cold weather and clunking shocks

[BAJASVT]

I have just over 8k miles on my 2014. Local temperatures recently took a dive (10-30 degree average) and I noticed the "clunking" sound from the front suspension too. It seems the noise happens during extension or right at the switch between compression and extension; I was in a parking lot with speed bumps this evening and could definitely notice the noise wasn't happening during compression.

 

[LFtrip]

I've been told the clunking noise is normal in stock fox shocks. Mine clunk no matter what the temperature is.

 

[Big Johnson]

I have noticed the same thing on mine, I wonder if a guy tried running a lighter oil in the shocks if it would make a difference? I wrapped the lower part of mine with a light foam insulation and it has made a bit of a difference. I drive insanely rough roads everyday so I have noticed that up to about -5c they are ok, any colder and it is very noticeable. I find it hard to believe that a truck designed to run in the heat of the desert will function the same in cold weather. Someone told me the fox red oil is 10w, can anyone confirm this?

 

[ntm]

It's a by product of the internal bypass design.
At slow shaft speeds the oil goes through the bypass port very easily, when it quickly compresses or rebounds it changes over to the piston damping. The change over dramatically ramps up the resistance.

 

[Big Johnson]

Yes I understand how an internal bypass shock operates, my question is would it operate better in cold conditions with lighter oil? Obviously if it only happens when the temp drops it has to be related to oil viscosity, I have read that the jm92 fox oil is rated to -70. Do the factory shocks come with fox red? Or jm92?

 

[ntm]

Yes I understand how an internal bypass shock operates, my question is would it operate better in cold conditions with lighter oil? Obviously if it only happens when the temp drops it has to be related to oil viscosity, I have read that the jm92 fox oil is rated to -70. Do the factory shocks come with fox red? Or jm92?

The factory shocks are fox red.
A more temp stable oil like jm92 helps, but doesn't cure it.
I suspect part of the issue is actually the bypass sleeve moving up and down due to looser tolerances in extreme cold. It sits directly on top of the ifp chamber, metal to metal, and is held in place by an o ring in the seal cap. It is possible that it could be banging around inside the main shaft body, and the last set I tore apart did have wear marks to support that theory...

 

[Big Johnson]

Ahh ok, that makes sense. I have never actually had them apart, so a different o-ring wouldn't help take up some of the clearance? I actually sent an email to fox and they said svt comes with jm92 already.

 

[Jordan@Apollo-Optics]

It wouldn't surprise me if the o-ring used is a specialized o-ring not available to the public. If it's a standard o-ring, you may be able to purchase the metric sized o-ring that's slightly larger to take up some of the loose tolerances.

 

[Gsteve]

I hope someone finds a fix. It makes a $$$ truck sound cheap.

 

[LFtrip]

I wish someone could record this clunk. I'd like to know if what I'm hearing is what everyone is talking about.