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Fork oil height with Racetech springs

Old 03-14-2010, 10:35 AM
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Fork oil height with Racetech springs

I am installing Racetech .90 springs in my stock forks. I have them all apart and cleaned up. My question is, given that the Racetech springs have a larger volume (they take up more room), than the stock springs, how will that affect fork oil level measurement? Since oil level is measured before installing the spring, the level should be lower than the stock spec of 130mm, but by how much?

I saw a recommendation on another post from 2004 that suggested 155mm, any comments on that?

https://www.superhawkforum.com/forum...fork+oil+level

Originally Posted by Random View Post
Here's what racetech used for my setup.

Type 1 Gold Valves
.95kg/mm springs 20mm preload
Oil ultra slick US "2"
Oil Level 155mm
Compression valving cH 36
Rebound Valving rH R-19A
Compression adjuster - out
Rebound adjuster 1 1/2 out

Somma that stuff only RaceTech guys understand. "as delivered" from race-tech, it was WAY too soft. (adjusters were all turned out). It's taken me about 500 miles of commuting/canyon riding to get it where I like it.
I suppose that I could OCD this by measureing fluid displacement in a pan of water with the different springs placed into it, but my shrink would object, I am sure.

Thank you.

JB
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Old 03-14-2010, 11:03 AM
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That may be a bit too low. I think I'm running about 5.75" (146mm) or so but I'm 215+
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Old 03-15-2010, 07:37 PM
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Originally Posted by residentg View Post
I am installing Racetech .90 springs in my stock forks. I have them all apart and cleaned up. My question is, given that the Racetech springs have a larger volume (they take up more room), than the stock springs, how will that affect fork oil level measurement? Since oil level is measured before installing the spring, the level should be lower than the stock spec of 130mm, but by how much?

I saw a recommendation on another post from 2004 that suggested 155mm, any comments on that?

https://www.superhawkforum.com/forum...fork+oil+level



I suppose that I could OCD this by measureing fluid displacement in a pan of water with the different springs placed into it, but my shrink would object, I am sure.

Thank you.

JB
Anywhere in the 135-140mm range is fine. Just make sure both sides are the same.
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Old 03-16-2010, 01:11 PM
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It's more a matter of the air volume, than the total oil volume.

I would start at the recommended oil height - regardless of spring. There wil be very little difference in displacement from the spring. It is not completely submerged.

You can then fine tune the ramp rate of the fork from there, by increasing/decreasing the air volume with oil height adjustment. Or leave it where it is and ride it!

Last edited by RCVTR; 03-16-2010 at 01:14 PM.
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Old 03-16-2010, 05:12 PM
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When assembling VTR forks I will normally run a fluid level of 120mm. A lower level can also be ok, but I've found the extra fluid helps with bottoming.
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Old 03-16-2010, 05:37 PM
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from a write-up between a guy in japan & UK racing they found that with stock valves 140mm air gap using 7w oil was a good setup.

they also step through grinding off the step on the rebound needle but i didn't want to go down that road.

http://www.ablett.jp/bikes/vtr/vtr_sus.htm


tim
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Old 03-16-2010, 06:11 PM
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I sent mine to Greg Nemish,he's in New York State. He worked his magic on them and there is a huge difference!I would give him a shout!
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Old 03-16-2010, 08:28 PM
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Originally Posted by Hopey View Post
I sent mine to Greg Nemish,he's in New York State. He worked his magic on them and there is a huge difference!I would give him a shout!
I intend to do that at some point, that is whay I am only replacing the the weak stock springs for the Racetech, and not doing any other mods.

I cleaned everything and replaced the seals, the bushings still show 100% teflon. I ending up using 7wt Belray with 135mm height. The spacers I cut to 72mm, that gives me 15mm preload at the softest preload setting (the adjuster all the way out) which is what Racetech recommends for spacer length. After I ride it a bit, I may adjust some of this. When I have more cash, I'll get the forks rebuilt. Thanks for all your help everyone. JB
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Old 03-17-2010, 02:02 PM
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[quote=residentg;257607]I am installing Racetech .90 springs in my stock forks. I have them all apart and cleaned up. My question is, given that the Racetech springs have a larger volume (they take up more room), than the stock springs, how will that affect fork oil level measurement?

Just a small maybe not that helpful comment but I would expect that the Racetech springs have a lower volume. Stiffer springs have fewer coils that are spread further apart. I also agree that the volume difference in the springs is insignificant to the total volume inside the forks.
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Old 03-17-2010, 03:50 PM
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Originally Posted by Hawkagain View Post
Just a small maybe not that helpful comment but I would expect that the Racetech springs have a lower volume. Stiffer springs have fewer coils that are spread further apart. I also agree that the volume difference in the springs is insignificant to the total volume inside the forks.
I had the springs side-by-side last night, now that you mention it, that was the case. Thank you. JB
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