Marzocchi 48mm CC Forks

[Jakobi]

The crossover is a variable. It depends how you set the whole stack up and what you wish to achieve.

I personally don't like to go too small on the crossover as it can give very different feelings depending on the force you hit things. A straight stack (or larger OD crossover) gives a more progressive feeling.

The GG uses a 12mm bleed on the BV. The Beta uses a staged 28, 12 bleed setup so it bleeds less. I think I may have totally removed the bleed on the base in my setup but would need to check my notes to confirm.

[Anders]

Haven't received any shims, seals or bushings yet, so no progress here so far. However, I have started thinking about also adjusting the rebound shim stack. I was out on the local MX track the other day, and ended up at 2 clicks out on the front rebound. I also did a enduro training yesterday and left the rebound at 2 clicks. It seemed better than before in a uphill climb with lots of loose 10cm to 20cm round stones with that setting.

So my conclusion is that I am very close to not being able to close the rebound any more, should the need arise.

I'm afraid I didn't order any suitable shims for the rebound, so I'll have to shuffle around the ones I find inside the cartridge.
Should I start out just reducing the bleed or perhaps remove another shim as well?

[Jakobi]

You might have some fun with that. Won't be too many shims available in the size you're working with.

Believe stock was
Rebound (from piston)
12x.10 - bleed
20x.10 (2)
18x.10
14x.10
11x 2.5 - collar

A start is to remove the bleed shim, and it makes a decent crossover if you're that way inclined. You'll then want to significantly beef up the HSR portion of the stack.

[Anders]

Originally Posted by Jakobi

You might have some fun with that. Won't be too many shims available in the size you're working with.

Believe stock was
Rebound (from piston)
12x.10 - bleed
20x.10 (2)
18x.10
14x.10
11x 2.5 - collar

A start is to remove the bleed shim, and it makes a decent crossover if you're that way inclined. You'll then want to significantly beef up the HSR portion of the stack.

EDIT: Yes, My stack was like you describe.

I have now rebuilt my forks, and for some reason, the rebound seems to be faster (less damping) than before. Perhaps lower friction from the SKF seals? or just me that can't tell if it's different? I don't know.

In any case, I have concluded that I need to to something. I would like perhaps 10 clicks more damping from what I have, to be able to place my clickers somewhere near the middle of the scale.

Edit: I have some 20mm x 0.12 shims, so I have something to install in addition to the OEM shims. The question is whether to use one single 0.12 or one 0.12 + 0.10?
According to the math, a 0.12 shim is approx 1.7 times a 0.10 in stiffness.

On the positive side, my compression damping now handles trail trash a little better, while I still would like some HSC less (I think).
I built a stack like this:

28 x 0,10 ( got this idea from the Beta stack)
12 x 0,10
2 x 32 x 0,10 ( replaces the 2 x 32 x 0,15)
21 x 0.10 ( here comes Jacobi's suggested crossover)
3 x 32 x 0,10 ( replaces the 2 x 32 x 0,15)
26 x 0,15
24 x 0,10
22 x 0,10
20 x 0,10
18 x 0,15
2 x 11 x 0,20

I think my next iteration will be to either remove one 32 mm shim from the HSC side, or try replacing the 26 x 0,15 with a 28 x 0,10 (as I have these in stock).

In reducing the compression bleed as described, I would have expected that the rebound would also give slightly more damping. That didn't happen as far as I can tell.

While building and testing stacks, it would have been nice to use some simulation software like the Restackor program or similar. Did any of you measure up the pistons in the Marzocchi and if so, are you willing to share the measurements as used in the Restackor?

[Herdy]

Hi
I stripped down the rebound shims stacks and found they were different in each leg (guessing they have been on the floor and just threw back in ?)
i could do with some guidance in the best way to put them back.
hopefully the pictures will explain it better Thanks shims.jpg

Update: have set rebound to standard and altered the cartridge stack slightly...been out today and they are working really good now.
video of one of the tracks i was finding the suspension to harsh

https://www.youtube.com/watch?v=BIxa...ature=youtu.be

[Anders]

Originally Posted by Herdy

Update: have set rebound to standard and altered the cartridge stack slightly...been out today and they are working really good now.

That's good news. Would you share how your compression stack was altered? And what oil you are using?

I'm rebuilding my own stacks at the moment. This my second attempt.



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[Anders]

Originally Posted by Jakobi

Believe stock was
Rebound (from piston)
12x.10 - bleed
20x.10 (2)
18x.10
14x.10
11x 2.5 - collar

A start is to remove the bleed shim, and it makes a decent crossover if you're that way inclined. You'll then want to significantly beef up the HSR portion of the stack.

Jacobi, you were right. There were 2x 20 x 0.10 shims in the rebound stack in mine as well.

I now removed the bleed and replaced one of the 20 x 0.10 with a 20 x 0.12. I will test this on Wednesday I hope.


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[Jakobi]

Good work Anders.

Quick question to stimulate some thoughts.. What, if any, effect do you think the PFP preload and cartridge pressure have on the rebound stroke?

[Anders]

Originally Posted by Jakobi

Good work Anders.

Quick question to stimulate some thoughts.. What, if any, effect do you think the PFP preload and cartridge pressure have on the rebound stroke?

That is a good question. I really do not know. But I have read GMP's explanations on the Beta forum where he states that he believes that the PFP is a kind of "cavitation threshold control". If that is the case, I think the PFP will have an impact on the rebound as well as the compression. If you get cavitation, the oil will act as if the viscosity is lower, and that will affect both direction of travel / damping.

[Jakobi]

That's one way to look at it and very well could be something. But you would then imagine that with less preload/pressure acting on the cart at full extension that the oil would be more likely to cavitate and as such offer less damping.

However, the oil pressure acting on the cross section of the damping rod and rebound piston would increase with PFP preload (being more noticeable towards full extension). I would expect the more PFP you wind on, the more force will be required to get the damper rod moving, and the faster it will return as well.