The old ones were replaced by a mechanic a few years ago, they have the brand name Leak-Proof. They should be named "Leak-for-Sure", the rubber isn't a great quality, the design is generic (added a washer over the seal to my setup, which we ended up discarding), and it was easy to see how they'd started leaking within six months of being installed and slowly getting worse over time. They're *awful*.
I ordered genuine Suzuki fork seals from BikeBandit. They're works of art compared to the Leak-Proof seals. Under normal circumstances, you only need the seals themselves, and new fork oil.
I used Maxima 20 weight fork oil, next time I'll use 15 weight. The actual viscosities and oil quality *are not* the same between fork oil makers; I'll post the chart if I find it. ATF is apparently similarly uncontrolled.
Set aside some time for the repair. I'd say at least four hours if you're slow like me. Get a friend to help if you can, four hands and an extra set of eyes make many things easier.
I held the front up with a big cinderblock and a piece of two-by-four under the exhaust headers under the engine. Remove the front brake calipers, I held them up with a bungee cord over the front end of the tank so they didn't hang by the brake lines, which is bad. Remove the front fender, front wheel, then remove the forks. With my particular bike, there's an air inlet on the top of each fork tube. I let the air out.
Have an oil catch pan nearby. Remove the dust covers on the top of the outer fork tubes. Remove the top of the fork by unscrewing it. We found a wrench that would get around the straight sides of the air-inlet fork caps (over a cloth so as not to mar the paint). Remove the cap being careful to have the oil pan nearby, because right when you get the cap off, you're going to want to get all the fork oil into the pan -- right when it releases the cap will try to go flying. Pour out all the old fork oil, pump the tubes a few times to work it out. Remove the snap ring over the seal.
Clymer's says you have to disassemble the fork tubes to take the seals out. They're wrong. Get a pick-and-hook set from Sears ($7). Push a pick into the seal (not all the way through!) and wedge it out. Don't throw it away, because you'll use it to drive the new seal into place. On the 37mm forks on my 1100GL, a piece of PVC (i forget the size..) fit perfectly, so we took a piece about 2' long and slid it over the fork inner tube and hit it with a mini-sledgehammer to drive the old seal on top of the new seal to get the new seal seated. (Make sure you clean the PVC pipe of dust, shavings, etc!) We had to go the pick-and-hook route because one of the drain bolts at the bottom (which also holds the damper rod in place) stripped out when we were trying to remove it... doh!
The Clymer manual has a table of fork oil measurements that include how many cc's should go in, or the better method we found, of how far from the top of the inner tube with the tube pushed all the way down. First pour in enough oil to cover the damping rod down in the bottom of the inner fork tube. Then pump the fork for a while, to get air out of the system. Then slowly add oil until it reaches the measured distance down the tube. We used the beginning of a regular 25' tape measure for this, just use it like a dipstick.
My bike handles MUCH better now, though the forks are a little stiff. I haven't added any air to the forks just yet, but I'll try and see what happens.
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