Page 1 of 12 1 2 3 4 5 11 ... LastLast
Results 1 to 25 of 282
  1. #1
    eBiker
    Reputation: Mr.P's Avatar
    Join Date
    Feb 2005
    Posts
    5,055

    Marzocchi 55 TST2 conversion to shim damping: step by step

    This is a modification to a Marzocchi 55 TST2 fork damper cartridge. This modification converts the lock-out to a low speed compression adjustment and adds a high-speed compression shim stack.

    (For a bleed only proceedure, see here: TST2 Bleed alternative w/pics )

    It all started with an MTBR post asking for help on how to set up a Mazocchi 55 TST2 fork...And turned into a complete damper modification.

    The problem I was having was high speed spiking. With the help of Flyag1 (he cracked open his damper cartridge and set me the pics) we were able to figure out that the damping was a port orifice design. The port orifice being the source of the high speed spiking. But from Flyag1's pics I also noticed something else; a blanked off potential compression piston.

    This compression piston was simply blanked off with just some thick washers. I speculated that we could replace the washers with a shim stack with the lock-out orifice acting as an adjustable bypass port. Sounds great, but modifying my new 3 year warranteed fork on some pics and guesswork was pretty racy for me. Then I got the dreaded hydro-locking damper cartridge - a week before Sea Otter (I was entered to race). And Marzocchi Tech Department replied to my post with confirmation of our guesses and additional great info, to give me the confidence I needed.

    I knew I had to crack open the cartridge to be able to run the fork for Sea Otter. I figured, if I'm in there I may as well give the damper mod a shot. I had my spacer ready, shims ready, beers ready...


    Here is how it went down:

    1) Pry up the lock out with a flat blade screw driver - it is held in by the friction of an O-ring.



    2) Remove the plastic bits and keep them in order



    3) Use a 22mm ground down socket and unscrew the top of the damping cartridge from the fork crown.

    This next part is NOT part of the Marzocchi recommended damper bleed proceedure - but I was able to do the whole modification and bleed without removing the damping cartridge.

    4) Push the fork to bottom (air and spring removed from spring side) while making sure that the damping cart is still extended out of the fork.

    5) Unscrew cart top. I used an old tube to friction hold the outside of the cart to keep it from spinning. It was tough and required a beer for courage. lol.

    6) After loosening carefully pull compression damper straight out.


    fixxxer0 provided a correction:
    its a 27mm socket you need to grind down, not a 22mm as stated in the picture below



    7) Remove bottom bolt from damper shaft. More beer for courage. Marzocchi Tech Department advised to heat the bolt as there is loc-tite on the threads - and I don't think I could have gotten the bolt off without doing so. Again, I used my old tube to hold the damper.



    8) Bye bye thick unflexing washers. Hello flexy goodness shims and spacer! Welcome speed sensitive damping!
    Right now it is a pyramid stack 17mm, 16mm, 16mm, 15mm, 13mm. All (I think) .010 thick except for the 13mm which is .005 thick. 18mm scraped the side of the cartridge. (all 8mm ID)

    The spacer is an aluminum chainring bolt spacer.




    9) Measure oil level in the damper at full extension. Flyag1 came up with measurement of 110mm from the top - it is dead-on! This will give an oil level just above the piston/shim for proper operation.

    10-x) Reverse rest of proceedure to put back together.

    Success = beer.


    RIDING RESULTS:

    Damping was controlled and felt as normal (pre-mod) with trail riding at wide-open. Then I stuffed the front wheel straight into the boneyards at speed; the smaller stuff was simply erased, 3" or larger squared rock stills had some feedback, but it was controlled and not spiked feedback (and could be related to spring ramp-up). It did make my rear shock seem less plush - not a technical issue just a feel issue. End of DH rock run, my hands were not killing me as they were prior to the mod. I did still have some arm pump, but that is expected on that particular trail.

    Drops and jumps seemed to go just a bit deeper into travel, (spring rate or less HSC?) but the ramp up of the air spring still gave that lovely landing-on-a-couch feel, and covered any mistakes.

    Lock-out is now a compression adjustment. Full lock out is firm compression (port orifice is off and piston/shim is active) that makes the fork only move about an inch under stand and pedal situations (2 inches max when stand and mash is tired and sloppy). The cool part this this retains 80% of the lock out benefits, but the travel remains well controlled and active - still eating up small and large features. I will never have to worry if I am locked or not on a downhill, as it is still perfectly rideable on "full lock".

    So am I happy? Hell yes! It is now the fork I thought I bought and wanted. I love that I can also easily modify to shim stack to shape the compression to my riding.

    I am using a quarter turn compression setting to give an nice controlled and efficient feel on XCish and flowy trails - it also helps with dive. (just a quarter turn gives me full shim stack only compression)

    MAINTENANCE RESULTS:

    After a couple of 20+ mile rides, 40-50 runs on the Sea Otter dual slalom course that included uncountable jumps and drops all is working fine (it should). And I am glad to say the damper has not hydro-locked. I should also note it only takes about 10-15 minutes to get to shim stack now.

    Start modding!!

    Thanks again to Flyag1 and Marzocchi Tech Department. They helped me to make a good fork great.

    P
    Last edited by All Mountain; 09-25-2008 at 03:18 AM.

  2. #2
    "El Whatever"
    Reputation: Warp's Avatar
    Join Date
    May 2004
    Posts
    18,645
    AM, please stick it or add it to the Service thread!!!

    Would ya, mate??

    P... Great post and mod.
    Check my Site

  3. #3
    No, that's not phonetic
    Reputation: tscheezy's Avatar
    Join Date
    Dec 2003
    Posts
    14,364
    WTF is Zoke thinking putting the thick washers in there and not just shipping the fork with shims in the first freaking place!!!!!!!!!!!!!!!!!!!!!!????????????????
    My video techniques can be found in this thread.

  4. #4
    mtbr member
    Reputation:
    Join Date
    Dec 2005
    Posts
    6,212
    Quote Originally Posted by Warp
    AM, please stick it or add it to the Service thread!!!

    Would ya, mate??

    P... Great post and mod.
    Done. It's in the Marzocchi Service Info Thread, accessible through the Fork and Shock service Information Sticky thread at the top.


    This thread indicates what we all suspected for the last few years.... that Marzocchi designers are not the sharpest tools in the shed.

  5. #5
    Where's my funny hat?
    Reputation:
    Join Date
    Aug 2006
    Posts
    455
    Hey Pat, nice work. Did you have to mod the spacer at all? Did you loctite the bottom nut back on? Any side view pics post mod, prior to reassembly? Thanks again, if I can get my ata cart sorted I will def be doing the conversion!!! Cheers, Steve

  6. #6
    eBiker
    Reputation: Mr.P's Avatar
    Join Date
    Feb 2005
    Posts
    5,055
    Quote Originally Posted by Stevo the Devo
    Hey Pat, nice work. Did you have to mod the spacer at all? Did you loctite the bottom nut back on? Any side view pics post mod, prior to reassembly? Thanks again, if I can get my ata cart sorted I will def be doing the conversion!!! Cheers, Steve
    Thanks Steve, no mods done to the spacer it had an ID of 8mm and a thickness of 3mm. NO additional loctite added (seemed tight enough and I want easier access)

    Here is a pic of the compression part of the damper that Flyag1 took. Note that this was from the previous thread when we were figuring things out and "Lock out blow off" is not correct.

    P
    Attached Images Attached Images
    Last edited by Mr.P; 05-09-2008 at 07:48 AM.

  7. #7
    Flying Goat
    Reputation: mrpercussive's Avatar
    Join Date
    Apr 2006
    Posts
    11,329
    nice job dude!!!

  8. #8
    "El Whatever"
    Reputation: Warp's Avatar
    Join Date
    May 2004
    Posts
    18,645
    Quote Originally Posted by All Mountain
    This thread indicates what we all suspected for the last few years.... that Marzocchi designers are not the sharpest tools in the shed.
    I don't think the problem lies in their designers.

    Shims cost more than regular washers. For us it's a few dollars, but for them could be thousands. And they can't let their cheapo model to have better damping than their top of the line. Money rules here.
    Check my Site

  9. #9
    fraid of heights
    Reputation: stiingya's Avatar
    Join Date
    Apr 2004
    Posts
    1,518
    By chance does anyone know if a similar mod could be done to the TST2 on the previous AM line of forks??

    Thanks...

  10. #10
    "El Whatever"
    Reputation: Warp's Avatar
    Join Date
    May 2004
    Posts
    18,645
    Quote Originally Posted by stiingya
    By chance does anyone know if a similar mod could be done to the TST2 on the previous AM line of forks??

    Thanks...
    If they're the closed cartridge type (not bladder), yes. Most probably.
    Check my Site

  11. #11
    eBiker
    Reputation: Mr.P's Avatar
    Join Date
    Feb 2005
    Posts
    5,055
    Quote Originally Posted by tscheezy
    WTF is Zoke thinking putting the thick washers in there and not just shipping the fork with shims in the first freaking place!!!!!!!!!!!!!!!!!!!!!!????????????????
    I think it was a marketing decision to put the washers in there. Perhaps they thought the lock out is what the market wanted, and the lock out requires blanking off the piston with the washers. (LO was kinda cool for stand and mash/hammer)

    And they can't have TST2 outperform TST Micro.

    It would be the same manufacturing process and cost of shims is cents.

    P

  12. #12
    Elitest thrill junkie
    Reputation: Jayem's Avatar
    Join Date
    Jul 2005
    Posts
    18,504
    Cool, hell it may even outperform RC2/3 due to the shimmed piston. It just shows you how much marzocchi has sacrificed in recent times. They *should* have a shimmed piston with both compression and rebound shims, maybe adjustable low-speed compression and rebound bleed. It's utterly rediculous to have a ported damper when performance can be so much better.
    "It's only when you stand over it, you know, when you physically stand over the bike, that then you say 'hey, I don't have much stand over height', you know"-T. Ellsworth

    You're turning black metallic.

  13. #13
    MK_
    MK_ is offline
    carpe maņana
    Reputation: MK_'s Avatar
    Join Date
    Nov 2004
    Posts
    7,124
    Nice work, man.

    _MK

  14. #14
    Sometimes has attitude
    Reputation: Marzocchi Tech Department's Avatar
    Join Date
    Mar 2008
    Posts
    700
    Quote Originally Posted by All Mountain
    This thread indicates what we all suspected for the last few years.... that Marzocchi designers are not the sharpest tools in the shed.
    If we weren't very sharp then we wouldn't have been able to supply this info to Mr. P. in the first place.

    All Mountain you have now gotten under my skin. ...and this just makes it harder for me to come here and help out....but what should I expect right???

    At least I have unsharpened tools in my shed....and I'm not one.

    FYI, TST2 was and is designed to be a climbing feature nothing else. If you want a tuned compression you should buck up and get the TST micro. It has all the performance you get from this mod and more.
    Last edited by Marzocchi Tech Department; 05-28-2008 at 09:57 AM.
    Ride Your Bike!

  15. #15
    Elitest thrill junkie
    Reputation: Jayem's Avatar
    Join Date
    Jul 2005
    Posts
    18,504
    Quote Originally Posted by Marzocchi Tech Department
    If we weren't very sharp then we wouldn't have been able to supply this info to Mr. P. in the first place.

    All Mountain you have now gotten under my skin. ...and this just makes it harder for me to come here and help out....but what should I expect right???

    At least I have unsharpened tools in my shed....and I not one.

    FYI, TST2 was and is designed to be a climbing feature nothing else. If you want a tuned compression you should buck up and get the TST micro. It has all the performance you get from this mod and more.
    So the TST Micro has compression shims in it?

    The reason I say this is that I had an AM1 with the TST 5, it included an orofice damper (the TST adjuster) and some sort of stiff-blow off, but no shims covering an orofice to react to impacts of varying force. I retrofitted a Z150 HSCV cart into it, which was a far superior ride in terms of suspension. I HIGHLY doubt that a TST Micro fork would be superior to this mod if it is anything like my TST5 damper. The AM1 tended to spike a lot over high frequency/fast impact bumps. This mod would give it a damper that's capable of dealing with low and high speed impacts with out that negative harshness that is caused by the orofice damper.
    Last edited by Jayem; 05-09-2008 at 10:12 AM.
    "It's only when you stand over it, you know, when you physically stand over the bike, that then you say 'hey, I don't have much stand over height', you know"-T. Ellsworth

    You're turning black metallic.

  16. #16
    mtbr member
    Reputation:
    Join Date
    Aug 2005
    Posts
    1,632
    Quote Originally Posted by Marzocchi Tech Department
    If we weren't very sharp then we wouldn't have been able to supply this info to Mr. P. in the first place.

    All Mountain you have now gotten under my skin. ...and this just makes it harder for me to come here and help out....but what should I expect right???

    At least I have unsharpened tools in my shed....and I not one.

    FYI, TST2 was and is designed to be a climbing feature nothing else. If you want a tuned compression you should buck up and get the TST micro. It has all the performance you get from this mod and more.

    Very, very tasteful.

  17. #17
    mtbr member
    Reputation:
    Join Date
    May 2007
    Posts
    88
    Quote Originally Posted by MaddSquirrel
    Very, very tasteful.
    What ever. He's human, not some PR robot.

    I will take answers to questions regardless if he gets rightfully pissy about people stabbing him with worthless insults.

    I think we can all be happy the TST 2 is even user tunable to begin with.

  18. #18
    mtbr member
    Reputation:
    Join Date
    Jan 2006
    Posts
    804
    Quote Originally Posted by Mr.P
    This is a modification to a Marzocchi 55 TST2 fork damper cartridge. This modification converts the lock-out to a low speed compression adjustment and adds a high-speed compression shim stack.

    (For a bleed only proceedure, see here: TST2 Bleed alternative w/pics )

    It all started with an MTBR post asking for help on how to set up a Mazocchi 55 TST2 fork...And turned into a complete damper modification.

    The problem I was having was high speed spiking. With the help of Flyag1 (he cracked open his damper cartridge and set me the pics) we were able to figure out that the damping was a port orifice design. The port orifice being the source of the high speed spiking. But from Flyag1's pics I also noticed something else; a blanked off potential compression piston.

    This compression piston was simply blanked off with just some thick washers. I speculated that we could replace the washers with a shim stack with the lock-out orifice acting as an adjustable bypass port. Sounds great, but modifying my new 3 year warranteed fork on some pics and guesswork was pretty racy for me. Then I got the dreaded hydro-locking damper cartridge - a week before Sea Otter (I was entered to race). And Marzocchi Tech Department replied to my post with confirmation of our guesses and additional great info, to give me the confidence I needed.

    I knew I had to crack open the cartridge to be able to run the fork for Sea Otter. I figured, if I'm in there I may as well give the damper mod a shot. I had my spacer ready, shims ready, beers ready...


    Here is how it went down:

    1) Pry up the lock out with a flat blade screw driver - it is held in by the friction of an O-ring.



    2) Remove the plastic bits and keep them in order



    3) Use a 22mm ground down socket and unscrew the top of the damping cartridge from the fork crown.

    This next part is NOT part of the Marzocchi recommended damper bleed proceedure - but I was able to do the whole modification and bleed without removing the damping cartridge.

    4) Push the fork to bottom (air and spring removed from spring side) while making sure that the damping cart is still extended out of the fork.

    5) Unscrew cart top. I used an old tube to friction hold the outside of the cart to keep it from spinning. It was tough and required a beer for courage. lol.

    6) After loosening carefully pull compression damper straight out.




    7) Remove bottom bolt from damper shaft. More beer for courage. Marzocchi Tech Department advised to heat the bolt as there is loc-tite on the threads - and I don't think I could have gotten the bolt off without doing so. Again, I used my old tube to hold the damper.



    8) Bye bye thick unflexing washers. Hello flexy goodness shims and spacer! Welcome speed sensitive damping!
    Right now it is a pyramid stack 17mm, 16mm, 16mm, 15mm, 13mm. All (I think) .010 thick except for the 13mm which is .005 thick. 18mm scraped the side of the cartridge. (all 8mm ID)

    The spacer is an aluminum chainring bolt spacer.




    9) Measure oil level in the damper at full extension. Flyag1 came up with measurement of 110mm from the top - it is dead-on! This will give an oil level just above the piston/shim for proper operation.

    10-x) Reverse rest of proceedure to put back together.

    Success = beer.


    RIDING RESULTS:

    Damping was controlled and felt as normal (pre-mod) with trail riding at wide-open. Then I stuffed the front wheel straight into the boneyards at speed; the smaller stuff was simply erased, 3" or larger squared rock stills had some feedback, but it was controlled and not spiked feedback (and could be related to spring ramp-up). It did make my rear shock seem less plush - not a technical issue just a feel issue. End of DH rock run, my hands were not killing me as they were prior to the mod. I did still have some arm pump, but that is expected on that particular trail.

    Drops and jumps seemed to go just a bit deeper into travel, (spring rate or less HSC?) but the ramp up of the air spring still gave that lovely landing-on-a-couch feel, and covered any mistakes.

    Lock-out is now a compression adjustment. Full lock out is firm compression (port orifice is off and piston/shim is active) that makes the fork only move about an inch under stand and pedal situations (2 inches max when stand and mash is tired and sloppy). The cool part this this retains 80% of the lock out benefits, but the travel remains well controlled and active - still eating up small and large features. I will never have to worry if I am locked or not on a downhill, as it is still perfectly rideable on "full lock".

    So am I happy? Hell yes! It is now the fork I thought I bought and wanted. I love that I can also easily modify to shim stack to shape the compression to my riding.

    I am using a quarter turn compression setting to give an nice controlled and efficient feel on XCish and flowy trails - it also helps with dive. (just a quarter turn gives me full shim stack only compression)

    MAINTENANCE RESULTS:

    After a couple of 20+ mile rides, 40-50 runs on the Sea Otter dual slalom course that included uncountable jumps and drops all is working fine (it should). And I am glad to say the damper has not hydro-locked. I should also note it only takes about 10-15 minutes to get to shim stack now.

    Start modding!!

    Thanks again to Flyag1 and Marzocchi Tech Department. They helped me to make a good fork great.

    P
    Wow, great post.
    I found basically the same thing with the ROCO TST coil. Way overdamped and slow for me. I had to remove 3 comp. shims. and 2 rebound shims to get a faster response. I guess it's difficult to design a damping system from riders 120 - 240#'s.

  19. #19
    Code Burr
    Reputation: thebronze's Avatar
    Join Date
    Jan 2004
    Posts
    1,376
    Sweet valley high! OK where did you get the shims and how much do you weigh? Did Tom help you size the shims?

  20. #20
    mtbr member
    Reputation:
    Join Date
    Sep 2005
    Posts
    53

    damn!

    Dude, where did you find the shims? Do you know if this will work with an 07 All Mountain 1 TST2 cart? I find the TST lockout to be redundant when ETA is available on the other leg. I was thinking of replacing the TST2 with an RC2, but this sounds a lot cheaper (provided it would work).

  21. #21
    mtbr member
    Reputation:
    Join Date
    Aug 2007
    Posts
    93
    Quote Originally Posted by thebronze
    Did Tom help you size the shims?
    Thats what he said:
    Here's what can be done. I did it and like it too but you loose the lock-out and turn it into a ripping performance setting. You will need 3 shims @ 18mm x 0.15mm thick with an 8mm ID hole. You will also need 3 washers 11mm OD by 11 ID. They need to be about 1mm thick.... Warning, if you break it you will pay for a new one.

    I would also like to know if this is also possible on All mountain with TST2. In one topic Tom said that it doesn't have bladder.

  22. #22
    eBiker
    Reputation: Mr.P's Avatar
    Join Date
    Feb 2005
    Posts
    5,055
    Quote Originally Posted by dougbot
    Dude, where did you find the shims? Do you know if this will work with an 07 All Mountain 1 TST2 cart? I find the TST lockout to be redundant when ETA is available on the other leg. I was thinking of replacing the TST2 with an RC2, but this sounds a lot cheaper (provided it would work).
    Shims can be had here:
    http://www.mx-tech.com/?id=products&subcat=153

    Or pilfered from Manitou forks.

    The pyramid shaped shim stack (large to smaller) is to create progressive damping. Less low speed, more high speed. Shims all the same size would create more low speed damping and less high speed.

    There is no real right or wrong way to set up the shim stack (within reason) - it is more of what is best for you and how you ride.

    P

  23. #23
    Stray Bullet
    Reputation: Nagaredama's Avatar
    Join Date
    Aug 2004
    Posts
    2,258
    Do you know if this will work on the 2007 AM 1 with TST2?

  24. #24
    mtbr member
    Reputation:
    Join Date
    Dec 2005
    Posts
    6,212
    Why does a 55 need a lockout for climbing?

  25. #25
    Code Burr
    Reputation: thebronze's Avatar
    Join Date
    Jan 2004
    Posts
    1,376
    The tst2 cartridge looks a lot like the ETA setup on my Z1. Does anyone know if they are similar inside and if you can even get the ETA cart apart? I need to take mine apart as the rod unthreads from the piston occasionally.

Page 1 of 12 1 2 3 4 5 11 ... LastLast

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •