You don't need to be an 'investor' to invest in Singletrack: 6 days left: 95% of target - Find out more
When I went to the Alps this year the fork leaked some oil in the bike box through the bleed valves (didn't think when packing them) so I decided to do a lowers service today to replace the oil with the correct amounts.
A normal amount of oil dripped out of the air side but when I freed the damper from the lowers it looked to be far more than the 40mm which should be there. More worryingly it looked to be dripping from the damper once the lowers were fully off.
Compressing the damper with the lowers off had me worried as it sounded and felt like air inside. Disaster confirmed when I reassembled and compressed the fork to hear it wheezing chronically. 🤬😭🤦
I freed the lowers in the normal way, by gently tapping the the 10 and 15mm sockets with a hammer. I can only guess that somehow that has caused the issue on the damper but I'm baffled as to how. I certainly wasn't heavy handed.
Can anyone suggest what's likely to have gone wrong? Or make me feel better by telling me it will be an easy fix for the local suspension tech dude.
Eurgh
Sounds like a blown damper. Still under warranty? Fox should fix it.
I only bought it earlier this year but it was a cheap CRC deal, just the fork and a manual in a box. Can't remember if I registered it with fox but I'll check and email them to see what they say.
If it's less than a year old, it's a CRC issue, not Fox surely? The only problem being if you've not had it serviced in line with the required intervals.
I'm guessing they'll tell me to sod off because I'm not a qualified cycle mechanic but I'll see what they say.
You've not caused a blown damper by removing the lowers.
That's impossible to do.
It'll either be a blown seal or bladder in the damper.
Just get em sent back for warranty.
All Fox require is proof of purchase for anything less than two years old.
Thanks all, those are the reassuring answers I was hoping for!
Interesting response from fox:
The Grip 2 damper damper is a semi-open bath damper, which means that excess oil is purged from the top of the damper during use. Whilst the fork is fully built, this oil is circulated back into the lower legs, as the 5wt PTFE damper fluid is the same as the lower leg lubricant.
When the whole fork is compressed, the chassis ensures that the damper is always full of oil, with no possibility for air ingestion. If your damper is now having little to no effect, air ingestion could be the cause. In this case I would advise having the fork booked in with us for assessment, so we can take a look at it for you. It is completely up to you on whether you would like to have this assessed via your retailer or deal directly with us. Based on the information you have provided, I would look at this as more of a goodwill investigation than a manufacturing or material defect, but we will have to assess the fork to be sure...
Based on the information you have provided, I would look at this as more of a goodwill investigation than a manufacturing or material defect, but we will have to assess the fork to be sure…
That's fair enough, "sounds like there's nothing wrong but we'll take a look to make you feel better. If there is something wrong we'll deal with it accordingly"
[the cynic in me reads "You're not the first one, we know what the issue is but don't want to admit it exists so we'll have a "look" and return it to you miraculously better despite not having had anything done to it"]
Air ingress would be a knackered crush washer, faulty or loose bleed valve, knicked seal head etc. I guess?
I assume, given the oil from the valve previously that might be the culprit.
Update from fox:
The warranty assessment is now completed, and we have carried out the following under warranty.
Lower leg service.
Rebuilt the Grip damper
Air assembly removed, cleaned and inspected, and re-fitted with fresh lubricant.
Customers damper settings re-applied.
Not clear whether anything was faulty so I've asked the question. But a good result regardless.
Rebuilt the Grip damper
That would seem to be the answer as to what was wrong with them.
Result either way.
It sounds like the damper was fine, but the lowers just needed a little more lube oil to ensure that the oil cycling could occur. If you damper was short on oil because it had been purging but not ingesting, the standard amount of lube oil on the lower might not have been enough to keep it in equilibrium once reassembled.
A final update in case it helps anyone else in future:
The damper was very much still full of oil, however based on your description of the issue with the damper, I suspect that the compression of the damper whilst on its' side had allowed it to ingest air into the damping fluid. This air passing through the compression assembly would result in little to no damping effect. Unfortunately the nature of the disassembly process of this damper generates a large amount of bubbles, so I cannot say this for sure.
Based on Foxs' documentation, there is nothing you have done incorrectly with the service process. Personally I would always advise against compressing the damper with the lower legs removed however. This is more of a precaution than anything else, to eliminate the risk of the damper ingesting air.
Personally I would always advise against compressing the damper with the lower legs removed however. This is more of a precaution than anything else, to eliminate the risk of the damper ingesting air.
That’s odd because during Fox’s YouTube online tutorial of how to change an air shaft they tell you do exactly that. Check it at 1.45 in: