scratched fork air spring- is there hope?
I bought a used (first mistake) Reba at a deal because the damper was blown out. so I bought a new damper and put it together. It worked well for two rides and then suddenly dropped as fluid and air leaked into the negative chamber. I was hoping it was just a seal but closer inspection revealed this inside the air sleeve
yeah, I already made a thread that got me to this point.
so the question now is, what are my options? I called SRAM and QBP, and niether has a CSU for this particular fork. I called Suspension Experts and they can rebuild my fork for more than it would cost me to buy a brand new one with new tech and a full warranty. perhaps I can find a used one that's not scratched up but my willingness to put any more money into this fork is about gone.
I have heard of people putting epoxy on forks and buffing them smooth but that is usually for scratched on the outside of the stanchions, not inside the air sleeve. this one is pretty deep and hard to get to.
if all else fails, I will sell the lowers and inside bits separately I suppose. any other suggestions?
Try swapping the air side to the damper side. They should be equal and you don't need a tight seal on the damper side.
It's worth a try.
The photo is a view straight down the springg-side stanchion. The white plastic seal is at the bottom separating the pos and neg air chambers, and you can see the scratch at about 2 o'clock. It's a few inches down the shaft. when the seal passes that scratch, oil and air get through.
If switching the air/ damper sides works, Warp, I will buy you a case of beer or something! I never would have thought of that.
Last edited by mack_turtle; 12-01-2012 at 05:48 AM.
is the scratch on a flat face? or is there a arch to it? if flat you can get an old car/small engine cylinder hone and smooth it out...
as to the switching.. what are you switching? isn't the scratch on the side wall of the lower?
The scratch is inside the left leg of the csu, inside the positive air chamber. One of my coworkers works on cars, i will ask him about that cylinder hone. Otherwise, i might try putting the damper in the left side and the air spring in the right, so the assemblies of the fork are just switched from the way it was designed. I have to disassemble the fork anyways, so I will see if that's possible and report back. I have nothing to loose but an hour or so of my time and I'll learn something new about my fork in the process.
As mentioned, he'd be switching the damper to the air side and the air spring to the damper side.
Originally Posted by thomllama
Both sides should be pretty much equal, but the main difference is that you don't need a tight seal in the damper. So that scratch is a non-issue.
Mack... if it works, don't thank me. I just read it somewhere else (maybe a mtb-news.de but I can't remember where exactly).
If there's coating on the inside that is a good one for sure
how could it get scratched?
*just saw it's used
I think I am going to buy a rebuild kit and cross my fingers.
I've seen this on several Rebas.
Originally Posted by Deerhill
Depending on the model/year, there is a rolled metal pin in the plastic part of the air seal head.
Sometimes the pin was not fully inserted during manufacturing and it sat close to the edge or not completely flush.
After just a bit of use it would score the wall and create a slight gap that the o- ring could not compensate for and the Reba would lose air pressure.
You can replace the o-ring and be fine for a few rides, but then the seal would fail again.
Pull the air assembly and make sure that the roll pin is fully inserted.
If it is, it's likely that the previous owner or a service center found the problem.
The tell tale sign of this manufacturing defect was a small scratch in one position on the inside of the stanchion that lined up perfectly with the rolled pin.
Unfortunately, on Rebas where stanchion's inner wall is used to make the seal, a scratch in it is going to be a problem for the o-ring.
Unless you can figure out a way to fill the scratch, the only permanent fix I know of is a new fork.
The honing thing may work if not too much metal is removed and you end up with a good seal for the o-rings.
I recommend against the hone if the stanchion ID is anodized
This. You may get slightly off rebound damping but its better than barfing air into the negative. Common fix.
Originally Posted by Warp
update (if anyone cares):
I rebuilt the fork with the air spring and damper assemblies swapped sides. it worked great for a few miles then farted out all the air again. riding a rigid fork is much better than riding a dead suspension fork.
I am at a loss now. I have nearly spent the money on parts what it would cost me to have just bought a new one in the first place. I am going back to my rigid fork (thank God I kept that!) and selling this pile of crap for parts.
What money did you spend on parts?
Originally Posted by mack_turtle
without going into specific prices, I work in the industry, so the amount I have spent on it so far is just short of what I would pay for a 2013 Reba. if I paid full retail for everything, it might be different. so far I bought the fork for $100, the damper, some bottles of oil, and some small bits.
if I can find them, I might just try to replace the o-rings in the air spring. perhaps I should have done that first, but if that fails, I give up.
Wow, sorry to hear. Kinda feel guilty for not point you out to dump it in the first place.
Originally Posted by mack_turtle
However, replacing just the O-rings is worth trying. The sizes are in another thread here on this board, so you can hit the local seal shop and get them.
Not all was for nothing, though. The oil and other tools will be put to good use in a new fork anyways.
it was a worthwhile experiment. i'll take another stab at replacing o-rings and see if that works. i don't mind taking the fork apart, the problem is having the fork blow out in the middle of a ride. it makes the last few miles out of the woods a real chore.
You need to replace the O-ring for the air seal.
The old O-ring is likely scored/worn where it rubbed on the scratch.