Rear shock rebuilds too hard for a home mechanic?

[c3024446]

I love to fix my own bikes, over time have built up all the tools to fix and service everything like brakes, Rock Shox forks, etc. There is one thing I can’t do though - Rear shock rebuilds / servicing. I know I would need a 500PSI shock pump for the Internal Floating Piston, an adaptor or needle to pump up the IFP chamber, a few other special tools that I don’t have yet…..

What I would love to do is pull apart a mate’s Monarch XX shock before he sends it away to a professional for $200 – it feels the same locked out as it does not locked, and I’m thinking that at least looking at the IFP pressure before sending it away would be a good idea. If I had the pump and the adaptor I could also play around with the pressures and tune my own Fox CTD shock…..

So….is a new shock pump and a few adaptors a worthy investment, or should the pros only do this stuff?

 

[moorey]

Even though I know it's s straightforward job, it's something I decided long ago I'd leave to the experts. Have a crack though, Chigs.

 

[SummitFever]

The Monarch's (and other RS shocks) are easily home serviceable with the only special tool being the IFP fill adapter. Also, complete rebuild kits with all parts are readily available (but not exactly cheap at around the $50-$80 mark). You may need some shaft clamp blocks, but they are easily made out of wood with a drill, saw and some sanding. Once you take parts and labour into account, the $200 your mate may be charged for an XX rebuild is not over-the-top.

The Fox shocks operate on exactly the same principles but the internal parts are not readily available in kit form to the public, the service manuals (and specs) will require a bit of googling to find and the IFP fill procedure requires a more complicated fill needle/rubber pellet, slotted allen key etc. If your frame has room, however, you can fit a schrader valve to the fill port.

If you're not a ham-fisted git, then give it a go. Just take your time and take methodical notes about the order in which parts go (particularly if you remove the piston and shims - order and orientation are critical).

 

[Daniel Hale]

i have a mate who works for a bike parts importer - the handle one of the well known brands -apparently on returns -it is cheaper to issue new shock then waste the man hrs & parts on fixing them

 

[The Duckmeister]

Rock Shox are more easily serviceable than Fox, in large part due to the IFP chamber being charged with natural air through a shock pump, while Fox use a nitrogen charge issued through specific weaponry that's not generally available.

 

[link1896]

Must be a Monarch RL if you need 500psi. That's not going to be easy with the average shock pump, my pumps struggle to get to 300psi. An old scuba bottle and adjusted up primary stage regulator will get you to 500psi with air. Alternatively a motorbike shop that does suspension work will be able to charge to 500 psi for you. My local guy charges 15 bucks for a nitrogen fill.

While consumable parts aren't cheap from SRAM, take them to your hydraulic repair shop, they will hook you up with o rings, quad rings, wipers and back up rings at a fraction of the price. There are threads on mtbr regarding o ring sizes. Have a search there.

While the first service might be a brake even, the next one won't be.

 

[StuartO]

I just rebuilt a fox float performance bv ctd with minimal tools. These only require from 175 to 250 psi in the ifp chamber. Ifp depths are available from online and a full service manual is available. Racetech supply a needle with schrader valve attached to inflate yhe ifp chamber.
Most seals won't require replacing unless it is a very old shock. There are kits on ebay for a good price from over seas with all available seals. I can provide links if you wish. They also sell upgraded lower shock bodies and internal floating pistons with better tolerances.
Not a hard job if you are confident and have quality tools and a mechanical mind.
I also changed to a lighter oil which which gave me a lot more performance out of my stock shock. Very happy with the result.

 

[StuartO]

There you go. This guy sells the seals, ifp's and shock bodies.

http://pages.ebay.com/link/?nav=item.view&id=291143836606&alt=web

If you contact shock treatment at walacia sydney, they sell the racetech needles for about $30 or so.

As i said i didn't replace any seals after about 18months on my shock. Not even the air can seals yet.

Also if you search peter verdone wiki, there is a chart which gives you shock oil viscosities which you can work with. The stock fox fluid is 47 cst at 40° and i changed to 32cst for a little more plushness.

You could go firmer if you wanted a better platform/firmer ride. Poor mans revalve but it works.

 

[SummitFever]

One other thing. There is no special magic about the Fox IFP that requires it to have a nitrogen fill (as opposed to the Monarch which doesn't). I have been refilling the my Fox IFPs with plain old air for years without any ill effects. If you've got N2 fill capability then do it, but if you don't then it won't matter. What really matters is just regularly maintaining the shock.

 

[MARKL]

One other thing. There is no special magic about the Fox IFP that requires it to have a nitrogen fill (as opposed to the Monarch which doesn't). I have been refilling the my Fox IFPs with plain old air for years without any ill effects. If you've got N2 fill capability then do it, but if you don't then it won't matter. What really matters is just regularly maintaining the shock.

Your about 78% there anyhow

 

[udi]

One other thing. There is no special magic about the Fox IFP that requires it to have a nitrogen fill (as opposed to the Monarch which doesn't). I have been refilling the my Fox IFPs with plain old air for years without any ill effects.

Agreed, regular dry air is 78% nitrogen anyway.

Racetech supply a needle with schrader valve attached to inflate the ifp chamber.

Could you post a picture of this? I presume it's literally a complete adaptor that you can screw onto the pump.
If so, how are you holding the needle inserted into the pellet as you pump, got some kind of strap/rig to make it a one-man job?

 

[link1896]

As summitfever mentioned, pure nitrogen isn't needed (maybe for hard working DH shocks) and air is ~78% nitrogen.

The racetech and motion pro needle assemblies use generic health care needles, e.g Becton-Dickinson 22 gauge 1/2" long. if the nurse approached you with one of these, f-ing run.

These are a steel needle into a plastic base that's clamped by the brass assemblies furnished by motion pro/racetech. Any sideways motion, e.g using a hand held shock pump, will snap the plastic very quickly. These needles are designed for a bottle/regulator/gauge setup.

To this day I've not found Schrader ended hoses good for more then 100psi, so I do all my fittings in bsp, best I've found is brass bsp to Schrader adapters.

 

[The Duckmeister]

One other thing. There is no special magic about the Fox IFP that requires it to have a nitrogen fill (as opposed to the Monarch which doesn't). I have been refilling the my Fox IFPs with plain old air for years without any ill effects. If you've got N2 fill capability then do it, but if you don't then it won't matter. What really matters is just regularly maintaining the shock.

The theory behind using pure nitrogen is that i's a little bit more stable in its behaviour as temperature changes. However given, as previously noted, air is around 78% nitrogen, the difference is so subtle that only very few highly tuned riders would actually be able to tell the difference.

Secondly, SRAM philosophy is that they prefer their bits to be more readily serviceable (preferably by trained techs) rather than having to send things off to some sorcerer's kitchen for minor works, hence opting for air rather than nitro IFP charge.

 

[StuartO]

My apologies i struggled to get the right file type on my phone. Here is the link for the racetech one. Same as above really.

https://www.google.com.au/search?q=...hXGGaYKHbsgDKEQ_AUIBygB#imgrc=EwLvdzlSL2vrTM:

I don't have a problem attaching my shock pump to the schrader valve but you have to be gentle when pumping as the needles are delicate. As stated i use air, a lot of people use air. Many will debate you need nitrogen until they're blue in the face. Good for them.

Also with the fox shocks you will need o ring cord. 6 or 7mm i believe. I actually used a rubber grommet cut to size. You will need to just copy the shape size of the original plug. They are a one use only thing.

 

[ctguru]

use generic health care needles, e.g Becton-Dickinson 22 gauge 1/2" long. if the nurse approached you with one of these, f-ing run.

orange 14G are the ones you freak out at!



for comparison the blue one is 22G

 

[Flow-Rider]

One other thing. There is no special magic about the Fox IFP that requires it to have a nitrogen fill (as opposed to the Monarch which doesn't). I have been refilling the my Fox IFPs with plain old air for years without any ill effects. If you've got N2 fill capability then do it, but if you don't then it won't matter. What really matters is just regularly maintaining the shock.

Half the blokes I ride with don't even notice their rear shock leaking, let alone what type of gas is in their rear shock.

 

[link1896]

orange 14G are the ones you freak out at!

View attachment 323194

for comparison the blue one is 22G

Eeeeew. I hate needles. My hatred of needles is up there with most people's hatred of heights.

 

[link1896]

My apologies i struggled to get the right file type on my phone. Here is the link for the racetech one. Same as above really.

https://www.google.com.au/search?q=...hXGGaYKHbsgDKEQ_AUIBygB#imgrc=EwLvdzlSL2vrTM:

I don't have a problem attaching my shock pump to the schrader valve but you have to be gentle when pumping as the needles are delicate. As stated i use air, a lot of people use air. Many will debate you need nitrogen until they're blue in the face. Good for them.

Also with the fox shocks you will need o ring cord. 6 or 7mm i believe. I actually used a rubber grommet cut to size. You will need to just copy the shape size of the original plug. They are a one use only thing.

7mm for all the fox shocks I've played with. I've a lot of 7mm continuous o ring in buna70, if anyone needs any let me know and I'll post you some.

 

[merc-blue]

I'm going to put it out there that there are many small details often missed by home mechanics on a shock service.

any monkey can rip open a shock throw in some oil seals and fill an IFP but that doesn't constitute proper service in my book

There was a time where I did alot of shock servicing and I always found it hard to explain to customers the level of detail that is taken on doing a proper detailed job on a shock service


I spose it depends on how well you want to do the job.
Look at Links thread for brain rebuild and the amount of tooling he had to make i can think of another 3 or 4 bits that i would have used to make sure the job was done "well" in my books.

 

[link1896]

I'm going to put it out there that there are many small details often missed by home mechanics on a shock service.

any monkey can rip open a shock throw in some oil seals and fill an IFP but that doesn't constitute proper service in my book

There was a time where I did alot of shock servicing and I always found it hard to explain to customers the level of detail that is taken on doing a proper detailed job on a shock service


I spose it depends on how well you want to do the job.
Look at Links thread for brain rebuild and the amount of tooling he had to make i can think of another 3 or 4 bits that i would have used to make sure the job was done "well" in my books.

There is definitely a component of trade craft that no manual can convey. YouTube videos on the other hand.

Tooling for a proprietary shock was never going to be easy, but that project got very silly.
One tool piece I never added to the thread was a chamfered nose piece for the damping rod so when I installed the bearing block I didn't damage the o ring.

I'd be interested to hear, if you're happy to share, the other tricks you've picked up.

When we rebuild redbruces shock I'm hoping we can get a video of the rebuild or at least a pile of good photos