Changing fork seals

A load of posts that show you how to do various projects, step by step.
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Hooli
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Joined: Thu Feb 19, 2009 11:52 pm
Location: Doncaster

Changing fork seals

Unread post by Hooli » Sun May 16, 2010 12:08 am

This was done on a modern Suzuki with adjustable forks but most older bikes are much the same, just easier as they have less bits.

Right then boys & girls are we sitting comfy?
Then we'll begin.


Once upon a time Mr Suzuki fitted seals that kept the oil in your forks. Over time nasty gremlins like dirt and useage made these seals fail. So now the nice Mr Hooli will give you a few tips to fix this.

I might have missed bits out here but I think I've covered all the important stuff.

Firstly lift the front of your bike up thus
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Then remove the brake callipers along with the mudguard bolts. Put the callipers out of the way, on top of the engine is ideal. Plus remove the front wheel of course.
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When you undo the mudguard bolts try not to loose the metal bits inside the guard, they should be clipped in but mine have broken free. They look like this.
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Next undo the pinch bolt on the top yoke.
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Followed by loosening the fork cap. You might need to take the bars off to get a socket on this if it's not been done for a while.
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Next undo the bottom yoke clamp bolts.
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Then slide the forks out, you'll need the bike high enough for this. This pic is the best I could do to show how much higher you need it. Oddly enough, the height you need is the distance between the top of the top yoke & the bottom of the bottom yoke.
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Once the forks are out remove the cap. It'll pull out a few inches and stop as it's screwed onto the damper rod. You need to hold this nut & unscrew preload part of the fork cap to remove it.
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Once the cap is off, remove the nut too. Then you can lift out the guts of the fork in the following order, washer, spacer, washer and spring. Later 14s don't have the spacer so probably only one washer. I lay these out in order so I can't do anything silly putting them back. Don't forget to push the threaded rod down into the fork & lift the damper tube out from inside it. If you don't it'll fall out on the next step.
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Turning the fork over will tip the old oil out and reveal the bolt that holds the damper in, this is it after removing the pinch bolts in the bottom of the fork.
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Using your specially crafted fork tool poked down over the hollow threaded rod hold the damper unit still when you undo the bolt in the bottom of the fork. I cut the end off an allen key to put into the bolt with a socket on the end. Once that bolt is out you can lift the damper unit out of the fork.
Next lever out the dust cover covering the fork seal & slide it off. Follow this by removing the spring clip holding the fork seal in. Now the seal is ready to remove. Take hold of both ends of the fork & pull it apart with a sharp tug, within a few jerks the fork should separate. You'll get the fork seal a spring bush & a washer come out. Try not to loose them. The completely stripped forks look something like this.
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Now clean any corrosion off the fork seal seat & where the clip goes etc, your now ready to rebuild the forks.

Start rebuilding your forks by putting the two halves back together. I clamp the bottom of the fork in a portable vice to keep it upright & make life easier when doing this.
First thing to put back is the top bush. That is the sprung bush that fell out when you popped the forks apart. Line it up with it's slot & tap it into place with a blunt screwdriver & hammer or similar.
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Drop the washer that came out with it on top of it. Then lube the new fork seal & slide it down the fork being careful not to tear the sealing lip. This will need drifting in to seat it as well. Finally clip the spring clip back into place.
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Now put the damper unit back in & do up the bolt in the bottom of the fork with a bit of threadlock. Next add the oil, I just add the amount from the manual which is 644ml for K2s. Others prefer to do it with the airgap. Then put the spring, washer, spacer and washer back in. Take care at this point to hold on to the threaded rod or it'll slide down inside the fork. Put the nut back onto the threaded rod & make sure it's top face is exactly 11mm from the top of the rod. This is important to set the base settings for the fork.
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Put the thinner tube back into the threaded rod & screw the fork cap back on. Then screw the cap into the top of the fork, you will need to compress the spring slightly inorder to do this.
Putting the forks back into the bike is reversal of removal as Haynes loves to say. Just remember to nip up the fork cap before doing up the top yoke pinch bolt.
Classics ain't built in Metric

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