Fork oil seal

On my ride today, I noticed that there was some oil on my front right fork. Upon further inspection, I noticed that oil had also dripped down the outside of the fork tube. I suspect a leaky fork oil seal.

1) Is this a reasonable suspicion?

2) How difficult is it to replace the seal?

3) How dangerous a condition is this (I have an appointment to have the bike in for service in a couple of weeks. Can it wait until then? Is the bike ridable until then?)

You are not in imminent danger of crashing. I've worked on bikes that had no fork oil remaining when they were finally brought in. Just ensure that you keep the oil off and away from the brake pads.

manic mechanic said:

You are not in imminent danger of crashing. I've worked on bikes that had no fork oil remaining when they were finally brought in. Just ensure that you keep the oil off and away from the brake pads.

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Yeah, I can see where that might be a Bad Thing.

If your airhead does not have fork boots, you might consider adding them. Earlier models have a nice "accordian" rubber boot that kept road gorp and hard shelled insects out of the fork seals. Later models eliminated the boots in the interests of style (or whatever) Some insects have very hard, sharp shells that easily slice through rubber seals. And sand or clay can scratch the chrome tube. Yes, I know that fork boots are considered unstylish, but they are a cheap, reliable way to protect the sliders and seals.

So, while your mechanic has the forks off to replace the seals, you might discuss adding boots.

pmdave

The seals on your airhead are even easier to replace than the seals on your F650.

flash412 said:

The seals on your airhead are even easier to replace than the seals on your F650.

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That's good to know. Can you describe the procedure, or point me to a site that does?

jmerlino said:

That's good to know. Can you describe the procedure, or point me to a site that does?

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Remove the wheel. Remove the fender. Drain the fork legs. Remove the bolts from the bottom of the fork legs. Remove the fork legs. Pop out the old seals with a tire iron or screw driver. Oil up the new seals, inside and out, with a bit of fork oil. Whack them into place using a piece of flared (1 1/2"?) drain plumbing that fits the seals (that you bought at a hardware store for <$1). Reassemble in reverse order. Refill with proper amount of 10 wt. fork oil (for improved handling and fork responsiveness).

flash412 said:

Whack them into place using a piece of flared (1 1/2"?) drain plumbing that fits the seals (that you bought at a hardware store for <$1).

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But ...

... don't whack with the fork vertical and the bottom on the ground or you'll close up the split in the bore for the axle. DAMHIK

Maybe insert axle first.

I'd also like to add that, while you have the fork sliders off, after the old seal is out but before inserting the new seal, you get a spray can of brake cleaner and clean out all the gunk in the bottom of the slider.

flash412 said:

Remove the wheel. Remove the fender. Drain the fork legs. Remove the bolts from the bottom of the fork legs. Remove the fork legs. Pop out the old seals with a tire iron or screw driver. Oil up the new seals, inside and out, with a bit of fork oil. Whack them into place using a piece of flared (1 1/2"?) drain plumbing that fits the seals (that you bought at a hardware store for <$1). Reassemble in reverse order. Refill with proper amount of 10 wt. fork oil (for improved handling and fork responsiveness).

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Saved for future reference.

Thanks, Flash.

lkchris said:

But ...

... don't whack with the fork vertical and the bottom on the ground or you'll close up the split in the bore for the axle. DAMHIK

Maybe insert axle first.

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Actually, I wouldn't WHACK it against anything. For that matter, I don't even WHACK them. I start them with a plastic dead blow hammer while holding the fork leg with my other hand. Once the seal is on it's way, straight, I sit down, grip the leg between my knees with the bottom of the fork leg on the sole of my rubber shoe. I TAP a bit of PVC pipe with a small ball-peen hammer against the seal until it hits bottom. (resonance changes)
I guess the point I'm trying make is that a properly lubed seal doesn't need a whole lot of FORCE to go into place, and that force will more than likely do more harm than good.

Also, placing the leg in the sun on a good warm day or in the oven on low for a few minutes will help enormously.

Got it back from service today with new seals in place. I took it for a short ride, and I can report that the front end feels much smoother now.