ok bought the umi panhard bar from summit racing part #2020 82-02 gm f body tubular non adjustable. My old panhard bar bolts broke on removal. So I bought the shohn rear panhard bar mounting hardware kit Part#983. There is a problem though. The I.D. of the umi bar bushing(where the bolt goes through) is 12.4mm. The spohn O.D. on the bolt is 13.7mm. I dont understand why. I have a call in to both companies to find a solution. btw the I.D of the stock panhard bar bushing is 14.4mm. so the bolts would work on a stock bar but not the umi bar...thoughts????

 

Aftermarket parts dont usually use the factory step bolts. They use either 12mm 1/2" hardware

 

It just dawn on me that I could use lower control arms bolts. they are 12mm just a little longer than panhard bolts

 

Both my cars have tubular panhard and use the factory step bolt on the left side. The '87 has a UMI double adjustable and the '89 an Edelbrock solid that was on the '87 when it was stock. Could you have it backwards?

 

If you look more closely at your factory panhard bar you will see nubs inside the thru hole that reduce the bolt shank from 14 mm to 12 mm (compatible with factory stepped bolt). The brackets on the car also have different size holes that match the stepped bolt.

Most aftermarket bars though have uniform diameter hole for a straight bolt because a stepped bolt is just a weird idea. And different companies will give you different size bolts because they do weird things too.

And the aftermarket bushings almost always will be inch sizes that don't match the bolt sizes provided. The bolts will rattle around inside the bushing.

You're just going to have to go buy your own bolts, washers, and nuts to get this right. Class 10.9 bolts if metric, Grade 8 if inch. Use a metal top lock nut, not nylon.

 

UMI uses a 12 mm bolt sized to the smaller hole in the stock bracket. Other side is a misfit to the hole.

I'd return the bar if you can, get something else.

 

I have the UMI on-car adjustable Roto-joint with a factory bolt at each end. Got it about 5 years ago, but the website still says it uses factory hardware. You said you have the non-adjustable, which doesn't say uses factory hardware, but the website's installed photos look like factory bolts.

Those Spohn bolts look too thick, but they're sold are replacements for "old rusty factory bolts." You said you broke your factory bolts, but do you still have what's left of them to compare to the Spohn bolts? Have you tried the Spohn bolts in the factory panhard bar that you removed? Factory bolts are available on ebay, if that's what you end up needing.

 

great information thank you

 

I have the UMI adjustable bar on mine and the aluminum bushings/bearings in the other end they sent with it were the wrong size. They were the same ones in the rear lower control arms that have a wider opening. I sent them a pic with the micrometer and they sent me the correct ones out the next day. So it is possible they have the wrong bushing installed in yours.