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Fork tuning, maximizing fork travel. Failing miserably.

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Fork tuning, maximizing fork travel. Failing miserably.

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Old 03-22-07, 12:59 PM
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AfterThisNap
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Fork tuning, maximizing fork travel. Failing miserably.

Ok, so I have a bit of a franken-fork. Marzocchi AM uppers/crown with Z1 thru-axle lowers, VF2 rebound damping cartridge in the right leg, ECC in the left.
Suggested psi is 35-45. claimed travel is 130mm.

For the life of me I couldn't get more than 100mm while actually riding, and even if I tried I couldn't get a harsh bottom out.
I took off both topcaps and compressed the fork all the way. There was very little chamber volume left in either side as the oil rose. Probably only 30cc of empty space in the left, less than 15cc for the ECC.

Sooo, I tried this: With both topcaps still undone I compressed the fork, easily going past 130mm of travel and feeling a mechanical bottoming out (essentially, using all of the uppers). So I figure the oil level is too high in one or both legs. I started with the ECC side, dumping 5cc of oil at a time until I could bottom the fork and get full compression with right air chamber top cap off (no preload).

Then I moved to the right side. Leaving the ECC topcap off this time, I dumped 5cc of oil from the main chamber until I could get just about 130 mm of travel with 10psi , no bottom out.

I put both topcaps back on, pumped it up to 25psi and the thing still only gets 115 mm or so of travel no matter what I do. I thought it was the ECC side, so I dumped a little more oil and now the cartridge cavitates so it only drops 1/2 as much as it did before. I can't imagine dumping any more oil from the main chamber as the compression damping at this point is ultra mushy and brake dive is redonkulous even at 30 psi. Rebound damping has been perfect regardless.
Golden Spectro 7.5wt in both sides.

Sooo, what to do? My thought is to add just enough oil so that the ECC funtions fully and I still get 130mm of compression for that side, then switch to a heavier oil, 10wt or so on the VF2 damper, increasing compression damping but maintaining a high chamber volume to ensure full travel.

I know that I probably shouldn't whine too much about a lost 15mm of travel, but I'm using an older chameleon frame and the marzocchi's axle to crown height is really long relative to a fork with equal or greater travel like a Pike (which I should have bought in the first place). I'd rather just have an extra 15mm of sag than 15mm of axle to crown height making the santa cruz into a chopper.


What am I missing, or am I going about this the wrong way?

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Old 03-22-07, 05:10 PM
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Old 04-23-07, 10:19 PM
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Not that anyone currently has the same problem, but I thought I would update for posterity.

Switched to 10wt in the VF2 damper side, 7.5wt in the ECC side. Noticeably improved resistance against brake dive, still not getting full travel, but it's more "useful" travel as I'm not blowing it all on braking bumps.

Gonna try switching out to 15 or 20 wt on the VF2 damper. It's such a simple and high flow/volume path that I think anything lower is just too thin.
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Old 04-23-07, 11:36 PM
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Time to turn to the Angry Asian for answers, I'd say.
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Old 04-24-07, 12:44 PM
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hah, that's what my friends call me.

That site hasn't been touched in how many years now?
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Old 04-24-07, 01:06 PM
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Originally Posted by AfterThisNap
That site hasn't been touched in how many years now?
Looks like the last question he answered was back in Feb. - -but I don't think that means he does not read and respond. Sometimes it takes a few days, though.
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