Mountain Bike Reviews Forum banner
21 - 40 of 83 Posts

·
I dig trails!
Joined
·
5,608 Posts
Discussion Starter · #21 ·
More pics!

flyag1 sent over some more pics for posting. :thumbsup:

They can speak for themselves.

Tuning options on the damper seem to include:
- lighter weight oil (the ham fisted approach - but effective)
- modify the blow off with a thinner and perhaps pyramid shim stack ( I guess one would have to start with a good amount of shims based on what is stock)

Anyone else with any more ideas?

P
 

Attachments

·
I dig trails!
Joined
·
5,608 Posts
Discussion Starter · #22 · (Edited)
Potential Improvement to Damper

So I got thinking about the blow off to shim stack, and began to think it is quite feasible.

After all it would only be used when the oil pressure starts to spike.

By putting lighter shims in a pyramid stack, lockout would be more like a platform, and high speed compressions would be directed through the shim stack reducing spikes. Does this sound accurate?

Anyone have any thoughts on implementation? It's so easy to think about but reality is a bit different :D

Pics of potential change below.

flyag1 measured out the stock blow off shims:
"There are actually 4 shims in the factory stack, (0.32 ID X 0.790 OD x 0.016 thick)"

One other possibility would be to reduce to blow off shim stack to just one shim. It would not be a progressive stack but working in conjunction with the orifice damper, might reduce the high speed spikes. Thoughts anyone?

Flyag1, was there any nitrogen in the cartridge? And if it is a seal issue that makes the cartridges crap out, any way for us to fix on a more permanent level?

P
 

Attachments

·
I dig trails!
Joined
·
5,608 Posts
Discussion Starter · #23 · (Edited)
UPDATE: New settings, damper info and ride report

Another ride :thumbsup: Another tweak. :D

The Cheese gave me a good tip to lower my oil height (while at same psi) to reduce down the spring rate mid-stroke. It was on the to-do list as my 55mm (Marz rec) height was not giving me full travel (about 30mm short), but his input made me be a bit more aggressive.

Settings:
23psi, oil height 62mm, rebound fast as reasonable

So I took the spring out and reduced the oil level to 62mm from crown.

While the spring was out, I decided to run some tests on the damper:

- no spring (coil & air), damper open = damper gets progressive at 60mm to bottom. Progressive to the point where it requires my full body weight to reach bottom. Air or nitrogen compression in damper? Me thinks less need for spring progressiveness. EDIT: it is the air in the damper side leg that was creating the progressiveness.

- no spring (coil & air),damper closed to lock out = super damped but still travels, rebound is damped normally.

Ride results:
- Same trail as all above.
- 150mm travel with a nose heavy landing on a 4' drop. :thumbsup: I'll save that last 10mm for a nasty oops incident.
- Small stuff at a moderate speed was invisible (I think my turning the fork upside down to lube the bushings helped the small bumps)
- 2-3" rocks at high speed were firm, but did not feel spiked like an RV type damper
- I nose heavied a 4' drop, over shot the landing on a 6' gapper, poorly landed a near flat landing and the fork just sucked it up without complaint. I love this fork for that. :thumbsup:

So, final opinion is that the damper's high speed compression is a bit over the top, not horrible for fast descending - but not great either, but the HSC rocks the freeride stuff!

I need to try this fork at Downieville - which can get very fast and rough - to see if it is a keeper.

Also, if the damper craps out on me, I might just try adjusting the blow off to a firm shim stack.

I want to keep the lock out as it can make a fast & efficient ascender on short out of saddle steeps. Never thought I would say that about a 160mm fork.

P
 

·
Registered
Joined
·
746 Posts
Mr.P said:
Another ride :thumbsup: Another tweak. :D

spring (coil & air), damper open = damper gets progressive at 60mm to bottom. Progressive to the point where it requires my full body weight to reach bottom. Air or nitrogen compression in damper? Me thinks less need for spring progressiveness.

high speed compression is a bit over the top, not horrible for fast descending - but not great either, but the HSC rocks the freeride stuff!

P
Mr P,
TST cartridge has no charge (no air... no nitrogen)

Yes the fork does get progressive... even with the spring side open,but it's not the TST cartridge. It's the fork leg itself, as it is sealed. Larger oil volumes in the fork legs will also allow greater buildup pressures inside the fork. Need a stiffer fork, add oil...need more travel and a softer ride take away oil....

It's even possible to have negative pressure in the right side of the 55 TST. To set up negative, remove cap and spring from left side... unscrew cap from TST side and compress fork and press the top cap of the TST cartitdge back into the right leg and re-tighten the top cap. Try to extend the fork and you will find if very difficult as the negative pressure will not allow you to do so....
Negative pressure could be used to decrease Crown to axle length?
Negative pressure could be used as a top out bumper?
Maybe the negative would provide small but plushness?
Of course, negative pressure would decrease usable travel.

I totally agree the shims are causing issues with high speed plushness. As you suggested I am experimenting with a lighter pyramid shape compression stack of shims, backed by a heaver stack. In theory small hits only require small volumes of oil movement, where as big hit will require larger volumes. The lighter shims at the beginning of the stack should allow small volumes of oil to pass the compression piston with very little resistance. The heaver shims behind the lighter stack should restricting total volume and induce pressure buildup inside the TST cartridge for big hits Hence: progressive travel... The air pressure buildup inside the sealed legs will aid in the progressive travel as well....
 

·
I dig trails!
Joined
·
5,608 Posts
Discussion Starter · #25 · (Edited)
flyag1 said:
Mr P,
TST cartridge has no charge (no air... no nitrogen)
Great info, thanks. So it is filled to the brim with oil. Doesn't the oil need a space to fill on compression?

flyag1 said:
Yes the fork does get progressive... even with the spring side open,but it's not the TST cartridge. It's the fork leg itself, as it is sealed.
Doh! I forgot about the cartridge side!

flyag1 said:
It's even possible to have negative pressure in the right side of the 55 TST. To set up negative, remove cap and spring from left side... unscrew cap from TST side and compress fork and press the top cap of the TST cartitdge back into the right leg and re-tighten the top cap. Try to extend the fork and you will find if very difficult as the negative pressure will not allow you to do so....
Negative pressure could be used to decrease Crown to axle length?
Negative pressure could be used as a top out bumper?
Maybe the negative would provide small but plushness?
Of course, negative pressure would decrease usable travel.
Very clever! I did something similar to my wifes fork, only created negative pressures on both sides to reduce coil spring rate. It worked great for her.

I wonder if this could work for small bump stuff? I bet it would. It might pull down the sag a bit, but the key would be to find that perfect balance between left and right leg pressures.

Or maybe just get a custom made coil for the coil side, no longer use the Air Preload, and let the static pressures add the progressiveness.

There is already a coil negative spring on the coil side.

P
 

·
Registered
Joined
·
52 Posts
Nice work guys. It great to see how the new dampers are.

It is interesting to see how Marzocchi tried to overcome the problems of the TST5 cartridge. And what I mean here was the blowing of the blander. The old TST5 cartridge used the rubber blander for the amount of oil that was dislocated by the rebound rod during compression. If some oil leaked from the cartridge, then air would get in during the rebound phase. And air into the cartridge meant that the compression piston didn't work anymore (it needs to be completely in oil).

With the new design the rubber blander is replace by the air chamber above the compression piston. The piston needs to be immerse into oil but, there needs to be a decent amount of air above it. So there is a specific amount of oil that needs to be put in the cartridge. At least this is what one can see from the pictures.

Those my believe is that blown cartridges are due wrong amount of oil. The cartrige will be damaged if there is too much oil in the damper! Just think about it. Under compression the oil dislocate by the rebound rod will not have where to go (even if there is a bit of air in the cartridge the pressure will extremely rump up). And the only way out of the damper is the rebound rod seal or one of the seal s of the upper or lower caps. If one of these seals brake, than the oil will be out and there will be no compression.

Thus I think that someone (Marzocchi!!!) needs to come up with the right oil levels for new TST cartridges. If I would have such a fork I would take out the cartridge and try to put as few oil into the damper as possible before using it. As usual Marzocchi has good design but screw things up at the assembly.
 

·
"El Whatever"
Joined
·
18,889 Posts
macadam said:
Nice work guys. It great to see how the new dampers are.

It is interesting to see how Marzocchi tried to overcome the problems of the TST5 cartridge. And what I mean here was the blowing of the blander. The old TST5 cartridge used the rubber blander for the amount of oil that was dislocated by the rebound rod during compression. If some oil leaked from the cartridge, then air would get in during the rebound phase. And air into the cartridge meant that the compression piston didn't work anymore (it needs to be completely in oil).

With the new design the rubber blander is replace by the air chamber above the compression piston. The piston needs to be immerse into oil but, there needs to be a decent amount of air above it. So there is a specific amount of oil that needs to be put in the cartridge. At least this is what one can see from the pictures.

Those my believe is that blown cartridges are due wrong amount of oil. The cartrige will be damaged if there is too much oil in the damper! Just think about it. Under compression the oil dislocate by the rebound rod will not have where to go (even if there is a bit of air in the cartridge the pressure will extremely rump up). And the only way out of the damper is the rebound rod seal or one of the seal s of the upper or lower caps. If one of these seals brake, than the oil will be out and there will be no compression.

Thus I think that someone (Marzocchi!!!) needs to come up with the right oil levels for new TST cartridges. If I would have such a fork I would take out the cartridge and try to put as few oil into the damper as possible before using it. As usual Marzocchi has good design but screw things up at the assembly.
:yesnod:

One thing... I may be dead wrong, but I seem to recall the TST2 had to be pressurized (at least for 2007's???) as people on a Spanish board was fixing the travel issues with the TST2's by letting air scape, letting some oil to come off and pressurizing again to 40psi or so (recommended by Marzocchi was in the order of 140psi or so).
 

·
Registered
Joined
·
52 Posts
Can one add air into the cartridge? Is there a valve on the top cap? Can't really see one in the pictorials. Can some post a picture of the top cap?

It can also be that this year TST2 is different from the 2007 model. Any idea?

I doubt there a valve with which one can set the pressure in the cartridge. Unless the blow-off shims don't need to be pressurized I don't see why needs to have air pressure into the cartridge.

I really wonder how someone can "bend" that blow-off shims under compression and let the oil pass!

Adrian
 

·
"El Whatever"
Joined
·
18,889 Posts
macadam said:
Can one add air into the cartridge? Is there a valve on the top cap? Can't really see one in the pictorials. Can some post a picture of the top cap?

It can also be that this year TST2 is different from the 2007 model. Any idea?

I doubt there a valve with which one can set the pressure in the cartridge. Unless the blow-off shims don't need to be pressurized I don't see why needs to have air pressure into the cartridge.

I really wonder how someone can "bend" that blow-off shims under compression and let the oil pass!

Adrian
I think the 2007's were slightly different... But let's hope someone with first hand experience chime in.

I don't see a reason to have the cartridge pressurized, either... When I get home I'll get the source where I got the info about the pressure on the 2007's.

I also don't understand Marzocchi's reasoning behind the stiff blowoffs. The one on the TST5 is a heavy, thick shim preloaded with a stiff spring.


By warp2003 at 2006-11-27​
 

·
Registered
Joined
·
746 Posts
Before anyone comments: my photochop skills are lacking:( but here is my understanding of the min oil level. You can also see the relative size of the air chamber above the rebound piston... per Marzocchi no pressure required . I was told to install the compression side of the cartridge, flip the cartridge pside down and fill the rebound side with 2.5 wt oil. Then insert the rebound piston / rod and torque. Following there instructions you will end up with the oil level as depicted in the cutaway... .

[/URL][/IMG]
 

·
I dig trails!
Joined
·
5,608 Posts
Discussion Starter · #31 ·
flyag1 said:
Before anyone comments: my photochop skills are lacking:( but here is my understanding of the min oil level. You can also see the relative size of the air chamber above the rebound piston... per Marzocchi no pressure required . I was told to install the compression side of the cartridge, flip the cartridge pside down and fill the rebound side with 2.5 wt oil. Then insert the rebound piston / rod and torque. Following there instructions you will end up with the oil level as depicted in the cutaway...
Ha! You are rockin' Photoshop!

Did they ask you put the TST in "locked" position?

Is the 2.5w oil different than what they specced? Or is the same?

P
 

·
Registered
Joined
·
746 Posts
Mr.P said:
Ha! You are rockin' Photoshop!

Did they ask you put the TST in "locked" position?

Is the 2.5w oil different than what they specced? Or is the same?

P
Oil is spec... and they did not specify tst in locked position... hence: in our personal communication I wrote, " I think before we post the oil levels, I better verify everything works correctly"

Almost everything in life is experimental:thumbsup:
 

·
Registered
Joined
·
52 Posts
Hi flyag1,

this sounds pretty good. However, I would say that one would need a bit of oil over the compression piston, like 1 or 2mm above. If you follow the procedure you just describe, it might happen that the compression piston will not be into oil. And in this case the lockout, and the compression adjust will not work (similar to Rock Shox MC, Manitou TPC).

I would rather mount the rebound first, then poor oil into the cartridge. Cycle the rebound rod couple of times (with the rebound fully open) to let the oil get beneath the rebound piston. You should have the rebound piston all the time covered by oil. Then I would measure the length of the compression unit, from the compression piston to the o-ring that seals the cartridge, lets say it has length X. Then, with the rebound rod fully extended (all way out the cartridge) set the oil level to X plus 1-2mm. In this way you are sure you have the piston sinked in oil. Then insert the compression unit, with the compression fully open. Basically is the same procedure like on the Manitou TPC/SPV forks.

Adrian
 

·
"El Whatever"
Joined
·
18,889 Posts
flyag1 said:
Before anyone comments: my photochop skills are lacking:( but here is my understanding of the min oil level. You can also see the relative size of the air chamber above the rebound piston... per Marzocchi no pressure required . I was told to install the compression side of the cartridge, flip the cartridge pside down and fill the rebound side with 2.5 wt oil. Then insert the rebound piston / rod and torque. Following there instructions you will end up with the oil level as depicted in the cutaway... .
I think you have the procedure right, the illustration wrong.

As per the illustration, if you extend the rebound rod, you'll end up with the compression piston depleted of oil. So oil level should be very close to the very top of the cartridge when the cart is completely compressed.

The procedure that was given to you is correct. You can do the other way around and measure the total depth of the compression assembly from the top threads to the upper face of the compression piston, then install the rebound rod, add oil up to the compression piston upper face depth and close the cart.

It's pretty much like a rear shock... Just that there is not IFP. In a shock, shock compression will move the IFP making the chamber smaller, on the TST2 (and Micro??) the compression assembly is stationary and the cartridge compression will raise the oil level past the compression piston.... just like Macadam mentioned.

Adam... I think air in the cart is not an issue... They just have to make sure oil covers the compression piston at rebound's full extensionas you well mention.
 

·
Registered
Joined
·
342 Posts
Hi all - quick question I hope one of you can answer. My 55 TST2 has too much oil in (can't get the last 20mm of travel) and I've been told (by Marzocchi Tech Support on here) to let some oil out. Does this just involve loosening the nut at the bottom of the non-TST side?
 

·
Registered
Joined
·
52 Posts
Hi arctic,

if you want to remove some oil from the TST2 I would open the top cap, the compression unit and remove from there. I would remove the compression unit completely and then measure the oil level such that it matches the length of the compression unit.

Adrian
 
21 - 40 of 83 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top