Author Topic: Fork Seal Replacement and Progressive© Spring Upgrade ( ST1100 ) *  (Read 10112 times)

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Written by Dave "the Brit" Richardson, STOC 5442.


Fork Seal Replacement and Progressive© Spring Upgrade

NOTE:  Left click on image for higher resolution at Webshots.

This is my workshop report on replacing fork seals on a 93í ST1100. First all, I read the chapters on all 3 manuals
I own. Hondaís workshop manual, Haynes and Clymerís.

After receiving the tool kit from John Oosterhuis, I quickly realized that the one page sheet explaining the process
was not going to cover all my needs. Well, thatís what I first thought anyway. The instruction was to basically
follow the disassembly / assembly in your manual. I have to agree after going through it, and now writing this
report, it was a correct statement. My personal experience was that the Clymer manual was the best to follow
actually. I hate to admit that, especially as Iím a Brit and Haynes is a UK publication. But Clymerís walk through
steps far surpassed Haynes on this occasion.

Iím not going to describe the actual procedure I followed, because again itís well documented in the manual and
Iím really not a technical writer. What I will do is try to convey, in pictures, the usage of Johnís toolkit.
Before I get into that though, I forgot to mention, I upgraded my springs to progressives. I also replaced my
damper rod at the suggestion of another ST member. The picture below shows the disassembled parts. It said in
the manual to do one side at a time, but I made sure I place each legs components together.

Notice at the bottom of each fork tube there are grey looking rings. They are the fork bushings. They need to be
replaced if there is any sign of copper showing through. Fortunately. For me there was not.

The picture below shows a blurred close up. But I think you will get the idea visually, no copper color showing

This is the slider bushing above. The inside must not show any copper color. Again itís blurred, but it is a grey
color and did not show any signs to replace. Thank God! Otherwise the project would have been delayed another
two weeks waiting for parts to be shipped

Below is the replacement spacer for the progressive spring. Itís PVC pipe, supplied in the box with the
progressive springs. You have to cut it to the correct size though.

Below is the fork cap, with a blue marker points. This was a suggestion given by another ST member, actually
included in the one page description that came with Johnís tools. I do apologize for not remembering the guyís
name. The intent though is to mark where the cap just starts thread on. When you compress the spring down you
know exactly where the cap is starting to bite by the marks lining up. Very, very useful tip I might add.

This is Johnís tool. Iím trying to depict via this picture how you re-insert the fork slider bushing using this tool.
Basically you slide it back and forth until the dull sound of making contact with the copper bushing, resounds
with a metal clang. That sound tells you that the pushing is completely in place.

Again demonstrating using the tool, placing the new fork seal in place. I attached the fork leg to a metal plate I
made up and secured the plate in the vice. Not an original idea. It came from the Clymer manual and worked well.

This is one of Johnís other tools that came in the kit. I could not figure out what it was until I started reassembling
the right fork leg. Basically what this is for is too allow you to pump the fork damper up and down
when you add new fork fluid. This again was a very useful tool, because you really need to make sure your oil
capacities are pretty accurate. The concept is that the pumping draws in the fluid and you can feel resistance as
the damper is filling with fluid. Again, the Clymer manual explained this very well.

[edit: the primary use of the damper rod holder is to extend and hold the damper rod while compressing the fork spring and slipping the Spring Seat Stopper (C-slotted washer) between the Spring Seat (washer) and the underside of the Lock Nut atop the damper rod]

I have never replaced fork seals before. This took me longer to complete, than others, I think. But having down it
now. I fully understand conceptually how these all connect together. I would not have a problem attempting this
exercise again. Without the toolkit, I donít know how I would of managed taking the seals out and back in again
so painlessly.

What did I learn:
I made one silly mistake. Inserting the first fork seal. I read the instructions I donít know how many times and
looked at the diagram even more. The key was to make sure the manufacturers letters were facing up. I guess my
eyesightís fading me, because I didnít initially see the very small letter. What I looked for was the spring facing
down. This is where I screwed up. I only saw one spring, I did not see the spring on the other side of the seal. So,
I put the seal in upside down. Damn! I didnít realize my mistake until I had inserted the seal on the right leg. It
somehow dawned on me, god knows why, that I had put the first one in upside down. Sure enough, after taking it
all apart again it was. That cost me another $40 bucks for another seal and more fork oil.
This is definitely where another person working with you comes in handy.
« Last Edit: January 04, 2013, 04:31:48 PM by Tom Melnik »