Oil in forks?

I just read somewhere that a non-clorinated brake cleaner spray is a good flush for the fork tubes (while they are still on the bike). Apparently this stuff does not eat at the rubber seals and leaves no residue, but I've always felt that brake cleaners evaporate too fast.

I've also read about some people using a mix of kerosine and acetone, or kerosine alone, But kerosine is a petroleum product, so won't it hurt rubber? Anyway, anyone heard of this?

polkat wrote:

I just read somewhere that a non-clorinated brake cleaner spray is a good flush for the fork tubes (while they are still on the bike). Apparently this stuff does not eat at the rubber seals and leaves no residue, but I've always felt that brake cleaners evaporate too fast.

I've also read about some people using a mix of kerosine and acetone, or kerosine alone, But kerosine is a petroleum product, so won't it hurt rubber? Anyway, anyone heard of this?

Non chlorinated brake cleaner is almost all acetone. I don't know if it will hurt rubber seals for sure, but it's pretty nasty on any kind of plastic.

Do you have or can you get/make any of the following tools?
air impact wrench
welder
old rake handle or broom handle
seal puller
1-1/2" pvc pipe & fittings

Sometimes you can remove the bottom allen bolt by hitting it w an impact wrench. It's hit or miss - it may come out OR the damper rod spins.

You could weld a nut to the end of a long 1/2" bolt - this tool would serve to hold the damper rod while turning the bottom allen bolt (the head of the bolt should be 3/4" which is ~19mm). Or....

Cut the end of a rake handle into the shape of a cone & jam it into the head or the inner cylinder (damper rod), then remove the allen bolt.

An off the shelf seal puller from the auto parts store will work fine. Alternatively & without buying or using a tool, some folks are able to remove the seals by pulling up forcefully on the upper tube in a piston-like manner until the seals come out (be sure to remove the spring clip first).

You could make a homemade pvc tool for driving the seals - I made mine out of a 2' length of pipe, a male & a cap & it works just fine.

Forgot to mention that there was NO pressure on the caps at all, by the time I screwed them out enough to remove! Is that right? Also, both springs seem to have closer coils at one end then the other. Does it matter which way they go back in? Thanks!

polkat wrote:

Okay, new problem. I got the caps off and pulled the springs. Everything that came out was covered in a gray sticky mess, almost like a light axle grease the same color as the nasty gray oil that came out when I pulled the bleeder screws. Frankly, I don't think in the 28 years of this bike's life, the forks have ever been serviced. There was no air in the forks when I tried to release it.

Anyway, as I do not have the tools to disassemble the tubes, is there any kind of flush or solvent I can run through them that won't hurt the rubber seals? Thanks!

I would mix fork oil 50-50 with naptha or mineral spirits and pump the hell out of the forks, then drain. Repeat until the oil comes out clean, then refill with clean fork oil pump/drain once more then refill with clean oil..

polkat wrote:

Forgot to mention that there was NO pressure on the caps at all, by the time I screwed them out enough to remove! Is that right?

That's how mine is if the front end is lifted off the ground.

polkat wrote:

Also, both springs seem to have closer coils at one end then the other. Does it matter which way they go back in? Thanks!

Don't know about that, sounds like a "progressive" spring which should work the same either way.

When I took mine out, the close coils were at the bottom. Thats the way I put them back in, close coils toward the bottom of the fork.

A guy down the block from me just told me that he flushes his fork tubes (while still on the bike, a Harley) with about a cup of plain old gasoline. He leaves the bleeder screws in, lets it sit about 10 minutes, then drains it out and lets it dry for a day. Okay, of course there's a safety factor here, but does this work, and work without hurting the rubber parts?

polkat wrote:

A guy down the block from me just told me that he flushes his fork tubes (while still on the bike, a Harley) with about a cup of plain old gasoline. He leaves the bleeder screws in, lets it sit about 10 minutes, then drains it out and lets it dry for a day. Okay, of course there's a safety factor here, but does this work, and work without hurting the rubber parts?

Ahhh.... the Richard Pryor school of auto repair.:laugh:

I couldn't guess if the rubbers are strong enough to handle gas. Fuel lines are made of special rubber. Vacuum lines are not and they dissolve in gas. I wouldn't put gas in my forks because there is just no need. Naptha is a good solvent and is not dangerous like gasoline.

Okay, that's it. I'm going to take the tubes apart and do it right. I understand that there's a tool I can make to hold the inside part while I loosen the bottom bolt. Can someone tell me about that? Thanks!

Long 1/2" bolt w a nut welded to the threaded end.
note: the bolt should have a 3/4" (19mm) head.

1/2" bolt w a welded nut used w ratchet extensions

left-hand-threaded 1/2" bolt-nut setup w ratchet extensions

hardwood dowel w one end carved into the shape of a cone

Disassembly is quite simple: all you have to do is unscrew the bottom allen bolt from the inner cylinder (damper rod). Apply some heat w a propane torch first.

From what I read, some people make the tapered wood dowel piece out of a broom handle.