I went to the shop for the annual rear suspension service. I have the Fox Float R, which is already few years old. I am not sure how old as I bought it 2nd hand.
A day later I got a phone call from the mechanic that the cylinder has a dent on it and that this might cause air to leak through the new seals. As I was not around to see it and as I have no experience with this, I told him to go ahead and replace the cylinder. I payed around $120 for the full treatment + replacing the cylinder.

But when I got there and saw the cylinder and the "dent" I was surprised - it is so small and so shallow it looks like a thin piece of paint flaked away. My camera is not that good that it can show how shallow it is but I estimate it is only as deep as 1-2 hairs (!).

Do you think the mechanic was correct in replacing the cylinder or was it just to make some more money on my expense

I added a photo so you can see what I mean. But if you want to read more information, I have it here.

If it is really dented/deformed, it needs replacing - if it's just scratched, so were you!

This is probably a borderline case, and the mechanic was probably being conservative to spare you a short lived repair and trip back.

It's possible that it might not have leaked much and been usable for a while, but eventually it would have scored the seal and gotten worse. Who knows how long it might have gone, but if the service labor is fairly high compared to the part it was definitely good preventative maintenance. if the part was expensive it falls into the gray area of judgment calls.

In a similar vein, whenever I replace my engines's timing belt I also replace the water pump bearing. The bearingis perfectly fine and might last another 20,000 miles or more , but replacing it while the front engine cover is off saves me repeating an expensive, time consuming job before I would need to replace the timing belt again.

FBinNY,

I found your post most useful. I must agree that this was a borderline case and the fact cannot be argued with: I was definitely losing air from the rear shock!

Thank you for taking the time to share your thoughts.

+1 Borderline. One advantage of doing the work yourself is that you can do interim repairs. But when you are paying someone $65 an hour to do the work, such interim steps don't make sense.

Hi wrk101,

Sorry, but what does "interim repair" mean?
I am not English mother language so that might be the problem

Thanks!

Interim means "in between" or in this case a short term repair.

The problem is that a Float R is a high pressure air shock. The seals in that sort of shock are under a lot of pressure and press hard against the slider tube. It takes only a very small scratch or ding such as this one to wear away at the seal and quickly generate a leak.

The idea of an "interim" fix would be if you were a racer and positively HAD to have the bike for that weekend and didn't mind the costs. In such a case you could have just stuck a new seal set in the shock and ran with the scratched tube. The seal may or may not start leaking by the end of the weekend's race but at least you would have been able to race and then do a proper tube and seal set replacement after the weekend.

Given the sensitive nature of air shocks and the requirement that their seals be perfect I think he was very right to suggest the tube replacement. Otherwise you would run the risk of an early seal failure and further air leakage.

It's also why I'm waiting for a LizardSkin pack to arrive for my own new bike that uses a Fox Float air shock. You may want to look into one, or something similar, for your own bike.

Hi BCRider,

great reply - thank you for taking the time to answer my question.

What is this LizardSkin material good for? Especially - what do you use it for on a bike? You got my attention here :-)

i've no idea for that