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X-Post Fox RP3 - Unserviceable?!?!?!

91K views 139 replies 35 participants last post by  fansaldi 
#1 ·
So, I've been around motorsports, snowmobiles, dirtbikes and the like over the years. I've also been biking over half of my life here on earth, so I know a few things about servicing Fox shocks. This brings me to my current rant.....

I have an older RP3 shock that needs new damper oil and a nitro recharge. I've done the air sleeve (many times) and I DO NOT NEED any custom valving (aka Push). Apparently NO ONE, I mean NO ONE other than Fox and Push can recharge the nitro?!?!?!

When I used to re-valve my snowmobile shocks we had a huge bottle of nitro in the shop. A matter a 30min to re-valve, re-charge and I was back riding my snowmobile seeing what effect the changes I made had to the suspension. It was no biggie. Anyone could do it. Seriously, it isn't hard to recharge the nitro with the needle tool.

This brings me to my current dilema..... I don't want to spend $100+ dollars just to rebuild the shock to normal condition. I just want to refill the damper oil and recharge the IFP chamber. Hell, I'd be just fine using air instead of nitro, but that doesn't seem possible without the tool. (which NO ONE has, except Fox and Push)
What is everyone doing with this situation? I talked to Fox and they want $120 for a full rebuild! I'd go the Push route for a little more than that, but I'm fine with the Comp and Rebound functions.

Has anyone found a cycle/sled shop that can recharge the nitro side of things? I'm worried the needle guage is slightly larger than what the MTB shocks need.
I've found some good info online and even found a massive zip file of Fox documents with exploded views, specs, and the like for my shock. IFP depth and the like. The file even has a service update in which Fox is telling dealers that the Nitro side of my RP3 is now getting pressurized to 400psi instead of the 'normal' 300 psi. I don't even have the means to pressurize something to 400psi......

I'm really frustrated with Fox right now. Great product until it needs servicing and then I'm supposed to pay almost half of the cost of a new shock, just to rebuild my old one!?!?
I am more than competent and confident to do this myself, but how?

Any help on the matter is appreciated and I know I'm not the first to ***** about Fox's proprietary damper. Feels like a Monopoly with Fox and Push being the ONLY ones that can work on these.

/Rant, Just needed to get that off my chest!

Please tell me I don't have just 2 options!
 
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#118 · (Edited)
I plan to rebuild my RP3 next weekend (to hopefully get ProPedal working and get rid of the squelching noise!).

I've got
- the Fox air can seal/oil kit
- Abagrizzli/Sheeep's seal kit
- Spare 7mm o-ring to make extra rubber pucks (if necessary)
- an old 4mm hex/allen bit to drill out
- an old football needle with a thread that fits my shock pump.
- syringe for bleeding

Missing:
A) hypodermic needle (which I will epoxy into the football needle). What size/gauge to get?

Edit: I happen to have 21 and 23 gauge needles in my medical bag. So will try one of those!

I figure a 0.9mm internal diameter needle has about 28.3 square mm surface area per cm, i.e. 0.045 square inches. At 400 lbs / sq. inch that's about 18 lbs or 8.2 kg, which I think is OK but I wouldn't go lower than this (i.e. > gauge 18).

The motion pro needle is a 22 gauge, going by internet forum posts.

(I would buy a motion pro needle but they seem outrageously expensive for what they are!)

B) Oil. Any suggestions? (I do have some old motorbike fork oil but doubt that is appropriate).

C) IFP depth settings! Any got a link to a table?

Edit: I am just going for the 48.3mm depth spec'd for the RP23 in same size.

D) Anything else?!

Thanks!

Edit: I bought a new Float CTD, "just in case", so I can keep riding :)
 
#119 ·
Hello, I am new here but I have some problems servicing my RP23.
I have a needle and a shock pump so I have no troubles putting more than 300PSI in my IFP chamber.
Problems comes from the fact that I cant take all the air from the damper when rebuilding it. I have followed all the steps from http://www.dhfr.ru/fox/Content/Service/Rear_Shocks/RP23_Rebuild.htm

But opon putting together the shock I have about 10mm of squishy in the upper travel.
I have followed the instructions and oil got out of the bleeding port for damper oil, after that I have inserted the steel ball and nut.
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Can you please give me some advices, maybe there some settings like full open and rebound full on, or full of ... i dono
 
#120 ·
You want to fill the damper body to the top with oil. Have the rebound fully open (fastest setting) and soak the entire piston etc. in another container of damper fluid. Keep the piston under the fluid and agitate it until there are no more air bubbles coming from the piston etc. Quickly transfer it to the damper body and screw it on. Lots of oil will overflow and some should escape out the bleed port as you screw the final few turns on the damper.
 
#121 ·
Thanks @TigWorkd, what you are saying makes perfect sense. To bad I haven't found an advice like this before servicing it.
For the moment I have tested the shock by installing it upside-down and the sound is still there so It makes me think that if there would no air it would be sitting on the IFP plate and not at the piston plate.
So I am thinking there is no air in the damper and the noise is caused by the oil passing through the shimstack and valves? Could it be like this?
 
#122 ·
@adyamg,

If you are getting 10mm of aerated oil, that is a lot of air. Fox's published bleed procedure doesn't get all the air out, but it's good enough. Definitely make sure both the compression and rebound are set to full soft/fast. If not, the ifp will displace and leave a pocket of air above the piston. When you do it right, quite a bit of oil will vent out the bleed port and run down the side of the damper body.
 
#123 ·
@ktm520 if it would be air in damper oil, when I have turned it upside down, the air should have moved to the ifp plate and should have not been felt at the beginning of the run! It should have been felt at the end of the run/stroke.

Besides that, I have got the oil out from the bleed port when threading the piston into the damper body!
The only think I haven't done is to submerge in oil the piston plate before threading it to the damper body.

Other fact is that I have tried tu purge the air by opening the bleed port on the top of the piston plate(I know that IFP depth got modified in this case). It only got out oil, no air bubbles.

So my gues is that if it is air it is located somwere in the piston, or maybe it could be normal operation noise of the shock caused by oil passing through shimbstack and rebound and all the valving in there?!
 
#125 ·
@ktm520, I have cycled the shock without the air can and I could not feel a swoosh, hiss, nothing, i would say it felt butter smooth.
After installing the air can when pumping it, at about 50PSI it makes a hissing sound, and that is the sound that I get when compressing the shock.

Can you please point me to what Fox said about bleeding and not getting all the air out?
Cane Creek stated something similar here: https://www.canecreek.com/products/suspension/lounge/forum/air-cs-soft-initial-damping
 
#129 ·
Hi all, I have a Van RC that bottoms out on my 2012 Trance X2 which I'd like to tune, would increasing the ifp pressure also increase bottom out resistance?

Could I just unscrew the old 4mm hex screw, screw on that Schrader valve and get pumping; no need to do a full rebuild on my shock?

I found a link from fox (https://www.ridefox.com/help.php?m=bike&id=63) that shows the ifp depth for the Van RC, it seems that they state the same depth for all the different travel versions of this shock, how could that be? Isn't ifp depth determed by the shock travel?
 
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