rlouder,
can you write your stack down, in order it's installed, with shim thicknesses? Then we could be able to tell what to expect from it.

 

It's a '10 drake, so I assume it's just like mullens on page 1. I was looking through the pdf to see what to try before I take the damper out. They only made one model of the drake in 10, so I can't imagine it would be different from his.

I'm looking for better hs small bump absorption if you want to point me in the right direction. The drake's stack looks much stiffer than anything in the pdf except the dj, so I may just remove a big shim and see what happens.

 

Removing a platform shim will help if you want to try something without buying any shims. But if you dont use the compression as a lock out, I would suggest adding a velocity shim to reduce the platform feel and in return, allow for more oil flow through the shim stack.

Something like trail stack # EK-012611-03

If you reeeaaallly dont care about about platform, A stack from the linear series would give you the best small bump compliance. I used a linear stack for a while and loved it.

 

This is a great post.
What set up will you use in a Manitou Tower Pro 100mm for a 220lbs rider on a 29 HT that will mainly be use for XC
It comes with the firm spring, should I get the Xfirm and what shim configuration will be the best?

 

I would only change shim stacks if your not happy with your forks performance. Its hard to suggest something without knowing what areas of performance you are looking to improve as well

 

Can anyone confirm whether Tower Pro comes indeed with the XC stack?

This is what I supposed in a previous post, but I have no official information. Has anybody inspected their shim stack?

Tower Pro will be my next fork, and so I'm curious


--> UPDATE:

Just wrote to Manitou's customer service asking this question.

In very few minutes they answered that usually Tower Pro's come with the Trail stack. However, some distributors in Europe have ordered them with the XC stack.

Difficult to say it for sure, so. I don't know if this is true in the US as well. Anyway, it's likely that your stack is trail-tuned, not XC-tuned.

P.S. Once again Manitou's support has been unbelievably quick! Great!!

 

Anybody have any info on adjusting the rebound stack? I'm thinking about trying to speed up the high speed rebound a bit while slowing the low speed down a tad. Just remove a shim? I haven't been in the damper yet to see what's there... 2011 Minute Pro fork, fwiw.

 

Rebound tuning is a lot different then compression tuning. When tuning compression, there are a lot of different variables at play(size of rider, size of hit, speed of hit, shape of obstacle...) When tuning rebound, the number of variables is much less because the only force that needs to be controlled is the spring, which generally speaking, is a consistent force. When a fork nears the end of its stroke, the spring force is much higher. This is the point at which the HSR shims will open. This is why HSR is often refereed to as ending stroke rebound by manufactures. The term "ending stroke rebound" is not technically accurate, but it helps people who do not understand the technical aspects correctly set up their rebound.

When it comes to tuning rebound on a fork, Manufactures tend to get it set up pretty well because its not as complicated. Extremely light riders who use very little air/light coil springs can benefit from removing a shim since the spring rate is much lower. Extremely heavy riders can benefit by adding a shim to compensate for the higher air pressures/ heavier coils. In most cases its not needed.

This is only the case for forks though. Rear shocks have the added variable of leverage ratios and this is when rebound tune becomes very important, and manufactures dont necessarily get it right.

Hope that helps:thumbsup:

 

Old Absolute is entirely different from either TPC or Absolute+. Instead of shims, it has a spring loaded needle-shaped piston. The top knob adjusts preload of that spring. Once pressure created by rebound rod entering the damper at compression stroke exceeds that preload, the piston opens and Absolute works like an orifice style damper.

TPC is different from Absolute+ in that it doesn't have a raised edge on the top of its piston, against which platform shims could be preloaded, so it cannot create platformness.

 

Thank you both for your sharing!

You speak of preloading platform shims. What does this mean?

As for Abs, if I understand it right, such an old damper had just one circuit, orifice-like, acting as both a LSC and a HSC?

 

Absolute+ platform shims have large enough diameter to reach that edge. When you tighten the nut that holds piston and shim stack assembly on damper shaft, the shaft, which is stepped above shim stack to a larger diameter, presses on the stack. This pressure deflects platform shims statically, so that their perimeters rest on that raised piston edge, and their centers are lower than their respective perimeters.

In contrast, speed shims and preload reducing shims have smaller diameter to avoid contact with raised piston edge. Any smaller shims placed below platform shims end up not preloaded.

 

:thumbsup:

 

The Golden Wrench: Manitou Absolute+ Tuning Awesomeness

 

Gotta love fork tuning.

 

Manitou ABS+ Tune kit Decline March 2012

I think the following article is very interesting indeed. It gives hints as to how to zone in the candidate right tune for you:
Manitou ABS+ Tune kit Decline March 2012

 

Hi
Very interesting post.

I have a circus 130 and i want to make it more trail friendly.I mean use more travel and be more plush but keep a good bottoming resistance.I do agressive trail with jump and some dj. .

Change the spring for a softer is the best start ?
For now i run it with no air ( i weigh 147 lbs) and i use less than 3/4 of the travel only on big impacts.

Big thanks in advance and sorry for my bad english

 

first thing to do is to check your sag. Since its a DJ fork, its probably over sprung and moving to a softer spring would help. It also has a very stiff shim stack, so removing a shim should help with small bump sensitivity.

 

thank for the answer.

the stock spring is a firm. i think i'm around 10/15 % of sag so a medium will be better.
i try to understand the function of each shim but i'm a bit lost.
It's the blow-off shim i must remove ?
i saw in the tuning guide, the difference between trail and jump stack is a velocity dependant shim (pink) and 2 blow-off shims (blue). What is the function of the pink velocity dependant shim ?

 

Generally speaking, Think of blow off shims as platform shims, meaning the more blow off shims you have, the more platform your shim stack will give you.

Speed shims are very similar to preload reducing shims. They reduce the preload on the shim stack making the blow off shims open easier. The difference between Speed shims and a preload reducing shim is that a velocity shim adds to the damping characteristics of the shim stack, and a preload reducing shim does not.

Velocity shims(are used as speed shims as well), are extra shims that add to the over all damping curve, but do not have an effect on platform. Instead, they control how the blow off shims open, giving extra support after the intial opening of the blow off shims.

It takes time to understand what exactly is going on. The Dyno charts help a ton when narrowing down the possibilities, but experimenting is the best way to learn what exactly is going on and how each shim effects the feel of the fork. The main thing for you to realize is that your stock shim stack is very stiff. It only allows oil to pass on very hard hits. Removing one platform shim is a good start to making the fork more trail friendly.:thumbsup:

 

may have missed it, i did not read this entire thread but there a rule of thumb what shims/order you should have for a given rider weight?

Ie; if I weight 210lbs what shim stack should I have for the best ride etc?

J-

 

Its a little more complicated then just weight. You have to take into account what characteristics you are looking to achieve. Do you want more platform? Less platform? More overall damping? Better small bump compliance? better pedal efficiency?

 

copy makes sense. I am putting my fork on tomorrow so I will see how i feels once I get it dialed in.

Just curious what is "platform."

J-

Platform is when the fork is locked out, how much pressure is takes to break the lock out and allow the fork to move. More platform = stiffer lock out. Less platform means a lighter lock out. Its all depends on what you want.

 

Platform is when the fork is locked out, how much pressure is takes to break the lock out and allow the fork to move. More platform = stiffer lock out. Less platform means a lighter lock out. Its all depends on what you want.

roger, sort of what I thought

thanks

J-

 

Thanks again !!

so first step i will try a softer spring and start the experiment
Hope i won't create a frankenstein fork

I will report the result here

 

Don't know if I missed it, but I'd say it'd be important to know how much the bottom bolt under the piston should be tightened. The tighter, the more the blow-off shims get preloaded, as they flex more.

I can't find any torque figure in Manitou's tuning guide. How much do you tighten that bolt?

 

Tighten it all the way. The amount of preload on the shims should be set by the stack itself and not the bolt that holds the piston on :thumbsup:

 

Regarding this issue, Randy Grob of ManitouTech wrote me:

you should torque that nut to.... (2.3 - 2.8 N-M)..(20-25 in-lb )

 

But not so hard as to strip the thread or break off the end of shaft.. didn't happen to me yet, but that kind of disaster looks doable.

 

If I torque my bolt a bunch it will deform the single shim that is preloaded by the spring on the bolt side of the piston.

 

Proceed very carefully with that shim -- it should not deform at all if everything is assembled correctly. It's possible to bend it permanently, thus creating significant oil bypass around the compression shim stack.

 

Great info!

 

How fun!

A new Abs+ damper for my Minute arrived yesterday. So today I replaced the one that I had broken last week.. :madman:

But before I unmounted the piston to inspect the shim stack--now I knew how to do it properly

Again, I found out that the new damper came with the production XC stack, as there were 2 blow-off shims, i think 19 x 0.20 mm.

I had hoped for a Trail stack, to try the effect of a speed shim. But anyway, I removed one of the blow-off shims to reduce platform. Till now I had been riding with the production XC stack, and I found 514 N of platform too much for me. With just one shim, platform is reduced to something like 257 N, which I feared would be too little though.

Well, I tried it for a short one hour ride and.. What a ride! True, I can feel bobbing when I climb uphill and push heavily on the pedals out of saddle. But I'm not particulaty keen on out of saddle pedalling, so platform may well be just what I need.

On the other hand, when descending on very rough rocky tracks I can now turn the adjuster to MAX-3, and the fork is so smoother. I think this depends on reduced brake dive, allowing for better use of the fork's travel.

I could descend faster, with less fatigue, feeling more secure, and feeling better terrain complaince. Although there were many pretty big stones, it was as if the front-end was stuck to the track. So much fun! :thumbsup:

Now I'm curious and want to try other configs. I'll buy some shims, cause I want to see what happens with a velocity shim. Why didn't I try it earlier?

BTW, I ride a front, and weigh 154 lbs. May be useful for comparison.

 

Manitou's damping curves

I was looking again at Manitou's graphs.

How comes that the Production XC stack CV-11411-03 gives 514 N of platform, when stack CV-11411-01 gives 220 N?

The first stack has 2 blow-off shims .2 mm thick, while the latter has only one blow-off shim .15 thick.

I would expect 257 N with one platform shim .2 mm thick. Therefore, with one just .15 mm thick I would expect around 108 N..

Am I missing something, or there's an error in the tuning guide?

 

I was looking again at Manitou's graphs.

How comes that the Production XC stack CV-11411-03 gives 514 N of platform, when stack CV-11411-01 gives 220 N?

The first stack has 2 blow-off shims .2 mm thick, while the latter has only one blow-off shim .15 thick.

I would expect 257 N with one platform shim .2 mm thick. Therefore, with one just .15 mm thick I would expect around 108 N..

Am I missing something, or there's an error in the tuning guide?

Interesting. My guess(and its only a guess) is that with just one shim, the preload is higher causing a higher blow off. Each additional shim added to the stack will have less preload, making them contribute less to the blow off point then the previous shim.

 

I see what your saying. The graphs are going to be taken straight from a dyno program, so the graph and the amount of force is going to be correct. If there is a miss print(seems like there is), its going to be on the side where it says the shim sizes. After taking a hard look at the graphs and stacks, I am thinking that its a miss print and the graph shows a single .2mm shim rather then the listed .15

Good catch, something doesnt add up for sure.

 

After taking a hard look at the graphs and stacks, I am thinking that its a miss print and the graph shows a single .2mm shim rather then the listed .15

Yes, that's what I also think. Just wanted to be sure that I wasn't missing something I don't know. Thanks!