Fork Seal Replacement

You may need air tools to remove or install this nut as there is no way to hold the inside nut.

The "inside nut" is actually the fork damper tube, and if you carve the end of a broomhandle into the shape of a pyramid, it seems to work pretty well. Just jam it down into the top of the fork damper tube after removing the cap and spring.
Some tubes have a hex on top of them, while others are kinda squished into an oval shape, the ones with a hex on top can sometimes be held with a long (or several short ones) 1/2" drive socket extension.
I have seen both kinds on 750 twins.

Post edited by: steell, at: 2006/08/19 12:18

Here is a tip gents (and the occasional lady)...I just replaced the fork seals on two sets of forks (1978 and 1977 KZ1000A forks, and they are quite different). To hold the inner cylinders motionless to loosen or tighten the lower fork bolt the 1977 Z1000A1 inner cylinder requires a special tool (no longer available) which fits over the top of the inner cylinder. The 1978 Z1000A2 requires a special tool (no longer available) that fits into the inner cylinder

As with other people, I had trouble disassembling the forks and ended up using air tools to loosen the bolts in the bottom of the forks. After I had them loosened, I still needed to hold the inner fork cylinder motionless to finish unscrewing (with hand tools) the bottom fork bolt. To hold the 1978 KZ1000A2 inner cyclinder motionless, I purchased a 3/8" X 36" wooden dowl (Home Depot) and wrapped the end with enough duct tape to make it difficult to force the wrapped end into the top of the inner cylinder. This works to hold the inner cylinder in loosening and tightening the lower fork bolt. The 'broom trick" will not work with 1978 KZ1000 models (the broom cannot hold the top of the inner cylinder motionless)...I can't speak for other models or later years. The 1977 KZ1000A1 forks were a different story. As was mentioned above, the forks also required a special tool to hold the inner cylinder motionless. I tried the 'broom trick' and was able to get one fork apart. However, no matter what I tried (carving, recarving) I couldn't get the second fork apart (= the inner cylinder always spun). Since I had the first fork apart, I was planning on using the inner cylinder as a template and have a machinist make me a socket to fit over the end. But then I had an epiphany...I went to Walmart and bought a 'Gator Grip' socket (3/8" drive with the "universal fit") They were well advertised on the TV a number of years ago and are essentially a large socket filled with pushpins that conform to the shape of the head of the bolt you are trying to remove. The head of the inner cylinder is essentially an odd shaped bolt (two flattened sides). The cost was US$10.00 and I had the forks apart in less than a minute. Add one of these to your tool box

You know, I saw those gator grip sockets on TV once and thought it looked like a great idea. Cant beleive no one thought of that for this kind of job!

I think ill grab one of those before I attempt this

I think I'm surprised this is any kind of mystery to anyone. Every bike I've ever owned has required fork seals to be replaced. A Suzuki GS750 was the worst, but I learned the most.

To avoid the problem of the inner tube spinning while trying to loosen the bottom bolt, and not having air tools, I use an impact driver, clamp the inner tube in a black and decker workmate, and have someone pull on the outer tube to put some tension in between the inner and outer tubes.

To get the nasty bastard old fork seals out, heating the outer tube adjacent to the old fork seal works well by either causing things to loosen up, or if that doesn't work, melting the old fork seal's rubber.

I use the old fork seal to drive in the new one.

Just be sure to have lots of shop rags around because fork oil gets everywhere.

The Haines manual for my KZ is far better at guiding you through this than the Kawasaki manual.

Have some fun.

The easiest way I have found to get the old fork seals out is to heat the top of the tube around the fork seal (I use an acetylene torch) and apply 100 lbs of air pressure to the oil drain hole. I leave the forks in the triple clamps when doing this so the seal don't go flying off into the far reaches of the shop

KZDon wrote:

To avoid the problem of the inner tube spinning while trying to loosen the bottom bolt, and not having air tools, I use an impact driver, clamp the inner tube in a black and decker workmate, and have someone pull on the outer tube to put some tension in between the inner and outer tubes

How do you clamp the inner tube with a B&D workmate?...it is on the inside of and at the bottom of the outer fork tube.:huh: :huh:

Post edited by: Mcdroid, at: 2006/08/20 15:51

Mcdroid wrote:

KZDon wrote:

To avoid the problem of the inner tube spinning while trying to loosen the bottom bolt, and not having air tools, I use an impact driver, clamp the inner tube in a black and decker workmate, and have someone pull on the outer tube to put some tension in between the inner and outer tubes

How do you clamp the inner tube with a B&D workmate?...it is on the inside of and at the bottom of the outer fork tube.:huh: :huh:<br><br>Post edited by: Mcdroid, at: 2006/08/20 15:51

I think he means the top inner tube, you know, the one that gets rust pits and eats seals

Hmm,well im halfway through this ordeal though now confusion strikes...

I have removed the old seal, but am just wondering how I will get the oil back into the forks...

I dont have my camera with me, so here is a diagram of where I am at if anyone can offer me some tips..

dirtylimey.com/Assets/diagram.JPG

Robjb84 wrote:

Hmm,well im halfway through this ordeal though now confusion strikes...

I have removed the old seal, but am just wondering how I will get the oil back into the forks...

I dont have my camera with me, so here is a diagram of where I am at if anyone can offer me some tips..

dirtylimey.com/Assets/diagram.JPG

The top of the fork up at your triple clamps DOES screw apart. You do want to have the upper fork rod clamped into the triple clamp, or it will be hard as hell getting the top cap off. That is also where you have to put the oil in once the forks are back together again. Don't forget to coat the new seals with a little oil also before putting it back together again.

BTW: I just used a crescent wrench to get the top cap off. there isn't an actual hex that you can put a socket on. The caps were extremely tight, so you have to put some force into it.

Hmm I couldnt see any way of doing anything at the top of the fork. I ended up holding the bottom bolt in of the lower fork, pouring the oil into the bottom form after isntalling the new seal, inserting the top fork into the bottom, then tightening the bottom bolt. Wasnt ideal but both forks are back on the bike and appear to be working fine as far as I can tell..

Here is what the top of my forks look like if I take the little plastic cap off and look down at them:



The slight circular indentation in the middle would offer no grip for any kind of tool I can think of (Need to get my camera back baaaad)

The top of the upper tube is is held on by a circlip.

If you take a big phillips screwdriver, stick it in the indentation, and push down, you should feel it shift downwards against the spring a little bit. Looking where it was, you'll find the C-shaped wire ring keeping it from sliding further up. Pry it out its groove with a small screwdriver & the spring should pop the top right out.

Just swapped the tubes on mine this afternoon

How did you get the allen bolt unscrewed without being able to hold the inside ?

I'll see if I can get this pic posted.



Post edited by: markmeinteil, at: 2006/08/20 23:29