Sooner or later it happens. You get back from a nice ride, climb off the bike, start to walk away, look back (we always look back, don’t we?) and bam! You notice the oily mess all over the front forks and a good part of the exhaust, the front of the engine and other places even harder to clean off later. Friggin’ leaky fork seals!

You spend quite a while scratching your head and wondering what happened. The seals were fine the last time you rode… as you recall, anyway. Baggers make it more of a chore to get to the bottom of the mystery, since A) the tin cowbells that cover the tubes are supposed to prevent leaks by protecting the tubes from crud and corrosion and B) you gotta get the bike up off the deck and drop the fork legs a little… just to see what’s causing the leak(s). The naked forks guys can check out easily and even a pair of rubber fork boots ain’t much of a hurdle to getting a visual on the seals and tubes. Anyway, once you have a visual, you wipe the fork oil off the tubes, look closely… yeah, dang nab it, they are a lot more crusted up than you thought. Even so, not nearly enough to rip the seal lips up… eh? Get the Q-tips and the cleaning rags so you can start eyeballin’ those seals next. To do that, you need to pop the dust wipers up with a screwdriver (and appropriate caution) so any tears or rips in the seal lip can be subjected to serious scrutiny. Still can’t see anything to account for the gusher that was once an oil-tight working relationship between those seals and those tubes… damn!

Tools to fix motorcycle fork seal

Caption: Among others, these are the basic tools required to dress down and smooth out any zits, protrusions, rusty sticky-outie thingys (whatever you wanna call ’em) to a “level” acceptable to the lip of a fork seal. The ones not pictured are patience and finesse supplied by the tool wielder. Start with Scotch-Brite pads to separate the crud from the metal, and once the crud is scrubbed off, you can use the whetstone edges to gently round off the sharp tips that love to snag on a fork seal’s working surface. Sandpaper (in increasingly finer grits) will serve to smooth and blend as a finishing touch, if needed. Just be aware you don’t want to install any flat spots in the tube, so go easy.

What makes that lack of clear evidence even more irritating is that you’ve already thought about the expense and “agro” involved in pulling the whole front end apart to replace two lousy little round rubber doo-hickeys. It ain’t cheap, quick or easy, even if you decide do it yourself, which you probably won’t if you can pay someone—like a dealer or repair shop—because it just isn’t a fun job. Gets even worse if you decide the crud and crap stuck to the tubes are liable to mean new seals won’t stay sealed very long. New tubes about double the expense, but you’re thinking that might be the only way to guarantee you don’t have to do this crap job over anytime soon… right?

Well, guys with springer front ends have already turned to another page with girls and tattoos… so the rest of us can kinda protect our precious emergency plastic cards (and quit cryin’ in our beer) once I let you in on a little secret. OK, maybe not a big secret, but a neat trick, for sure. See, the thing is, over 80 percent of the time (some say 90 percent), a leak from the forks does not mandate a seal replacement. What it does mean is that you need to get the grit and crud cleaned out of ’em instead. Fine, you say, but just exactly how do you go about that little task?

Seal Mate fork seal toolCaption: As far as I’m concerned this Seal Mate tool is the great enabler. Meaning it enables us mere mortals to fix leaky fork seals without the hassle, expense and effort required to replace the seals. Believe it: this cleaning tool does the trick more often than not in about five minutes for about five bucks!

The five-dollar fix
Actually, to make this work requires some additional supplies, but even with a trip to the store and all, the whole exercise shouldn’t involve more than $25 and somewhere between 10 minutes and two hours of your time. Even though old dirtbags like me have been using things like 35mm film, or 0.004″ feeler gauge blades, or even a cut-up plastic bottle or old aluminum can, the whole process (as always) goes a lot better, smoother and quicker with the proper tool. In this case, the tool is called a Seal Mate and you can get one from anyone who sells Motion Pro products… although for our purposes that tool isn’t the whole story… not even close!

Loctite Super Glue

Caption: Filling in the pits can be done with epoxy (JB Weld comes to mind) for tubes that are absolutely cratered (and/or unobtainable as new replacements), but 95 percent of the time it’s better to use something that won’t ugly-up the tube and will work fine on the more typical smaller depressions in the hard chrome. Apply in “toothpick dabs” to the center of every pit and wait until dry to check for the need of a second application. Once the dried filler of choice (Super Glue Gel and/or fingernail polish are mine) is just slightly rounded up and out a bit from the tube surface, then (see step one above) work the surface back flush with the tube so it’s as smooth as possible.

The story really begins with the working surface of a fork tube. Specifically, how clean and smooth it is… or you can keep it or make it. Most likely, you clean and wax your fork tubes more regularly than I do. Well, it isn’t often enough! There’s also the “oily rag” treatment… carried with you and applied both before and at the end of any long, dusty, wet or generally dirty ride… routinely. The point is, fork tubes can’t ever be too clean. Especially when it comes to keeping fork seals happy. Just in case you rode the bike to check and just got back with bad news about the surface condition of your own tubes, there might be a way to bring ’em up to snuff again.

Zits and pits
There is nothing that will help you decide what to do next other than human hands or old pantyhose. (Stop laughing… it’s true!) Quite simply, you need to head back out to the bike with both… and slide ’em lightly up and down the fork tubes. Anything that snags the nylon or feels rough to fingers or palms fails the “the oil seals feel it too” test and has got to go away. If you recall much about the nature of industrial chrome, such as what’s used on fork tubes, you know from day one there are microscopic pores involved in the smoothest of plated surfaces, every one of ’em just waiting to let dust, dirt and worse, moisture, into the metal. Neglect, age and usage allows this “characteristic” to become a real issue… real easy. Once it affects the tubes it will require a little finesse and a lot of elbow grease to put right—presuming you don’t wanna buy new fork tubes all the time.

First determine whether the blemishes in the afflicted tube(s) project out (like zits) or are sunken-in pits.

Seal Mate fork seal tool

Caption: Although not recommended, rather than try to pull up the dust seal you can, in fact, get the Seal Mate down past it into the oil seal… like this. Couple laps around the tube using both hands and a fair bit of jigglin’ and wrigglin’ will scrape the crap, crud and craziness outta there quite effectively. Once the rubber doesn’t have any grit or dirt in the way, the seal once again works just fine! You’d be amazed at how little of that stuff it takes to keep the seal from being able to wrap itself around the fork tube properly.

Pits can be plenty counter-intuitive, but by and large you are going to have to fill them in with something that can be counted on to stay put and stay smooth. Lots of folks have had success with epoxy “metals” like JB Weld, but I’m not a fan. Firstly, it looks like you patched a tube! Secondly, getting it mixed to a consistency that fills in the pit nicely yet doesn’t fall back out during the smoothing process that comes after ain’t that easy. For most of us, something a little more cosmetically acceptable and easier to apply is in order. Some proven choices are Super Glue and nail polish… both clear. (Remember we’re talkin’ pits, not craters.) Apply just enough for it to barely stand proud of the tube surface. You might have to apply (your choice of) product a few times, but be certain to allow plenty of time for it to dry and cure, because afterwards the little bulge it leaves will be treated like a zit.

If pits need to be built up to the same level as the tube, it follows that zits need leveling down to that same level. All this to fake the seals out and (pardon the expression) keep their lips sealed. Buffing zits down is probably best done by using the edges—not the flats—of a whetstone, very lightly applied. Seems easier to detect the zits that way and, once done, they can be knocked down level and smooth… gingerly, always using fork oil or penetrating oil as lube. Others have had good luck with 600, 800, 1000-grit sandpaper, rubbing only up and down the length of the tube in a kind of narrow-angle “cross-hatch” pattern. The objective is for the tube to pass the nylon/skin test and it might take a while so don’t push it too hard… literally. Best to let the whetstone or sandpaper do most of the hard work.

 Zits, pits and lips

Caption: Since 35mm film rolls are getting rare, other alternatives like the ones shown here and tin cans (which aren’t) can be pressed into service (less successfully than the Seal Mate) in dire, roadside emergencies. However, every alternative (except a feeler gauge which has rounded edges, anyway) needs to be cut up and shaped like the Seal Mate (particularly the hook part) to work worth a damn. Probably better to carry the Seal Mate with ya. Just sayin’!

A Mate for life
Once satisfied that the tubes are round, straight, repaired, cleaned, smooth, waxed and oiled, clean the area around the seal with a rag and/or Q-tip. Now, you’re ready to use the Seal Mate tool (or if you like living dangerously, a dirtbag facsimile) mentioned earlier. Since the Seal Mate only costs about five bucks, you know which I’d choose! Using the tool is pretty straightforward. The official instructions tell you to remove the dust boot with a flat-tip screwdriver, but if you’ve looked at a bare Harley fork lately, and you’re as lazy as I am, you can sneak the tool past the boot and into the seal without any real difficulty. There should be a photo nearby showing exactly this… and that the tool is sunk in to nearly the first letter of the logo, to get completely between the seal and tube. Inserting the tool via the rounded lower edge and a little wriggling, you then rotate it until it is parallel to the tube. Using both hands, you keep wriggling all the way around the tube a couple of times, always moving in the same direction as the “hook.” Pull the tool out gently and look at the hook; it’s almost bound to have gook and grit you never imagined all over it. Even if you don’t see much, you moved what was there off the seal lip. So wipe the tool clean, go at it once more and call it good. Then get on board the sled and pump the forks up and down, vigorously, at least a dozen times. You’ll see oil on the tubes again… but don’t panic. It’s just the seal lip re-establishing full contact with the tube. Wipe the oil off and pump the forks again. That should be it! No leaks and no squeaks… for little money and less time! Performing the Seal Mate ritual every riding season (which the dirt bike guys have done for years after every ride) will keep those seals working practically forever—as long as fork tube cleaning is a much more frequent part of your maintenance routine.



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