Topic: front fork rebuild question....use spring spacer, or not, with shorter forks.

[Jerry E.]

I am rebuilding the forks on my 1973 Cb750, and bought new stock length progressive springs and fork tubes that are 1" shorter than stock(21 13/16"). The springs come with a 1 3/8" PVC spacer to set the preload of the springs. The springs stick past the end of the new tubes by an inch, since the tubes are 1" shorter. If I leave out the spacer, shouldn't the preload be alright, since the tubes are shorter than stock? The tubes caps will add a little more preload, putting the top of the spring at the bottom of the cap threads. Anyone see a problem with doing it this way? Also, can I still use 7 0z. of 10w-30 oil to fill the tubes, or a different amount, since the springs are different and the tubes are shorter?

[becken]

I would contact Progressive and ask them. With shorter fork tubes you may be getting close to coil binding the springs before you get to the end of your travel, even without any preload spacers.

[Jerry E.]

Using shorter fork tubes is fairly common, I believe, and I haven't read any posts where anyone has had a problem with the springs binding. Have never seen shorter springs for sale. I am going to try this setup, and see how it works. The amount of preload applied by the shorter tubes(with top cap installed), is very close to what I would have using the spacer supplied with the springs, using stock length tubes. The forks compress/ rebound well, off the bike, hopefully I won't have a problem.