Fork bushing play?

[z2345]

I took my fork apart at 43K to replace the seals/oil/bushings. The bushings all appear to be good, no wear marks or visual differences in the bushing surfaces. Having put the two legs back together, with no oil in them and without the oil and dust seals in, there is a slight bit of play. Is that normal?

I have no pointed caliper to measure thicknesses, but they look the same. Is the extra slack taken up by oil between the surfaces?

Wanted to get an opinion before putting the expensive oil back in.

 

[FinalImpact]

There doesn't seem to be a spec for it.
Inner tube outer diameter 43.0 mm (1.69 in)
Inner tube bending limit 0.2 mm (0.01 in)

Question:
What resources do you have? A dial indicator could be helpful as well as some simple feeler gauges.
Also, if bottomed, does it have the same play?

Off hand, I'd replace them but there is a chance it may not take out all of the play.

Anyway - if the body were mounted in a vice and the stanchion set mid travel, the dial indicator could be used to measure deflection. If its just a few tho, I might leave it unless one is different than the other. You'll need a good driver to get the new ones in w/out damage.

Lets see what others say.

 

[z2345]

No dial indicator. Used a PVC piece to put the outer tube bushing in. The movement is with it bottomed. I didn't feel this movement when I first took them off the bike (but they had oil and seals then).

I guess I'll swap them out.

There doesn't seem to be a spec for it.
Inner tube outer diameter 43.0 mm (1.69 in)
Inner tube bending limit 0.2 mm (0.01 in)

Question:
What resources do you have? A dial indicator could be helpful as well as some simple feeler gauges.
Also, if bottomed, does it have the same play?

Off hand, I'd replace them but there is a chance it may not take out all of the play.

Anyway - if the body were mounted in a vice and the stanchion set mid travel, the dial indicator could be used to measure deflection. If its just a few tho, I might leave it unless one is different than the other. You'll need a good driver to get the new ones in w/out damage.

Lets see what others say.

 

[aclayonb]

As a rule I don't reuse fork seals. They're too cheap and too easy to replace. Something about having a stable front suspension on a two-wheeled vehicle makes me nervous about re-using parts that a designed to be replaced.

 

[z2345]

We're talking about bushings....

As a rule I don't reuse fork seals. They're too cheap and too easy to replace. Something about having a stable front suspension on a two-wheeled vehicle makes me nervous about re-using parts that a designed to be replaced.

 

[FinalImpact]

No dial indicator. Used a PVC piece to put the outer tube bushing in. The movement is with it bottomed. I didn't feel this movement when I first took them off the bike (but they had oil and seals then).

I guess I'll swap them out.

Does the amount of movement change depending on "where" the tube is?

To answer your question; yes, the oil is supposed to prevent metal to metal contact and it will cushion.

Can you ball park guess how much it moves? I mean, the thickness of "cheap paper is 0.0040" and you could feel that. But getting rid of it entirely would mean locking it solid.

With oil in the new bushings, does it take up some of this free play?

 

[aclayonb]

Der.... disregard my last....

 

[z2345]

There was only a thousandth or two diff in thickness between the old and new bushings after 43K. Depending on where it was measured, equivalent.

With the new bushings, it felt like there was very slightly less play. With oil in and the seals/wipers on, no play is felt at all.

I guess the do-them-while-you're-in-there will set me up nicely for the foreseeable future.

A piece of two inch PVC cut and zip tied to the diameter of the stanchion worked perfectly for driving the outer bushing, the oil seal, and the wiper into place.