bad fork seals? [Archive] - Sportbike Forum: Sportbike Motorcycle Forums

: bad fork seals?

02-16-2003, 07:06 AM
While out on my usual Sunday group ride today I hit a pothole at around 75mph. After pulling into a gas station less than a mile after that I could see a coating of oil on my left fork, the right fork is still clean, no fork oil. I've never had fork seal problems before this so I am wondering if the presence of ANY fork oilmeans my seals are definately shot or if it is possible that just a little oil was forced through the seal, resulting in the oil I noticed.

I did clean it off and after riding a little more I noticed some more oil on the fork so I cleaned it again when I got home. I then went out for a (slow) ride around the block and came back and didn't see nearly as much oil as I had seen earlier. This is what is making me wonder if maybe justa little oil made it past the seal without ruining the seals or if they are definately shot.

I figured some people here would have had this problem before and would know if they definately need to be replaced (I have a bad feeling they should never let ANY oil past the seal, reagrdless of the bumps/potholes you go over unless the seal is shot...but can anyone tell me otherwise? How difficult is it to replace the seals on a 2000 GSXR600?

Thanks for any info you can give!


02-16-2003, 08:08 AM
Count on replacing them. Also, your fork oil level is now out of whack. It effects the volume of air that is captured in the fork. Due to compressability, the air acts as a rising rate spring and is an important element in the suspension. The more air, the less spring. Hope that helps.

02-17-2003, 03:24 PM
It's not difficult to do if you have the tools. If you don't, take it into a shop, or someone with the right tools.

I'm guessing most people don't have the appropriate size seal driver hanging around. That's the only "special" tool that you'll need.

Rags - lots of rags.

Good luck.

02-17-2003, 06:03 PM
If you're a serious rider, now would be a good time to just send the legs to a shop like RaceTech, Circuit 1 or any of the other suspension shops. They can put in the right springs for you, revalve, and put in some good oil. You think your forks worked before - it will be night and day.

Unless you're going to do it yourself...but any oil visible means problems.

02-17-2003, 06:05 PM
Dad is 100% correct in short fork seals & level of the oil.

02-18-2003, 02:20 PM
Thanks for all the replies!

Bummer. Looks like I'll be doing the seals after all, or taking it in to the shop soon.

The weird thing is that I took it for a ride today and there is very little (if any) oil present on the fork tube. I did clean it off really well but I assumed if it was leaking I would still see more oil. I know only a little oil made it past the seal, maybe a copule drops at the most. I just wonder why it (seemed to have) stopped leaking.....strange.

I would like to have the forks reworked in a shop as was suggested but this probably isn't the best time for me to do something like that as this month I got a speeding ticket (first one on a bike--been real lucky), had to buy Valentines day gifts, and her birthday was two days after Valentines day. Talk about an expensive month! I am a serious rider but am still at the leve where the stock suspension is still fine for me. I do like to push the limits (so far my limits, not the bikes) so maybe in the future I'll get my suspension set up a little better. About how does it cost anyways?

02-18-2003, 02:31 PM
On MANY 'used' bikes & yours could be the same ------ the oil has been gushing out for quite some time & now you are possibly only running on the springs (bar a small it of oil still in the forks, but really not doing much) & not the effect of true hydraulic f/forks. They may be acting presently as cheap spring only tele-like looking forks (so common in small bikes back in the 60s to 80s & yes even now on small bikes).
Rather then a costly f/fork job have the fork seals & possibly new scrapers or whatever and THEN you can think about a special fork job in the future or might be pleased with what you have once rebound, compression & preload set properly.

02-19-2003, 12:21 AM
I work in the shock business, Engineering. If your fork seal was damaged it would continue to leak. It is possible that the impact forced a small amount of oil through the seal. If there was only a small amount (not measureable) I would not worry about it. If it continues to leak, go ahead and have both fork's seals replaced.

Steve S.

02-19-2003, 03:22 AM
Steve, you say that if the seal was damaged it would continue to leak. That's what I thought, too. I just thought it was strange that I saw some oil right after the impact but now, rather than getting worse, it's actually getting better. Perhaps there is some oil on the dust seal and it is gradually smearing off, explaining why the problem seems to be getting better, not worse? The total amount of oil lost is VERY small, probably not even measurable.

I suppose it would be safe to continue to ride for a while to see if it clears itself up or continues to leak, am I right?

Many thanks to everyone for their help!


02-19-2003, 03:57 AM
Originally posted by Gixxer6oo
... The total amount of oil lost is VERY small, probably not even measurable.

I suppose it would be safe to continue to ride for a while to see if it clears itself up or continues to leak, am I right?

Because I am one who was quick to suggest replacement, I'll also agree that your description above suggests it's O.K.:) What Ssallber said is certainly theoretically possible and appears to be your situation. My experience has been that once you see oil, it's done. Clean it up and keep an eye on it. If it stays dry, consider yourself lucky.:)

Also, from the tone of your question, it seems that you're most worried about the safety of riding this while making the determination. Keeping in mind that a little oil makes a BIG mess, don't panic. A lot of oil will leak out before the shock absorbing ability will be lost. In the meantime, the loss of spring assist as the oil level drops would only hurt in extreme riding situations. I hope that helps.

02-19-2003, 07:49 AM
Thanks, Dad, and thanks to everyone that helped me with my leaky fork. Like I said, it seems to have stopped leaking so I'll just give it some time to see what happens but, just in case, I do have a set of fork seals ordered so I can replace them in the event that they do continue to leak. I figure eventually they'll come in handy.

Thanks again!

02-19-2003, 07:53 AM
Ehhh, Quit being a pansy!!

I've had one blown fork seal for a while now, and I still ride the wheels off that thing! Sliding the front tire into the corner, spining up the rear on the way out!

BE A MAN!!!!

Just kidding,

If it quit leaking, the I wouldn't worry about it. It might handle a little bit differently , but remember, you still have the other fork. For everyday riding, that should be more then enough damping. Just get it rebuilt when you can afford it.

Biggest thing to watch out for with a leaking fork seal is fork oil getting on your brake pads. Good luck!

02-22-2003, 03:28 AM
Sounds like everything is ok Bryan. Go ride and have fun!

Steve S.

02-22-2003, 08:56 AM
I would go ahead and have the seal changed (one if not both). And yes, Kevlar has a good point about the oil getting onto the brake pads.

I had a leaky seal once, and honestly, I DID notice it, but I didn't think too much about it because it SEEMED to ride ok. Well, I rode it everyday, so gradual degradation was'n't apparent. Well, the oil made its way to the pads and started to "polish" my pads. I thought my pads were getting old, so braking power had degraded as well.

When I broke down to do some maintenance on th bike, I found about half to three-quarter of my fork fluid was gone from the right fork (left was ok). The brake pads were still in good shape (only about half used), but soaked in fluid. After I changed the fork fluid, changed the seals, changed the brake pads, bead blasted the rotors, it seemed like a whole new bike. :D

Bottom line, the seals should run you about $12-$15 each. I mentioned earlier that most people don't have seal drivers laying around in their garage, but I've resorted to a roughly sized piece of PVC. It took longer to drive the seal into the fork legs, but it worked like a charm (at about 80 cents). Assuming you have front and rear sands, basic shop tools, your section of PVC pipe, your $15 seals, fork oil, and a measuring tool, you should be good to go.

I'd do it, just for a little piece of mind.

02-22-2003, 11:24 AM
Here's an update on the seal problem. After riding it for a few days it seemed as though there was no leak whatsoever. I thought it was fine. This morning I get on the bike to meet my family for breakfast (slow speeds, smooth road) and I look down as I was riding and noticed a significant leak.

I had already ordered some seals and was due to bring my bike to the shop today for a new front tire so I brought it in and had both fork seals replaced and a new BT012 front tire put on.

Now I should be all set for the twisties tomorrow!!:D

02-27-2003, 01:48 PM
A penguin is riding his motorcycle on a hot summer day. His front suspension suddenly goes screwy, so he pulls over, luckily in front of a convenience store just a few doors down from his bike dealer.

A hot day is even worse for a penguin in leather, so he stops in and gets a nice cold Eskimo Pie. Refreshed, he trots down to the dealer, who comes out to see what the problem is.

The dealer takes one look and says, "Looks like you just blew a seal."

The penguin gets a sheepish grin and wipes his chin; "No...that was just a bit of ice cream."

02-28-2003, 04:08 AM
Don't have a seal driver? Use the old seal on top of the new one, and drive the new one home by tapping on the old seal with a hammer & screwdriver.