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Fork Cap Seized

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I have an '83 XL600R, second owner, spic-n-span bike. Need to change the fork fluid, but I can't get the right side fork cap (bolt) to break loose. I've loosened the top pinch bolts, even spread the clamps a bit to ensure they weren't binding on top of the fork leg. Slathered PB Blaster all over the top of the fork, making sure it gets into the crevice around the cap bolt. It's pretty obvious that the forks have never been apart.

All I've managed to do is hideously mangle and round off the head of the bolt.

Any ideas on how to get this puppy to break free? The left side came loose very easy.

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Have you tried the ole' hammer and chisel trick? Or if you have an air chisel.. or air hammer i forget which its called :)

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Have not. The fork is still on the bike at this point. I have tried the six-point and 12-point sockets of appropriate size and the vice grip and hammer technique. The top bolt is also the air valve and is made of pretty soft aluminum.

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Have not. The fork is still on the bike at this point. I have tried the six-point and 12-point sockets of appropriate size and the vice grip and hammer technique. The top bolt is also the air valve and is made of pretty soft aluminum.

Hmm.. Have you tried totally breaking it off then buying a newone?

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I assume the top cap is like a 50mm (approx) socket?

some caps are rounded, some are like an octagon.

if yours is an octagon, and the sides are still good, put it upside in a clamp, with just the cap in the clamp, very tight, make sure its perfectly squared up too. you might need 2, maybe 3 or 4 guys. and twist the tube off with your hands as hard as you all can. thats the way ive always gotten seized fork caps off. works every time.

or put it in the triple clamp, tighten the pinch bolts, and spin it off with a pair of vice grips. I would use the clamp method first though.

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I assume the top cap is like a 50mm (approx) socket?

some caps are rounded, some are like an octagon.

if yours is an octagon, and the sides are still good, put it upside in a clamp, with just the cap in the clamp, very tight, make sure its perfectly squared up too. you might need 2, maybe 3 or 4 guys. and twist the tube off with your hands as hard as you all can. thats the way ive always gotten seized fork caps off. works every time.

or put it in the triple clamp, tighten the pinch bolts, and spin it off with a pair of vice grips. I would use the clamp method first though.

His ideas are better then mine. listen to him :)

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The top is a 17mm socket....or was. Now its pretty much squared-off. But even at 17mm, its not very thick. And the fact that its an air valve (old-fashioned air-assists forks) means that if I squeeze it too hard (or round off the caps much more), then I won't have anything to grab onto.

Other than the valves, the caps are flush with the top of the fork tube.

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The top is a 17mm socket....or was. Now its pretty much squared-off. But even at 17mm, its not very thick. And the fact that its an air valve (old-fashioned air-assists forks) means that if I squeeze it too hard (or round off the caps much more), then I won't have anything to grab onto.

Other than the valves, the caps are flush with the top of the fork tube.

oh, are you talking about cartridge type forks?

I think you are, dual chamber werent around till like 97-2000 or something.

you say the tubes are flush with the fork tube, why not try this, it has worked for me too.

put the fork tube into the triple clamps like they normally sit. then loosen all 4 bolts and let the fork tube slide down about an inch and a half, what you want to do is tighten the bottom (bottom bolt also, then top one, then bottom again, its important that your last toruqed bolt is the bottom) of the upper triple clamp just around the cap, not the fork tube. theres only aout 1/8 of an inch that you get to put in the triple clamp. if you can tighten it tight enough around the cap youre good to go. just get a few friends and torque on the tube, or do it yourself if you have the strength of superman.

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You say the fork is still on the bike. I assume the triples are still tight. Loosen the pinch bolts on the upper triple. Obviously the lower must be tight to hold the fork.

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I had a really hard time getting the caps off on my xr400. I thought I was in trouble when I rounded the caps with a 16 point socket. To get mine off I took a file and clean up the edges of the cap that I had rounded. Then went out and got a good quality 6 point socket so it would put pressure on all sides of the nut not just the corners. I borrowed an air compressor and a big impact wrench from a friend and that took it right off.

Hope that helps and good luck.

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I had a really hard time getting the caps off on my xr400. I thought I was in trouble when I rounded the caps with a 16 point socket. To get mine off I took a file and clean up the edges of the cap that I had rounded. Then went out and got a good quality 6 point socket so it would put pressure on all sides of the nut not just the corners. I borrowed an air compressor and a big impact wrench from a friend and that took it right off.

Hope that helps and good luck.

Best idea, also loosen the top triple clamp bolts

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I had a really hard time getting the caps off on my xr400. I thought I was in trouble when I rounded the caps with a 16 point socket. To get mine off I took a file and clean up the edges of the cap that I had rounded. Then went out and got a good quality 6 point socket so it would put pressure on all sides of the nut not just the corners. I borrowed an air compressor and a big impact wrench from a friend and that took it right off.

Hope that helps and good luck.

yeah I was gonna recommend this too, but with an angle grinder not a file.

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I've loosened the top triple clamp bolts....did this before I started the process.

I'm thinking its time to remove the fork tube and stick the head in a vice...see if I can get a grip on it that way. There isn't enough of the head left in socet form to get a 6 or 12-point on it.

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I've loosened the top triple clamp bolts....did this before I started the process.

I'm thinking its time to remove the fork tube and stick the head in a vice...see if I can get a grip on it that way. There isn't enough of the head left in socet form to get a 6 or 12-point on it.

why would you wanna loosen the top triple clamp bolts? now im confused.

just remove the fork from the bike, put it upside down in a clamp like I mentioned earlier.

or an easier/quicker way, if it can be done, it use the bottom part of the upper triple clamp to act as a clamp on the fork tube cap. some forks it works on (honda, yamaha) some it doesnt (suzuki) (I also mentioned this earlier with a better explanation)

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The top clamps 'clamp' directly on the area surrounding the cap. (caps and top of the fork fit flush in the top clamp). If you don't loosen the top screws, you WON'T be able to get these caps off. It at least tells you that much in the service manual.

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The top clamps 'clamp' directly on the area surrounding the cap. (caps and top of the fork fit flush in the top clamp). If you don't loosen the top screws, you WON'T be able to get these caps off. It at least tells you that much in the service manual.

you mean the crack between the cap and top of the outer tube is under the triple clamp? in that case just loosen the upper clamp, let it slide down until NONE of the fork tube is in he upper clamp, but the fork cap still is. use the triple clamp as a vice. it will work.

either way it shouldnt be this hard to figure out how to take a fork tube out of the triple clamp and take its cap off :)

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There is a tool called a strap wrench. Go to your local hardware store, Sears tool Center, Or Home depot. They should be less than twenty dollars.

Sounds like you've already destroyed the cap anyway, so do the upside down in a vice method. The strap wrench will easily grip the fork leg, and turn it, leaving the cap in the vice jaws. (You won't need four buddies!) It absolutely will not crush the fork tube, or even mar it in any way. Just be ready for all that oil thats gonna come out of that upside down tube. Just break the cap loose, and then invert the tube before it rains down all over the floor. Then you should be able to take the cap off the rest of the way by hand. The next step would be to order a new cap. When you put it back together, put some antisieze compound on the threads to keep it from corroding and being so hard to remove the next time. The antisieze compound is available at Autozone, Pepboys, or any hardware store.

Problem solved

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ust be ready for all that oil thats gonna come out of that upside down tube. Just break the cap loose, and then invert the tube before it rains down all over the floor.

yeah only put it in the clamp to crack it, or do 1 revolution max in the clamp. the rest you can do with your hands the proper way up. it wont stat to leak oil until you have done about 5 revolutions.

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Got it off last night!! I put the fork tube in a padded vice and put a pair of vise-grips around the 1/16" of the cap that was showing above the fork tube. Then whacked the crap out of the vise-grip with a small sledge hammer. When it finally broke loose, you could see white powder where the aluminum had oxidized. That cap had never been off, and didn't want to come off in the first place! New cap has been ordered (let's hope it's availalbe, like HDL says!).

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