Fox 40 Stanchion Wear......

[jenk0s]

Hi all, i've recently purchased a new bike (well for me at least) and the stanchion on the damper side has started to wear at 4-5 o'clock (fox 40's), this happend from being barley visible to quite distinct within one ride. I took it to a bike shop, and they think the lowers are bent, and that is why it was only wearing in one spot. So essentially they reckon i should buy a new fork, considering i just bought this bike, im kinda out of money and i've been thinking of ways to get around this issue. One idea that popped into my head last night was that the issue was a combination of a few things. One that the oil was dirty and wearing the stanchions, two there was not enough oil left inside and three the axel was on too tight, causing the legs to be pulled together. Could this be the culprit? or are the forks dead? on a side note, when sliding the stanchions out of the crowns with the wheel and axel still in, it was very tough to get them in, took me 20mins....., but when the axel was out, they slid in much easier. Thanks in advance for the help, I really want to get back out on the trails and ride this new bike....

 

[Shredden]

on a side note, when sliding the stanchions out of the crowns with the wheel and axel still in, it was very tough to get them in, took me 20mins....., but when the axel was out, they slid in much easier.

Sounds like its bad.

 

[jenk0s]

Yeah, i'm pretty annoyed at the guy who sold it if the lowers are bent, considering he said it was perfect

 

[gregp]

There is another possible cause, not very likely, but you should check it to at least eliminate it. Measure the front hub width from end of one spacer to the end of the other one. Should be 110mm. If it's less then the lowers are being bent at the arch when you install the wheel and that's why it's hard to get the lowers off with the wheel on. Take measurements with the wheel off and on, because this distance can change when you tighten the axle and compress the hub.

How much do you tighten the axle before locking it with pinch bolts? If you're using too much torque on the axle, you could be compressing the hub axle/bearings too much and bending the lowers at the arch, causing misalignment between the stanchions and the lowers. It doesn't take much torque on the axle to cause this to happen.

 

[T-Rex]

Regarding your three ideas on the cause of this problem:

1. No
2. Unlikely
3. No.

The hub is a fixed width, and you can't crush it by overtightening the axle and pulling the lowers together, unless you have left an end cap or the inner sleeve out of the hub, in which case the bike wouldn't even be ridable.

Dirty oil or no oil is also unlikely to take the anodising off.

What's more likely to take anodising off is an accumulation of dust in your seals, caused by lack of servicing. Mixed with the original grease, it makes a really aggressive grinding paste.

If the staunchion is bent enough that it's binding on the bush, and this is rubbing the anodising off, you would feel it catching. Pop the spring out, and see if the lower moves smoothly, or if it binds. If the latter, the bike shop was right.

 

[jenk0s]

Hmm ok thanks for that gregp, i will go and take some measurements. I might have overtightened the axel when i first got the bike, don't remember unfortunately, but it was on reasonably tight when i took it off. And thanks too T-Rex, with your theory of the dust mixing in, the wear is only on one section of the stanchion, not all the way around, would it be possible for that paste to only accumulate in one spot? also the wear is on the damper side not the spring and it feels reasonably smooth, not to keen to push it through its stroke right now though because there is no oil in the lowers at the moment.

 

[merc-blue]

send them to Tekin or NS for a check over if you want to be certain.

 

[jenk0s]

Update:
Redid seals and oil and had a fiddle with the hub, seems to have fixed the issue which is good, been on a couple of test rides and is yet to show any signs of continuos wear. Decided I wanted to try a new suspension linkage other than maestro, already had a reign...... so I am selling the bike, but I wanted to fix the issue before I got to that. Thanks again for all the help

 

[udi]

and you can't crush it by overtightening the axle and pulling the lowers together, unless you have left an end cap or the inner sleeve out of the hub

Actually no, that still wont happen on a 40.
The axle is designed to not clamp the lower legs together when tightened, rather it just clamps the hub against the threaded leg alone (i.e. pulls it to one side). This is done on purpose so that hub width tolerances don't affect the parallelism of the lower legs.

 

[T-Rex]

Actually no, that still wont happen on a 40.
The axle is designed to not clamp the lower legs together when tightened, rather it just clamps the hub against the threaded leg alone (i.e. pulls it to one side). This is done on purpose so that hub width tolerances don't affect the parallelism of the lower legs.

Actually UDI, yes it does. How do I know? I've done it, by leaving the inner sleeve out of a Pro II.

Kids, beer and hub servicing do NOT mix well...

Another FW thread-worthy update from the big old lizard.

 

[merc-blue]

Actually UDI, yes it does. How do I know? I've done it, by leaving the inner sleeve out of a Pro II.

Kids, beer and hub servicing do NOT mix well...

Another FW thread-worthy update from the big old lizard.

No it doesn't.
Take your axle and wheel out and then flip it and put it through there is nothing stopping it going completely though..

Look at the correct fitting setup and you will see

 

[udi]

Actually UDI, yes it does. How do I know? I've done it, by leaving the inner sleeve out of a Pro II..

No, it doesn't.

It does not matter how far you thread it in, it does not have an extrusion or lip to allow clamping the fork together. See merc-blue's post above.

What you experienced was the hub being tightened together against ONE side of the fork because you're a muppet and left the sleeve out.

What you claim on the other hand is physically impossible.