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Rear Shock Knowledge / Rant Space

englertracing

you owe me a sandwich
Mar 5, 2012
1,057
637
La Verne
Indeed, good catch!

Still, the flow areas don't make sense to me...
It is a bit odd
But the check valve appears to have a ton of lift/float. Only needs to be sufficient to replace the shaft volume. Perhaps they aren't small but the compression ports are oversized.

They are probably bigger than a motorcycle showa or kyb that uses a 16mm shaft.
 

Happymtb.fr

Turbo Monkey
Feb 9, 2016
1,285
640
SWE
The shaft is 14mm on the Storia.

I realise now that the piston center hole is larger on the other side and allow the nut to grip more thread.
You can see how much float there is for the check valve on the picture below
20210606_202306.jpg

the orientation of the piston was definitely right
 

Happymtb.fr

Turbo Monkey
Feb 9, 2016
1,285
640
SWE
Huh, so SUPER light. I don't have anything even close on hand currently.

What did you end up using?
Rockshox 2.5wt should come pretty close according to my French suspension guru.

I went for Motorex Fork oil 2.5w and removed 1 or 2 shims at the top of the rebound stack. The rebound was on the slow side originally and the thicker oil made the shock less noisy. Not sure if this will impact on the HBO...
 

englertracing

you owe me a sandwich
Mar 5, 2012
1,057
637
La Verne
Rockshox 2.5wt should come pretty close according to my French suspension guru.

I went for Motorex Fork oil 2.5w and removed 1 or 2 shims at the top of the rebound stack. The rebound was on the slow side originally and the thicker oil made the shock less noisy. Not sure if this will impact on the HBO...
maybe you should consider a 2 stage rebound stack.
 

englertracing

you owe me a sandwich
Mar 5, 2012
1,057
637
La Verne
What would be the benefits?
Whelll
On a typical linear kidney port piston.....
A standard tapered shim stack is slightly degressive.

A subtle 2 stage actually ends up being more linear. While a not so subtle 2 stage gets progressive.

You want a pretty linear rebound action in my experimentation in offroad suspension systems. Seal drag and system friction is already providing some very low speed resistance/friction.

Not so subtle 2 stage rebound stacks are um not ideal either.
 

iRider

Turbo Monkey
Apr 5, 2008
3,514
1,421
Mine seems to be awfully quick on the last bit of rebound and seems to have more resistance during the initial 1/10 of the stroke than say a Fox or RS shock. Normal? I bought it used and it came fresh from a service from the German Manitou distro.
 

Jm_

sled dog's bollocks
Jan 14, 2002
13,283
5,014
AK
Mine seems to be awfully quick on the last bit of rebound and seems to have more resistance during the initial 1/10 of the stroke than say a Fox or RS shock. Normal? I bought it used and it came fresh from a service from the German Manitou distro.
Mine has a much improved rebound stroke after modding. It was crazy slow stock. Compression still over damped though. I’m probably going to take a crack at that side soon. The later ones came with an updated piston and lighter rebound stack. For some reason these were coming with some wacky tunes still.

I ordered some shimz from the avalanche shimz site, per the recommendations on the McLeod tuning thread.
 

iRider

Turbo Monkey
Apr 5, 2008
3,514
1,421
Mine has a much improved rebound stroke after modding. It was crazy slow stock. Compression still over damped though. I’m probably going to take a crack at that side soon. The later ones came with an updated piston and lighter rebound stack. For some reason these were coming with some wacky tunes still.

I ordered some shimz from the avalanche shimz site, per the recommendations on the McLeod tuning thread.
On which bike do you have it? King Can? Mine is on the Tracer 2, King Can and I guess it has a custom tune. Rebound seems to have a large range from super slow to super fast. This stickness off the top and the super fast rebound towards the end although it seems right during the rest of the travel bothers me.
Mid travel support is way better than the Fox that was on there before, so I kind of like it minus these issues.

How easy is it to work on? The manual says you need a lot of special tools?
 

Jm_

sled dog's bollocks
Jan 14, 2002
13,283
5,014
AK
You only really need the 3:1 tool for getting the valve core out and the other fitting. Everything else is normal stuff. Strap wrench for the can, shock pump, etc.

One thing that was all hyped up was that this had a non-dished rebound stack that “actually worked”, but again, it had a wacky heavy stack/obstructed flow and was a lot better with some tuning. You were supposed to be able to run “real slow” rebound without consequences. Just read the whole McLeod thread on mtbr, most of that info is there. Only thing is they make some small references to a piston or shim stack that “might” be there, but chances are you have those f-ed up initial stacks/pistons. They make it out like everyone has the better stuff.

I had to use the king can, otherwise the shock was way too progressive. On my XC pivot 429sl.

But yeah, pretty east to work on. Typical shim stack piston stuff.
 

iRider

Turbo Monkey
Apr 5, 2008
3,514
1,421
Cheers for that!
How did you work around the bleed tool? Put shock in a bucket full of oil? Not sure why they pressurize it?
 

Happymtb.fr

Turbo Monkey
Feb 9, 2016
1,285
640
SWE
Perhaps due to a comparably stiffer mid valve comp stack and their "turbulent oil flow"-hocus pocus?
I heard that it is a possible configuration with preloaded shimstack depending on the volume of fluid being displaced by the shaft and the stiffness of the stack.
That was from a former BOS employee.

It might not be a complete explanation but it was enough to quiet my armchair level of suspension engineering :busted:
 

Jm_

sled dog's bollocks
Jan 14, 2002
13,283
5,014
AK
Cheers for that!
How did you work around the bleed tool? Put shock in a bucket full of oil? Not sure why they pressurize it?
They have a YouTube video showing it. You basically get it topped off and the ifp set right by adding a certain amount of pressure and holding the shock a certain way, then screwing down the cap so it’s totally filled. You end up pressurizing it. It doesn’t de-gas as well as vacuum, but seems to work pretty well.