Author Topic: Cleaning leaking fork seals  (Read 2725 times)

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Offline hapsh

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Cleaning leaking fork seals
« on: April 04, 2008, 08:11:21 am »
We all have had to deal with leaking fork seals over the years.  Most of the time we just replace the seals.  Recently I tried one of those Motion Pro Seal Mate cleaners on my FZR forks.  At first it didn't really seem to help, I still had a good amount of dripage after each ride.  But I found a way to maximize the cleaning effect.  First drain your fork oil and replace.  Go for a good ride and drain and replace again.  Check for metallic debris.  You may have to do the drain and fill up to 3-4 times to fully clean out the old metallic particles.  Once you have clean oil in the shocks top them off a bit higher than usual, maybe .5 ounce more (this helps get the oil to the top of the shock closer to the seal).  Now lift your dust caps exposing your oil seals.  Clean off the fork tubes and seal tops very carefully with a clean rag, a q-tip and maybe some WD40.  Once it is cleaned, pump the shocks until you have oil coating the fork tubes.  You will probably notice there is still some dirty crap coming out of the seals even though you have clean oil in the shocks.  Wipe clean the fork tubes and seals again.  Now is the time to use the seal cleaner.  Oil the tip of the Seal Mate with WD40 or similar to keep from damaging the seal.  Work the tip of the seal cleaner down between the seal and the fork tube and then slide it around the tube to scrape the debris from the seal.  Slowly start removing the seal as you are still sliding it around the fork tube.  Once the seal cleaner is out clean the tip of the seal cleaner with WD40.  Now pump the shocks again and you should notice there is a little less oil coming out and it should be slightly cleaner.  You will have to insert the seal cleaner 3 or more times depending on how much grime is wedged into the seal.  Once you have it clean though you will see no more oil coming out after pumping the shocks.  Now drain the fork oil again and fill with your normal amount.  I have now done this on three bikes with total success and saved myself quite a bit of time by not having to rebuild the front forks.  At least in my case the reason the seals were leaking was that the PO never seemed to change their fork oil so there was quite a bit of Grey metallic dust in the oil.  This gets carried into the seal which causes it to start leaking.  In this case it is NOT outside dirt causing the seals to leak, it is internal debris.  Hope this helps.
'71 CB500/550, '72 CB450, '79 RD400 Daytona, '90 FZR600R

Offline edbikerii

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Re: Cleaning leaking fork seals
« Reply #1 on: April 08, 2008, 08:13:33 am »
I tried cleaning a leaky fork seal last night, but I had no luck.  First of all, I couldn't get a business card down inside the seal without it bending and then ripping.  So, I switched to a thin piece of plastic I cut from a blister pack package to roughly the same shape as the "seal mate".  Still no way to get that plastic down between the seal and the fork tube.

I replaced the stock fork seals with "LeakProof" brand fork seals several years ago, so perhaps there is some difference in this brand?  They seem to be VERY tight against the fork tubes.  Maybe tighter than stock?  Also, I'm thinking that maybe this task needs to be done when it is 90 degrees outside and the seals are very soft and pliable.

In any event, I pulled the circlip, and the metal washer that covers the seal, and cleaned up all of the gunk that was in there, and I thoroughly cleaned out the surface of the seal, which was very cruddy, and I'm hoping that this is enough to see an improvement.
SOHC4 #289
1977 CB550K - SOLD
1986 GL1200I - SOLD
2004 BMW R1150R

Jetting: http://forums.sohc4.net/index.php?topic=20869.msg258435#msg258435
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