There's a scraping sound on my rear suspension for my 300SD as I move over any sort of bump. It gets really disconcerting since I hear it all the time and am nervous there's something seriously wrong with the rear suspension. It's definitely a scraping like noise and not a thud or a creak or anything else.

I don't think it's the springs since that sounds more like a creaking noise anyway.

I've been thinking it's the shocks, but I don't know how I can otherwise tell. Is there a tell-tale sign or way to check their quality? Even if I have to remove it.... How might I check to see it's life?

Someone suggested it may be the sway bars. I'm not sure what exactly the purpose of the sway bars are. Can someone elaborate?

How might I be able to tell whether the sway bars are problematic? What can possibly go wrong with them? Should I be able to re-create the scraping sound somehow, perhaps by disconnecting the bars from the link and moving each piece in full to see if I hear/see anything odd? It would especially be nice to try and pinpoint it without having to remove the shock and/or spring. And I'd like to avoid paying for replacing things I don't know the quality of, especially when we could be talking hundreds of dollars.

Then there are bushings.... I've been told the trailing arm has bushings - where are they? The little rubber stoppers that the trailing arms hit up against on the body seem to be in decent shape. The rear differential mount seems okay too.

Any other possibilities? I've had the car 6 months and haven't done anything to the rear suspension and the noise hasn't gotten much different, but I'm trying to ascertain the severity of the problem and worth of fixing it in the 25 deg F weather. I'd like to be able to pinpoint the issue in my garage without constantly driving the car and tinkering, replacing, etc.

I would look at your wheel alignment angle. If it is leaning too much the rear trailing arm may be rusted. It is a common problem and the cure is to replace the trailing arm. If it is needed a used arm can be sourced from a southern or western car and the installation is anywhere from 150 to 300 labor.

Good luck!

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

I've got some oversized tires on my daughter's 84SD that hit the fender wells under some conditions. Maybe you have a similar situation.

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

Wheel alignment angle as in the wheels not being perpendicular to the ground? ie inward at the top, slanted as viewed from the back?

I have a parts car with decent trailing arms. Problem is getting them off seemed to involve a bit of creativity/leverage removing the mounting bolts (not much clearance) or just removing the entire rear subframe. Seemed like a lengthy project I can definitely do, just not really ambitious about it. There is rust on one of the trailing arms, but not in a location that would make that sort of sound, unless the rust is somehow warping the motion of the arm as the car goes over a bump.

My other car (300TD wagon) is generally in better shape (minus the pending crankshaft seal replacement) and so I may just put the sedan aside until next spring/summer, and only use in emergencies. At that point I may as well swap the entire subframe and eliminate any rust issues.