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How Do You Replace The Fork Seals On Usd Forks


beta boy
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im giving my bike a service before the trials season starts and one of the things i need to do is change the fork seals. i have a 95 techno and it has usd forks i have unscrewed the caps off the tops and dranied the oil but where do i go from there i the sliders wont come out so i cant get the dust seals off which means i cant get to the clips to take the seals out

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This is not specific info to the Beta forks, but works for USD forks in general.

You need to remove the damper assembly (internals) from the fork. To do this, you have to remove the base valve or bolt that is in the bottom of the leg (down by the axle clamp.) This is done externally, using an air impact wrench.

Once the bolt or base valve is removed from the bottom, the internals will come out and you will be able to separate the inner and outer tubes.

Don't forget to remove the clip holding in the seal or you risk damaging the outer tubes.

Hope this helps.

Rob

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Beta Boy. I had the same predicament last year on my ole 95 Techno. I called Commo's in the US to ask for assistance in how to take them apart. I got told that "If I didn't know how to do it, then I shouldn't attempt splitting them". So back to the bench for another night of pulling my hair out, but, eventually worked it out.

1st) Drain the oil out of the forks.

2nd) Remove the forks & put them in a vice (just easier then chasing them all over the work bench).

3rd) Pry off the dust cover with a small screwdriver. inside you'll see a circlip (ringclip) take that out & pull apart.

You might still get some resistance but its just spacers & bushings, keep sliding the piston out & remember which way everything sits before pulling it all apart. Hope this helps.

Taff

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Just replaced seals in an old TL125 a few months ago and it was basically the same process. I had to apply heat with a propane torch to get the seals out. They have a steel cup made on them that presses in. I heated the outside of the forks lightly and they came right out. Used a small pry bar to get them out being careful no the scratch or bend anything. Used a big socket that was the same diameter as the seal and tapped the new seals in. No leaks and it took about 45 min. to strip, clean, put in seals, fork oil and go for a ride.

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does it have a snap ring in there holding the seals in? Or is it a simple wire ring with no ends to grab onto?

Y175 used a wire ring with tapered ends. If the ends rusted, there was no way to grab the ring. I measured down from the top (or bottom in your case) of the slider and drilled a 3/32 hole into the slider from outside to intersect with the wire ring. Then I could push a pin punch through that hole and push the wire ring ends inward, snag behind with a thin screwdriver, and get them out. Lots of grease when reasemby. I think I repalced the wire rings with snap rings, can't recall.

k

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The TL dust deals were just pressed on and once I got a small flat screwdriver blade between the seal and the fork I just twisted it and the cover started to come off. It was on there tighter than I expected but a few gentle taps on the screw driver with a hammer should wedge the tip in there. My friend has a Aprilia with USD forks and we changed out his seals the same way. The only other thing I can think of is that the dust seals on one of our z50's screw on. May check that as well.

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right i got the dust seals off removed the clip tugged and the seal and bushes came out there is a silver washer and copper bearing and another big wide clip at the top but how do you get the seals in with a socket if you have to have them on the slider when you put them in

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  • 2 weeks later...

Beta Boy: Good job getting them this far apart without a manual. If you haven't taken them to a bike shop et, this might be a good time to do it. The Commos are right this shouldn't be done by the faint of heart or wallet. You can easily ruin the epensive parts and be out of a bike to ride for want of some obscure Paioli piece. In answer to the question of reinstalling the seal. Take all the washers, bushings etc. off the fork and use masking tape to cover any sharp edges, the pack the seal spring with grease or petroleum jelly. Install the seal onto the fork tube then put the washers, bushing etc all back on the fork tube as they were. Put the fork tube back into the slider and secure it with it's retaining bolt if there is one. The hard part is to build or buy a fork seal installer. It should be comprised of two halves of tube the size that just fits onto the fork tube, has enough surface area to not ruin the seal and will fit down into the slider openings without damage. It took me five hours to fab seal intaller "colletts" which I use to tap the washer and bushing down into the slider 'til it's seated. They have to be held solidly together with hose clamps for the pounding in of the bushing, and then the seal. Next tap the seal down into the seal housing. Problem is you have to support the seal housing with a vise and some rags to prevent it from going away from the seal as you tap it in. This will damage the seal housing very easily so you must use great care! Lastly intall the sap ring and the dust seal. The oil quantity is different from side to side and should be in your manual. I don't recall what it is. Good luck you poor bugger! Jay

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BETA BOY BE CAREFUL WITH THOSE FORKS. SOUNDS LIKE A JOB FOR A PROFFESIONAL MECHANIC WHO KNOWS WHAT THEY ARE DOING. IT MAY COST YOU A LOT OF MONEY AND TIME IF YOU CARRY ON TRYING TO TO DO THEM YOURSELF.ALSO NOT TO MENTION THE TIME YOUR BIKE MIGHT BE OUT OF ACTION IF THOSE SEALS STILL LEAK ONCE YOU GET IT ALL BACK TOGETHETR . ANYWAY GOOD LUCK :)

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Good choice B.B.

As Jay says if you don't know what you're doing best seek professional advice/assistance.

I replaced my fork seals exactly how Terry explained. With a 1 1/2" pvc pipe.

My question to the commo's was exactly the same as yours Beta boy (as I also didn't have a manual & the first time changing USD forks), "How do you get the dust covers out without wrecking them?".

I guess a licenced HD mechanic shouldn't be asking for advice cause I should know it eh?

Taff

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