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Old 01-25-09, 01:22 PM   #1
gabekeating
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'99 marzocchi Z1 bomber fork repair.

I rebuilt my front shock for the first time. Its an older oil cartridge system. I used instead of the stock 7.5 wt, a 10 wt fork oil. It has such poor responce. It stoped bottoming out but is taking to long to rebound. The recomendation was to replace the cartridge, ... I didnt do that. How do I know that they are even bad? and is the 10 wt. just to thick?
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Old 01-25-09, 01:51 PM   #2
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If the oil weight seems to affect rebound and compression. So it seems that the thicker oil is the reason. I have never seen the inside of a bicycle fork, but with motorcycle forks, adding more oil reduces the amount of air space in the fork, effectively increasing the spring rate as the fork bottoms. If I am satisfied with the spring rate and damping, I raise the fork oil to reduce bottoming. I would think that there has to be an air space above the oil for the fork to function properly. Be careful to not add too much such that the suspension hydraulic locks before reaching full travel. It is not uncommon for motorcycle forks to give a minimum and maximum fork oil level.
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Old 01-25-09, 05:58 PM   #3
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oil weight

Replace oil with 7.5 weight synthetic motorcycle shock oil. I used a straw to mark factory oil level before changing. Remove both top caps and compress legs all way to measure oil level in each side. My cartridge was on right side on mx pro and oil level was inch or two down into tube. I noticed the shock compressed a easier with the synthetic, so you might want to add a little more than regular oil.
http://www.windwave.co.uk/documents/...itechinfo.html
http://www.marzocchi.com/spa/mtb/?LN=UK&Sito=mtb
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Old 01-25-09, 11:16 PM   #4
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If you liked the rebound performance with the 7.5wt, I'd put 7.5 wt back in, and then raise the oil level a bit compared to the original level to combat bottoming.
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Old 01-26-09, 05:07 AM   #5
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This fork should have a ridiculous amount of adjustability via the little screws on top of the fork. Try to back out the rebound screw a couple turns and you should be fine so long as the oil level is correct.
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Old 01-26-09, 09:04 AM   #6
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Originally Posted by gabekeating View Post
I used instead of the stock 7.5 wt, a 10 wt fork oil.
It has such poor responce.
It stoped bottoming out but is taking to long to rebound.
and is the 10 wt. just to thick?
your springs could be too soft for your weight.
not all fork oils have the same viscosity for a given weight.
you can make custom fork oil by mixing equal parts of two different weights.
5wt & 7.5wt=6.25wt
7.5wt & 10wt=8.75wt


http://www.peterverdonedesigns.com/bikesuspension.htm
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Old 01-26-09, 08:33 PM   #7
gabekeating
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thanks everyone, ...however when i came back from getting new oil and started loosening the screws I noticed that my clamp area was cracked today, where the stanchion tube meets the crown. Guess I tightend it too much the last time I assembled it the other day. LAME! So new plan...
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Old 01-27-09, 02:12 AM   #8
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So new plan...
does the new plan include a torque wrench?
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Old 01-30-09, 02:13 PM   #9
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I would like to find a crown for that model. But if your saying that a torque wrench will stop me from tightening it to tight and cracking it again, than maybe i'll try that. I am here to learn something that I dont know that much about ..yet. But for now I put on the forks that came stock on the bike just to keep those wheels movin.
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Old 01-30-09, 09:01 PM   #10
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But if your saying that a torque wrench will stop me from tightening it to tight and cracking it again, than maybe i'll try that.
I am here to learn something that I dont know that much about ..yet.
don't make the same mistake twice.

buy a torque wrench.

learn how to use it.
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Old 01-30-09, 09:19 PM   #11
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Do you have the same type of fork thats on the bike in the pic? If so PM me because I put a rigid fork on the C'dale and it's now my off road commuter. The Marzocchi fork is just sitting in my garage collecting dust. If you would like it let me know.

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