[OGRipper]

I've searched prior posts, read the go-ride article, and checked other resources, and can't find an answer to what I thought were fairly simply questions. Before I start with trial and error (which I'll probably do anyway) I figured I'd tap you all for the skinny.

How can I increase the rebound damping on my 888?

How does changing oil height impact damping performance if at all?

What is the effect of running different oil heights or weights in the different sides of my fork?

I am really digging my 888 and am working on getting the oil level just right for my preferred feel, which is basically what the stock forks gives: plush initial travel with a progressive ramp up to resist bottoming. But I'm having trouble getting the rebound right. During the initial parts of the travel it feels good with the rebound knob turned in all the way, but on harder hits and faster burly sections (when the progression kicks in) the rebound is too fast and it feels like it wants to buck me out of the rocks. Basically I want the rebound damping to be more sensitive to position or speed (?) so that as the spring rate curves up near the end of the travel I'll get more rebound damping to keep it under control.

I do all my own work but don't have a very sophisticated understanding of what's going on in the damper cartridges. I'm thinking that maybe I need to run more oil in the rebound side than on the compression side...or maybe a heavier viscosity oil on the rebound side...any thoughts???

 

[Jm_]

I dont know if it will help, but I generally find that most people use way too much rebound damping. The reason is that they set it for relatively slow-speed riding, they don't set it and test it going mach3, they do it in the parking lot, stationary on the ground, on the bike stand, running it into curbs, etc. Generally at slow speed the fork should seem overly-springy, kind of like a pogo stick. It isn't going to be set to "zero", but it's going to seem like a lot less rebound than you'd want. Then after testing it at high speed you can make adjustments, but generally, I find most people run too much and they don't "set" their rebound for the high speed stuff. What they are usually feeling is the fork packing up, it may not be "excessive", so it just feels somewhat harsh.

I'm almost 200lbs, and I start with the rebound at about 30% of full (depending on model of marzocchi, 3-5 turns). That's where I make my adjustments from, and it doesn't take much for my liking.

Most fork and shock manufacturers err on the side of too much rebound, because it wont "buck" you off the bike, but it will feel harsh when you are running too much, so their "guidelines" are subjectable to the explaination above, although they are doing it for liability concerns.

These are very subjective topics though about tuning.

 

[Wallstreetbiker]

I've searched prior posts, read the go-ride article, and checked other resources, and can't find an answer to what I thought were fairly simply questions. Before I start with trial and error (which I'll probably do anyway) I figured I'd tap you all for the skinny.

How can I increase the rebound damping on my 888?

How does changing oil height impact damping performance if at all?

What is the effect of running different oil heights or weights in the different sides of my fork?

I am really digging my 888 and am working on getting the oil level just right for my preferred feel, which is basically what the stock forks gives: plush initial travel with a progressive ramp up to resist bottoming. But I'm having trouble getting the rebound right. During the initial parts of the travel it feels good with the rebound knob turned in all the way, but on harder hits and faster burly sections (when the progression kicks in) the rebound is too fast and it feels like it wants to buck me out of the rocks. Basically I want the rebound damping to be more sensitive to position or speed (?) so that as the spring rate curves up near the end of the travel I'll get more rebound damping to keep it under control.

I do all my own work but don't have a very sophisticated understanding of what's going on in the damper cartridges. I'm thinking that maybe I need to run more oil in the rebound side than on the compression side...or maybe a heavier viscosity oil on the rebound side...any thoughts???

Agree with everything JM said above, and I'll add some more based on my experience with the 888. Oil height will only change the progressiveness of the fork, not the dampening, per se. Stick with Golden Spectro 7.5wt (125-150), which is stock and recommended by Marzocchi, and don't fool with different viscosities. The rebound adjuster on the 888 is highly functional, more so than the compression. You have 22 clicks to experiment with, but as JM said, most people run with way too much rebound, as they set it in the parking lot. I usually set the rebound so that when I compress my fork and pull up on the bars quickly, the front tire stays on the ground until the fork is fully extended. Right now I'm running 6 clicks of rebound and it seems perfect. As far as setting the rebound to match a spring rate curve - I believe the rebound dampening on 888 is linear, so don't think you can achieve this, but based on my experience on the fork I don't think it's necessary if everything else is set up correctly, especially sag.

 

[Alloy]

I've searched prior posts, read the go-ride article, and checked other resources, and can't find an answer to what I thought were fairly simply questions. Before I start with trial and error (which I'll probably do anyway) I figured I'd tap you all for the skinny.

How can I increase the rebound damping on my 888?

How does changing oil height impact damping performance if at all?

What is the effect of running different oil heights or weights in the different sides of my fork?

I am really digging my 888 and am working on getting the oil level just right for my preferred feel, which is basically what the stock forks gives: plush initial travel with a progressive ramp up to resist bottoming. But I'm having trouble getting the rebound right. During the initial parts of the travel it feels good with the rebound knob turned in all the way, but on harder hits and faster burly sections (when the progression kicks in) the rebound is too fast and it feels like it wants to buck me out of the rocks. Basically I want the rebound damping to be more sensitive to position or speed (?) so that as the spring rate curves up near the end of the travel I'll get more rebound damping to keep it under control.

I do all my own work but don't have a very sophisticated understanding of what's going on in the damper cartridges. I'm thinking that maybe I need to run more oil in the rebound side than on the compression side...or maybe a heavier viscosity oil on the rebound side...any thoughts???

When you say your getting bucked out of the rocks, my guess is its not because the damping is to fast but because the fork is pumping down not leaving any more travel for the next hit. Like Jm and Wallstrbiker said back off the rebound some and you may see a difference, if not there are some other things to try.

I’ll try to give you a better understanding of how the fork works so that you may better tune it for yourself. I can tell the rebound damping is constant. Basically its just a tube with a piston in it and as the fork decompresses the piston moves up the tube forcing oil through itself, restricting the flow, causing the fork slow down. The adjustment knob acts only on the piston. On the compression side it also consist of a tube with a piston in it except it restricts oil on the down stroke. The reason you don’t feel any difference from turning the compression knob is because there are ports in the side of tube relieving the oil until the piston passes the port "which happens at about the last 1.5 inch of travel." At that point there is no place else for the oil to go except through the piston where it is restricted, slowing the fork.

About the red compression sleeve mentioned in the go-ride article, what this does is cover up some of the ports so that the compression damping kicks in at different points throughout the travel. It has 3 settings witch will cover up different holes giving you either complete compression damping, dampening in the last 3.5 inches or dampening in last 2.5 inches. Basically it will slow your fork down so it doesn’t blow through the travel as fast. It works similar to how a motorcycle fork is tuned, where some tech brazes up holes and drills some new ones depending on what your riding style is.

Anyways if you really want to learn more about it just take it apart and experiment, you’ll learn much more that way than in anything you can read.

 

[OGRipper]

Ok, I appreciate everyone's comments here and will do some more experimenting. It's true that I initially set the rebound at slower speeds but I have progressively turned it up because at speed it rides like a pogo stick and tops out with a noticeable knock when I get the front wheel off the ground unless I run the rebound pretty much all the way in. I understand the low speed compression issues and have been thinking about getting the sleeve, but I don't think my concerns have much to do with the fork wallowing deep in its travel.

What I'm most concerned about is the interplay between the progressive rate at the end of the travel (which I like) combined with consistent (linear) rebound damping. It feels great in the initial portion of the stroke but doesn't feel like there is enough rebound resistance when I get closer to the end of the stroke. So for example on big drops, the fork goes through it's travel and the rate ramps up to resist bottoming, which is good, but the ramp up causes the fork to spring back more quickly at the end of the stroke and it feels like the fork wants to buck me. I guess I'm forced to choose between too little rebound at the end of the stroke or too much at the beginning.

Wallstreetbiker's comment about how changing the oil height will not impact the damping is helpful and will save me some trial and error. I was thinking that maybe running more oil in the rebound side would help on the theory that there would be more oil to push through the rebound damper. Similarly, I thought running heavier viscosity on the rebound side would help slow things down so I wouuld get a better range of adjustment. Right now I wouldn't think about running less than 50%. I'm also about 200 lbs so maybe something is wrong with the rebound cartridge. If I can't get the performance I want I'll send it to 'Zoke and have them check it out.

 

[leprechaun]

If the damper is turned up all the way then the fork will nearly be stuck down in it's travel.We have come across 1 or 2 888 forks w/ inconsistent rebound damping which was caused by a malfunctioning damper.It should never give you a bucking feeling from deep in the travel.I run the rebound fairly light but it feels slow enough from bottom.I would recomend sending it to Zoke rather than waste valuable ride time messing around w/ oil,etc.Do however make sure you have at least the minimum amount of fluid-210cc's per leg.

 

[OGRipper]

Yeah thanks Krispy, I'm beginning to think something is up because my experience is so different from everyone else. I'll jerk around with it a little more (my time's not that valuable and I'm an addicted tinkerer) but will send it back if it doesn't improve. I've changed the oil so I know the level is ok. Thanks again, later.