Rebound dampening ?

[BrentMartell]

I know this is a basic question but I am chasing down a problem and need some confirmation of my thinking...yeah, scary huh!

So, let's say you had little to no rebound dampening in the forks..... what net/overall affect would this have on the fork feel/action?

[HuskyDude]

When was the last time you were in a boat on a windy day...

It would bounce you all over the trail and you would have very limited control at higher speeds.

[iancp5]

It'd be like a Pogo Stick!

[widebear]

Think of dropping a basketball.

More damping would be like less air in the ball .

Less damping would react like too much air and would have the ball rebounding way high.

In the case of forks more rebound damping, turning clicker in, would keep energy from being released to fast, this energy originating from the reaction of compression on the mechanical and air springs . Excess damped energy gets turned in to heat via friction from the oil passing through a more restricted shim stack.

[GMP]

This is one problem(probably the biggest) with the OEM Zoke valving. It can mask itself as a harsh compression issue as the fork snaps back very fast on initial rebound, especially deeper in the stroke. Having trouble keeping the front end down in turns as well? There is a stupid amount of free bleed in this fork.

[BrentMartell]

GMP- this is exactly what I found and am trying to correct. Originally the pistons were re-drilled (manufacturing defect from hell) and then re-shimmed the stacks. Rebound was left alone. 5wt oil. Rebound dampening...there was no dampening period. Installed 7.5 wt oil, mucho better. Installed 4.6 springs, even better, but...............still not right.

I pulled the spring on my Race Tech set up WP 48mm fork and compared to the zoke 45. I left the settings as I rode the bikes. Direct comparision the WP forks were slightly slower compression and significantly slower in rebound. I turned zokes to full hard and they are still 3x faster on rebound then the WP. This test was simple: I compressed the forks and picked them up by the cap, one in each hand, and watched them race to full extension.

Compression testing was more difficult to see and feel. I need more of a controlled test, such as adding a 5 lb weight to the caps and comparing.

I am not as concerned about compression yet as think the rebound is my problematic area that needs to be addressed.

[BrentMartell]

GMP, I have not noticed an issue in the turning department. By that I mean the front end has not washed out, understeer. In fact I have to be careful and not oversteer corners at this point. I can turn way inside my KTM lines, and I LOVE my KTM's. I hope this fork BS goes away so I can improve my race results!

[widebear]

Originally Posted by GMP

This is one problem(probably the biggest) with the OEM Zoke valving. It can mask itself as a harsh compression issue as the fork snaps back very fast on initial rebound, especially deeper in the stroke. Having trouble keeping the front end down in turns as well? There is a stupid amount of free bleed in this fork.

I concur whole heartedly on that point, the problem even worse with heavier springs. One ride on the 011 and the forks are going in to Riders Edge for a revalve, asap!

[BrentMartell]

So imagine this: 2 rides on stock bike, then a 100 mile desert race. Thought I was going to die. 2 more rides, revalved, changed oil weights back and forth, stock springs, then a 85 mile desert race. Better, but not right had to slow down pace to where bike worked better. Installed .46's, 2 rides, and although it is better I could not figure out what was wrong. I thought perhaps it was too light in the mid valve. I think the whole problem is rebound at this point.

Should I try 10 wt oil or shim the rebound stack?

[GMP]

If your comfy with valving, the fork comes apart easy. You will be shocked. There is free bleed in the rebound stack, at least in the Zokes from '07 and these seem to have the same issue. There is also a bleed hole in the rebound piston, which makes the adjuster less effective. Les did mine originally, and I added a bit more to the high speed rebound stack. The bleed hole remains but all the free bleed in the stack is gone. I also added a light midvalve, as stock its just a check plate. For a fast desert guy I would think you may want this. Spectro 125/150 oil (approx 7W) MAJOR difference. I'm a 190 lb B, and ride mostly slow to mid speed rocky stuff. I'm running .44s and could probably go to .45s easy for the faster stuff. .46s for you are probably a good choice. The fork works awesome now. The other thing is to keep the preload low on the springs. I think you can get it to where you want it for technical woods even at a fast A level.

Do a search on user name "pobit" in this forum, he figured a lot of this light rebound problem out.