Tech Tips: Replacing Fork Seals 1

Maybe you just noticed a bit of oil weeping dow your fork tubes, or the puddle underneath the front wheel in the garage, either way it's time to replace your fork seals! Get some hands on examples and tips from some of the best in the business, Race Tech, along with finding out what you need to get the job done.

Remember, if you need to get your hands on some new seals, suspension tools, and other related parts; hit up

For any other motorcycle parts, accessories, or gear needs, you can find them at

Transcribed version:

Michael Lindsay: "Hey, this is Michael Lindsay from Vital MX. We're here at Chaparral Motorsports today. The last time that you joined us, we had Josh from Race Tech helping us clean a set of fork seals. If they're still leaking, today, we're going to show you how to replace them."

RaceTech employee: "So a couple of tools you're going to need will be a 50-millimeter octagon wrench for your cat, a regular flat-blade screwdriver, 21-millimeter socket, 17-millimeter open-end wrench, and another thing you will need is a seal driver. These are 48-millimeter forks, so you're going to need one of those too. The first step you're going to want to do is [count clickers]. From here, you're going to loosen the cap, drain the oil. It doesn't need to be completely empty, because you're going to be tearing the whole fork apart anyway and you'll be able to clean all the dirty oil out from there. 

Now that we have the fork in the vice, we can loosen the bottom bolt with a 21-millimeter socket. Now that that's loosened, this fork, we can bottom mount already. You're going to take your 17-millimeter open-end wrench and separate these two from the locknuts. So from here, now that your cartridge is out from the foot, you can go ahead and slide this all the way out. We can go ahead and clean off all the dirty oil with contact cleaner. If you have an air hose or an air gun, you could clean it up right now too, or just a clean rag will do. 

Go ahead and set that aside on your bench. The next step will be to separate your inner and outer tube. All right. So from here, you're going to separate your dust seal from your outer tube with a flat-blade screwdriver or one of our clip tools. Be careful not to nick the tube or anything like that, or damage anything. There will be a clip inside of this tube now, before you slide hammer them apart. You're going to want to get that out before you do anything else, because you'll never get the fork tubes apart anyway. Now that that's out, we're ready to slide hammer these fork tubes apart. 

So when you're slide hammering the tubes apart, don't be afraid to throw some force into it. All right. So from here, you can slide your dust seal down. Your clip is still on there. Here's your oil seal, your vacuum washer, your outer bushing, and then your inner bushing will be up top. We can go ahead and take this off now. So you want to look for punctures, debris in it. Make sure there's no aluminum or any debris, because you do not want that in your fork. Now, we have our outer bushing. The same thing, now it's going to be on the inside of it. You're going to want to inspect all the Teflon and make sure it's in good shape. 

I know some people will look on the outside. That's not going to matter. Your main concern is how is this Teflon the shape of it? On this one too, it looks great. So we'll reuse that one. Then, you have your washer. Because we're replacing these seals, I'm not worried about tearing them on the outside. From here, you're going to want to inspect your tubes. If these are chrome, it's going to be chrome. These are DLC-coated, so you're going to want to look for any fading in the coating. You're looking for nicks, just in case that's what was causing your seal to leak. 

So now that we have our new dust and oil seals out of the package, we will need to put a little bit of assembly grease. You're only going to need a little bit on your dust seal and your oil seal. On your dust seal, never over-grease them, because grease is going to attract dirt more than anything. Now that your seals are greased and ready to go back onto your tube, be aware that there are two share edges on your inner tube. You can use a fork bullet. You could also use a plastic baggie. I do not use anything, because of how I rock the seal around, if you are just gentle, and you can go ahead and slide that down. Now, your oil seal is next. This oil seal will not have a lip to it, and there's a wrong and right way of how this is going to go on. If you can see here, there is a cup on this side and there is none on this side. It's just a spring. The spring will go down, away from the tube or away from the top. The same thing, you want to be very gentle, because this is a brand-new seal and you do not want to cut it. The same thing, just rock it around that lip and slide it down. Next will be your vacuum washer. Your next step will be your outer bushing, or your slider bushing. Then, your inner bushing will be next. 

I like to kind of get them to pinch a little bit more. When you were taking them off, you kind of bent them. So from here, we can put our tube back into the outer, and I will let my outer bushing and my washer slide down. So when I'm slide hammering my outer bushing, I am doing it one step at a time. First, your outer bushing has got to get slide hammered together, and then your oil seal. You cannot do them all at once, because you will never know if your outer bushing is seated correctly or not. A lot of times, it will be seated incorrectly and it'll be crooked, later causing premature wear or damage to your inner tube. 

So we can go ahead and there's a distinct sound when it's seated. Now that your outer bushing is seated correctly, you're going to want to slide your oil seal down. From here, we can slide hammer this together too. The same sound, it's got to be very distinct when it's seated. So next, you're going to have your clip. We can go ahead and slide that over your tube. I'll work it around, and then use your clip tool to later seat it correctly into its clip groove. You're going to want to make sure that is in the groove. So inspect it thoroughly. All right. So from here, you can either slide hammer your dust seal the same way, or you can just bring the tubes together and it will go right in. All right. So now that your tubes are both as one again and you have a clean cartridge, we can go ahead and slide it back in. Now, this is the SFS fork on the damper side only. If you have a spring on any Showas or KYBs, twin-chamber forks, this is when your clip tool will come in handy, when you're compressing the spring inside the fork. So for now, we don't need to worry about that. From here, your rebound adjuster rod is going to slide into your damper tube, and go ahead and thread that on too. 

Now, you want to bottom this bolt onto your damper tube. You're going to have a gap in between your jam nut and this bolt. You're going to want to bring that jam nut up to it, instead of the opposite way. That way, we know we're seated correctly and we're going to tighten it correctly too. So once you have that jam nut tight, there is a torque spec on this bolt. Refer to your Owner's Manual for that. All right. So from here, I'll slide my whole assembly up to the fork foot. I'll get a couple threads going. All right. So as with your jam nut, this will have a torque spec as well. Refer to your Owner's Manual on this too. Always put these back together by hand. You never want to impact these in, just because you will cross-thread this bolt. So now that the fork is completely together again, we're going to be putting oil in the outer chamber. On this fork, in particular, we're going to be putting 310 cc's of oil. From here, we can loosen your cap from your outer tube, slide that down, and we can go ahead and fill this up with your oil now. 

Know because there's no bleeding on the outer chamber, you're basically filling up an air pocket. The bleeding would be if we were to go into the cartridge. Cool. We can bring this tube back up, get the thread started, go ahead and throw your fork into the vice, right where your bottom clamp would be, and from here we can go ahead and tighten this down. Again, there's going to be a spec on this. Refer to your Owner's Manual for that. Now that your fork is back together, go ahead and set all your clickers, your compression and rebound back to your previous setting. Thanks for watching."

Credit: Joe Carlino
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