Reba Pressure

bailsofhay

Hi all,
Last week I was riding and hit a bump at which point my left side dust seal popped off my 09 reba sl dual airs. I disassembled and replaced all the air seal o rings and the foam ring on the neg piston and reassembled exactly as described in the service manual. Now I went to pump them up first ve+ and then ve- at equal pressures for my weight as I have always had it set but for some reason sag is eating almost all the travel. I have checked and there is no air leakage and both the + and - are retaining their set pressure. The only way I can get sag right is by running +120psi and -95psi but I from official docs this is a bad thing and they should be equal or even +ve < -ve .
Does anyone know where I am going wrong or if it is damaging/ dangerous to run them @ +ve120psi/-ve95psi? Is it possible there is a moco problem on top of the air leak I fixed?
cheers

oxocube1

Sounds potentially like an issue with the damper side. There was a relatively common fault with Rebas around that age and the solution can be found here.

bailsofhay

Thanks oxo, I have the damper service kit that came with the air set so I guess I will have a a go and see if a service fixes it. Just wish I had done it when I had them apart yesterday. Thinking back I don't recall an abnormal amount of oil coming out of the lowers but I wasn't really looking closely at the quantity.

rockmonkeysc

I had exactly the same problem with dual air Pikes of a similar age several times. You need to rebuild the air spring.
It's worth getting a air spring rebuild kit to replace the o-rings.
What happens is one of the main o rings pops out of it's seat and either leaks air between positive and negative air chambers or the negative air chamber leaks I'm to the lower and blows out the lower leg seal.
It's a simple job if you follow the manual, be methodical and make sure everything is spotlessly clean when you reassemble.
You will need isopropyl alcohol spray, oil of the correct weight, lint free cloth, seal kit and circlip pliers.

bailsofhay

Hi Rockmonkey, What you describe was my initial problem but I just did the air spring rebuild and pressures are holding but not behaving as they should and sag is taking over 50% of the travel. Equal pressures in the dual air chambers causes major loss of travel when it shouldn't so i'm gonna do a rebuild of the damper and see if that helps. Fingers crossed...

rockmonkeysc

It won't be the dampers, they have absolutely no effect on the sag. Dampers just control how fast the forks move, they don't effect how far they will move (except when travel is limited by speed of movement obviously). I always used 10psi more in the positive side. It does sound like you have a leak between the positive & negative chambers though.

coulddobetter

Plus one for air spring seals. Solved same problem on my dual air Sid by replacing them.

Dirtydog11

I disassembled and replaced all the air seal o rings and the foam ring on the neg piston and reassembled exactly as described in the service manual. Now I went to pump them up first ve+ and then ve- at equal pressures for my weight as I have always had it set but for some reason sag is eating almost all the travel.

You have a vacuum in the lowers!

This has happened because when you reattached the lowers you did it whilst the legs were compressed, then when you reinflated you've created a vacuum in the lower legs, that vacuum in the lowers acts like a secondary negative chamber sucking the forks into their travel.

Solution: WITH FORKS AT FULL EXTENSION either push a cable tie down past the dust/oil seal of each leg and allow pressure to equalise or remove lower nuts/crush washers and release lowers (no need to remove) to allow air pressure to equalise, re-tighten and reset +- chambers.

bailsofhay

Thanks guys, it was as you said Dirtydog. I did the damper service anyway and was getting the same results till I did as you said and equalized the pressure via the lowers fixings. Definitely a learning experience but now I have silky smooth forks again and feel a bit more confident about servicing!

Cheers for all the help!