[300hp]

Hey doods.
I'm in the process of re-doing my Sunday. It's fighting me literally every step of the way. I check the piggyback pressure 2-3x a season. I would do it more if it wasn't such a colossal pain (I have the old school setup with the threaded pin that goes thru the shock eyelet).

Anyway. I'm pretty sure I have a bad schrader valve. Can I replace this with any high pressure schrader valve, or is it special to fox or something else special?

Assuming that I replace the schrader valve, if it still won't hold air, is there an O-ring around the schrader fill valve itself? How do I get to it and replace it if so?

Finally, when there is 150 in the piggy and I cycle the shock with no spring, I can hear sounds like oil moving. Is this normal with the RC4, or should it be dead silent (indicating I have a very slight amount of air in the system?) I only hear it on the initial compression, then it goes away after a cycle or two. No dead spots in compression or rebound.

If this is not normal, and I have a very slight amount of air in the system, can I do a quick "burp" by depressurizing, submerging the front of the shock in oil, popping the bleed port, and cycling it slightly all while submerged....or do I have to go about it the other way, by exposing the IFP, covering it with a bit of oil, then popping the bleed screw?

Lastly, if I do it that way, what should the IFP be? 9.5X3.0....My service stuff only goes up to 2008.

THANKS SO f'ing much guys. Pulling something good out of this mess will be a plus.

In the meantime, I'm off to track down some bearing setting compound per Udi's instructions to make this Sunday run another couple seasons.

Hunter.

 

[Racebike]

The piggyback will lose pressure during a season, nothing peculiar about that.

But, if the pressure loss is excessive, the most probable cause of your problem is the valve core. Try and replace that for starters.

You can get a valve core from Fox or an auto shop or even an tube with a schrader fitting if you like. Just make sure the length of the valve core is the same as the one used before.

If this doesn't fix your problem the valve core housing or the o-ring that sits on it may be leaky or bad.
There is also an o-ring seated on the adjuster that the schrader valve sits in, that may be the cause as well.

Check the image I have attached for placement of the seals.

Shocks do tend to make a small amount of sound while oil rushes between the compartments but if it goes away after a cycle or two that may indicate that a bit of air has slipped into the oil compartment.

If you have no dead spots as you say you're probably fine but it is good to service the shock and replace the oil once a season if you ride regularly anyway.

If there indeed is air in the shock it will be of little use to "burp" it as you put it, or for that matter fill the piggy with oil and release the bleed screw. The air can be at both ends (piggy and the main chamber) or even in between, stuck in the passage from the main chamber to the piggyback. Get a proper service done if you want to open the shock.

IFP-depth for that size I do not recall and I'm not at work so I can't check. Maybe Udi or someone else in the know can chime in here.

Don't know how restrictive Fox are where you live, but the rebuild kit for the RC2/4 has Fox p/n: 803-00-379
That kit does not include a new schrader valve or valvecore though.

Side note:
If the pressure loss is massive, the easiest way to spot it is by pressurizing your shock and (with the blue adjuster knob on the piggyback removed) submerge the shock in some water, you will easily spot the leak.

 

[300hp]

thanks man!

Great response.

The shock was losing air at a massive rate. A new valve core appears to have fixed the problem, but I'm going to do a leak down test on it this afternoon.

It looks like I'm going to have to open it up. As long as the piggyback endcap comes off without a fight, it should go alright.

If anyone knows the ifp depth it would be mad helpful, I'm hesitant to measure from where it is now in the event it displaced.

Otherwise, I'm going to default to the dhx setting for a 9.5x3.0, 38mm.

Thanks!
H

 

[Udi]

34.8mm for 9.5x3 RC4.
It's measured to the lowest part of the IFP (flat face) rather than the outer lip or middle.

 

[300hp]

Thanks!

Shock is holding air now, don't feel any dead spots in the travel, and is running silently.

score.