I have an annoying clunk sound coming from the rear, I think it is from the Spohn LCAs. The factory bolts are M12 which measure 0.460" diameter. The holes in the Spohn LCA bushings are 0.500" so the bolts are quite loose and I think the LCAs are clunking around. Anyone else have this issue? Also, the holes in my Strange relocation brackets are 0.500" so they are also too big.

The factory holes on the subframe measure 0.460" so the bolts fit nice and tight through the factory holes.

I think I will machine some new brass bushings with a smaller ID so the bolts fit nice and snug inside the bushings?

 

That is not how it works. If the bolts are torqued to spec, they are not free to clunk around regardless of the size difference. The friction in the bolted joint is what keeps it together, the bolt does not act like a pin.

 

THANK YOU!

As a manufacturer we carefully consider hole sizes in every component. Too tight and the phone rings off the hook. We consider bolt size, powder coat thickness and extra clearance to ease assembly without being excessively loose.

ramey

 

Interesting when I got mine from founders they just barely cleared the bolts. I will admit it would be easier with a little more clearance but they were as tight as anything factory.

I remember some specific words about why there were that way in the instructions.

Although I would be willing to put up $$$ that is probably does not matter much.

 

So where does the movement occur in LCA bushing?

Is it between the OD of the poly and the ID of the clamshell?

i.e.) The inner metal bushing doesn't move at all?

 

The bolt should clamp down on the center metal spacer. The spacer prevents the bushing from getting crushed. In a stock rubber bushing I think you will find that the rubber is attached to the center metal spacer and the outside metal. Hence when the suspension flexes the rubber is torqued. There is no smooth rotation interface. This is why on a stock bushing it is necessary to tighten the bolts with LCA at ride height/angle. Really this is not an ideal situation as when you torque the rubber it want to spring back to its original position. You really don't want your suspension links contributing to the spring rate.

I won't speak for the any Poly bushing because that is not something I have ever been interested in or seen in person.

 

Ah, I didn't realize the factory rubber actually flexes to allow movement. What do you run for LCA bushings?

 

I'm resurrecting this thread because I still have the annoying clunk, and I am making new bushings for my Spohn LCA's right now with a 0.465" ID so the factory bolts fit perfectly inside the metal bushings. I will test drive the car and post results. If it fixes the issue I will be selling these bushings.

 

Why not use new grade 8 hardware (1/2") and drill out the holes? That would be cheaper, easier, and you also have the piece of mind of replacing 25+ yr old bolts...

 

I did use 1/2" hardware on the axle side of the control arm because the holes are easy to access and drill out. However, there is only a few inches of clearance on the frame side so I don't see any way to properly enlarge the holes on the frame to 1/2". You can't fit a drill in there and drill straight through the factory holes. You would have to do it at an angle, which would give you an oval shaped hole. Have you done this?

My new bushings work fine with the factory M12 bolts, no more rattle.

 

drilled mine out to .500, no problems.

 

Did you just drill at an upward angle for the subframe holes?