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  1. #1
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    How to guide: Reshim your ABS+ HSC shim stack

    Seems like there has been a lot of talk on here about Manitous ABS+ damper and how good it is. I have been playing around with the HSC shim stack over the last few months and figured i would make a "how to" guide so others can do the same. It only takes 15-20 minutes and once you get a shim stack set up for your weight, The ABS+ damper is even better!


    Use a 2.5mm allen wrench to take the top cap off. Take it off carefully!

    Be careful not to loose the little ball bearings and springs, They are very tiny and easy to loose track of.When you reassemble, it doesnt matter where they springs and bearings go as long as they are across from each other.

    Once the top cap is off, unscrew the damper from the leg and pull it out. Pull is out slowly and you wont loose very much oil. Keep a rag near by because you will loose a little no matter what.
    Damper after being pulled out.

    At the very top of the damper, there is a place for a 10mm wrench to hold the damper while you use a 13mm socket to unscrew the nut on the bottom of the piston.

    One shim that is used as a check valve and a spring are under the piston. This just allows oil to flow freely back into the leg after the fork is compressed and re-extended. When reassembling, The spring goes back with the wider end toward the piston and the skinnier end toward the nut.



    Close up of bottom of piston

    Close up of top of piston

    Shim stack installed


    My 2010 drake has 6 compression shims stock. 3 the same size, and 3 that get progressively smaller in a pyramid shape. Lighter rider can remove shims to allow the HSC to open with less force, while heavier riders will want to add shims. Endless possibilities for shim configurations, So if you try this, post your weight and shim stack.


    Reassemble same way you take it apart. Make sure the LSC is all the way open(counter clockwise) when you put the damper back in the leg. Oil height should be 87mm from the crown when fully assembled. If your careful taking it apart you shouldn't loose a significant amount of oil, but always check to make sure.


    Key points from that this thread has turned up:

    1. Thanks to Solitone, we have the Manitou ABS+ tuning guide which includes dyno charts and many different shim stack combinations. Its probably the single best find this thread has produced (thanks Solitone)

    This link should work:
    http://goo.gl/JaqWO

    2. Spring rate needs to be set up correctly. I get PM's and hear of people trying to get their fork to feel right when it is way under/over sprung. Spring rate trumps damping and should always be set up correctly prior to trying different shim stack configurations.

    3. A good place to order shims is MX tech.
    MX-Tech Suspensions
    Last edited by mullen119; 01-17-2014 at 01:06 PM.

  2. #2
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    Is that a dished piston? With the outer ring protruding slightly more than the inner seat which the centre of the shims are compressed against?
    Owner of www.shockcraft.co.nz and NZ Manitou Service Agent.
    www.dougal.co.nz Suspension setup & tuning.
    SPV Devolve

  3. #3
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    Quote Originally Posted by Dougal
    Is that a dished piston? With the outer ring protruding slightly more than the inner seat which the centre of the shims are compressed against?
    yes, there is a small lip that the shims sit on top of. From memory I would say is about half a mm tall

  4. #4
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    Quote Originally Posted by mullen119
    yes, there is a small lip that the shims sit on top of. From memory I would say is about half a mm tall
    Cool, there's another tuning dimension manitou have given you. By relocating small shims to under the largest one you can reduce the preload on the shim stack and have it opening sooner.

    Basically now you've got platform starting point on top of all the usual shim stack options. By closing the freebleed it's a total platform.
    Owner of www.shockcraft.co.nz and NZ Manitou Service Agent.
    www.dougal.co.nz Suspension setup & tuning.
    SPV Devolve

  5. #5
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    that's a great point dougal. I never thought about it, but that would open up even more options.

  6. #6
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    So, for a total shim newb here, do you remove one of the largest diameter shim to decrease HSC? Conversely, do you add a shim equal to the largest diameter shims to increase HSC?

    What do you torque the nut to?

    Is there some place I can read about the underlying mechanics of how this shim system works?

  7. #7
    PMK
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    Yes the stack preload can be a good tuning option for those that understand it.

    Currently Race Tech has this option with their G2 series Gold Valves.

    Race Tech takes it a step further by allowing the preload shim the ability to run different diameters that alter the port area.

    Those wanting to understand more should do some searching about Penske dampers. There should still be tech articles about the various piston or valve body designs.

    Also, remember, that as you unload the stack, you almost always must firm the stack. The downside of running a non preloaded stack is in most instances you will increase HS damping and often create deflection issues.

    PK
    Last edited by PMK; 02-21-2011 at 07:53 AM.

  8. #8
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    Subscribed. (great thread!)

    P

  9. #9
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    I have the Drake '10.

    I am not a suspension engineer.

    How does rider weight affect the purpose of the shim stack?

  10. #10
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    Quote Originally Posted by JLantz
    I have the Drake '10.

    I am not a suspension engineer.

    How does rider weight affect the purpose of the shim stack?
    The purpose of the HSC shim stack is to open as a "blow off" when oil pressure builds up because it cant get through LSC circuit fast enough. Heavy riders are going to create more pressure then lighter riders, causing the shim stack to open on smaller hits that a heavier rider may not want it to open on. On the other side, lighter riders will have to hit a much bigger hit to get the same shim stack to open. Think of it as a 250lbs person is going to be much harder on a fork then a 150lbs person, So them same shim stack on the same fork will feel a lot different to those two people.

  11. #11
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    Quote Originally Posted by half_man_half_scab
    So, for a total shim newb here, do you remove one of the largest diameter shim to decrease HSC? Conversely, do you add a shim equal to the largest diameter shims to increase HSC?

    What do you torque the nut to?

    Is there some place I can read about the underlying mechanics of how this shim system works?

    You can add and remove any size shim, you will get the biggest effect by adding or removing the biggest shims, but for fine tuning, you can change any of them. There is also different shim thicknesses that you can use for more tuning options.

    I couldnt find a torque number for the nut. I just snug it down fairly lightly and have not had any problems, But if anyone find a torque number it would be good to know.

    use google to find information on shim stacks, Lots of good information out there

  12. #12
    PMK
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    Took a moment and found a link to the Penske site info.

    http://www.penskeshocks.com/files/Adjustable_Manual.pdf

    Later pages discuss the various piston design formats.

    Pretty technical but should be more than enough information to make your brain hurt.

    Granted it is not bicycle specific in title but is applicable.

    PK

  13. #13
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    Good link PMK

  14. #14
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    I've got an introduction to shim stacks on the www.dougal.co.nz website below, because it's frames (yeah it needs updated), but follow this path
    www.dougal.co.nz
    -> click to enter
    -> Suspension
    -> Advanced tuning tab will turn up below. Read the basic tuning one first

    The Penske one is a gold mine once you've got a handle on it.
    Owner of www.shockcraft.co.nz and NZ Manitou Service Agent.
    www.dougal.co.nz Suspension setup & tuning.
    SPV Devolve

  15. #15
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    Quote Originally Posted by Dougal
    I've got an introduction to shim stacks on the www.dougal.co.nz website below, because it's frames (yeah it needs updated), but follow this path
    www.dougal.co.nz
    -> click to enter
    -> Suspension
    -> Advanced tuning tab will turn up below. Read the basic tuning one first

    The Penske one is a gold mine once you've got a handle on it.
    Thats a great link dougal. It explains shim stacks in detail and it written in a way that I would think a noob would understand pretty easily.

  16. #16
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    Quote Originally Posted by mullen119
    Thats a great link dougal. It explains shim stacks in detail and it written in a way that I would think a noob would understand pretty easily.
    Thanks, I always appreciate good feedback.
    Owner of www.shockcraft.co.nz and NZ Manitou Service Agent.
    www.dougal.co.nz Suspension setup & tuning.
    SPV Devolve

  17. #17
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    here is a good place to buy shims. I still need to measure the shims ID and max OD. I will do so and post them when I get a chance.
    Last edited by mullen119; 03-06-2011 at 11:38 AM.

  18. #18
    www.derbyrims.com
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    Quote Originally Posted by Dougal
    Thanks, I always appreciate good feedback.
    Dougal, did the quake affect your area?

  19. #19
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    Quote Originally Posted by derby
    Dougal, did the quake affect your area?
    Hi Ray

    I live about 450km away so that quake and the aftershocks were just able to be felt here. But I do have a lot of friends and also family in Christchurch. So far every report I've heard from people I know is good, but it is still early days and there are a lot of people still to get news from.
    It will be some time before the extent of the casaulties are known.
    Owner of www.shockcraft.co.nz and NZ Manitou Service Agent.
    www.dougal.co.nz Suspension setup & tuning.
    SPV Devolve

  20. #20
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    Quote Originally Posted by Dougal
    Hi Ray

    I live about 450km away so that quake and the aftershocks were just able to be felt here. But I do have a lot of friends and also family in Christchurch. So far every report I've heard from people I know is good, but it is still early days and there are a lot of people still to get news from.
    It will be some time before the extent of the casaulties are known.

    Good to hear you are ok dougal, Hopefully all your friends and family are as well.

  21. #21
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    Subscribed!!!
    As I have a 2009 Minute modified with the ABS+ damper.
    It's a great setup BTW.
    Look, whatever happens, don't fight the mountain.

  22. #22
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    Hello everyone. I own a Manitou Minute Expert 100 mm.
    Weight around 158 pounds, maybe 165 equipped.

    Have been riding the fork for about 10-15 hours already and still feel it kinda stiff on its travel.

    One click from fully open is what i usually use when going downhill, on very rocky terrain. Im running the fork at around 10 psi.
    Im getting maybe 70 or 75 mms of travel from it, even from big, soccer sized football rocks.
    So i was thinking about getting rid of one of the medium shims.

  23. #23
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    Take the 10 psi out and go for a ride. Taking a shim out would allow you to run the 2-3, maybe even 4 clicks of low speed compression to dial out brake dive and some pedal bob and still maintain small bump sensitivity, But not change the amount of travel you use. Since your fork is a coil fork with air preload, you may need to change to a softer coil spring. That being said though, hitting a soccer sized rock should not bottom your fork, It should only use close full travel on a 2-3 ft drop or a pretty hard hit. What does the fork give you for sag?

  24. #24
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    Thought this would help out: Find your fork and your forks travel. The first number after is is stock oil height, Second set of numbers is acceptable range of oil height.

    Circus Comp/Match 80mm 83 80-85
    Circus Comp/Match 100mm 83 80-85
    Match 130mm 83 80-85
    Circus Expert/Drake 80mm 87 85-90
    Circus Expert/Drake 100mm 87 85-90
    Circus Expert/Drake 130mm 87 85-90
    R7 80mm 83 80-85
    R7 100mm 83 80-85
    Minute 100mm 87 85-90
    Minute 120mm 87 85-90
    Minute 140mm 87 85-90
    Drake 29er 80mm 87 85-90
    Drake 29er 100mm 87 85-90
    Drake 29er 120mm 87 85-90
    Minute 29er 80mm 87 85-90
    Minute 29er 100mm 87 85-90
    Minute 29er 120mm 87 85-90
    R7 MRD 80mm 103 100-105
    R7 MRD 100mm 108 105-110
    Minute MRD 100mm 108 105-110
    Minute MRD 130mm 113 110-115

  25. #25
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    Bob

    Just switched out my old 100mm minute absolute air (with ABS+) for a 120mm Tower Pro. I had the 100 dialed so that about 2-4 clicks, I had no bob on the climbs, but had the action that I wanted for travel. On my 120, the only way to control the bob on climbs is full lock out. Would you say adding about 1-2 big shims would put my "happy" range somewhere between full lock out and 0? I weigh 165 and have no idea which springs were in each of those forks, they had what ever was "stock".
    Thanks!

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