Diving into the Sachs 48mm forks - wish me luck?

[swazi_matt]

isn't that typical of GG to have different cartridges!

I see you also have some nylon preload washers in there as well.

I also trashed one of my clicker screws, got twowheels to sort it out when he did the revalve. I am sure he will tell you how he did it.

 

[swazi_matt]

Not sure how you are holding your cartridges, but from what i have seen guys cut the correct diameter into two pieces of wood and use that to hold the cart in the vise.

keep the pics rolling i have wanted to do this for a while bt as soon as i have my forks off i can't wait to get them back on and go riding!

 

[twowheels]

I tried for a long while to undo the cartridge, HOLY CRAP these are tight.


Next problem is the best way to undo the bottom of the cartridge when it is locked. How is this done? I'm tempted to stick a bit of 6mm rod through the oil holes in the bottom of the damper tube and use that to undo the tube from the spring land? Is this safe to do?

Temptation isn't a sin until you act on it - STOP BEFORE YOU TWIST THE CARTRIDGE TUBE LIKE A BARBER POLE.

The proper fitting tool (your cartridge cap being different than any I have seen), lots and lots and lots of heat without melting the seal inside, and a sharp impact are what's needed to get the cap off.

 

[n_green]

Temptation isn't a sin until you act on it - STOP BEFORE YOU TWIST THE CARTRIDGE TUBE LIKE A BARBER POLE.

The proper fitting tool (your cartridge cap being different than any I have seen), lots and lots and lots of heat without melting the seal inside, and a sharp impact are what's needed to get the cap off.

Yeah I know. But thanks for the intervention confirming what the back of my head already knew.

So what's the best way to hold the cartridge? Is it like Matt said, hold the cartridge tube in a vice using correct sized jig and then use the tool/heat/impact to get the cap off?

 

[twowheels]

Yeah I know. But thanks for the intervention confirming what the back of my head already knew.

So what's the best way to hold the cartridge? Is it like Matt said, hold the cartridge tube in a vice using correct sized jig and then use the tool/heat/impact to get the cap off?

That Matt's a smart fella - what he said.

 

[n_green]

Another question, how tight is the base valve stack nut done up? I'm guessing not very but even with my torque wrench set to 2nm it was tightening it more then it already was prior to removal. It's a cheapie torque wrench though.

Is finger tight a specified torque? Lol

 

[Jakobi]

That brass clicker has scared you now. Hahah! I have no idea on torque specs for the shim stack retainer bolt, but I would be taking a guess that a bit of red locktite, and a bit more than finger tight would be in order. More like firm Haha! You don't want it coming undone and floating around your internals.

Also if you've using a bit torque wrench it probably won't be accurate. Most are only really accurate in the middle of their specified ranges so coming out to the ends introduces variance. I have a 1/2" drive kincrome for the big jobs which I rarely use, and a small GearWrench 1/4" drive which was purchased for doing 4T top end valve gear. Its ace for the smaller bolts everywhere! Was a pricey lil wrench though! (http://www.gearwrench.com/catalog/t...wrench/stockdetails.jsp?view=stock&part=85050) I'm sure I paid more than I wanted to when I bought it years back. See them around $100-$140 now which isn't much more than I paid for the kincrome. Tools tools tools!

 

[n_green]

Well the clicker wasn't as bad as I thought. All I had to do was run an 8mm x 1mm die over it which cleaned it up nicely. I also had to run the 8mm tap through the cartridge rod to clean the female thread up a bit as it had squared off the beginning of the thread.

I did stuff the first two threads on the clicker screw but there is still 5 threads left and there's no load on it. Still winds all the way in and out when the fork cap is on the rod too. Very lucky!

 

[n_green]

Success (sort of)

Clamped the cartridge in a "proper" tool

Then after removing the spring guide used this tool that Terry Hay custom made for me today (can't speak highly enough of the service at Shock Treatment) to crack the cartridge. Good tip from Terry, lay the cartridge on a hard flat surface and with a hammer rap the cartridge where the cap threads into it, it helps break the loctite. He made it look easy, didn't even use heat. I'm back at home with the remaining cartridge and even with heat still can't crack it without it twisting in the cartridge holder.

 

[n_green]

Removed the rod from the cartridge. Pulled the shim stack.

Rebound Shim stack is:

Piston
23 x .1 (2)
20 x .1
18 x .1
16 x .1
12 x .15
10 x .3
13 x 2.15 washer (2)

Mid-valve shim stack is:

Piston,
25 x .2 check plates (2)
and has a 1.1mm float.

 

[n_green]

To completely disassemble the damper tube I'm guessing you undo this as well?

It's very tight and until I know if I should definitely remove it I won't.

Also discovered that one of my cartridges is 'sticky' and the damper tube binds in the cartridge cap during the last inch of travel. The other cart doesn't do this and neither do the two spares I got from Simmo.

Synergy is this the nylon bushing you were talking about that has too small an ID and causes binding? (located on the underside of the cartridge cap. Pain in the butt to remove, tiny little cir clip in a groove in the cap itself, I couldn't get hold of it so gave up for now. Is there anything other then the nylon/plastic bush in that cap?

I haven't even looked at it yet but between the spring guide and cartridge cap there is a small round bush that sits in a recess on top of the cartridge. What is this? Should I leave it alone?

Thanks again for any info.

 

[n_green]

Also, what's the best way of tightening the base valve?

The cartridge tool I had made will work but I have to remove the spring guide to fit it, does putting the fork back together and compressing it upside down (reverse of undoing the base valve) work?

What torque do I tighten it to?

 

[Jakobi]

I'm no genuis here, but I'd assume that one side of the stack will control the compression, and the other side, as the fluid returns through the valve will be your rebound control. Probably more noticable on your base valve. I'm sure someone more knowledgable will guide you though..

Good luck with those internal snap rings. They were the most challenging part of servicing the shock! Theres a definite 'knack' to it.

 

[Jakobi]

Also, what's the best way of tightening the base valve?

The cartridge tool I had made will work but I have to remove the spring guide to fit it, does putting the fork back together and compressing it upside down (reverse of undoing the base valve) work?

What torque do I tighten it to?

Sure does work. No idea re torque values.

 

[n_green]

I'm no genuis here, but I'd assume that one side of the stack will control the compression, and the other side, as the fluid returns through the valve will be your rebound control. Probably more noticable on your base valve. I'm sure someone more knowledgable will guide you though..

Good luck with those internal snap rings. They were the most challenging part of servicing the shock! Theres a definite 'knack' to it.

I've only just started the suspension bible so I'm sure all will be revealed in the next 100 pages or so.

I gave up on the snap rings because I was only armed with a small flat blade screwdriver. Trip to a tool shop tomorrow to buy a pick and I'll take them on again

 

[n_green]

Sure does work. No idea re torque values.

What did you do it up with? Cordless impact driver same as used to undo it? That makes me a little nervous....

 

[Jakobi]

I never put the Sachs back in the legs.

I went to Ohlins gold which uses an internal cup stop and the base plug. The TTX which is basically a gas strut, then threads back through the base plug the other way. It technically doesn't have a base valve stack, so I had to use an impact to rattle that in until I could get it to bite enough to get a torque wrench on it. As per Ohlins documentation.

 

[twowheels]

Removed the rod from the cartridge. Pulled the shim stack (this is the mid-valve correct?)

Shim stack is:

seat spring,
25 x .2 (2)
Piston
23 x .1 (2)
20 x .1
18 x .1
16 x .1
12 x .15
10 x .3
13 x 2.15 (2)
Nut

This may be a dumb question, is this the mid valve stack? Where is the rebound stack?

Nope. That's a rebound stack with a check-plate ilo a midvalve on the other side.

While your tool appears to have let you into the cartridge, it fails to function when reassembling the base valve. You can rattle-gun it if you want, but those soft aluminum base valves didn't get any stiffer sitting on your bench.

 

[GMP]

I have a 3/8" drive air tool that is pretty tame for use on a base valve with a good socket. Don't go at it with good 1/2" gun.

 

[n_green]

Nope. That's a rebound stack with a check-plate ilo a midvalve on the other side.

While your tool appears to have let you into the cartridge, it fails to function when reassembling the base valve. You can rattle-gun it if you want, but those soft aluminum base valves didn't get any stiffer sitting on your bench.

I have a 3/8" drive air tool that is pretty tame for use on a base valve with a good socket. Don't go at it with good 1/2" gun.

Thats the reason the rattle gun method makes me nervous, even though its only an 18v cordless it doesn't have torque settings and I have no idea how tight it would go.

I'll have to make up a tool from smaller OD PVC pipe I guess. Is there a torque value to do this base valve up or is it simply 'tight'?

Twowheels I believe you had a fix for the mid-valve, can I ask what that was?