GT380: replacing fork seals

[Scorch]

With riding weather quickly going away, I thought to do some maintenance. The fork seals have been leaking a while now, and I have done fork seals before on a couple of bikes. My 1975 380 has a clip on top of the seal, that came out pretty easily, but getting the seals out is TOUGH!


Any suggestions?

And what's the deal with the top half, the spring must be in there. Do I need to disassemble this or should I leave it alone? I see a clip holding the cap on, instead of the usually screw on fork cap. Yes, I am kinda scared to take that clip out...


Is it under a lot of pressure?

[Scorch]

I read somewhere about immersing the seal in boiling water...it softened the rubber but still cannot get the seal out.

What scares me, is that I cannot tell what is part of the seal, and what is part of the forkleg, so I am worried I am trying to prise out a part of the fork leg, that I think is part of the seal.


Are those metal lips part of the seal?

[Suzukidave]

Here is a view of whats in there http://www.bikebandit.com/1977-suzuki-g ... #sch278666" onclick="window.open(this.href);return false;

[Coyote]

All of that needs to come out. The original seals installed at the factory were 14mm tall. New ones are 11mm tall - even if you order them from the mother ship. Somewhere on this forum there was a thread about installing 3mm risers under the seal, but I can't seem to find it. On my 550, I just drove the new seal in till it bottemed out, then I put the snap ring in for safe measure.Never had any problem as they fit really tight.
Also, run your finger across the outside of the new seal. You will feel a slight step. It almost appears to be a starter diameter. IT'S NOT! Larger diameter goes in first. Ask me how I know The longer bevel faces out.

[Scorch]

All right, then, thanks.

Ues, I ordered new bottom bolts (#12) and o-rings (#8). Will be interesting getting those bungs out.

[Suzukidave]

I also remember reading reading a post of the forks being disassembled .. once the C clip is removed the bung may not pop right out , in the post he tapped down on it useing a socket and then it sprung out like a shot so be prepared for the insides to fire out

[Scorch]

Aye, I've read that too.

Success!


A combination of a chisel, screwdriver and gently applied dremel cuts. It was really stuck in there.

There was some scarring of the fork tube, hopefully it will still seal.




Somehow I have two sets of seals for this bike. I guess I have been planning this job so long, I ordered an extra set. One is from Suzuki, the other is a generic brand, probably gotten off ebay. I imagine using the Suzuki brand is the right way to go?



Coyote! How about looking at the seal and suggest which side should face up? Seal on the left, or the one in the fork?

[AFRetired]

The one in the fork is correct.

The side with lettering or markings always goes away from the oil

[Coyote]

I thought the side with the wound spring should face down. Chime in anyone?

[Scorch]

Well, it appears there is a wound spring on both sides of the seal. Anyone else want to help out here, maybe we can get a consensus...

Got the top bung out, not too bad, about 45 seconds of medium tapping with a socket and hammer.


Not wanting to dare the dremel again, I searched the toolbox and found this--a seal remover! Actually, it's a tire iron but it worked perfectly. Just take it easy on the pressure, pry a little at a time, don't fracture the fork tube.


Yes, it eases the seal up. Of course, once the seal gets flush with the fork tube, the tire iron pushes it back down on the near side, so to get the seal fully out,...


...I used vice-grips and the edge of the workbench for leverage, and worked it on out.

[Suzukidave]

My first thought was the spring side goes toward the oil but being yours has springs on both sides .

[gt-keith]

Engineering practice usually says if a void containing oil is to be sealed then the 'open' side with the spring round goes to the oil side.
And if its grease the 'open' side goes to the outside, so when grease is pumped in it doesn't hydraulic lock preventing grease getting in or blows the seal out.
So looking at your photo of the one in the fork leg and the other between your fingers, I'd say the one in the fork is correct.
You can get what they call 'double lip' seals but its unusual to have a spring at both sides, that looks like an expensive kind of seal for a special application.
Great photo's by the way.

[Scorch]

Thanks. I think the seal in the fork leg is the correct placement, and it is the only way to press the seal into the leg. I'm afraid doing it with the lips up will break the seal.

[Scorch]

Any suggestions on fork oil, what weight, how much? Clymer says 145 cc of SAE 10/30w oil, ATF, or special front fork oil. Special?

[Barry S.]

ATF is cheap and good enough for these old forks, can't make much difference.