For those interested, today I attempted servicing my Sachs shock on my 2010 TE450. The workshop manual is a pretty good comprehensive yet understandable to the layman, so don't be scared to give it a go. I had a very good suspension tuner help me so I knew I was doing the job right. Things I noted... You need a vice with aluminium (or "aluminum" for you Yanks out there) jaws to make sure you don't damage the shock. A decent circlip pick is needed to remove the circlips. The manual says you can use 2 screw drivers, which is correct, but a pick makes it heaps easier. Rather than trying to pull the clip up at first, push it down near the gap in the clip. Once half of it is out of the groove it's much easier to then pull the other half up and then the whole clip out. A Gasket Scraper or slightly blunted wood chisel makes getting the shock absorber cover off easier. Be careful when pulling the piston and forkrod unit out as it pops out once the O-ring gets past the circlip groove. It's quite easy to hit yourself in the face if you aren't careful. I wasn't going to bother disassembling the piston unit, but I'm glad I did. There is quite a bit of dirty oil trapped between the shims that needs to be cleaned out with a degreaser first, then some brake cleaner followed by a blast of pressure air to remove any residue. You can either put a screwdriver or a loop of wire on the end of the rod and pull the whole shim stack and piston assembly onto it to keep everything in order while you clean it. When cleaning make sure you get in between each shim. I wasn't going to bother replacing the seal and bush - I just wanted to change the oil - but upon inspection the bush was a bit worn and it had caused some minor damage to the forkrod. Nothing that could not be sorted by a bit of fine grit sandpaper to cross-hatch the rod again. I had to use a punch to dig into the bush in order to get it out - a little violent I though but it was the only way to do it. Pushing the new bush in was a bit of a mission, so I will be investing in a little press bullet to do this in future. When putting the new seal on, either get a shock-rod-bullet or put some insulation tape on the sharp edge of the rod near the threads so you don't damage the seal. It's also a good idea to put some grease on the seal to make it slide on easier. I didn't bother disassembling the compression adjustment. Makes the job quicker and easier, and I'm not sure there's benefit in doing it. I didn't bother removing the reservoir either. Before reassembling everything I made sure I cleaned both inside and outside with degreaser, then brake cleaner followed by a blast of air. The manual says to top up the shock absorber body with fresh oil first, but my tuner recommended filling the reservoir first. Fill it up to the brim (no need to measure a set amount) then put the diaphragm making sure you don't trap any air - which you shouldn't if you fill the reservoir to the brim. Put some grease on the O-ring on the diaphragm to make it slide in easier. Push the diaphragm down till oil appears in the shock body. This way you can be pretty sure you've forced all the air from the compression adjustment parts. Once you've done that, put the reservoir plug back in and make sure you put the circlip back in place otherwise it'll pop off when you push the piston in. Top up the shock body up with oil then push the piston assembly in. There will be resistance so you need to keep releasing air pressure from the reservoir. Push the piston down fairly gently so it is well covered by oil, then move the piston up and down slowly. You should see air bubbles coming up. Once no more bubbled are coming up, pull the piston up to a couple of cm's (just under 1") from the top of the shock body, making sure it is still covered with oil. Tap the forkrod firmly (but not too hard) to cause sufficient shcok to force oil past the shims. You should see more air bubbles rise when you do this. Do it several times till no more air bubbles rise. Now you can be pretty sure there's no air left in the system. Top the oil off to the circlip groove in the shock body and push down on the rod making sufficient pressure is released from the reservoir valve to allow the circlip groove to be seen in the shock body. Now put the shock cover and push it down till you can see the circlip groove - it may require releasing pressure from the reservoir valve to so this. Once you can see the groove, insert the circlip to the cover is secure. Now using a low pressure pump (like a bicycle pump) put air into the reservoir valve until the shock cover seats itself on the circlip securely. Probably around 40-50psi. Once it is seated properly, release the air from the valve then get it charged with Nitrogen. The manual says 10-12 bar of Nitrogen which is quite a wide range. My tuner charged it to 150psi which is just under 11bar. You can now push the shock rod down and it should slowly push its way out on its own. Now put the spring back on and you're ready to put the shock back on the bike One of the issues I had was that I could not find any "Shock Oil" at my motorcycle shops so I didn't know what to use. My tuner has done some pretty extensive testing on a shock dyno with various oils and has determined the Motorex 5W Fork oil (yes, FORK oil) is stable enough to use and performs well. So that's what I used. The important thing with whatever oil you choose is its viscosity (measured in Centi Strokes - cSt) and not its "weight" rating. Sounds like it's quite a job but you can knock it over in a hour or so if you have everything prepared. I'm glad I've learned how to do it now and will be servicing the shock every 12 months from now on. Apparently by the end or 12 months the viscosity index improvers in the oil have significantly broken down and so the viscosity when the oil heats up is wrong for your damping circuits.
Great write-up! I've been using Maxima Light Shock Oil in my Sachs and WP shocks and it seems to be working very well. In my older Ohlins duals, the Maxima Heavy matches the Ohlins oil specs very closely and works great. Why Maxima... cuz my dealer has it!
A cool trick I learned is to stick safety wire between the piston and the first compression shim, at each port, with a long tail all the way to the clevis. This holds the shim open just a hair, so you don't get air trapped under it, and you don't have to pump it up and down to bleed it. You just insert it, pump a couple times, and yank the safety wire out! Be careful putting it in and yanking it out, but I've done it several times now with no problems.
Fantastic! Im knocking this job out this weekend. Thanks for the write up. (Even though its 2 years later
I'm looking at the manual for the TE 630, and the following caught my eye in the disassembly section: Keep the shock absorber in the vice taking in nearly vertical position. If you drain the oil, you will need to replace the reservoir floating piston. Pour the oil into a clean pan and leave it to settle. Do they mean 'replace' as in 'put it back', or do they mean 'it is screwed up, you need a new one'? From this I assume the TE630 has a floating piston and not a diaphragm, so it needs the same bleeding procedure you use on KTM shocks? Anyway, just curious if anybody has freshened up such a shock and has tips not covered in the manual.
I haven't rebuilt a TE630 Sachs, but every other Sachs I've done has a piston and not a bladder in the reservoir. You do not have to put a new one in when you change the oil, but you will have to reset its position in the reservoir to proper spec.
I don't know if it fits, but it's really not needed on the Sachs. It works great with some valving. Also, I'm wondering if y'all are mixing up the 2 pistons in this discussion? There's a floating piston in the reservoir and a valving piston on the shock shaft.
That's the floating piston from the reservoir. Take that O-ring off without scratching the grove, and make sure the groove is SMOOTH! They tend to corrode under there and then nitrogen will leak past and get into the oil. I use a dremel to polish that groove to a mirror finish. Make sure the O-ring is not smashed/distorted, then lube and reinstall.
Mine is a 2001-2 WR360 with Sachs shock that i recently gave a birthday. I got a RaceTech gold valve kit for it only to find the kit was for a 46mm body while mine has a 50mm body. Anyway it had an alloy floating piston with an O ring plus a ring type fibre seal on the oil side. The hollow side of my floating piston was on the oil side so when you push it back into the reservoir with the shock part full of oil you trap an air pocket. so once i had the shock back together i had to turn it over so the comp adjuster was the highest point and remove that to release the air pocket then top up and fit the comp adjuster back in. So if i was only going to change the oil then i would do it from the comp adjuster as its much easier. hope this might save some else a lot of time Mike
Your separator piston is in upside down. I do Beta Sachs often with the same piston and the flat side is the oil side. You trap no air with the flat side to oil, done correctly.
Since the sachs doesn't have a bleeder screw, I was wondering if a funnel could be made to thread into the compression screw. Got the idea from this vid: View: https://www.youtube.com/watch?v=LsPTYlW3REo&t=662s Would make for a much cleaner service process
