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I have a Marvel pro. The exploded assembly drawing in the Manitou service manual shows a smaller diameter cartridge damper. What diameter compression shims do I need to alter the standard XC compression stack to something with less platform? It looks to me that the 19mm platform shims listed in the manitou tuning document might be too big.
 
I have a Marvel pro. The exploded assembly drawing in the Manitou service manual shows a smaller diameter cartridge damper. What diameter compression shims do I need to alter the standard XC compression stack to something with less platform? It looks to me that the 19mm platform shims listed in the manitou tuning document might be too big.
The small diameter Marvel Pro ABS+ I've worked on had four shims. 2 spacer shims and 2 damping shims.
By moving the two spacer shims (one at a time) to between the piston and damper shims you reduce the preload and platform.
 
Thanks Dougal, So the standard shim configuration is 2 'platform' shims up against the lip on the piston, then the 2 spacers? Do you recall if moving one spacer to the other side of the 2 platform shims made a meaningful difference? ( I'm only running ~70psi and find the standard platform excessive). You don't recall the diameters of these by chance? I'm wondering if I need to buy a few various sized shims to fine tune.
 
Thanks Dougal, So the standard shim configuration is 2 'platform' shims up against the lip on the piston, then the 2 spacers? Do you recall if moving one spacer to the other side of the 2 platform shims made a meaningful difference? ( I'm only running ~70psi and find the standard platform excessive). You don't recall the diameters of these by chance? I'm wondering if I need to buy a few various sized shims to fine tune.
I moved them both as the rider was apparently ~40kg. Unfortunately I didn't get a chance to test ride the fork. But a major complaint was "can't get all the travel".

I would have to dig out the service sheet for the measurements of all the shims in that fork and what the final configuration was.
 
SW-
my recent experience buying a new 2016 marvel comp was that it came setup with
stock XC tune CV-11411-03 consisting of 2x 19mm platform shims (and a thicker clamp shim on top) but there were not other smaller thin shims included in the stack that could be moved around to tune it. The platform and dampening curve were definitely stiffer than I liked.
I changed to XC tune CV-11411-04 by adding a single 10mm OD x 0.25 thick preload reducer spacer below the two stock 19mm platform shims. The preload reduction cuts the platform and overall dampening force curve roughly in half from the original CV-11411-03 tune, much more to my tastes.
Because the 10mm preload reducer shim is smaller than the piston ports, it does not actually ever flex, it is just a "dumb" spacer between the platform shim and the piston. I just made my own reducer spacer from a thin aluminum washer instead of sourcing a stainless steel shim, (as is needed if the shim actually bends). I first started out with a 0.4mm thick preload reducer shim but it was too thick for my taste. It only left 0.2mm of the original 0.6mm of preload and so barely had any platform remaining. Difference between 0.4 mm preload spacer and a 0.25mm spacer was very significant.
Do study the manitou shim stack graphs for better understanding of the stack tuning variables; http://goo.gl/JaqWO
 
The stack tuning seems pretty logical. Its just all the shim size information is in relation to the larger 'in leg' damper. I was hoping someone might know shim diameters for the smaller diameter cartridge ABS+ unit so I can buy a few shims before I take the thing apart. Scaling from a jpeg found online suggests the platform shims are d6mm x D15mm. I might just pull it out and measure.
 
I have a Marvel pro. The exploded assembly drawing in the Manitou service manual shows a smaller diameter cartridge damper. What diameter compression shims do I need to alter the standard XC compression stack to something with less platform? It looks to me that the 19mm platform shims listed in the manitou tuning document might be too big.
I was under impression that only rebound circuit is smaller diameter and compression damper is exactly same.
 
I have the 2015 and it's the same. The piston is different diameter. But the shims ARE THE SAME. 17mm od for speed shims, 19mm od for platform shims. The only difference is the cartridge damper piston is machined smaller on the outer area where the oring is seated. Same as with the rebound piston. Outer part of the piston where the Teflon seal is is machined further to reduce overall diameter.

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The stack tuning seems pretty logical. Its just all the shim size information is in relation to the larger 'in leg' damper. I was hoping someone might know shim diameters for the smaller diameter cartridge ABS+ unit so I can buy a few shims before I take the thing apart. Scaling from a jpeg found online suggests the platform shims are d6mm x D15mm. I might just pull it out and measure.
I've pulled my service sheet.

This cartridge ABS+ has 6mm ID shims.
2x 9mm OD preload shims
2x 14mm OD damping shims.

All approx 0.23mm thick (vernier measurements so +/- 0.02mm, I didn't use micrometers to check).

As this fork came to me it had one 9mm above and one 9mm below the 14mm shims.
I rearranged to both 9mm shims below to reduce preload.

The piston has a 0.6mm lip, so with both shims below it still has some preload.
 
Oh they did update and made the entire thing smaller. Figured mine was recent version but seems not. Nice because the big price difference for 50g lighter damper was a bit insane.

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The weight of the damper is only a small part. There's something like 100cc less oil in the cartridge versions which is about 0.2 lb savings in oil alone.

It's generally only the pro models which get the smaller cartridge damper.
 
Ok, enough with the guess work. I removed the compression damper assembly (fantastically easy by the way). The piston seals directly in the inside diameter of the stanchion, no cartridge damper here (despite manitous spec saying so for the marvel pro). So as per tigris' experience the platform shims are 19mm.
What soon became evident was the source of the excessive platform force. There was four 19 x 0.2 shims stacked. If you extrapolate that from the manitou's tuning info which shows damping characteristics for 2 and 3 19x0.2 shims you get a max platform of 1000N. Considering I only weigh 65kg (so maybe 25-35kg on the forks) no wonder they felt a bit harsh. Not sure how 4 shims ended up in the stack but I assume just assembly error?
Put it back in with 2 19x0.2 shims (what is supposedly the stock XC setup?), still ample platform to almost lock out at max setting but far more progressive in how the adjuster dials in the amount of platform.
Now I can source some shims to fine tune.
 
Speaking of updates.... I've got a Manitou Minute Comp 2015. I was told by the techs that the stock fluid in that fork is Maxima 5wt fork fluid. Which is lighter than the Motorex 5wt....

My issue is that I'm experiencing minimal/no change from full open to closed rebound. And I'm seeing brake dive on MAX LSC when travelling slowly but pulling hard on the brakes.

All of this leads me to believe the fork is under damped. So I'm thinking of switching to the Motorex 5wt. Thoughts? Do I have that right?

Notes: My weight = 160lbs, shim stack is stock trail stack.
 
ilikefire - I have used different oils and the difference between closed vs open rebound has always been very noticeable. So I doubt that the problem is about oil viscosity.

How does your rebound feel - is it always fast or always slow? If it is always fast then perhaps something is wrong with rebound shims - like they are not closing completely.

Stupid question, but have you checked the oil level?

I would take the damper side open, clean it completely, make sure that rebound knob does its job and put it back together.

BTW I went with Silkolene RSF 2.5 oil that is even lighter than Maxima 5 (Suspension Fluid - Pvdwiki). I had aeration problem with thicker oils (especially at lower temperatures) where fork got stiffer during the ride. With light oil the bubbles rise to the top faster and oil becomes normal faster.
 
ilikefire - I have used different oils and the difference between closed vs open rebound has always been very noticeable. So I doubt that the problem is about oil viscosity.

How does your rebound feel - is it always fast or always slow? If it is always fast then perhaps something is wrong with rebound shims - like they are not closing completely.

Stupid question, but have you checked the oil level?

I would take the damper side open, clean it completely, make sure that rebound knob does its job and put it back together.

BTW I went with Silkolene RSF 2.5 oil that is even lighter than Maxima 5 (Suspension Fluid - Pvdwiki). I had aeration problem with thicker oils (especially at lower temperatures) where fork got stiffer during the ride. With light oil the bubbles rise to the top faster and oil becomes normal faster.
Yes I find rebound too fast. I did pull the rebound damper out. Low speed rebound dial looked to be working fine. I didn't pull the rebound shims apart though. I'll have to make sure the check valve is properly covering the ports....

I still don't understand the brake dive issue though... Shouldn't max LSC eliminate brake dive?

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I'm thinking the same thing, shims are out of place. If your on MAX CLOSED (knob turned all the way back towards you) and you get brake dive something is not right. I'm 270lbs and the stock XC stack was still practically locked out at low speed.

BTW that's NOT an oil problem, the tiny difference between the 2 will not make a big difference like that.

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I'm thinking the same thing, shims are out of place. If your on MAX CLOSED (knob turned all the way back towards you) and you get brake dive something is not right. I'm 270lbs and the stock XC stack was still practically locked out at low speed.

BTW that's NOT an oil problem, the tiny difference between the 2 will not make a big difference like that.

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Yeah OK I think you're both onto something. I'm starting to think I've got two separate problems here.

1) I think my brake dive issue is because I didn't snug the nut on my abs+ damper enough. Found the piston and shims floating around in the fluid.

2) I think the rebound issue is a loose or damaged piston seal. Is it possible for the seal/o-ring to shrink? The piston does not feel tight against the stanchion. I'm thinking the fluid is going around the piston instead of through.

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