Marzocchi 48mm CC Forks

Took one fork leg down yesterday. Once I released the cartridge cap, I immediately tried and successfully compressed the spring and reseated it. No big deal IMO. I used a bar as Steve suggested. The oil in both the cartridge and the outer oil was quite clean for 20 hrs. The outer oil volume was low, no way could it have been to spec. I disassembled the comp piston, and plan to tweak the valving. I can't easily remove the rebound adjuster assay from the damper rod to remove the rod and access the rebound piston. I realize I need a damper rod holder. If you have a seal driver for 45mm Zokes, it makes a good holder in a vise for the 48 Zoke cartridge. I didn't think that the stiction on the seals was bad at all. One thing I cannot see is how the spring seat on the cartridge is moved to adjust preload.:confused: There are no obvious adjustments.
 
GMP said:
One thing I cannot see is how the spring seat on the cartridge is moved to adjust preload.:confused: There are no obvious adjustments.
Click to expand...

Glenn: Tip the cartridge up so that the spring seat is pointed up. Slip the cartridge into a vise that has brass or aluminum on the tops of the jaws, and then close the vise so that the cartridge will just slide between the jaws.

Pull the cartridge down sharply in a repetitive fashion, turning it in your hand between blows. You're essentially slide-hammering the spring seat up to reveal four circlip grooves.

Slightly medieval but it works ;)
 
I put an o-ring around the fork leg to measure how far down the fork has been.
It is about 8 cm travel left when I ride on our track, the track is rocky and technical.
After a contest yesterday on another track with lots of whoops, jumps and fast sections it was the same, about 7-8 cm left.
Compression 24 clicks out rebound 6 clicks out.
I think the bike is bumpy and hard.
The fork has never bottomed out, even though I have the smallest compression damping. (26 clicks out).
Feels like something is not right.
I have 190ml of oil in the outer leg (5W Maxima racing oil ~16cts).
I have the original springs (4.2 front, 5.2 rear).
Static sag 40mm.
I weigh 82 kg without protection.
I have about 30h on the fork.
Is there anyone else who feels the same or could it be something with my fork?
Wrong springs?
Too hard PFP spring?
Wrong Oil?
 
FWIW, the right side cartridge I disassembled did not stroke completely through so the locknut contacts the sealhead, about 40 - 50mm short. This was limited by the PFP system as when the comp assy was removed it moved freely and completely. The outer tubes move completely as well. I'm a novice as far as this fork is concerned but could there actually be too much oil in the cartridge that was not expelled, causing the PFP to be too high/stiff and or lock?

I think the fork works decent in the rocks, and faster stuff. Its the mid speed bumps that seem to be more harsh, like the fork gets too stiff in mid travel. I'm thinking that its decent in rocks because its all bleed and when the stack kicks in its stiff, which is OK when its a big hit but not a medium hit. That comp piston is huge, you could breath through it! No flow complaints there. Makes valving a bit off the map though. Stock stack has a bleed shim I may scrap or move between the two 32x.15s.

Steve, thanks for the tip, it was just not obvious. I'm treading lightly around this thing untill I get to know it. I really need to get that rebound adjuster off to pull the rod and acess the rebound stack. I'm concerned about grabbing it on the sealing surface of the rod. What do you use, standard Race Tech rod clamp? Your own? Is it tight? Thanks.
 
GMP said:
Steve, thanks for the tip, it was just not obvious. I'm treading lightly around this thing untill I get to know it. I really need to get that rebound adjuster off to pull the rod and acess the rebound stack. I'm concerned about grabbing it on the sealing surface of the rod. What do you use, standard Race Tech rod clamp? Your own? Is it tight? Thanks.
Click to expand...

I've got a RaceTech clamp with multiple diameters that fits cartridge rod. Some may disagree, but I measured and recorded the length of the rod from the bottom of the compression chamber to the top of the jam nut, then undid the adjuster body / jam nut at the bottom of the main rod exposing the brass adjuster. All that's left is to pull the adjuster and the transfer rod out of the main rod - there's an o-ring up at the top near the needle so it takes a little force. Wrap the newly exposed threads on the main rod and disassemble as you would on any other fork.

As a related note, both cartridges and legs stroked fully before dis-assembly.
 
OK, I've been measuring parts, doing math, and reading this thread again and some things just don't add up.

First, we are assuming that the correct PFP preload upon install of the comp assembly is 7mm with the cartridge bled and the damper rod fully extended.

The damper rod is 12mm diameter, the PFP piston/bore 36mm. Thats a 9:1 ratio. What that means is that for every 9mm the damper rod moves into the cartridge, the PFP piston will move up (and compress the spring) 1mm. The piston must move the distance that equates to the volume displaced by the damper rod.

Now, the holes in the cartridge are positioned on the edge of the PFP bore, where the lower oring engages and makes its seal. This is 58mm from the top of the cartridge cap, which we will use for reference.

When assembled, the comp assembly cap is flush with the cartridge cap. The distance from the top of the comp assembly cap to the edge of the lower PFP oring is 135mm. What this means is that if you try to overfill and let the piston push the excess out, KYB style, you can theoretically have up to 77mm PFP preload, but you would not be able to close the cap.

The top of the comp assembly cap to the point where the threads just start is 7mm. So, it would seem that with the cartridge bled, and at zero preload, the comp assembly cap would be threaded in the cartridge with just this last 7mm protruding. The problem with this is that you can't push the assembly down past the threads to bleed the system.

Both my cartridges would not stroke completely, and both were different. This means too much oil and different levels. I think thats why some of you guys might be having trouble with travel limitations and harshness, you actually might have a lot more than 7mm PFP preload, especially if you wrestled with the cap. I think that the reference oil volume method is easy to describe but hard to bleed and keep consistent volumes.

I know my fork had way more than 7mm PFP preload, so either the factory fill was wrong or the spec is wrong. What do you guys think, am I off base here?
 
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Both of the cartridges on the forks I tore down had 210cc of oil, which when measured on the refill equaled an oil height of 130mm. Somewhere in this thread it was shown that 130mm of oil equates to 7mm of PFP preload when the external adjuster is backed all of the way out. No need for overfilling or special tools.

As a related aside, these 48mm forks are light years better in terms of construction than previous Marzocchi efforts, and better even than KYB, WP and Showa offerings of late.

Besides the adjustable PFP preload, I was glad to find the main-spring preload adjustment that allowed me to install 470mm 0.45 fork springs with the same preload as the 475mm long 0.42 stockers.
 
When I'm tired I should just go to bed.:o The ratio is 9:1 not 3:1, so what that means is that there is not enough travel in the cartridge to do as I was thinking. I'll edit post above to avoid confusion.

The question of why some of these cartridges stroke to different lengths still remains. I can't see how all the air would be purged without a slight overfill, and if the taper in the PFP rod allows a blow off of air and excess oil to the top of the piston and ultimately the outer chamber, why should there be a difference between forks? Also why such a longer compression of the spring on assembly. Is it working against the top out spring to an extent?

On another note, the holes in my cartridges were fairly sharp on the inside, enough to tear lint from a shop towel. Vindicator, maybe this is the cause of your oring leaks, nicked orings as the lower edge of the holes is right on the edge of the PFP bore. A small piece of #400 on my finger cleaned it up nice.

Here is the position of my comp assembly after slowly releasing all of the preload from the factory fill without introducing air, a lot more than 7mm.
 

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Ever notice this? Maybe good the fork did not bottom on the wiper.:eek:
 

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I just worked the three circuits over a bit and got the cartridges back together ready to refill. Now I know why the rebound felt so sloppy, they have a thing for bleed shims. The rebound neede rods had the adjuster and needle ends crimped on less than straight, and had a real high drag in the damper rod. Are they all like this? Thats the only sloppy detail in the fork I have found. That Slavens o-ring trick is brilliant!
 
GMP said:
I just worked the three circuits over a bit and got the cartridges back together ready to refill. Now I know why the rebound felt so sloppy, they have a thing for bleed shims. The rebound neede rods had the adjuster and needle ends crimped on less than straight, and had a real high drag in the damper rod. Are they all like this? Thats the only sloppy detail in the fork I have found. That Slavens o-ring trick is brilliant!
Click to expand...

Bleed shims? What bleed shims? That must be what got left on the bench when the forks went back together ;)
 
Steve,

What oil did you use, I forgot to ask Les? Since its a lot like a KYB I'd guess a 5W.
 
GMP said:
Steve,

What oil did you use, I forgot to ask Les? Since its a lot like a KYB I'd guess a 5W.
Click to expand...

I run KYB 01M fork oil (5w) unless I'm working on Marzocchi 45s in which case I homebrew a 7.5.

The 0.45 fork springs I popped in are also KYB - send me a pm if you're after some (other unique rates too, aided by the preload adjustability of the forks)
 
Thanks. I assume you were able to get all the air out of the cartridge and ulilize all travel by fully compressing it using 210cc/130mm of oil? Mine were not right from the factory.

Les tells me too that the stock springs should be good for my 176lbs. They don't feel obviously soft. I set my '07 up with .44/5.4 when I was a few lbs more, and now it still seems softer than the '12 with the stock springs, funny. I thought perhaps because its a CC fork, and the shock linkage geometry is different. I'll run it for a bit with the valving changes, and let you know if I want to try the stiffer springs.
 
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