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Compression & rebound DRZ400 suspension


bmwpowere36m3

yeah I know a lot of you are just going to say look it up there are tons of threads about this already. BUT I already have and I have looked through a lot but don't really understand a lot of it, im looking for 2 things

1. a solid and simple explanation of rebound and spring rate all that

2. a recommendation of "cheep" fixes.. I called a local shop and I don't want to pay 600+ for them to change springs and revalve.

(not just being a cheap a$$) I am looking to upgrade to a new bike in the next year or two so im tired of dumping money into it.

im replacing my fork seals this weekend and I figured if I was going to have them open I minds well try messing with it

with all gear im about 230 and I ride street... if anybody has any clicker info or anything with shims stacks with similar weight would be great

thanks

1. Compression & rebound are pretty self-explanatory. Compression is when the suspension collapses/compresses and rebound is when it extends/rebounds. Most dirt/trail/enduro/mx bikes have adjustable (to a degree) suspensions. Generally the external adjustments include: low-speed compression (on forks & shocks), high-speed compression (usually only shocks), low-speed rebound (on forks & shocks) and spring preload (on forks & shocks). Internally damping is adjustable via shim stacks, bleed ports, pistons, etc…

Generally low-speed compression and rebound are adjusted with what are known as "clickers" (on the DRZ they look like flat-headed screws, with only the head visible). When you adjust them, you move a needle (right in image below) that sits within an orifice (left in image below).

13-MAXclks.png

Under low-speed movement of the suspension, some of the fluid inside moves through these orifices. By adjusting the clicker "IN" (generally clockwise) you partially close off that orifice. The more you adjust "IN" the more it closes the orifice. By closing the orifice, it takes more energy for the fluid to pass through because essentially you are making the orifice or hole smaller. So for compression it makes the suspension collapse slower (feels firmer) and for rebound it makes the suspension extend slower. The inverse is true when you adjust the clicker "OUT".

It's important to note, that the range of these clickers is limited. If you find yourself at the limits of their adjustment, then you need to revalve the suspension.

Spring rate, is a way to quantify a spring and it simply means the amount of force it takes to compress the spring x amount of inches. So a stock DRZ400S/SM rear spring is 5.5 kg/mm, meaning it takes 5.5 kg of force to compress the spring 1 mm. If the spring is linear, then it'll take an additional 5.5 kg to compress another mm and so on (11 kg for 2 mm, 16.5 kg for 3 mm, etc…).

2. At 230 lbs you need firmer springs both for the shock and forks. That'll run you around $200, no adjustment will compensate for springs that are way too soft for your weight. And no, adding more preload is not the answer… Then as far as re-valving, if you're a DIY kind of guy, you can make changes to improve the damping (I did myself). You will however need a few shims to make those changes as the stock valving is very soft.


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