clunk in rear when going over bumps

[richie_s999]

also check the diff bolt, sub frame mounting points on M3's are reinforced from the factory, so shouldn't be torn, if they are I wish you luck, I tore them right outa my e36, was a hell of a job welding them back in and welding on the M3 reinforcement plates, but it was an excuse to upgrade all the bushings when I had it apart

[dcramer]

I just put a new diff in the car, so the bolt is good.

I'll let you know what I find after I pull it apart.

[Axxe]

Exhaust hanger rubber weak from years of heat exposure. Mine got so bad that they broke the seal on the midpipe. Just figured it out the other day. They get too soft laterally and the muffler bangs around in the tunnel. Easy way to check, see if the heatshield in the muffler tunnel has gouges in it from the pinch weld. Could also be the top from over extension over negative curvatures.

[iverson03tj]

Originally Posted by T.Dot_E30

That's a good point, I've been checking that area for cracks each time I look at my mounts but haven't found anything.
My trunk carpet has been out for years, so I do have easy access to it. My shocks have been in and out many times due to the stupid externally adjustable koni setup.

how come u have to take the shocks on and off? im guessing u got he Koni SA's?

[dcramer]

Originally Posted by Axxe

Exhaust hanger rubber weak from years of heat exposure. Mine got so bad that they broke the seal on the midpipe. Just figured it out the other day. They get too soft laterally and the muffler bangs around in the tunnel. Easy way to check, see if the heatshield in the muffler tunnel has gouges in it from the pinch weld. Could also be the top from over extension over negative curvatures.

Yes, even new they aren't worth a crap on the track. What do people do with track cars ? There must be a decent aftermarket hanger ?

That being said that isn't the clunk that I am hearing I know about that one.

Dave

[Axxe]

I am going to fill the voids on the new ones with urethane. Also I completely missed the part in your initial post about eliminating the muffler. Mine makes the weirdest noise leaving the driveway, took me a while to pinpoint.

[dcramer]

Originally Posted by Axxe

I am going to fill the voids on the new ones with urethane. Also I completely missed the part in your initial post about eliminating the muffler. Mine makes the weirdest noise leaving the driveway, took me a while to pinpoint.

Interesting. I'd like to see that and to see how well the urethane stays in.

Dave

[InfiniteDice]

It stays in well. I've done it. Many bushings come with a wax like coating over the rubber to protect it. You'll need to use a dremel or something on low to just scuff up the rubber (inside the void) a bit, then wash the void out with some alcohol. Fill the void wait 8 - 12hrs or whatever the working time is, then install.

In the case of the e30 rear carrier mounts: The urethane in the void would form a solid 3" long chunk, the carrier mount bottom plate would prevent that from coming out even if it did come loose of the rubber.

The urethane stuff I bought is awesome, hardens up and feels like a hockey puck. Oil/gas resistant, I think it was nearly 20$ at Carquest.