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I have a 2004 vintage set of the above forks that adjusting the rebound knob on the bottom of one leg doesn't seem to have much effect.
I've had the forks to bits (first time since owning them 😳 ) and I can see that the adjuster does open and close ports in the mechanism and when the rebound is set to maximum I can hear more oil 'squelching' noises compared to set at minimum.
On rebuilding them I used the stated amount of fork oil in each leg.
Any ideas?
I used to have a pair of 2004 MX comp ETAs which I'm 90% certain are the same as the pros except the rebound was adjusted internally via a rod, turning the rebound made no noticeable difference.
I think it's just how they are.
I have a 2006 pair, exact same internals.
How are you measuring what effect the rebound knob has? Mine makes a noticeable difference.
I think it's just how they are.
+1
Even after having them serviced by windwave (this was a few year back), but they definitely still work better than most of the rubbish forks you get for £200+ nowadays.
I was trying to find a decent video on rebound setup, but the one I was thinking of doesn't appear to work, and I failed to find anything else useful.
I did find this page which states 'On adjustable forks good initial test is to push down on the fork while standing still, and then release it quickly and check that the rebound rate just about keeps up with your hands when you release the pressure. Otherwise rebound damping is adjusted to suit the rider and the trail conditions. Rebound damping that is set too high will cause the fork to "pack" or "stack" where the fork has not recovered from the previous impact before the next one comes. Rebound damping set too low will cause the fork to jump back or jump up into the rider after a big impact. '
http://www.performancebike.com/bikes/Content_10052_10551_-1_SuspensionForkAdjustment
Of course this all relies on you using the correct weight oil in the rebound leg for the amount of air (or spring) that you have to run to achieve correct sag and travel. I'm around 99kg and couldn't get anywhere using air alone, so converted to coil in the rebound leg. Took me a few goes to get the correct weight spring, and I'm now using 38 cSt@40 C weight oil (20ml 5W Castrol Fully Synthetic Fork Oil/105ml 10W Castrol Fully Synthetic Fork Oil) to achieve correct static rebound with the knob in the central position. I can then tune rebound on the trails as conditions dictate by 4 turns +/-.
Hope that helps.
Might we worth noting that Marzocchi spec a heavier oil for riders over 200lb, and that the ratings written on suspension oil bottles are fairly worthless.
http://www.peterverdone.com/wiki/index.php?title=Suspension_Fluid
The futility of going by bottle figures can be seen by looking on the chart at Silkolene Pro RSF 7.5w which is similar in viscosity to RockShox 15w!
Marzocchi standard fluid is 26.40 cSt@40C, with 10w (so up to 42 cSt@40C depending on brand) recommended for riders over 200lbs.
Anyone near me is welcome to come and see that with the correct weight oil, the rebound knob does give very noticeable adjustment. If you can't get rebound down slow enough your fluid isn't thick enough. Simples. I'll put up a video over the weekend showing how slow mine rebound when at slowest setting.
What exactly do you want the forks to do?
The last MX pros I messed about with hada rebound adjuster, it definitely worked.
If you want to slow the rebound down, put thicker oil in.
Are you running any air preload in them? This speeds up the rebound.
When you put the oil in, you have the fork lowered, did you pump the fork slowly a few times to allow the oil to get in the system when finalising that height?
I've got the exact same fork, the rebound knob has never had much effect. Just how they are? Doesn't bother me
Thanks for comments,
I am running air pre-load in them.
TBH I've had them from new and hadn't known how rebound damping should work until I recently got a pair of Fox TALAS and with the Fox I can slow the rebound to a snail pace (almost) but on the Marzocchi they are still very 'boingy' at maximum.
I was wondering about experimenting with different oils
Heavier oil would help. The problem is the air preload, this speeds up the rebound. Try taking all the air out and seeing if it makes any differencem, at least then you'll know if the adjuster works or not.
Hi Tucker...i've got a set of 2005 MX Comp ETA's THAT i'd like to service?
Do you have an email I can contact you on?
Cheers.
Putting air in make no difference at all to the rebound damping.
Putting air in make no difference at all to the rebound damping.
I dont know which MX forks you've used, but the ones Ive had were coil sprung with air assist preload. Adding air speeds up how quickly they rebound. Same with all marzocchi air assisted forks.
It can have no effect at all on the damping! All you are doing is increasing the effective spring rate. Higher spring rate may need more rebound damping.
Yeh, you're right. Sorry I didnt explaint myself better.
If you add air, you need more damping.