Fork rebuild, now feels rough

[kvanderploeg]

I rebuilt my forks, cleaned the crap out of them, put in Progressive springs, used new All Balls seals, and 175cc of ATF fluid in each fork. Now, when I hold the front brake and bounce the forks up and down, it feels like the springs are scraping against the sides of the fork tubes. Is this normal? Did I not feel this before due to all the crap that accumulated on the inside? Is this because I used ATF fluid instead of true fork oil? Thanks for the help!

Kent

 

[5twins]

I'm used to dealing in ounces so I don't know how that 175cc relates to that. What I can tell you is these forks work better with slightly more than the stock amount of oil in them. The stock spec is just under 6 ounces. I run about 7 and it makes a big difference. Pull the springs, compress the forks fully, and set the oil level to between 6 1/2" to 7" from the top of the tube. I would use real fork oil too.

 

[kvanderploeg]

OK, 6oz would be 177cc, 7oz would be 204cc. The manual calls for 169cc (5.7oz). Hugh's tech write up called for 175cc (5.9oz), so that's what I went with. Maybe I'll just pull the spring and set it by height.

Kent

 

[5twins]

If you've got lowered forks then disregard everything I just said. You're on your own with those.

 

[kvanderploeg]

Nope, not lowered, I just used his guide for the pics and tricks. Only difference is the Progressive springs that should displace a bit more oil.

Kent

 

[jd750ace]

I would use real fork oil. ATF's primary mission in life is thermal transmission, aside from fluid dynamics. It is also not "graded" by weight, which is important to metering. It begins life somewhere near 7 weight, and does not hold up for long. That's why we end up dumping what looks like brown or black water out of the forks. No body to it when it's worn out, so the damping action is terrible. Contributes to short spring life.

Fork oil lubricates everything, deals with the thermal issues, and stays "in grade" viscocity-wise, so the damping is consistent between hot and cold forks, and stays that way much longer.