[Mlody]

Hey,

I'd like to rearrange the shims in my fork, and I need some help.
Stock shim stacks in my fork (2005 Dorado TPC+) are as follows.

Rebound:
15mm x 0.1mm
15mm x 0.1mm
16mm x 0.1mm
17.7mm x 0.1mm
17.7mm x 0.1mm
11mm x 0.1mm
20mm x 0.1mm
20mm x 0.1mm

Sliding piston (all are 0.1mm thick):
16mm
16mm
18.6mm
19.1mm
19.1mm
19.1mm
20mm
20mm
20mm
20mm

Fixed piston (all are 0.1mm thick):
17.7mm
19.1mm
20mm
20mm
20mm


I don't have any spare shims, so I can use only those stock ones, but I'd like to have less HSC (take some shims out?), less rebound damping (take some shims out of the rebound stack as well?) and more LSC (add those shims which I took out of the HSC and rebound?).

Anyone can help me with that? Which shims should I remove, which should I add and where to add them?
In short - what to do in order to have more lsc, less hsc and less rebound, without having to buy different shims?

-Dave

 

[Udi]

I'm no expert, but two things:

- The two compression shimstacks in the TPC damper don't define LSC/HSC. It's actually a position sensitive two stage / additive damper, so the upper (fixed) stack is responsible for the initial stroke, and then when the lower (moving, sprung) stack slides up far enough, oil is then forced to flow through both dampers, hence increased damping. The needle adjusted port will control LSC, with the two stacks controlling HSC (as well as position sensitivity). But often, getting more LSC requires heavier shimming, which leads me onto my next point:

- You might have better results here if you post your initial settings (# clicks in of # total clicks) and then try to explain what areas you are unhappy with in terms of your actual riding experience on the fork. Just so that there is no confusion on what exactly you want to achieve.

 

[OBB]

I thought this thread was a joke before I opened it, meant to upset dropmachine.

 

[Steve M]

What Udi said, and also just for the sake of clarity, you are referring to the fixed piston as LSC and the moving one as HSC right?

 

[Mlody]

I'm no expert, but two things:

- The two compression shimstacks in the TPC damper don't define LSC/HSC. It's actually a position sensitive two stage / additive damper, so the upper (fixed) stack is responsible for the initial stroke, and then when the lower (moving, sprung) stack slides up far enough, oil is then forced to flow through both dampers, hence increased damping. The needle adjusted port will control LSC, with the two stacks controlling HSC (as well as position sensitivity). But often, getting more LSC requires heavier shimming, which leads me onto my next point:

- You might have better results here if you post your initial settings (# clicks in of # total clicks) and then try to explain what areas you are unhappy with in terms of your actual riding experience on the fork. Just so that there is no confusion on what exactly you want to achieve.

Ok, I thought that there's one stack for LSC and one for HSC, thanks for clarifying this.

My settings are:
Rebound fully opened (but trust me on that, it's pretty slow), I'd like it to be a bit faster. I don't remember exactly how I had rebound set-up in my 2007 Boxxer, but if 100% would be "fully opened" than I had it around 85-90% IIRC, and "fully opened" in Dorado is ~70-75% of that in Boxxer.

Compression knob has around 120* of movement and I have it around 20-40* from fully closed.
I'd like to have it fully closed in terms of LSC, but HSC is too firm on that setting and the fork becomes too harsh. On my Boxxer I had the compression knob 2 clicks from fully closed. My Boxxer was a Race model with the "Nyloc Nut Mod" so I had my floodgate about 20mm from the bottom of the blue rod, again if I remember correctly. Maybe that Boxxer comparison will help...

Anyway, I'd like to have some more LSC and just a tiny bit less HSC. Right now, on my settings, Dorado dives slightly in corners and under braking but HSC is ok - spiking sometimes but I like it to behave that way.
When I set the compression to fully closed it (almost) doesn't dive but is way too harsh in terms of HSC.
Of course I don't want the HSC to disappear in high speed corners/heavy g-outs .

And rebound...
It's not packing, but there's a lot of clicks of the rebound knob and only the last 30% are "almost ok", the first 70% are just way too slow.
So, once again using %'s - if 0% is ultra-slow and 100% is super-fast, than Dorado starts at 0% and ends at 70%, I'd like it to start at 30% and end at 90%

What Udi said, and also just for the sake of clarity, you are referring to the fixed piston as LSC and the moving one as HSC right?

Yes, I referred to the moving one as HSC and the fixed one as LSC.
http://www.waz.ca/bike/Dorado_Internals.jpg - Here's how it looks like in Dorado, moving piston is the upper one and fixed one is the lower.

 

[RedOne]

And to make it more complicated, the LSC needle also changes how much the floating piston is moving or how much force is going into moving the piston. Closing the LSC port means more force on the floating piston.

Second thing is that you can change the initial position of the TPC+ or floating piston. There is a clip limiting how far the spring can push the piston upwards. You can remove the clip, so the piston is starting from the most extended position, and there is a second groove for the clip, so you can set it to a lower starting point.
This changes how far the piston has to move before its shims come into play.



TPC+ is explained in the video in this 2009 Dorado preview on sicklines, starting from 08:15.
http://www.sicklines.com/2009/02/24/preview-2009-manitou-dorado/

 

[TheTruth]

It almost sounds like you want your fork to de-ramp? Or do you just want a totally linear feel?

With that question asked, I am sure somebody else could help you with one of those because for one I know nothing of shim stacks, but also, I am pretty sure there may be a better setting for you with your mid travel. I know there is definitely a way to prevent dive in corners like you described.I just don't know if you want to sacrifice small bump sensitivity just for this.

My $0.02: Use heavier spring but the same oil. It could also help if somebody on here knew how to eliminate front end dive. I think you could possibly be happier with your fork then. Since you are only coming two clicks away from full compression setting, it may be better to have low compression settings with a stiffer spring. It also seems like you are compromising a lot of oil flow and that could be why the rebound is slow? But I don't know much. It is only a guess. Perhaps somebody can correct me..

 

[Udi]

I'm not going to dive into this one (maybe Socket wants to since he's played with the TPC+ a fair bit), but a couple more things:

Leading on from what RedOne said (who is absolutely correct), I would go as far as suggesting that if you are going to tune the damper anyway, you might as well ditch the twin piston compression system and set up the damper conventionally. It's probably easiest to just remove the lower floating piston (and spring + clip) completely. I think this would be a better base for reducing dive, as you don't have reduced damping at the start of the stroke.

From there onwards, I'd really recommend finding a source for shims. Those 0.1mm jobbies that are littered throughout the damper are a pain to tune with in my experience, and it would be a good start to have at least 1 of each stock diameter shim in 0.2mm thickness.

The rebound should be easy enough to work with as it is though, I would suggest just removing the duplicate 20mm and 17.7mm shim (as shown below). It looks to be a two-stage stack with an 11mm crossover which I'd leave. I would presume you'd be happy with that change, but if not, you probably want to elaborate on whether you want it faster (/slower) earlier in the stroke or later in the stroke.

Rebound:
15mm x 0.1mm
15mm x 0.1mm
16mm x 0.1mm
17.7mm x 0.1mm
11mm x 0.1mm
20mm x 0.1mm

 

[Steve M]

Ok, I thought that there's one stack for LSC and one for HSC, thanks for clarifying this.

My settings are:
Rebound fully opened (but trust me on that, it's pretty slow), I'd like it to be a bit faster. I don't remember exactly how I had rebound set-up in my 2007 Boxxer, but if 100% would be "fully opened" than I had it around 85-90% IIRC, and "fully opened" in Dorado is ~70-75% of that in Boxxer.

Compression knob has around 120* of movement and I have it around 20-40* from fully closed.
I'd like to have it fully closed in terms of LSC, but HSC is too firm on that setting and the fork becomes too harsh. On my Boxxer I had the compression knob 2 clicks from fully closed. My Boxxer was a Race model with the "Nyloc Nut Mod" so I had my floodgate about 20mm from the bottom of the blue rod, again if I remember correctly. Maybe that Boxxer comparison will help...

Anyway, I'd like to have some more LSC and just a tiny bit less HSC. Right now, on my settings, Dorado dives slightly in corners and under braking but HSC is ok - spiking sometimes but I like it to behave that way.
When I set the compression to fully closed it (almost) doesn't dive but is way too harsh in terms of HSC.
Of course I don't want the HSC to disappear in high speed corners/heavy g-outs .

And rebound...
It's not packing, but there's a lot of clicks of the rebound knob and only the last 30% are "almost ok", the first 70% are just way too slow.
So, once again using %'s - if 0% is ultra-slow and 100% is super-fast, than Dorado starts at 0% and ends at 70%, I'd like it to start at 30% and end at 90%


Yes, I referred to the moving one as HSC and the fixed one as LSC.
http://www.waz.ca/bike/Dorado_Internals.jpg - Here's how it looks like in Dorado, moving piston is the upper one and fixed one is the lower.

I'd recommend doing what Udi suggested - remove the floating piston altogether. That thing is a bit redundant in my opinion, and forces the fork to behave in the opposite manner to what you seem to be looking for (lots of HSC, little LSC). Unfortunately to get the most out of it, you're really going to need a few other shims on hand. It sounds like you want a very heavy overall compression tune, so what I'd suggest trying is something like:

20.0 x 0.1
11.0 x 0.1 [if you can get your hands on one, don't go taking it out of the rebound stack though!]
20.0 x 0.1
20.0 x 0.1
19.1 x 0.1
19.1 x 0.1
18.6 x 0.1
16.0 x 0.1
16.0 x 0.1

What you can look at from there is:
1. Adding another 20.0 at the face (front) of the stack, between the piston and the 11.0 if you feel you need more LSC
2. Adding another 20.0 after the 11.0 (2nd stage of the stack) if you feel the mid to high speed compression is too low, ie blowing through travel on bigger hits like drops/jumps
3. Adding another shim towards the back of the stack, either a 17.7 or another 16.0 if you can find it, if you feel like really fast, sharp hits are blowing through travel.
4. Removing shims from the above positions to reverse the above effects.

Personally I've had good luck with piston mods, but those mods are irreversible and most people aren't willing to mess with the piston for that reason. As far as the rebound goes, I reckon Udi is on the money as usual.

 

[Mlody]

Many thanks for help!

I took those 2 shims out of rebound, I'll try to buy that 11x01mm shim and get rid of the floating piston.
It should look like in the attached image, right? (blue knob is at the bottom of the lower leg)

 

[Mlody]

The rebound should be easy enough to work with as it is though, I would suggest just removing the duplicate 20mm and 17.7mm shim (as shown below). It looks to be a two-stage stack with an 11mm crossover which I'd leave. I would presume you'd be happy with that change, but if not, you probably want to elaborate on whether you want it faster (/slower) earlier in the stroke or later in the stroke.

Rebound:
15mm x 0.1mm
15mm x 0.1mm
16mm x 0.1mm
17.7mm x 0.1mm
11mm x 0.1mm
20mm x 0.1mm

So if I'd like to have some more damping earlier in the stroke I should add a shim before that crossover shim? (e.g. 20mm->20mm->11mm....)?

 

[Udi]

That looks right to me, you can probably remove that little o-ring as well.

And yeah if you want some more damping earlier on I would try 20>20>11. Short of being able to get these things on a dyno, it's pretty much just educated guessing, so feel free to play around with it as it will give you a better feel for how certain changes affect the curve. Did you try it out and have some topout or something? Too fast?

Socket's compression stack looks pretty similar to how I'd do it as well, so I'd try that out. I don't think it would hurt to try it without the 11mm crossover until you can get your hands on one.

 

[RedOne]

I have a single TPC piston in my 32mm Boxxer with a quite similar stack, but softer overall.
It is definitely easier to set up a single piston damper, and you still can get really good results.

20.0x0.1
11.0x0.15
11.0x0.15
20.0x0.1
20.0x0.1
17.8x0.1
17.8x0.1
17.8x0.1
16.0x0.1

But I have that PUSH rebound kit with a harder spring on the compression side shim (it's meant to work with a standard motion control compression damper). Maybe that's why I need that two 11mm spacers. The fork gets too harsh on small bumps with only one spacer.

I'd recommend doing what Udi suggested - remove the floating piston altogether. That thing is a bit redundant in my opinion, and forces the fork to behave in the opposite manner to what you seem to be looking for (lots of HSC, little LSC). Unfortunately to get the most out of it, you're really going to need a few other shims on hand. It sounds like you want a very heavy overall compression tune, so what I'd suggest trying is something like:

20.0 x 0.1
11.0 x 0.1 [if you can get your hands on one, don't go taking it out of the rebound stack though!]
20.0 x 0.1
20.0 x 0.1
19.1 x 0.1
19.1 x 0.1
18.6 x 0.1
16.0 x 0.1
16.0 x 0.1

What you can look at from there is:
1. Adding another 20.0 at the face (front) of the stack, between the piston and the 11.0 if you feel you need more LSC
2. Adding another 20.0 after the 11.0 (2nd stage of the stack) if you feel the mid to high speed compression is too low, ie blowing through travel on bigger hits like drops/jumps
3. Adding another shim towards the back of the stack, either a 17.7 or another 16.0 if you can find it, if you feel like really fast, sharp hits are blowing through travel.
4. Removing shims from the above positions to reverse the above effects.

Personally I've had good luck with piston mods, but those mods are irreversible and most people aren't willing to mess with the piston for that reason. As far as the rebound goes, I reckon Udi is on the money as usual.

 

[Steve M]

I have a single TPC piston in my 32mm Boxxer with a quite similar stack, but softer overall.
It is definitely easier to set up a single piston damper, and you still can get really good results.

20.0x0.1
11.0x0.15
11.0x0.15
20.0x0.1
20.0x0.1
17.8x0.1
17.8x0.1
17.8x0.1
16.0x0.1

But I have that PUSH rebound kit with a harder spring on the compression side shim (it's meant to work with a standard motion control compression damper). Maybe that's why I need that two 11mm spacers. The fork gets too harsh on small bumps with only one spacer.

The PUSH rebound kit offers SFA in compression - if there was any significant damping at all, it'd cavitate pretty badly if you ran the Moco compression assembly full open.

Unfortunately comparing shim stacks on different pistons/different forks doesn't tell you anything useful either. I like the look of what you've done with your stack though. What fork did your TPC piston come out of?

 

[RedOne]

The PUSH rebound kit offers SFA in compression - if there was any significant damping at all, it'd cavitate pretty badly if you ran the Moco compression assembly full open.

Unfortunately comparing shim stacks on different pistons/different forks doesn't tell you anything useful either. I like the look of what you've done with your stack though. What fork did your TPC piston come out of?

I know it is not really comparable, just wanted to confirm that your stack setup is the right direction.
It is a piston off a Sherman Slider, which uses three identical for compression and rebound.

This is what PUSH says on their website regarding the compression midvalve
"Compression Mid-Valve which increases support to reduce the “porpoise” effect during multiple deep stroke impacts as well as increasing the damper’s response during high frequency events."

I had a boxxer before that had been worked on by an Austrian suspension specialist. They did the same thing, i mean sticking in a harder spring, but with a stock rebound piston.
I think that must be changing something or they wouldn't do it.

Sorry Mlody for getting a bit off topic.

 

[Steve M]

I know it is not really comparable, just wanted to confirm that your stack setup is the right direction.
It is a piston off a Sherman Slider, which uses three identical for compression and rebound.

This is what PUSH says on their website regarding the compression midvalve
"Compression Mid-Valve which increases support to reduce the “porpoise” effect during multiple deep stroke impacts as well as increasing the damper’s response during high frequency events."

I had a boxxer before that had been worked on by an Austrian suspension specialist. They did the same thing, i mean sticking in a harder spring, but with a stock rebound piston.
I think that must be changing something or they wouldn't do it.

Sorry Mlody for getting a bit off topic.

Yeah I find it hard to take that particular claim seriously - the MoCo comp damper at full open really offers almost no damping whatsoever. If the rebound piston check valve provides any more pressure drop over the valve than the compression piston does, it'll suffer from cavitation, and I seem to remember Push specifically claiming that it doesn't cause cavitation at any setting. Of course, it'll have SOME effect, the question is whether that effect is significant - my educated guess would be no. Not to say the rebound piston is useless, obviously it's a great upgrade.

The piston in my 32mm TPC Boxxer was out of a Sherman too (though a Flick not a Slider) so it's interesting to see your shim stacks.

edit: yeah apologies for the off topic discussion, I think it's interesting and at least vaguely relevant though..?

 

[Mlody]

Yay!
After a few hours of "fun" I got to the setup that seems ok.
Rebound was spot on - now I have it around 5-7 clicks from fully opened, but I had to change compression as it was a bit too light. Here's what I ended up with:

20.0 x 0.1
20.0 x 0.1
20.0 x 0.1
20.0 x 0.1
19.1 x 0.1
19.1 x 0.1
18.6 x 0.1
17.7 x 0.1
17.7 x 0.1
16.0 x 0.1
16.0 x 0.1

LSC is perfect, but I was just playing the "what feels right on the parking lot" game, so I'm pretty sure that I'm gonna change it after some DH runs.

I can't find one 19.1 shim, but I'm pretty sure that I haven't put it on the shimstack...
If I did, than there's three 19.1 shims.

 

[Mlody]

RedOne, Socket:
I like to have my suspension set-up perfectly and to understand how it works, and I think I'm not the only one - so feel free to talk about it in "my thread". Doesn't matter if you're talking about MOCO, shimzzzz or SPV, as it still may help someone in understanding how his fork works and how to improve it.

 

[Mlody]

One more thing - Is it true that smaller shim will be stiffer than the bigger one with the same thickness?
E.g. 16x0.1mm is stiffer than 18.1x0.1mm ?

That would be logical, but maybe I got it wrong?

 

[Steve M]

One more thing - Is it true that smaller shim will be stiffer than the bigger one with the same thickness?
E.g. 16x0.1mm is stiffer than 18.1x0.1mm ?

That would be logical, but maybe I got it wrong?

Only if you measure shim lift force vs displacement at the edge of the shim, which is not directly relevant as any shims you're varying the OD of are obviously not at the front of the stack. If it's supporting any other shims between itself and the piston, the larger OD shim will offer higher stiffness.

 

[EVIL JN]

Okey since were on the topic of tuning, could i get my rc4 to have more of a two stage rebound?
I cant seem to find a good setting or feel compared to my vivid that i used on my sunday, the rc4 is on a new demo 8 2011. I like to have my rebound quite fast deep in the travel so it rebounds from big hits and dont bog down to hard in terms of ride height while having a fairly slow beginnig rebound for stabillity and composure.

On the rc4 i feel like there is just a few clicks of useable range which still dont match up with the boxxer up front, i felt the same with my old dhx 5.0 on the sunday kind of the reason i went with the vivid.