Marzocchi Dirt Jumper 4's

[parabola]

 

Question regarding the spring rate on the Marzocchi dirt jumper 4 front shocks. I bought a bike with these a few months ago, and find that even when I adjust the preload to its maximum setting, the shocks are too soft for my liking. I only use the bike for dirt jumping and so I want to shocks to be nice and stiff. Not really wanting to change the springs as its a bit expensive and I would rather buy a new shock. I've thought about fitting a spacer between the top cap and the spring, as I think this would increase the preload significantly but was thinking someone may have a better solution.

 

Also the rebound dampening is non-existent, however I've heard of okes changing the oil to a more viscous one to increase the dampening. I took it apart this morning and from my initial observations it appears that the shock is coil and grease only and doesn't use oil.

 

Can anyone shed any light on these problems, and possibly how I can fix them for cheap  Thanks guys

parabola2009-09-21 04:23:01

[flats4life]

Im not familiar with the DJ4's but I have the JDPro's and you can stiffen them up by increasing the air pressure. On my forks this is done in the top of the right fork leg. Adjusting the preload is a waste of time (it does nothing). Damping is adjusted internally and works very well. If you increase the air pressure you need to do damping as well to avoid top out. Like I said Im not familiar with your forks but thats how it works with mine.

[parabola]

Thanks for the reply, unfortunately the DJ4's do not have any air pressure adjustment at all and are only coil

[Matchstix]

the spacer is going to be the easiets way to stiffen them up.

check out the oillevels on the marzocchi website this should also be a bit of help.

 

 

[droo]

The spacer will increase preload, but won't stiffen the spring up. Basically all preload does is increase the amount of force needed to start the fork moving. It does zero for the spring rate, so you'll blow through the travel just as easily. New spring is the best option, they're not that pricey - otherwise have a look at the oil levels and viscosities in the manual - you may (check this before you believe me...) be able to slow down your compression damping by using a heavier oil. But you might also trash your shim stack.

[parabola]

I was contemplating reverse engineering the current spring and then having one made up which is about 20% stiffer, cheaper than buying one from Marzocchi, but it will still cost several hundred,  so I may as well just get a new fork  Theres a DJ2 for sale on the hub but its got a through axle, so would have to get a new hub as well.

 

Preloading with a spacer wont change the spring rate but it will mean a stiffer fork for dirt jumping.

 

[droo]

Are the springs that expensive? If so, you could always swap the lowers out and sell the DJ4 with thru-axle lowers. Then you wouldn't have to rebuild the wheel. But... how do you know the spring in the new fork isn't the same as the one you've got now?

[parabola]

 

DJ2 is quite a bit better than the DJ4, as I found out this morning. I think I'm just going to go with a smallish spacer (10-20mm) can be quite easily made and will stiffen up the fork *enough* to keep me jumping until I something comes up on the hub. The rest of the bike (Giant STP2) is good enough to warrant a nice Rock Shox Pike or similar, and then I will rebuild the wheels with new hubs. Reckon a thru-axle is the way to go anyway for a dirt jumper.

parabola2009-09-21 07:26:44