Author Topic: Fork rebuild after dog encounter  (Read 855 times)

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Offline pzak95

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Fork rebuild after dog encounter
« on: May 14, 2012, 12:48:02 am »
Got my 95 C10 back on the road after the run in with the dog back on 3/28. Replaced both fork tubes and in the process used new factory springs that came with the the new tubes. Rebuit the forks and used 15W Belray oil. Since this was a complete rebuild I used the amount of oil called for in the factory service manual 380mL. Now the suspension seems softer than it did with the progressive springs that were in the forks before. The only reason I replaced the springs is because the progressive springs measured less the the service limit called for in the book. Are the factory springs that much softer even when brand new?


Offline GF-in-CA

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Re: Fork rebuild after dog encounter
« Reply #1 on: May 14, 2012, 01:48:44 am »
According to the service manual the service limit for the spring length on the '95 is 21 inches, and the "standard" length is 21.38 inches.  The free length of the Progressive spring is 20.75 inches, so it looks like the Progressive spring is shorter to begin with than the standard stock spring by about 7/8".  If you are sure you had springs made by Progressive you probably didn't need to replace them.  The original springs are dual rate and look like progressive springs, hence the comment about being sure you had Progressive springs to begin with.

The springs made by Progressive are stiffer than the OEM springs.  The Progressive springs have a rate that varies from .80 to 1.25 kg/mm, where the OEM springs have two rates, with a beginning rate of .61 kg/mm.  I'm not sure what the final rate is, but because the springs are dual rate, they will feel softer than a true progressively wound spring for most of the suspension travel, so the OEM springs will feel soft compared to the Progressives, as you are experiencing.  The good news is it sounds like you can reinstall the Progressive springs and get the stiffness back that you had.

The amount of oil in your forks should be determined by the level of the oil measured from the top of the tube with the fork collapsed and spring removed.  The factory recommended oil level is 171 mm or about 6.75 inches.  The volume number is used to determine how much oil you may need, but the final setting should be the oil level.  EDIT:  If you use the Progressives, check with them for the recommended oil level.

Hope that is helpful,
« Last Edit: May 14, 2012, 01:58:02 am by GF-in-CA »
Gary F.

1998 ZGX1100
Central Valley California