Help..marz marathon S 03 105 to 85mm

Just getting a set of these of Carl (Harryburgundy). Deals in porgress either way however I would really like to convert them to 85mm or lower

Does anyone
A: Know how its done?.. Marz website says its defo possible and dimensions are specced in owners manual but not how its acheived, is it a spring change or a spacer shift ala Sids?

B: have the service manual pdf/link..not the owners manual, that easy to get from marz website.

C: know if theres anyway of actually Mega modding things to really lower the travel down to 65mm. ie cowboyish cutting of the springs or other.

thanks in advance.

When I changed my Z1 Mcr's from 130 to 110 all that was required was a spring change. You need both the main and top out springs if they have both. The top out spring was longer than for the 130mm travel.
I would check any Marzocchi fork with a similar station diameter (probably 32mm??) and the travel you want and see what springs it uses.

Maybe something like this?

http://www.chainreactioncycles.com/Mobi ... odelID=522

Cheers Rob, have seen that kit but still not sure if thats all that is involved. found some rumblings online that different cartridges where also involved. Havent found anything concrete which is the issue.

The instruction manual said it can be had in both travel options so I would think its unlikely they'd make different damping cartridges for the different travel options. My Z1 forks didn't need a change in damping carts and IIRC it had an extension travel adjuster lockdown thing and a SSVC (sp?) cartridge.

Not much help perhaps but if it was me, for the sake of a 20mm travel reduction (so say 16mm after sag) I'd run them at 105mm. You could, if you want, set them up with slightly less preload so that they run deeper into their stroke plus you get the benefits of more negative travel, namely improved ground contact over stutter bumps and roots.

Frame angles are going to change by less than one degree anyway, so not worth bothering about other than on paper. What frame are they going on anyway? - if it's a Kona definitely leave them at 105mm.

Cheers Andy, not thought about that as an option

yep they're for the KK. And I'm a solid 16 stone.. So doubt I will be lacking in sag and may stiffen them up a good deal.

I'd second that.

Do you know what weight springs the forks have in them? If they have the regular medium springs in they will be too soft for your weight (I am similar in stature so I know the problems!). I think your forks may have an air assist on the spring but not sure if it is just for preload or will increase the spring rate. If it doesn't change the spring rate you may find you can get loads of sag but the forks will blow through their travel all the time and bottom out constantly. So it might be worth getting some firmer springs anyway. My Z1's and my newer RS Pikes were transformed when I swapped the stock springs for firmer ones

Update..after taking them apart and reversing the thinking I can confirm that it's not a basic spring swap. You could bodge it so that the fork sit on the spring at a much lower atc but this would mean the spring stack would come loose when you topped out. This is because you cannot alter the rod length

I managed to secure a less mint genuine set of 85 mm versions and had them to bits. And yes the cartridges are different. One is the same size but the central rod is shorter. The other the cartridge its self is a different length. The bonus also being the 85mm set also came with fat boy springs and canti bosses. So I have enough parts to build a mint set in 85mm for my weight.

A lot of agro for a not overal fancy set of forks but these where the first set I ever owned, so fancied revisiting them on the KK.

When you reduce the travel on Marzocchi forks you have to add the longer top out spring. They come in the "travel reducing" pack. IIRC when I changed my Z1's from 130 to 100 the main springs were shorter and the top out springs the same length longer as the main ones were shorter (I think 30mm each way).
If you only try to change the main springs you will come across the problem you have described.