05-06 Marzocci valve specs
- Thread starter pobit
- Start date
Ktmlew, Pobit, and Terry Hay, your guys experience really opened my eyes regarding the need of clearence at these bushings.
It is funny though, that a fork can be too rigid.
I need to defer all credit to Terry Hay. He pointed it out and I just looked at the Cannodale forks to see if the problem still existed. Yep!
I don't want to get into a battle - but based on what I understand there is nothing wrong with this fork that needs to be "fixed".
What matters is the clearance between the bushing and the fork upper - and on some forks it does make sense to relieve the "land" in order to increase this clearance (race-tech does this on certain showa forks). The marzocchi fork has more than sufficient clearance in this area and no modification is necessary to "fix it".
jeff
p.s. The only reason I am saying something here is that I don't feel that there is anything wrong with this fork in this area - when properly valved the fork is very, very supple - even with very little break in time on them.
What matters is the clearance between the bushing and the fork upper - and on some forks it does make sense to relieve the "land" in order to increase this clearance (race-tech does this on certain showa forks). The marzocchi fork has more than sufficient clearance in this area and no modification is necessary to "fix it".
jeff
p.s. The only reason I am saying something here is that I don't feel that there is anything wrong with this fork in this area - when properly valved the fork is very, very supple - even with very little break in time on them.
IMO these have EXACTLY the same problem as the old Showas.
The Marzocchi Shiver fork I had apart had ZERO clearance for the bushing to move ON the tube. Seems to me that would create a "scraper" type situation? Could be why they tend to foul the oil quickly? Whether you "fix" the bushing land or hone the upper tube, you are re-engineering a poor design. I wouldn't want to take the chance of cutting thru any hard-coated anodizing in the upper tube though.
If these don't suffer from binding why do they have to be valved so soft?
Not trying to argue just have an entirely different opinion of what I've seen.
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These forks do not have the same problem as the showas - the showas didn't have enough clearance between the bushing and the upper fork leg. You are stating that having the bushing fit tight on the lower leg is an issue - given the choice of having it fit snug and having it "float" - I would prefer to have it fit snug; Having it fit snug doesn't turn it into a "scraper" as you suggest.
The other comments you make about the fork are not consistent with what I know about this fork; I confirmed this with a suspension tuner who has done over a hundred sets of these forks...
1. This fork does not have to be "valved so soft" to compensate for "binding". They are valved like any other "good working" fork.
2. These forks do not "foul the oil" quickly when installed properly. There will be dirty oil if the triple clamp pinch bolts are improperly torqued to a high value; The causes the upper fork tube to collapse and the fork to bind, and wear, when the slider passes this area.
Both a friend (the suspension tuner friend of mine) and I have cannondale marzocchi forks mounted on a different bike - valved for my weight and terrain and they are "pure magic". My friend has had both sets apart and there is absolutely nothing wrong with them.
Again, I don't want to battle. And the only reason I am saying anything is that the fork is being unfairly characterized. And both the fork and the bike are being improperly demeaned as a result.
jeff
GMP
Active member
My take on this:
I understand the logic, just not sure it exists. I beleive that KTMLew's reasoning is that the fork outer tube will always be slightly compresed, regardless of T clamp torque, and there must be some bushing play to account for it. Well, theoretically this could be done in two ways: static clearance, with the bushing fixed to the inner tube, or dynamic clearance between the bushing ID and land OD, where the bushing is allowed to compress slightly, like a piston ring. Valid point, but whos to say the static clearance is inadequate? Any data? Bore mic the fork outer along its length and lets see the effect of T clamp bolt torque. It would be interesting.
Also, I think most people overtorque their T clamps, and some listed specs are too high. I clean the fork tubes and clamp bores and go no more than 15 -16 Nm.
When I had the Husky Zokes apart, The first thing I noticed is how "loose" they felt compared to my sticky WPs. Not in a bad way, but a good stiction free way. This, and excellent performance, would seem to point to adequate clearance. You would think if this was a widespread problem, all the big tuners here would be on the bandwagon machining fork tubes for additional $$, especially now, since Husky sales have exploded.
Besides some anticipated valving changes(like I always need for rocks) I'm looking forward to riding the '07 Zoke fork.
I understand the logic, just not sure it exists. I beleive that KTMLew's reasoning is that the fork outer tube will always be slightly compresed, regardless of T clamp torque, and there must be some bushing play to account for it. Well, theoretically this could be done in two ways: static clearance, with the bushing fixed to the inner tube, or dynamic clearance between the bushing ID and land OD, where the bushing is allowed to compress slightly, like a piston ring. Valid point, but whos to say the static clearance is inadequate? Any data? Bore mic the fork outer along its length and lets see the effect of T clamp bolt torque. It would be interesting.
Also, I think most people overtorque their T clamps, and some listed specs are too high. I clean the fork tubes and clamp bores and go no more than 15 -16 Nm.
When I had the Husky Zokes apart, The first thing I noticed is how "loose" they felt compared to my sticky WPs. Not in a bad way, but a good stiction free way. This, and excellent performance, would seem to point to adequate clearance. You would think if this was a widespread problem, all the big tuners here would be on the bandwagon machining fork tubes for additional $$, especially now, since Husky sales have exploded.
Besides some anticipated valving changes(like I always need for rocks) I'm looking forward to riding the '07 Zoke fork.
GMP
Not to beat a dead horse but...I have only had the 02-03 fork apart and inspected the bushings fit on the tube. The bushing snap fits and you can NOT turn it on the tube. Zero end-clearance. Only forks I've ever seen with this build. Fixed position = binding when the upper tube flexes. Don't see any reason you couldn't just narrow the bushing slightly to allow it to float some but that still doesn't address the bushings need to be able to "rock" slightly when needed. It's not something you can feel when cycling the forks without a sufficient load to flex the outer tube.
I look at things strictly from an engineering viewpoint. Couldn't care less who built the product. Didn't come here to bash, just trying to relay the info I have SEEN with my own eyes not what someone else told me. NOT opinion, facts. Bushing fits too tight on tube...
As I said before, it's my understanding they tried to address some issues around 04 but I don't know if this is one of them?
Not to beat a dead horse but...I have only had the 02-03 fork apart and inspected the bushings fit on the tube. The bushing snap fits and you can NOT turn it on the tube. Zero end-clearance. Only forks I've ever seen with this build. Fixed position = binding when the upper tube flexes. Don't see any reason you couldn't just narrow the bushing slightly to allow it to float some but that still doesn't address the bushings need to be able to "rock" slightly when needed. It's not something you can feel when cycling the forks without a sufficient load to flex the outer tube.
I look at things strictly from an engineering viewpoint. Couldn't care less who built the product. Didn't come here to bash, just trying to relay the info I have SEEN with my own eyes not what someone else told me. NOT opinion, facts. Bushing fits too tight on tube...
As I said before, it's my understanding they tried to address some issues around 04 but I don't know if this is one of them?
Hi Lew,
As a sidenote, GMP and I are both very well qualified engineers as well...
You have stated as fact that the bushing being tight on the land will cause binding in this fork. This is not fact; It is your opinion and is not supported by reported experiences with this fork. (e.g. it is very plush when revalved and not spikey in any way, shape or form).
By the way, I spoke to Les at LTR and he said nearly all the marzocchi forks he sees have this bushing fitting tight, but that's it not an issue on this fork due to this fork having more than sufficient overlap. (He services and revalves 5-10 sets of marzocchis every week and has been doing so for the last several years...)
I have personal experience with 5 sets of the marzocchi shiver fork - three of them are cannondale surplus stock. The ones on my XR have tight fitting bushings and I am amazed at how good they are, even with very little break in time on them. I am an A rider with 35 years of riding experience and I ride very aggressively through roots, rocks and whoops; I can confidently say that if they had any issue - I would feel it...
This is kind of like a guy going into a doctor's office for their annual checkup and having the physician tell him that his knee has an issue that is causing severe pain; Performing a knee-ectomy will resolve the issue. Given that we are all human - some folks would immediately feel this pain and request to have their knee hacked off. Hopefully, a large percentage would say "my knee doesn't hurt" and spend the rest of their day looking for a new doctor...
jeff
As a sidenote, GMP and I are both very well qualified engineers as well...
You have stated as fact that the bushing being tight on the land will cause binding in this fork. This is not fact; It is your opinion and is not supported by reported experiences with this fork. (e.g. it is very plush when revalved and not spikey in any way, shape or form).
By the way, I spoke to Les at LTR and he said nearly all the marzocchi forks he sees have this bushing fitting tight, but that's it not an issue on this fork due to this fork having more than sufficient overlap. (He services and revalves 5-10 sets of marzocchis every week and has been doing so for the last several years...)
I have personal experience with 5 sets of the marzocchi shiver fork - three of them are cannondale surplus stock. The ones on my XR have tight fitting bushings and I am amazed at how good they are, even with very little break in time on them. I am an A rider with 35 years of riding experience and I ride very aggressively through roots, rocks and whoops; I can confidently say that if they had any issue - I would feel it...
This is kind of like a guy going into a doctor's office for their annual checkup and having the physician tell him that his knee has an issue that is causing severe pain; Performing a knee-ectomy will resolve the issue. Given that we are all human - some folks would immediately feel this pain and request to have their knee hacked off. Hopefully, a large percentage would say "my knee doesn't hurt" and spend the rest of their day looking for a new doctor...
jeff
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Nice try...
Wrong. You have stated that it is a fact that having low clearance on this bushing causes the fork to bind. This is not "fact"; This is your opinion. The marzocchi shiver fork's excellent behavior in the field would not lead a reasonable person to believe that this opinion is valid.
We will just have to disagree on this one!
I do agree with this statement.
jeff
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Hi pobit, thanks for this very interesting post and pictures.
I did post your pictures at a forum at thumpertalk.com, hope you don’t mind? A guy claims the suspension of his ’07 Husky WR250 is very different from his ’04 WR250, so maybe the ’07 husky has this new valving. I did mention where I got the pictures from of course.
I have a question. Am I pointing at the “mid-valve” in the picture?
I did post your pictures at a forum at thumpertalk.com, hope you don’t mind? A guy claims the suspension of his ’07 Husky WR250 is very different from his ’04 WR250, so maybe the ’07 husky has this new valving. I did mention where I got the pictures from of course.
I have a question. Am I pointing at the “mid-valve” in the picture?
#36 is the rebound/mid-valve piston. The upper side is the "mid-valve" but in this picture it would just be a check-plate set-up. #33 is the check-spring and #34 is the check-plate. If it had mutiple shims of different dia's it would then be consdiered a mid-valve. #37 is the rebound stack.
