By Joe Gresh
I have two motorcycles with upside down forks. Both of these motorcycles have leaking fork seals. Coincidence? I think not. I have no love for USD forks and one of the reasons I wanted a Buell Cyclone was the conventional forks those bikes came with.
Alas, I ended up with a Thunderstorm, which is mostly the same as a Cyclone except for the forks. Mine were leaking, which is not unexpected for a 30-year-old motorcycle.
New fork seals were kind of hard to find. I tried contacting the OEM manufacturer, White Power (that name didn’t age well), but I got no response. Through the wonder of the internet, I found a company in England that had the seals.
The seals were reasonably priced at $14 per set, but the shipping was expensive. I bought three sets since the shipping was the same. Now I have enough Buell S2 fork seals for the rest of my life. On a side note: a week after the seals were delivered FedEx sent me a $20 invoice for “fees.” I haven’t paid the fee yet; I’m not sure, it may be a scam. The fees may be re-named tariffs.
The Buell has a large front disc. To remove the wheel, you have to remove the brake caliper. To remove the brake caliper, you have to remove the brake pads and then retract all six of the caliper pistons back inside their respective bores.
The old Performance Machine brake caliper pistons were pretty crusty, and I didn’t want to push all that mess across the bore seals into the caliper. Removing the brake disc from the wheel allowed enough wiggle room to get things apart.
The WP forks were super tight in the triple clamps. I used a wedge to expand the fork tube bores and still it was a struggle to slide the forks out. Once out, disassembly was fairly straightforward (although oily) experience.
You’ll need to make a seal installer to press the new seals into the forks. I made mine from PVC tubing in the hope of avoiding scratching the sliders. The new seals fit well, and the hardest part was compressing the fork spring while holding the damper rod up with a bent wire and using a third hand fitting the damper rod spring keepers. My Buell shop manual describes this process as a two-man job. And it really is.
It took a couple days to figure out how to one-man a two-man job. I ended up employing an oxy-acetylene welding cart as a prop to hold the fork. The T-handle on the cart was in a convenient location and height to loop the damper-rod holding wire over and I still had two hands free to compress the spring and slip in the keepers.
The Buell manual called for 7-1/2 weight fork oil. I should have ordered fork oil online, but I didn’t, so I called around and the local Honda shop had some. It’s a 20-mile drive to the Honda shop. The Honda fork oil bottles are confusingly labeled. What looks like 7 weight ended up being 5 weight, but I wanted to get the front end put back together. So I poured a pint of 5 weight into each fork leg. Stay tuned for a follow up report if I can feel any difference between 5 and 7 weight fork oil.
While the forks were off, I re-greased the steering head bearings. They still had a little grease remaining but thinly applied. I walked out the old stuff and smooshed in fresh grease. That left just the front caliper to clean up.
The caliper came apart easily, but the pistons did not. I used to have a big pair of reverse pliers (the jaws expand rather than close when the handles are squeezed). I would use these pliers to grab inside the hollow pistons and pull them out of the caliper. I would, that is, if I could find them. I spent a few hours looking for the pliers and finally gave up.
A snap ring Oliver was pressed into service and I managed to get all six pistons out. Performance Machine uses chromed steel pistons and the bit of piston that was exposed to the elements had corroded. Finding new pistons would be an impossible task and a new caliper would cost $600, so I polished the corroded pistons on the buffing wheel.
I’ve had good luck piston polishing. Yes, they re-corrode, but the section of piston covered with brake fluid doesn’t corrode. I look at it as an ongoing maintenance item rather than a bad part. You’ll have to wait for new brake pads to arrive to see if the caliper leaks in Buell Fever Part 7.
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Sadly, I sold my Sportster this summer and am without a bike for the first time in decades. I love these articles and especially the honest explanation of the kinds of mistakes and homemade engineering we all have experienced. Great job!
Craig,
Time to buy another Sportster. Prices are way down. Buells are even cheaper.
Very interesting read Joe. I love the “fixit with what you got” ideas and attitude. Welding cart third hand ,who woulda thought!
Fun to read, but how does the different piston sizes in the caliper distribute the wear evenly? I can’t grasp that concept with my feeble old mind.
The different size pistons apply different pressures. Larger= more squeeze, smaller= less pressure.
If they were all the same I think the leading edge of the pad would wear out first.
Very educational! I replaced the fork seals on my’97 Honda Valkyrie one winter.
I put wheel bearing grease in the concave cuvy,they never leaked again! I can relate to your methods,very innovative 😉
I’ll try that next time. Because they will leak again.