I pulled the k-frame out of my 74 Road Runner this week. The back mount area has some rust although I think it is just a shim that is rusted. Problem is the shims aren't where the factory manual says they should be. Anyone got pics of their k-frame - in particular the top side of the rear mount area? I've attached the service manual pic and an image of my drivers side mount area.

No you're not missing anything, there is no shim. The k-frame is double thick in that area. The normal thickness of the rest of the k-frame steel plus an extra layer is welded on top in the hole opening area. You can kinda see the extra piece in this pic. Other than this it's just your isolator bushings, washer and bolt. The original bushings had the rubber sandwiched between a pair of thin steel washers that were welded to the metal sleeve that goes inside the bushings. The remains of that may be what you are seeing on your pic. Merry Christmas.

Thanks daytona. The pic in my post looks worse than what you can see in person. The double thickness is there although it looks like there is a circular disc on top of that. Its the circular disc that is rusted. It is also not obvious to me whether that disc is a "shim" or part of the welded on metal that increases the thickness of the k-frame in the mount area. It does look as if it is spot welded, but they are very small and look like eighth inch holes more than what I expect a spot weld would appear. I'll clean it up this afternoon to see better what is going on.

Depending on how your car was built it could have shims on any of the 4 mounting points of the isolated k frame....I had 2 shims on the back,right bushing on this last build...A resto before had one on the left, front.... ...You need to determine if it is in fact a shim or remnants of the bushing hardware...If the hardware in question is'nt at the location in your factory pic then chances are it's just the bushing assembly...After you clean off all the bushing pieces the k frame should look like the pic in the above post...On that note...I snagged the urethane bushings on this last build and the k frame hole was bigger than the supplied bushing...I ended up welding the perimiter of the k frame holes to make a tight fit for the 2 urethane parts...At first I thought I needed to use the original inner shell from the old bushings but those would'nt fit the new parts either.... ...So the welding was the smart choice in this case...

My urethane bushings fit snug in the oval holes in my k-frame, and the bushings are oval-shaped where they pass through the k-frame, which is why I suggest that metal will scrape right off your k-frame to reveal it to look just like mine.

Runnin74, pm me if you want to buy a set of lightly used poly k-frame bushings in great shape. I've got an extra set.

the rusted metal your looking at may be a metal piece from the oem insulator.

is this it?



if so, that's part of the original rubber isolator setup, and should be removed.

Yep Cudazappa I believe that is it. Makes sense now what I'm looking at.

It came right off. No problem.

You can throw that piece away and not worry. All I ever ran with the poly bushings was them and the bare k-frame. No issues and I had my poly bushings in the car for 7 or 8 years of daily driving in the summer.

you need to throw them away if you want to run the solid isolators, Mopar or Aftermarket. I learned that AFTER I powdercoated the K-frame.