Fixing a fork leak: a dumb question...


1 reply to this topic
  • gregk

Posted September 19, 2007 - 10:29 AM

#1

Hi all,

last time I went to my (unofficial :thumbsup: ) motocross track, after about 1 hour of jumping attempts I detected a leak in my left fork seal. Not a large leak, but the brake caliper looked wet (which seemed strange, as the track was almost completely dry), I checked and it was oil, not water...the oil did come from the fork, leaking slowly along the chrome inner tube and wetting the caliper.

The jump (yes, THE jump...there is only one on the track :thumbsup: ) have a flat reception, and my landings were a little bit rough...However, I am a beginner and do not jump high, so I rate the probability of me (75 kg) breaking something in the fork of a WR450 2004 with standard spring as really really low (or maybe I progressed faster than I though and my jump are not as ridiculous as before? :worthy: ).

More likely, I compressed the fork more than usual and some dried dirt got trapped under the seal. I do not want to attempt seal replacement, fork disassembly is quite frightening and I think the 35mm film trick is better to be tried first, given that the leak is not very strong...

Now for the dumb question: I first tried to do the film trick under the dust seal (I did not know there were 2 seals....noob, I told you :ride: ), there was an improvement in the leak, it looks like it was more or less solved, but reading thumpertalk I realised my error and I think the oil is simply accumulating above the dust seal and will leak again when I jump a few times...
I would like to clean the oil seal properly, but question is, how do I remove the dust seal in the first place????
I have removed the fork gard and it's guiding nylon ring, but the dust seal is still fixed quite strongly. Do I have to take it down by inserting a screwdriver between it (rubber) and the bottom of my upper fork tube (aluminum)? Pulling with fingernails only it does not seems to come down, and there is no obvious fixation system (I hoped the nylon ring was somehow responsible for holding the dust seal, but it is not the case obviously). There is nothing about this in the manual, unfortunately, they just say "remove the dust seal" :thumbsup:
Before I start applying some force with a screwdriver on a rubber part, I prefer to ask the board than risking damaging something....

Thanks for any help!


Dummy Noob Greg.

PS. While I am at it, a technical question about jumping...The better rider seemed to land rear wheel first (slightly first, but the rear wheel did land before the front) and adviced me to do the same. I tried to and managed (before, I had a tendency to nose-dive and land on my front wheel). However, while landing front wheel first is scary (especially when the nose dive is significant...you definitely feel you sucked big time and you better correct your take-off before you land on your helmet :bonk: ), landing flat felt the best. In fact, landing with front wheel just slightly down is not as good but still felt smoother than rear wheel first. Landing rear wheel first seemed to make the front fork hard, like if the force on the front wheel when it hit the ground was not aligned with the fork and tried to make the wheels further apart (not easy to explain, but I hope the experienced rider get what I mean). That's what I meant when I said I had a few rough reception, in fact feared it could be the cause of the leak, but looking at the pro I guess my bad receptions are not possibly rougher than a good rider perfect reception, given the difference in jump height :bonk:.

So what do you think? Is landing rear wheel first really better, or flat landing on flat reception is best and the advice "rear first" is just for security, as it is better to land too much on the rear than too much on the front? Or maybe it is rear first but there is something else I do incorrectly and make it rough...

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  • oldmanx

Posted September 19, 2007 - 11:38 AM

#2

More likely, I compressed the fork more than usual and some dried dirt got trapped under the seal. I do not want to attempt seal replacement, fork disassembly is quite frightening and I think the 35mm film trick is better to be tried first, given that the leak is not very strong...

Now for the dumb question: I first tried to do the film trick under the dust seal (I did not know there were 2 seals....noob, I told you :thumbsup: ), there was an improvement in the leak, it looks like it was more or less solved, but reading thumpertalk I realised my error and I think the oil is simply accumulating above the dust seal and will leak again when I jump a few times...
I would like to clean the oil seal properly, but question is, how do I remove the dust seal in the first place????
I have removed the fork gard and it's guiding nylon ring, but the dust seal is still fixed quite strongly. Do I have to take it down by inserting a screwdriver between it (rubber) and the bottom of my upper fork tube (aluminum)? Pulling with fingernails only it does not seems to come down, and there is no obvious fixation system (I hoped the nylon ring was somehow responsible for holding the dust seal, but it is not the case obviously). There is nothing about this in the manual, unfortunately, they just say "remove the dust seal" :thumbsup:
Before I start applying some force with a screwdriver on a rubber part, I prefer to ask the board than risking damaging something....

Thanks for any help!


Dummy Noob Greg.

No question is dumb. We all have to learn sometime/somehow. I've done the film thing several times...successfully. Use a screwdriver to separate the dust seal from the fork...carefully...don't ding the fork. Drop the dust seal down out of the way. Instead of 35mm film, I've been using the plastic sheets that are used laminate paper/cards/etc. I run them through the laminating machine so that both sheets are bonded together. Then I cut 1" wide strips of the plastic...usually cut a radius to eliminate any sharp corners which might tend to nick the seal when you slide it up in. I've also cut a hook onto the end of a strip so that you can go arond the fork and pull out whatever dirt you encounter. I believe that you can buy something like this...called a Sealsaver or something of the sort.
Before you push the dust seal back into place, put some white lithium grease inside it, the whole way around it's diameter. Your service manual will tell you to do this.




 
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