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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: https://forums.mtbr.com/showthread.php?t=410888 )

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. :eek:

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. :p

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! :eekster:
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! :thumbsup: 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
 

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Warp said:
AM, please stick it or add it to the Service thread!!!

Would ya, mate??

P... Great post and mod. :thumbsup:
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.
 

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Where's my funny hat?
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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
 

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I dig trails!
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Discussion Starter · #6 · (Edited)
Stevo the Devo said:
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
 

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"El Whatever"
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All Mountain said:
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.
 

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I dig trails!
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Discussion Starter · #11 ·
tscheezy said:
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. :nono: :eek: :p

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

P
 

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Elitest thrill junkie
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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.
 
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All Mountain said:
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. :mad: ...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.
 

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Elitest thrill junkie
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Marzocchi Tech Department said:
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. :mad: ...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.
 

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Marzocchi Tech Department said:
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. :mad: ...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.
 

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Mr.P said:
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: https://forums.mtbr.com/showthread.php?t=410888 )

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. :eek:

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. :p

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! :eekster:
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! :thumbsup: 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.
 

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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).
 
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