Replace 1970 Honda CB350 Fork Seals

| 4/5/2016 12:00:00 AM

replace fork seals 

The forks shown here are off our 1970 Honda CB350 project bike, which, given the state of the rest of the bike, we knew needed new seals at the very least and more likely new fork tubes. Stripping them apart we learned two things: First, early series 1968-1971 CB350 forks are amongst the easiest we’ve ever worked on; and second, yes, we need new fork tubes.

To be fair, our original fork tubes are perfectly serviceable. They might not be pretty, but they’re straight and the critical wear surface area where the seal makes contact is fine; it’s just the top third, hidden under the upper fork tube covers, that’s rusty. Although we’ll be swapping in a new set of fork tubes from Forking by Frank, what you see here is pretty representative of what you’ll see on most old survivors; fork tubes that are a little battle scarred and ugly, but still perfectly usable.

BikeMasterRemoving the forks is straightforward. First, remove the fork drain screws and drain the old oil. With the bike suitably supported, remove the front wheel and the front fender. The upper end of each fork tube is choked down and fits hard up inside the upper triple clamp. Remove the chrome bolts (these are also the fork oil caps) securing the tubes to the upper triple clamp. Next, loosen the clamp bolts on the triple clamps, two on each side, and pull the fork legs out.

As always, we suggest having a shop manual on hand for parts identification and placement, and to confirm proper torque specs.

replace fork seals 

4/21/2016 7:56:24 PM

new fork tubes are always nice - and alternative to rechroming or replacement, depending on the 'severity' condition of the original tubes: have a precision brass sleeve made that can be tightened about the rusty fork tube. place the tube in a lathe chuck with the brass hone sleeve on it and then slowly spin the fork tube while slip lapping the affected area with progressively less aggressive lapping compounds....then keep them good if you go thru the trouble off...