07 sachs? rear shock packing/hard/no rebound?

[stainlesscycle]

welp, i'm thinking my sachs has the infamous no rebound deal. gotta tear into it today.

symptoms: when cold, i bounce the bike and it appears to have rebound and work fine, etc.

when riding. beats me to death. kinda a mixture of pogoing, packing, and just hard. it would bottom occasionally. never had an issue with it before...

it doesn't make any funny noises, and the seal/shaft look fine/no leak. i've not torn it apart/removed it yet.

i'd like to send it out, but i have a race on sunday, don't think i can get it back in time. so i'll probably just tear into it myself. i read the writeup on les' site, anyone have a source for the proper o-ring? or one that works?

or is it case of just changing oil/refilling nitrogen and it will be fine for a few weeks until i have time to send it out??

also - what psi on the res?

 

[GMP]

I have to look into doing mine as well. Always had Les go through it in the past. From what he told me the early '07 ones were better, the latter ones had the check valve issue. Mine is just spent and needs basic service, got a bit rough in a race yesterday. I put a lot of this stuff off on the '07 figuring the '12 would be here and I'd get back to the '07 later. Now I'm faced with a few mid season service issues.

 

[stainlesscycle]

in general will just a fluid change and nitrogen refill solve problem? obviously i'll have it open and see if anything is wonky. once i get it off, i can check it without spring and see if it's fine (which means it's the rebound issue i would think)

 

[GMP]

If the oil is hammered it will fade quick, and if its real bad it could foul the valving, but thats pretty bad. Rebound is the first thing to go. I have no idea if your shock has the check valve or not.

 

[stainlesscycle]

did a quick purge/refill. filled through the compression adjuster hole - seemed easier than pulling the shaft ( collar wouldn't budge..). gotta take it over to the shop and get some nitrogen put in. 195psi? then to check it, and hope that fixes the issue.... or else it's gotta come off again..

 

[GMP]

Can you do it that way? How are you sure about the seperator piston position? I heard of a guy assembling shocks in a fish tank full of oil to avoid any bleeding problems.

 

[BrentMartell]

My opinion: If your bike is cold and has rebound it is oil related. If you bike is cold and there is no rebound it is internal. On my ohlins I spin the rebound to see if it is making a click sound, if not, it is usually related to NO NITROGEN. BTW, I think 150-160 is normal in Nitrogen. 195 seems high but I am not experienced on sachs. Showa, WP, and Ohlins are around 150-160.

 

[moto9]

Can you do it that way? How are you sure about the seperator piston position? I heard of a guy assembling shocks in a fish tank full of oil to avoid any bleeding problems.

You can do it that way, just pull the rez cap and push the rez pistion into place and let the excess oil flow out the comp adj hole.

Probably would be pretty messy though.

I have a rez cap with a fitting that I hook up my (home built) vacuum pump
bleed system.
For a quick oil change I remove the bladder/rez cap only, hand pump out the old oil into a bucket...then install the rez cap with the fitting and cycle in new oil and bleed the shock at the same time...quick, easy almost no mess.

Also I get a complete bleed with degassed oil...you wouldn't beleive how much air is trapped in non-degassed oil.

 

[stainlesscycle]

you can position the separator piston with a few psi of air. holds it still while you fill it. then just pump/filll.. before you reassemble adjster, you gotta play with it a bit to burp the last air outta the res side..

i might have made an error. doesn't the seperator piston go all the way in when you fill on the sachs? or is there a specific height it has to be at?

 

[stainlesscycle]

My opinion: If your bike is cold and has rebound it is oil related. If you bike is cold and there is no rebound it is internal.

this is what i am hoping.. i took the spring off, and it had compression and rebound. spun the clickers a bit and they all seemed to make a difference..

On my ohlins I spin the rebound to see if it is making a click sound, if not, it is usually related to NO NITROGEN. BTW, I think 150-160 is normal in Nitrogen. 195 seems high but I am not experienced on sachs. Showa, WP, and Ohlins are around 150-160.

i know the ohlins won't click without nitrogen. i think the sachs will still click - dunno.. there was nitrogen in there, the oil was not great, but i've definitely seen worse. hopefully it'll work, can't run over to shop to fill till tomorrow. so if anybody knows the correct psi of nitrogen, let me know


i have stock valving, and i've got all adjusters at around 13-15 clicks out. i have it written down, but not with me now.


'

 

[GMP]

This originates from les, found on TT about a year ago:

1) Fully open rebound and compression clickers then remove shaft and reservoir piston
2) Drain oil from shock body
3) Clean innards and dry with air
4) Fill body with fluid and watch it drain over to the reservoir
5) Fill reservoir and watch it drain over to the shock body until the reservoir was full
6) once reservoir was full, insert reservoir piston to bottom and from the piston to the reservoir edge it should measure at 79mm
7) While holding piston down, insert shaft assembly to bleed it of air, make sure seal head is on the clevis end.
8) Put shaft seal head towards valve stack again and hold the reservoir piston while inserting shaft, let the shaft seal head get to right where the sealing o-ring is just above the lip of the body and let all the oil drain naturally
9) Once all the excess is drained, finally plunge the seal head sealing o-ring into the body and snap in the ring that holds the seal head and shaft. The reservoir piston will naturally rise when this happens.
10) Measure the piston depth and it should be 68-70mm at this point if you got it right.
11) button her up, she's good to go.

 

[stainlesscycle]

SO maybe I gotta open it back up. Looks like piston depth is approx 9mm from bottom. Mine is at bottom. How critical is this - I would think I may lose a few mm of travel. Any trick to getting the shaft collar off? I made a pin spanner for it, and it wouldn't budge .


Or could I just remove res cover, pump shock once or twice to move piston down. Set piston depth 68mm. Hold piston with 68mm rod, pump and fill/burp res - fill through adjuster- Button it back up.

 

[stainlesscycle]

doh! i was under the impression there was no such thing as a manual for this shock. just saw the link, gotta check it out.

 

[stainlesscycle]

does shaft collar screw off? i've been trying to screw it off, looks like it pops off with a drift?? is it a screw type collar or is it just a press fit 'dust cover'??? also found 10-12 bar (145-175 psi) is nitrogen psi. wold have been nice to have this manual when i built the shock. looks like i'll tear it down again and redo it.

got it all apart. everything looks good, no mechanical issues. just gonna fill it and see what happens.

 

[stainlesscycle]

got it all done. i can't see how les would get it to bleed out to 68-70mm. there's no air in mine, and i got close at maybe 65mm depth. of course that's why we pay him to do it get well soon, so i can get this thing done right!

it feels no different right now then before., i put 120psi of air in there just to held things still til i get it to my nitrogen guy. hopefully it was just bad fluid...my back is killing me from yesterdays crappy race..

oh, and i forgot to mention - my 07 does not have the rebound check valve.

 

[Simmo737]

If it still doesn't work, step cut the piston band and see if you can find an oring the same size as the one underneath, maybe one size thicker.

If you can't find one, a husky race tech kit will give you a new piston, band and oring for 150 from oem cycle, you will have to use their valving which I personally think is good.

You can also buy bladder kits, can't remember the place (they sell groovy water pump impellers too) which makes bleeding them way easier

Edit: checkpoint offroad for the bladder.

 

[lonetree]

Mannual???????????
Link???????
Where?????????

 

[GMP]

Les has done mine since new and its been updated, pistons faced, and revalved for rocks. Never an issue and no need for a bladder. Just going to do an oil change and inspection. I have a setup I made with a gauge and a zero loss schrader fitting connector. I use this for Tubliss inserts with air but its the same thing needed for shocks with nitrogen.

 

[moto9]

I don't think rez piston depth is that critical, as long as it doesn't bottom out in either direction.

 

[Simmo737]

Can you buy no loss schrader fittings? Or are they something you've machined up.

I am waiting for your book on everything bike to come out, it will be a best seller!