Gus pivot cups

[Martin Reaves]

The pivot cup on my Gus truck is cracked, and I am looking for another one. Randal and large tracker cups dont fit. Any idea where i can pick a replacment up? what about a different company that will fit?

anyone have one they dont need?

thanks
martin

edit: would a large, hard khiro pivot cup work?

[Luke Melo]

khiro makes pivot cups. not sure if they will fit though. they come in 2 diff sized. one fits randal 180's, and on fits crail dh's (if that helps in terms of size)

[Martin Reaves]

here's the thing:

randal 180 pivot cups will fit into the hole of the Gus truck. however, they are thicker, and therefore the pivot cannot fit in.

[Chris Barker]

You sure you have a Gus truck? Does the baseplate have JAP or JPN stamped on the bottom? They don't really have a normal pivot cup. It's like a rubber sleave around sphere that the weak, skinny pivot fits into. Take a close look at your pivot casting and make sure it is not cracked. Marion Karr broke two of those things completely off. I will never again let a friend ride one of those. Maybe you got the one I passed on to Philthy before I knew how weak that truck is.

[Eric Brammer]

What you want to do here is either make 'findable' pivot cups fit that spherical pivot, or fit the pivot sphere to cups that're available. Since it's easier to ream out plastic pivot cups, I'd go with Option A. Khiro's,Tracker's,and Randal's cups all fit in a GUS baseplate.
[ BTW, while you're messin' with these cups in this baseplate, poke an 1/8" hole thru the base at the pivot's center, then you 'push' pivot cups out when you need to replace them.]

So, how do you best fit this kind of cup to the GUS ball-pivot? Find a ball-reamer that has more than 6 flutes to it in the size of the pivot ball. These should be available thru machine-tool supply companies. Sorry, I can't recall the exact size of that ball-pivot, but you've got one,so..
One other thought would be to have someone like Geezer-X mold up new, harder plastic pivot cups, which may end up being less expensive than trying to find the reamer, pivot cups from Khiro, and a drillpress. Worth a shot, imho.

If you down-size the ball-pivot, you'll need to find a machine-shop that can work from molds taken from the pivot cups (be those Tracker,Khiro,Randal or other), so that they can size the ball to fit. That shouldn't take more than a few minutes on a simple lathe to mill down to size. Another thought here would be to pull the pin that the ball-pivot sits over, and have a smaller, threaded-into-the-hanger ball pivot made from Stainless Steel 1/2" bar stock. Again, that'd be pretty simple to do with a decent lathe and tap/die set.

[Martin Reaves]

Thanks for the input guys.

the things is that the pivot cup as of now actually does work. it has a crack down the side of it, but when its put into the baseplate, and the pivot is it in, the crack is pushed together and everything fits nicely.

i asked this becasue, at some point, i will want a new cup. right now it functions just fine, but in the future i may run into problems. I was basically figuring out if the stock ones are easy to come by, or if i am going to have to improvise.

if i run into problems in the future, this is my plan. I am going to get a large, hard khiro cup and use that. Then, i will get a friend to lathe down the ball so it fits into the cup.

thanks for the help

[Justin Readings]

just a suggestion. im not sure what the truck looks like but why dont you lathe the inside of the pivot cup? instead of the truck.

[Eric Brammer]

Justin, I mentioned a ball-end ream for a reason, that being that a Khiro or Tracker pivot cup is already somewhat hollow, and are of fairly slick plastic to begin with. How would You chuck this in a Lathe? Some collets would grip it, I'm sure, but you'd want to pick your cutting tool with care. Of course, you can go thru someone like Ryerson Plastics and buy roundstock delrin, and cut what you'd need. Plus there's the issue of getting the interior curvature, which by hand could be a few passes (though easy enough with a CNC).So, yeah, with the right tools on hand, nice idea.

With a multi-flute ball-end reamer, you can fit the spherical ball of the truck nicely, and hold the pivot-cup by hose-clamp and vise-grips, plus this can be done on a simple drill-press. No Lathe needed. Keep in mind that some maching tools aren't so readily available.

The other options, of milling the ball pivot, or molding new custom-fit cups, are still legit in their own right. Doing a few molds of new cups (with maybe better plastic) is probably the most cost-effective fix in the long haul. Milling the pivot ball, or better, fitting a new, smaller+able-to-fit-Tracker-cups pivot ball would ensure easy future cup replacements. Fitting a stronger pivot pin and ball onto the hanger is probably wiser, as the pivot design, as is, is a potential weak spot.