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OK...I admit being lazy about it...have had my shock serviced by a 'local' (within the state) guy. Now I find the guy MOVED to OKLAHOMA 'fer crine out loud. That's a WEEK shipping...ONE WAY!

There have been some posts about it..not a lot.

How many have tried it and found they DIDN'T like the result?

I'm contemplating doing it myself..and this will be my virgin shock venture.

I am basically familiar with the process..and know some of the tricks having watched accomplished tuners do it.

Still....I can't imagine getting the thing back together with ZERO bubbles. Well, unless you submergerged the whole thing in a bucket of fluid when you put it back together.

Speaking of which, of those that have done it, what was your fluid choice?

Did you use 'special' bladder grease?..or did you use something else?

After reading some rather technical test results on using 'air' vs: nitrogen for pressurization, I'm less convinced that nitrogen is a necessity. Maybe a hand shock pump would suffice....??

Whadd'ya all think?

Thanks!

My guy hasn't moved yet,, so I'm not contemplating anything......

On the air VS nitrogen I've often wondered the same thing.
How much gas, volume wise, goes in there?
Air is %70+ nitrogen, the other gasses, oxygen and such, shouldn't hurt anything.
The construction is pressurized gas behind a rubber bladder pushing on the oil in the shock, right?

Are we worried about a little water? Doing what, changing the gas pressure due to temperature changes? What about the gas changing pressure due to temperature changes? And the oil viscosity changing due to temperature changes?

I suspect they are actually filled with nitrogen as a way to remove a possible variable and because it is cheap and easy.

just musing......

Well, I guess I shouldn't answer since I have always liked the results ...but I've serviced my own shocks since day one and have never had a problem. I've used everything from various weights of fork oil (to change the flow characteristics when I didn't have the time or patience to figure out the valving) to expensive shock stuff gotten from Race Tech.
I've never had a problem getting rid of the bubbles, you just cycle slowly (so you don't generate more foam) until the bubbles are gone then put the bladder in place which forces out the excess oil.
I've always used nitrogen - I'd bet any comparative air vs nitrogen studies were done with air that was completely purged of moisture (moisture IS a main culprit of air expansion problems) and other contaminants. I don't know if you could get that kind of stuff any easier than nitrogen.

I've never used any bladder grease (i've never heard of it til now), the bladder is wet with oil when you push it in place.
For a guy with your mechanical experience it should be easy IMO.

I once watched a west coast suspension expert revalve and service a shock in his van. LOL... he used a claw hammer to assemble the thing - unbelievable. And this guy modifies pro's shocks!
It's not the rocket science some think it is.

I didn't save the link..and didn't go looking for it, but the 'study' came from a guy that had always wondered the same thing...in regard to the 'new' craze of filling vehicle tires with nitrogen. He tested pressure differentials in several different pressurizing gasses..air, damp air, wet air, water left in the tire, and nitrogen. He found that with a reasonable 'air' fill-up (not something out of a tank 1/2 full of condensate), there was very little difference between it and nitrogen.

And, yeah...'air' being +70% nitrogen as you say to START with..what indeed is the big deal?

Yes, I imagine that NO moisture is better than SOME when it comes to bladder 'corrosion' or debilitation...but over what period of time? Many years?

Nitrogen fill is cheap and easy if you have the setup to do it. If you don't...it's not so cheap OR easy.

Re: '..a guy with my experience...'

Like the seven some hours I spent on suspension maintenance yesterday? Like the notable part of that time spent looking for the ONE pin that dropped out of the Unitrack where I have one PivotWorks (uncaged) bearing?

Good grief! What a lot of soaking, scrubbing, spraying, cleaning, drying, packing.....

Knowledge doesn't always come from 'experience'. Experience may indeed be the best teacher..but that don't mean the learnin' is easy OR that it even takes place!! You can have the best teacher..and not learn diddle! I have never been at all even a little impressed with anything I think I know...'cuz I know the LACK of knowledge is HUGE.

I'm familiar with summ'a that high$$ susupension fluid stuff from RaceTech..just from looking into various fluids.

Did you find you preferred one type of fluid over the other? Or have a preference having used different fluids?

I think you did a write-up sometime back about basic shock maintenance? If not (or I can't find it) would you be so kind as to run though a basic 'how-to'?

That would be very much appreciated.

Thanks!

Yeah, I was in it enough once to justify the cylinder cost. Don't you have a nearby shop with a cylinder who can charge it after you assemble it?
You still need a special filler valve that closes the shrader valve prior to releasing the filler hose - but they aren't too expensive. Most shocks are designed for at least 140 PSI, so just releasing an ordinary air chuck will amount to virtually depleting any pressure within the very small volume of the bladder.

If the air doesn't work out it would be no big deal to replace it with the nitrogen later I suppose.

Edit:
Basic shock maintenance (my el cheapo version) is just about replacing the seals (if leaking), lubing or replacing the linkage points, and replacing the fluid - nothing more. Every brand of shock is valved differently or has some different retaining clip arrangement or whatever, so it is important not to disassemble any more than necessary, unless you want to work harder than I do. If the seal isn't leaking you don't need to take anything apart to change the oil, other than removing a replacing the bladder.
They aren't complicated...just be sure to release the pressure before you begin to work on the thing so you won't end up smelling like dirty fish oil.

After I flush out the oil with new stuff, I let the shock sit overnite upright to let any foam disperse before I finish it off.

I have never developed a preference for an oil brand - they all seem to work the same, and I often use whatever I happen to have on the shelf, including 5W fork oil.

I am not a purist.

I know at least one local shop will NOT pressurize a shock they didn't put together.

I haven't gone looking for someone that WILL do it.

Yeah...considering the HUGE volume (not) you're dealing with, one 'pfffft' with a pressure gauge (not that I HAVE a 160# gauge!) should be good for 10-15psi, 'eh?

Oh yeah, the reason I don't do any more than noted above, is that if the shock is so worn that you need to replace any of the damping elements, my experience is that the cylinder body is shot also. Time to replace the shock.

what about fredette? I had mine done and it wasn't that expensive, his turn around was also pretty good.

My shock works fine..it has been valved and revalved to suit..no leaks, drips, runs or errors.

Excuse my ignorance..but you can get the shock body refilled with ONLY the bladder out?

Maybe you could add a nickel or two to your 'el-cheapo' version?

Oh...I did search the site..found some references to complete 'how-to's that didn't actually show up (as far as I've been able to find)..and some links that aren't what they say anymore (after a few years).

Heck! Go crazy!! Gimme the 2-bit ($.25) version!!!!

Re: FRP?
Freight out of the state has gotten to be pretty much insane! Cost AND time-wise.

Sure...now remember this is from a self-trained dufus ( who hasn't done a rebuild in about 5 years) so reader beware...

1. Take the spring off the shock.
2. Depress the end of the shock reservoir with a socket that fits over the schrader valve. Sometimes you need to pop it loose with a hammer blow or use a vise if you've got a big enough one.
3. After about 1/4 to 3/8" or so you'll see the retaining ring, which is now removed.
4.Remove the bladder.

Now, if all you're going to do is change the fluid you can cycle the old stuff out using the reservoir as the inlet - what I have sometimes done to speed things up is to pull the damping adjuster assy and filled from there. (I don't know if you can do this with all shocks, but it's no big deal to look and see). Using this method generates foam, that's why I let the shock sit overnight to clear before I finalize the job.

5. Fill the bladder with fluid with the shock shaft extended, and install the bladder forcing out excess oil - once enough inside the reservois put in a small amount of air (I'm talking hand pump gently) to assure the bladder is to shape but not inflated. Replace the snap ring. Recharge.

If you are going to do a full rebuild or revalve, you'd take off the dust seal on the shock body, depress the inner seal and pull the snap ring that holds the inner seal, (2 snap rings in a showa), then remove the shaft assy.

Once you replace any shaft parts and the seals. (just like a fork ass'y you've got peened threads you'll have to deal with during disass'y and you'll need to use locktite to reassemble). Next you'd fill the reservois body with oil and replace the reservois bladder while letting it overflow. Install the snap ring. Put a bit of air in it (enough to hold the shape so the right amount of oil ends up in the shock) and refill the shock body with oil till it overflows. Then you install the shaft assy with that oil overflowing.
Replace the shock body snap ring(s) and you're ready for nitrogen.

Now, I've gotten away with 140 to 150 lbs in the shock in all my bikes because that's all my regulator can handle. I've never noticed any difference. But, normally Kayaba's used to run about 160 lbs and showas ran about 200. At least that's what they used back when I did that kind of stuff.

Anyone else is welcome to chime in...I'm sure mine is not the only way (or best way?) to do this... But, it's always worked for me.

sounds about the way I did it (oh, and I'm a dufus too )
If I may add, once you've got the shock apart, might as well clean everything before adding new oil, worth the extra 15 min (to me). Last time I did it the oil was black and there was god know what in the valve between the shims (crud, gremlins, what ever, don't belong there anyway)

I just followed the steps to the letter....

It would have been much easier to depress the bladder if'n I'd let the gas out first!

...a guy asks a favor then gives you crap about....now there's a dufus for 'ya!!!

At the least, a jerk!!

Thanks!!

Questions??:

Did you use grease on the bladder on reinstall? What kind? I know there is a 'special' grease for that purpose.

How is the dust cap held on? It's not threaded, is it? An o-ringed friction fit?

What's your choice of cleaning agent? I don't know if Brakleen would be good. It's not supposed to contact 'rubber' parts. I don't have an Agitene tank!

Does it matter which end gets put in first? Because pressurizing the fluid is going to force any air to the 'end' (by repeated shaft actuation) my first guess would have been to fill the body first...clear the fluid by repeated strokes, then fill/place the bladder. No?

I found a 0-300psi shock pump on the web: Here.

It's advertised to have a no-leak release setup for the express purpose of equalizing pressure in separate shocks. I'm making the assumption that a 0-300psi choice means the pump will put that much pressure.


Thanks for the input/help/assistance. I greatly appreciate it!!

Who's coming up for a ride this-a-way next month? Check 'Group Rides'. Californy is right next door!!!!

**edit**
Howz about putting the shock pump in a plastic bag 'filled' with canned air? I'm not sweating using air..but that might be a hokey way to get something other than atmospheric air in there......

I've never used bladder grease, I've never had a problem getting 'em back in. The dust cap is pressed on; a friction fit.
If you're gonna tear the whole thing down conventional wisdom states the bladder should go in first (at least that's how the pro's do it) then the shock body is filled with oil and the shaft assy inserted. Either way will work, and I honesty don't have a personal preference based on my own experiences -
I've always just used clean oil to clean it out, if the shock is not completely disassembled. I distrust solvents not knowing how they might affect seals, etc. whose composition can be a derivative of animal, vegetable or who knows what....fish left-overs?

Howz about putting the shock pump in a plastic bag 'filled' with canned air? I'm not sweating using air..but that might be a hokey way to get something other than atmospheric air in there.....

I think you're trying a little too hard there...

Who is your guy who moved to Oklahoma? Was he good? If so, any idea where he works?

If I can do it shirley you can do it

It was not very hard

But I can't 'member any specifics.... twas a long time ago....

hunnerds of gallons of OS, I bet

CC, just do it, it snow big dill. You've done a lot harder than this. The only thing that I had a problem with was getting the old seal out of the seal head because I didn't really understand that you had to bend the metal up on that part. once you do it its pretty simple, but I would just buy a complete new seal head from Racetech next time, since I think it was about $40, and it took me about 2 hrs of screwing with it.

As for cleaning the thing, as said previous, the oil and parts turn black inside, you want to get that out. So you need to grind the peening off the shaft so the nut can come off. Axially, sense yours has already been rebuilt before, the shaft should be ground. Might need to hit it with heat if they used loctite. for solvent I used mineral spirits, then dried everything well. I did use brake cleaner on the empty shock body. getting the air out is easy on a Kawy cuz they have the bleeder screw. Yamies don't have that.

For oil I used some Motul "KYB type" stuff as I recall. I pumped mine up with my compressor when I was done to make sure it would hold 130 psi, then let the shop see it was that high and they let the air out and pressurized it with nitrogen for about $15. They trusted the shock since I had already pressurized it. Another shop wouldn't touch it, but they're a bunch of brain-dead pussies on other accounts.

I thought I posted about this back when I did it, with a lot of feedback from Jeb, but maybe I'm Miss Tooken.

The Premise behind using Nitrogen, Is that it is FAR MORE STABLE during Temp. Changes compared to air. A lot of Pro riders use Nitrogen in their Front Tires.

I believe the other reason for using Nitrogen is that it prevents the shock oil from oxidizing( and any other part inside the shock for that matter). The shock oil is exposed to high heat and agitation-great conditions for oxidation to occur. If there's no oxygen, then no oxidation. No oxidation, equals slower degradation of the oil, and no acid/gum formation. While I don't think I'd bother with nitrogen in the tires I'd definitely use it on my shocks.
Joe

Green Hornet wrote:The Premise behind using Nitrogen, Is that it is FAR MORE STABLE during Temp. Changes compared to air. A lot of Pro riders use Nitrogen in their Front Tires.

That's the publicized BS about it. Fact is, relatively dry air (meaning nothing special) is so lttle different in that respect as to be negligible. Again...air IS almost 80% nitrogen in the first place.

There is no contact between whatever fills the bladder and the shock oil. Hadn't better be, or you have a lot bigger problem than what you pressurized the bladder with. 'Air' in the bladder never touches the oil in the shock.

I'm not saying there is no difference whatsoever, so why bother. I'm saying, given that I don't have a $200 nitrogen setup, the expense and the bother...WHY bother? If I paid $65 for a shock service, I would NOT say, 'Hey! Fill it up with air 'cuz I don't care!'. It would already be part of the deal.

The tuner's name is Richard Wilson. The name of his suspension business is 'House of Horsepower'. Google the name, and you will find him at the top of the page..phone numbers, address, email addy...the whole enchilada. He comes off as an abrubt hot-rod to some folks. If that's the way you choose to describe a no-nonsense #1 plate holder in the district, fine. I've been in his shop, asked plenty of questions, hand delivered some of my stuff and waited while he got it out the door for me within the hour. I got along fine with him. He's probably better on punkins than some other type of suspensions..cuz that's what he rides (used to anyway). He was a punkin dealer in this area for awhile. I have very much enjoyed his work on my shock..it suits me perfectly. I DID prefer Jeremy's (MX-Tech) valving over his on my OEM RSU forks. Give him a call! Make up your own mind. Tell him, 'Hi!' from The State of Jefferson! (He might recognize that as formerly the State of Oregon).

Re: 'I think you're trying a little too hard there...'

See the little guy rolling the rock? Yep! Trying too hard (and likely not actually getting anywhere) is what I do best!