front fork play


13 replies to this topic
  • aggiemoto99

Posted October 11, 2008 - 08:30 AM

#1

There is play in a 2004 showa front fork my friend has, and after replacing bushings, it's still there.

The part numbers are correct, the old bushings were worn, and the inner tube looks great, no noticeably wear.

Installation went well, any reason for the play?

  • mog

Posted October 11, 2008 - 09:51 AM

#2

depends on how much play, is it both sides, people have talked about putting a feeler guage between the bush and the fork stantion, if 0.1mm goes in its a looser than idea fit.

  • aggiemoto99

Posted October 11, 2008 - 11:07 AM

#3

It's enough to easily notice if you grab the lower fork tube and rock it....way more than I feel comfortable with. But thanks, the other one seems to have play but much less.

  • mog

Posted October 11, 2008 - 12:08 PM

#4

is this the brake side with the play?

  • DaveJ

Posted October 11, 2008 - 04:49 PM

#5

Some play is normal and necessary.

And of course, you'll see a lot more play with the fork extended than compressed.

You may need to take some measurements on the tubes.

  • aggiemoto99

Posted October 11, 2008 - 04:50 PM

#6

No, actually the other side....

Both sides seem to have some, it's off an 04, so Maybe it's just worn out.

  • DaveJ

Posted October 12, 2008 - 11:10 AM

#7

No, actually the other side....

Both sides seem to have some, it's off an 04, so Maybe it's just worn out.


So...run a ball mic on the bushings, in various spots, and if need be, run a bore gauge into the upper tube. Whatever the problem is, if you look hard and long enough, you'll find the evidence.

By the way, you can also shim bushings....which I have regrettably done in the past.

  • mog

Posted October 12, 2008 - 02:12 PM

#8

dave why regrettably?

  • aggiemoto99

Posted October 12, 2008 - 04:50 PM

#9

So...run a ball mic on the bushings, in various spots, and if need be, run a bore gauge into the upper tube. Whatever the problem is, if you look hard and long enough, you'll find the evidence.

By the way, you can also shim bushings....which I have regrettably done in the past.


Great advice....and of course more play upon full extension, I figured (know) that at least.

Fuel for fire, I would bet the factory teams "A" kit run much tighter tolerances...?

and in another thread, kelstr says the kashima coating contributes to stiction....I thought it was to eliminate stiction..

Whats up with that!

  • mog

Posted October 13, 2008 - 07:26 AM

#10

the factory kits to reduce clearances and use coatings to reduce friction, however i tried to reduce clearances on 94 kx 125 fork and the tube wasnt true enough, and caught at different parts of the stroke.

  • aggiemoto99

Posted October 13, 2008 - 07:36 AM

#11

the factory kits to reduce clearances and use coatings to reduce friction, however i tried to reduce clearances on 94 kx 125 fork and the tube wasnt true enough, and caught at different parts of the stroke.


Ha! I would never have thought about that! I bet the factories have it honed to just the right size, then coat it with a known thickness.

  • mog

Posted October 13, 2008 - 07:40 AM

#12

well they start with almost perfect componants where as production ones have a quality but to a budget.I was surprised how out of round a fork leg was(in certain areas)

  • DaveJ

Posted October 13, 2008 - 11:06 AM

#13

dave why regrettably?


I noticed that my forks felt tighter and more responsive when new bushings were installed. After the bushings broke in, this was lost.

So it's an old road racer trick to shim the bushings in order to lower the tolerance, which may have been a good thing on some bikes but not all of them.

To acheive this, I used plastic shims in order to create the perfect size and thickness. Of the two sizes I used, .003 (.076mm) and .002 (.051mm) both created that same tight effect that I liked from the stock bushings.

The fork felt more responsive and had really good feedback.

But then I started testing the fork on the bench with a device that I could apply side loads with, while measuring the force required to compress the tubes. This is when I found that the tolerances were too tight and ended up causing more harm than good...mainly at full extension.

That said, there may still be something here but perhaps with a thinner stock. I have stock that is as thin as .0005 (.013mm) so perhaps I'll go back some day and test that.

I also never tested to see if the new bushings generated a problem either.

In either case, it does seem like there is some room for improvement when it comes to the design of bushings and how the fit and function within the fork.

  • shockdoc

Posted October 14, 2008 - 07:48 AM

#14

In either case, it does seem like there is some room for improvement when it comes to the design of bushings and how the fit and function within the fork.


Dave, this is something (new designed bushings) that Rob from Synergy Seals has been working on. Would be nice to hear his thoughts.

doc





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