Removing PTFE Sleeve Bearings

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In that case

1. The slide hammer sounds a much better idea
2. They may not be very tight anyway

MichaelG.

My thinking Michael was that in operation the fork leg has to withstand the dive of the front end of the bike under heavy breaking which is probably going to be far greater than any shock force you could produce by whacking the end of the piston with a large hammer. If the bearings can be removed with the slide hammer method as manufacturers suggest then they don't need a great deal of force to shift them. Certainly less than the burst pressure of the fork leg. So the bearing is going to give in before the fork leg does. It's a moot point anyhow now we know about the slots in the bearings. I suggested the method because the means seemed to be at hand rather than making or buying a slide hammer.

regards Martin

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32mm diameter piston, driven hard enough to move a bearing with such a small end-area [wall-thickness is only 1.5mm] suggests some pretty high fluid pressures.

Happy to be wrong; but I think a slide-hammer might be safer.

All depends on how tight the bearing is fitted into the bore of the leg.

MichaelG.

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Quite so, Martin

We've explored some options, which might be useful if anyone has a similar problem.

MichaelG.

Is it a bush or is it a baked on Teflon coating? Ian S C

What bike is this off ? Just for interest. Only time I've seen this sort of fork bearing the bushes were split, as if made from rolled plate. A light -weight machine but can't remember what.

If this job is for a production motorcycle and the bushing is in fact a serviceable item there s probably a factory tool or procedure for getting the bushings out. If it is a Japanese made machine I would look in the online bike ads for a replacement, a procedure, or a factory tool.

Since you say the bushes are PTFE coated I would guess the machine is from the 1970's or later. In that case replacements are likely available unless it's a rare make like a Hodaka or something.

Years ago I recall a friend had a three jawed fork bush tool with a conical wedge that expanded the jaws outward, then a slide hammer type extension was operated to yank out the fork bushings. I believe it was a factory tool for Suzuki dirt bikes with replaceable bushes. A few people shared the tool around but since factory replacement fork legs complete with new bushings and new seals for these bikes were about 12 dollars each at the time and a set of replacement bushings was 8 dollars, it didn't make much sense adding more labour cost fighting with the bushings- just replace the fork legs. They often had cracks or broken lugs or leaky seals anyway. JD

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Jeff,

Unless I have misundertood ... Ben has stated that the forks are Swiss, and made for a pedal cycle.

MichaelG.

Sorry, I missed the pedal bike note.

The three jaw puller type device I mentioned may work if it can be made small enough to get in the tube.

Are bushings available to replace the ones now in the bike? or will Ben substitute bronze pressed in ones? JD

Ahhh all now becomes apparent. It's a push bike not a motorcycle. Now I understand why Michael G was worried about burst pressures and there was I thinking back to my Yamaha 750 rebuild and going

"burst the fork leg ?. . . what !!!"

Amazing how cross threaded these threads get.

;0)

Martin

Yep, the bearings are fitted to a push bike suspension fork. The exact model is DT Swiss EXM130 **LINK**

I had a brief chat with Dunlop BTL **LINK** and they have advised that the bearing is probably available (but to be sure would need to see them first hand).

Will keep you posted.

Thanks.

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Wow!! ... Those are beauties

The technical manuals are works of art, too ... But unfortunately only appear to document the 'small service'

MichaelG.