Marzocchi setup help - 08' EC250

[ferguscawley]

Originally Posted by nick790

Where can I buy shims in the uk?

I got them from windwave in the UK - they are the marzocchi importer. Speak to Dan there. He is very helpful.

http://www.marzocchi.co.uk/

You need to remove the compression stack from your forks - on the sachs this is simple as you can just turn the fork upside down, remove the entire compression valve assembly by rattling it out with a 19mm socket. Then its simply a case of removing the nut from the top of the assembly, removing the small spring and piston and then the shims are available toyou.


Its been over 2 years since I did a marzocchi fork so cannot remember exactly how I did it. I thionk you have to split the forks for the marzocchi but am not certain.

Fergus

[nick790]

Ok, I have my forks apart and there are signs that they have been apart before, I checked for any spring markings but found nothing. Is this normal how do I know what springs are fitted???

I also had a quick look at the comp valve, they dont seem to have a bleed shim as described in other threds, but I will post up the stack sizes and some photo's soon for your comments.

I realy like to know what springs I have fitted

[iancp5]

Originally Posted by nick790

I realy like to know what springs I have fitted

Unfortunately if they're not marked there is no way to be sure without having them measured by a suspension specialist. Theoretically if you have some weights and can keep one from bending you could put the weight on and see how much it compresses.

Standard is 0.42 (I think that's Kg/mm but could be N/m or something)

So ... stick a 10Kg weight on and see how much one compresses.

Alternately pump someone else's forks and see if they feel the same but this is tricky as they could have different air gap, different oil and clicker settings.

[nick790]

Had the forks apart tonight, found the following.



In the comp valve I have 17 shims

1, 22x10
2, 22x10
3, 22x10
4, 22x10
5, 22x10
6, 22x10
7, 11x20
8, 21x10
9, 20x10
10, 19x10
11, 18x10
12, 17x10
13, 16x10
14, 15x10
15, 14x10
16, 13x10
17, 12x10


Your notice no bleed shim against the piston, but I did find this half way dow the stack



Looks like at some point it was against the piston as a bleed shim??

So does anyone think someone hase been messing, or is this ok?

Also, 1 litre is'nt enough oil

[nick790]

Come on, someone must have some thoughts??

Also, how do you get the rebound valve out?? could see it in the tube but was'nt sure how to remove it, I'de like to have that apart at some piont ane see whats in there.

Is there anywhere I can go to fine out the standard shim stacks??

Once I have refilled the forks with oil, can I then turn them upside down and buzz the comp valve out, make adjustments, and refit without disturbing the oil??? or will this cause problems?

[nick790]

One at a time gents!!!

[nick790]

I had them apart again tonight,

Checked the rebound stack:-
1,22x1.0
2,12x1.0
3,19x1.0
4,17x1.0
5,15x1.0
6,12x1.0


After the mass of replys you guys have given me and the fact that I have a race on sunday I have decided on changing to the following:-

Rebound-

1, 22x1.0
2, 21x1.0
3, 19x1.0
4, 19x1.0
5, 18x1.0
6, 17x1.0
7, 15x1.0

This is as close as I could get to Pobit's stack with the shims I had available.

Compression-

1, 22x1.0
2, 22x1.0
3, 20x1.0
4, 14x1.0
5, 17x1.0
6, 16x1.0
7, 14x1.0
8, 13x1.0
9, 12x1.0

Dont ask me how I ended up with this, I looked at alot of posts, and got some info from Marzocchi UK and had to make do with what shims I had.
I guess sunday will be the telling of it, to be honest I dont think it could be worse. The rebound has far more control than it did before, I can tell that by pressing against the ground.

I write this for my own notes, as nobody seems to have any veiw on the subject?

[MattR]

I have not did my own fork revalving yet, but can offer a few suggestions based on my suspension background (automotive shocks). The shim/disc stack is very sensitive to both diameter and thickness changes. The stiffness of a disc is proportional to the cube of its thickness (in other words... thickness ^ 3). The real equation is complex but this will give you an idea. So changing even a single disc can have a dramatic effect on the entire valve stack. Also, a small diameter disc directly below a larger diameter diameter disc acts as a "pivot" disc. It causes the larger disc to pivot/bend at that location.

Just looking at the numbers you posted... your original compression stack looks very stiff. It's no surprise that you had harshness over small stuff. You had 6 discs with same diameter and thickness for the initial stage. Very stiff! Your newer compression stack should be better, but only riding it will tell you. The 14mm diameter disc will be the first pivot disc and breaks the stack into 2 stages. The discs listed below this one look like a pyramid stack and will contribute to the mid to high speed stuff.

Your rebound stack now looks quite stiff with no smaller diameter pivot disc. You basically have a pyramid stack (think upsidedown decreasing diameters).

Leave it alone for now and ride it... let us know the outcome and make only a few changes next time. A word of caution: it's best to make 1 or 2 changes at a time and test the result. You made a whole bunch of changes and are really starting from scratch here. Good luck!

[getndirty]

Originally Posted by nick790

Ok, so these are my idears so far, please advise as you see fit.

1, increes oil air gap, I'll go quite low at first and top it up to get the right feel.
2, replace fork oil, the bikes about 16 months old. The manual says SWA 5-7.5? what should I use?
3, Check lower fork clamp bolts, how tight? any thred lock?

Now we get to the trickier part, after reading through some threds, i was thinking of making some shim stack adjustment, can anyone advise me on exactly what I should and should not touch? I unterstand the the forks may not have enough rebound adjustment? and I read you can remove a bleed shim to speed this up? Can anyone advise?

Should I look at the comp stack at all?

Thank for the help, just like to add the only time I've ever been inside the fork are for standard sevice resons, this is why I'm keen to get as much info as possible, not that I'm worried about doing the work, infact I find the whole subject quite intresting .

I'm zero help in the re-valving department, but I just re-sprung my zokes last week with springs that I got from Les at LTR. I'm 225 dry and 250 in full gear. He recommended I run 120mm oil height and said the zokes like 7.5w high quality oil. Re: lower fork clamps - tighten the middle screw to 10 Ft Lbs and snug the other two up. He didn't mention threadlock - I've checked the torque on both clamps twice (two rides) and haven't seen any movement yet.

Hope that helps a little.

[nick790]

Originally Posted by MattR

I have not did my own fork revalving yet, but can offer a few suggestions based on my suspension background (automotive shocks). The shim/disc stack is very sensitive to both diameter and thickness changes. The stiffness of a disc is proportional to the cube of its thickness (in other words... thickness ^ 3). The real equation is complex but this will give you an idea. So changing even a single disc can have a dramatic effect on the entire valve stack. Also, a small diameter disc directly below a larger diameter diameter disc acts as a "pivot" disc. It causes the larger disc to pivot/bend at that location.

Just looking at the numbers you posted... your original compression stack looks very stiff. It's no surprise that you had harshness over small stuff. You had 6 discs with same diameter and thickness for the initial stage. Very stiff! Your newer compression stack should be better, but only riding it will tell you. The 14mm diameter disc will be the first pivot disc and breaks the stack into 2 stages. The discs listed below this one look like a pyramid stack and will contribute to the mid to high speed stuff.

Your rebound stack now looks quite stiff with no smaller diameter pivot disc. You basically have a pyramid stack (think upsidedown decreasing diameters).

Leave it alone for now and ride it... let us know the outcome and make only a few changes next time. A word of caution: it's best to make 1 or 2 changes at a time and test the result. You made a whole bunch of changes and are really starting from scratch here. Good luck!

Sorry about that, I was getting desperate. Thanks for the help with this.
I've tried not to anything to drastic, but as you can see, it looked like some big changes needed to be made.

I'm gonna run it tomorrow and see how it goes, unless i'm plesently suprised, i'll probably get it professionaly re-valved. I really wanted to make some changes so it was more bairable for tomorrow.

We will see