want to keep it nice really, will do some research this week and try and get the rebuild kit.

[P-Jay]

I've serviced and rebuilt various forks of mine dozens of times.

You probally only need to do a 'lower service' and it's easy. Have a look on TF Tuned website, they'll sell you a service kit. Then check youtube for instructions.

[J4CKO]

P-Jay said:

I've serviced and rebuilt various forks of mine dozens of times.

You probally only need to do a 'lower service' and it's easy. Have a look on TF Tuned website, they'll sell you a service kit. Then check youtube for instructions.

Cool, that's useful, found a thread that shows that the model I have is an OEM version of the Fox RL fork.