Analyzing the shim springs was definitively just a fun intellectual amusement, not an outright replacement for try-it-and-ride-it tuning. Understanding the relative individual shim spring rates however did help me with interpreting the manitou example shock dyno tuning charts and I think I would have an easier time with developing custom shim stacks.

 

I had the standard Trail stack (11x0.5 clamp, 2x19x0.2 preloaded shims and 17.5x0.2 speed shim). I removed both preloaded shims and added 17x0.1 shim on top of existing speed shim.

 

Actually, I'm glad minkitkat posted this. It's a good reminder to me as sometimes I forget to do this or am not patient enough to follow the procedure correctly. I'm sure my oil level has been off because of this.

 

What are you talking about, none of that has anything to do with what we are discussing??? Everyone modifying shim stacks has the manual and knows how to do the work so wondering why you posted that?

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Wanted to report back. Changing to prep m in the air chamber and going linear stack is amazing. I ran LSC 3 clicks open and no dive issues at all, Bob was unnoticed and small bump compliance was freaking amazing. 120mm seems to have brought the bike to life too. Smoother control leaning in the corners and much more stable coming down without killing response to steering inputs.

Like riding a much more fun and new bike lol. And the 30% sag is enough that I can still keep the weight forward on the climbs without issue

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So I am a newbie with Manitou forks. I previously owned an X-fusion Velvet in 2011 that was fairly easy to service, as I had installed Enduro fork seals no problem. I am now a proud owner of a new 120mm Mavel Pro 29er fork and not a clue, until now somewhat, how to go about opening it up and changing oil, seals or removing platform shims. I just went to the Manitou support online and opened up this service video:

My first question is - is this video relavent to my Marvel Pro in any way? I quickly noticed the Mattoc requires 3 specialty tools: flat ground 24mm socket, 8mm thin wall socket and a cassette tool. Any chance these are also needed on the Marvel?

I have also been told that I may want to loose the platform shims altogether in an effort to gain plushness and small bump compliance.... is this also true?

I think the right thing to do first is ride the snot out of this fork for 30-50 miles and then decide what needs to be done under the hood, yes? Great info here and enough to make my brain hurt, but thanks!

 

The marvel is a lot easier to service than the Mattoc. No special tools.

Just remember the damper side (8mm hex) screws INTO the fork to remove it.

 

if it were me, like you said ride the piss outta it before opening it up. except mine took much more than 50 miles to break in.

 

I dont think that the mattock video is particularly applicable to your marvel, the mattock is a more complex fork. You can get the ABS+ dampener out of your marvel for tuning in just a couple of minutes work just using normal hand-tools, see post #1 of this thread and start reading through the manitou tuning training manual; http://goo.gl/JaqWO

 

Do NOT take out all the platform shims UNLESS you buy "speed shims" to tune with in their place. Removing the platform shims in the marvel means removing ALL high speed damping shims.

Unless manitou changed it the stock abs shim stack is 2 platform shims and nothing more. Ya u need shims in there or you want have any damping.

Manitou has a service manual on their website. Marvel forks are INSANELY easy to work on with standard tools. But it's not something you should do without good reason. Many snap off the damper shaft not taking the forks apart properly

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Manitou has service manual up in their site: http://www.manitoumtb.com/assets/Service Manuals/2012 Service Manual.pdf It's old, but contains all the information you need.

You can get shims from here: Revalving Shims You need 8mm ID shims. Get couple of 17mm OD shims with 0.1, 0.15 and 0.2mm thickness. Also you might want some thicker (e.g. 0.25mm) shims with 10mm OD if you decide you need some light platform. You can use those to reduce the preload of the platform shims.

 

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.

 

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'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.

 

Item 3, page 27 of the 2012 Manitou service manual seems to show a smaller diameter compression piston.

 

What model year do you have? If it is newer fork then the damper is different. Check out this: https://drive.google.com/file/d/0B7grOSQ82keNRFRyNGJDdndyUUk/view?pref=2&pli=1

 

Ok, thanks for that. Is that assembly drawing for the latest (2016) model?
I bought it late 2015 from CRC, so assume it is 2015. I'll take the cartridge out this afternoon to measure it.

 

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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Newbie with a Marvel Pro



So I have a 2016 Marvel pro (bought from Chain reaction in Jan 2016), I can confirm as above, the shims are 8x19mm. I'm guessing the earlier marvels must have had the smaller diameter.

So anyway my situation is, after reading this forum, I had bought the Marvel Pro to put on my hard tail, which is essentially a commuter and occasional have a play on easy XC trails. Truth be told I have probably done about 50km off road and 500km on road. In that time I felt it was a good fork, 3 or 4 clicks back felt good for "road bumps" compliance, and max definitely locked it out.

Anyway my main bike is a 2013 Rocky mountain element, which I am really happy with except the Fox CTD has always felt ordinary. Well the fox fork finally packed it in so I (re)read this forum to get some ideas and confirm my decision to add the Marvel Pro to the Rocky.

So Last night I opened it up to check the Shims situation (i've been a dirtbiker for years and never touched the things, but get the gist of them) Anyway the factory setup on my forks:
4 x 19mm platform shims and it had 72mm oil height

I dont have any spare shims yet, so all I could do was remove some shims. First up I took 2 platform shims out, so that it had the standard XC stack, when I put it back together I made the mistake of bouncing forks up and down on ground (since not installed on bike yet) and I thought it was not stiff enough to act as a lock out on Max, so put 1 shim back in, which makes it the same as CV-11411-07.

So I left the oil height at 72mm as well (even though this is more than specs say). I set sag at 25%, which was about 70psi.

Anyway I took it for a ride this morning on classical XC single track, pretty smooth, just a few small roots and rocks, a couple of 1ft jumps and drops.
My findings were:
1. full open on dial was still too stiff for small roots and rocks.
2. I used about 70% travel, So I think sag/pressure is about right, or maybe a little too high.
3. in general damp comp damping was just too stiff
4. rebound maxed to + and still felt like it needed more (maybe side affect of compression being too harsh
5. too stiff to notice brake dive
6. i think I will do the standard mod of dropping back to only 1 platform shim.

Anyone have a comment about oil height? will that add to general stiffness?

 

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.

 

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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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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There's a teflon seal on the rebound piston, it's supposed to slide up and down easily, not fit tight. But if all you compression side parts were floating in there you need to test the forks down and check the rebound shims now. Make sure you didn't damage anything.

Other thing is in stock form rebound settings are hard to feel the difference. It's just fast and faster lol. But when I hit a batch of roots or similar at speed you'll notice the difference in performance. Just very subtle otherwise. And if your heavy like me, a change to its shim stack is needed too as high pressures in the spring overcome the stock rebound shims. So lack of decent rebound control.

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Having though about this a little more, I suspect the 4 x 19x0.2 shims might be right to achieve the standard XC platform force in the marvel pro. It seems like the damping curves and shim configurations in the Manitou tuning document (2011) may relate to having a rebound piston running directly inside the stanchion.

tigris, what diameter is the rebound piston in your fork?
If it is smaller as per the assembly drawing shared by arnea then the pressure generated by the smaller diameter rebound piston for a given input force is probably close to twice that for a larger rebound piston. So to achieve a similar platform force as for an in leg rebound piston, the preload force on the platform shims would need to be doubled, hence the 4 19x0.2 platform shims.
This would also imply the velocity dependent damping force is half that shown in the Manitou tuning doc damping curves? (given the fact that the flow rate generated by the smaller rebound piston is half). I'm thinking I might add some 17mm shims to the valve face to increase the progression of damping force at higher velocities.

 

Didn't like the feel of the marvel pro 120 out of the box so decided to play with some shims.

First of all i thought the pro had a smaller diameter dampener inside a tube of the fork leg to save weight. Mine just has the standard size dampener.

The stack that came with the fork was a 4x 19mm x .2mm. No wonder why it did not have initial stroke smoothness.

 

Didn't like the feel of the marvel pro 120 out of the box so decided to play with some shims.
The stack that came with the fork was a 4x 19mm x .2mm. No wonder why it did not have initial stroke smoothness.

Interesting that the stock tuning did not utilize a clamp shim as all of the example tunes from the 2011 manual included a clamp shim.

For a large diameter platform shim that is not backed by a clamp shim or a stack of decreasingly smaller shims, the location for the flexing of the large diameter shim gets concentrated toward the inside diameter of the shim. At least with the forces encountered in motorcycle shocks, there is a concern that metal fatigue from concentrated flexing of the shims will eventually cause the shim to crack. A clap shim helps to both stiffen the platform shim and to move the location for the flexing outward
and and distribute the stress over a wider area.

Perhaps the forces for MTB shocks are not high enough to cause fatigue of the unclamped platform shim? I wonder what (if any) benefit or tuning characteristics are derived from not including a clamp?