Slide metals specs

[Tom R]

Hi all. Does anyone know the serviceable limit for slide metals on 37 mm fork tubes? According to my calipers, mine are now 36.92 mm.
I'm seeing a lot of metal in my fork oil - could this be the cause?

 

[Billy Ricks]

Hi all. Does anyone know the serviceable limit for slide metals on 37 mm fork tubes? According to my calipers, mine are now 36.92 mm.
I'm seeing a lot of metal in my fork oil - could this be the cause?

It probably has more to do with the bushings in the forks. There's usually an upper and lower bushing in each leg.

 

[Tom R]

I was calling them slide metals because that's what Suzuki calls them; but yeah, they seem like bushings to me.
There is a bushing/slide metal in the upper part of the outer fork tube (not sure of my terminology here) and one on the lower part of the inner fork tube - this is the one that is 36.92mm OD.
Looking at the parts diagram for this fork ('82 gs850), the slide metal on the inner fork tube is shown and replaceable for about $12; but no sign of the SM on the outer fork tube.
I don't have inside calipers, so I can't get an accurate measurement on that one.

 

[Billy Ricks]

I'm not finding the upper slide metal either. They are teflon coated so if you can see bare metal they are shot.

 

[Tom R]

Teflon? None of that left on these. Hopefully it's the slides themselves shedding metal - neither of the tubes is showing excessive wear; though just by eyeball, maybe the outer tube mushrooms out a bit where the SM would wear against it. Maybe.

 

[Tom R]

After closer inspection and cleaning, the bushings do have a teflon coating. There are a few places where it's thin enough that you can see metal (copper?) underneath it, but the teflon is not worn through.
I figured the residue i saw on the rag I was wiping them with earlier was soft bearing material; but turns out it was just old fork oil still in the crevices.
I did manage to put a couple of very thin scratches in the teflon when I thought they were trash. I'm just gonna smooth that with 600 and put them back together as is.

Is it normal to for fork oil to look like aluminum paint after only a few thousand miles? There isn't any excessive wear that's obvious in these forks.

 

[Billy Ricks]

Fork oil gets pretty dirty. It's a combination of contaminants including fork internal wear, dirt and bugs that get past the seals, and moisture that gets past the seals as the fork travels up and down. The seals wipe away the bulk of stuff that ends up on the tubes but just like windshield wipers a tiny bit gets past them.

 

[Tom R]

Good to know. The only other bikes I've changed the fork fluid on have had fork gaitors - they're a little out of style, but effective.
I think I may have/or had some alignment issues too. I noticed the upper bushings in the lower fork tubes both showed wear on the right side. The bike tracked straight though.