Author Topic: Clunk Bushing Diagnosis?  (Read 745 times)

DaveinOC

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  • USA, CA, Anaheim
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Clunk Bushing Diagnosis?
« on: June 22, 2023, 01:20:35 »
Hi alll,
I've been a member for quite a few years and have relied on the technical manual (thanks for the linkage tour!) and forums for a lot of information and tips. Sorry if this is a bit long, but I think I need to expalin a bit about me and my  230 SL. I worked as a mechanic for several years in an independent Mercedes ship when I was in college about 45-50 years ago! This was the late 1970s so we saw a lot of W113 types with things like blown head gaskets (most of the cars in SoCal have port/dealer added A/C - they had the dreaded blown "bypass" hose) but at that time they weren't wearing out the suspension parts.  I've owned this car for about 35 years now and have done all of the work myself.

I had my rear brake shoes relined and the drums turned aout 4 years but only a couple hundred miles ago. I noticed the car seemed to surge and the brakes grab when backing up. I've double checked and the shoes are installed properly, but the linings appear to not be wearing evenly (remember only a few hndred miles so they may not have fully seated yet) that I attribute to him maybe not arcing the shoes properly. That's not my real issue. I suspect that the shoes are grabbing in reverse. and that will go away when the shoes seat fully.

I've developed a clunk when the grabbing occurs, and it seems to be coming from the right side of the rear axle. I can also induce it by going on and off the throttle a bit harshly. I recently replaced all of the trailing arm bushings and pads and installed a new germany sourced differential center mount (the one in the trunk.) and all of the locatiing arm rubber cushions. If anything the clunk is more pronounced now! I don't see that the differential center bushing (clunk bushing?) is collapsed but that seems to be the only thing left. I also checked the shock mounts and they appear fine and still have some pressure in the shocks. I think I'm left with the"clunk" bushing. Any suggestions on correctly diagnosing it before I get estimates for pulling the rear axle and replacing it? If that's what my problem is does anyone have a suggestion for repair facilities in Southern California, Orange County if possible as I'm in Anaheim. I sure wish we had somebody like Benz Dr around here. (Ontario CAlifornia is close but not Ontario CAnada.) I'm not about to drop the axle myself on the garage floor at my age!
1966 230SL