Occasional hard "BANG" from rear seat area or trunk. Thoughts?

[irish44j]

Something silly but fixed a few... Jack and or spare not properly secured? Or battery tray bolts missing or broken.

Nah, All that stuff gets removed for rallycross, and the battery is probably bolted down more securely than any other e30 on here, lol.

[bmwguy325is]

you know.....I just thought of the fact that when I am moving and pull the parking brake (to rotate the rear end in rallycross) there is a hard clunk from the right rear. I've always thought it was just one of my cables out of adjustment, but I'm definitely going to check that now. I wonder if one of the retaining pins isn't in or something.... Could be binding in the same way.

Other thought i had is that I removed the rear spring isolators (to drop the rear end down a bit) and when the rear is off the ground the spring is kind of "loose" in there. Maybe it's binding when the car comes back down on it.

Thanks. Your post made me think of 2 key things to check :D

Park break fo sure. I run coil springs in the rear on perches. They are only loud when I hot large bumbs but its more of a thud when the spring comes back down.
Parking brake I could go with that

[Holland]

you know.....I just thought of the fact that when I am moving and pull the parking brake (to rotate the rear end in rallycross) there is a hard clunk from the right rear. I've always thought it was just one of my cables out of adjustment, but I'm definitely going to check that now. I wonder if one of the retaining pins isn't in or something.... Could be binding in the same way.

Other thought i had is that I removed the rear spring isolators (to drop the rear end down a bit) and when the rear is off the ground the spring is kind of "loose" in there. Maybe it's binding when the car comes back down on it.

Thanks. Your post made me think of 2 key things to check :D

I've had my rear spring pads out before, and all they did were make an obnoxious rattling noise.

[ZM Blue Devil]

Something silly but fixed a few... Jack and or spare not properly secured? Or battery tray bolts missing or broken.

[Nick_V]

Thanks. Your post made me think of 2 key things to check :D

Not a problem. Good luck!

[irish44j]

Disasterman says that there's a chunk out of your spider gears...

...but he comes from 2002land where diff spiders are notoriously weak...

t

seems like that would be more apparent. I seriously only feel this every once in a while. I can drive hard all day and not hear it, and then randomly it will do it when pulling into my driveway.

[irish44j]

I had a similar noise that was driving me insane in my E36 (flame suit on). After throwing money at all the usual suspects (RTABs, CSB, guibo) to no avail, I eventually discovered a broken rear spring. That wasn't it either. Tore out some hair and decided to check the parking brakes. It seems that the initial impact of the spring breaking caused the spring retainers for the parking brake shoes to partially tear out of the backing plate. The hand brake still worked but apparently was binding randomly on that side, causing a violent bang. Took the guts out of that side, BOOM - no more noise.

you know.....I just thought of the fact that when I am moving and pull the parking brake (to rotate the rear end in rallycross) there is a hard clunk from the right rear. I've always thought it was just one of my cables out of adjustment, but I'm definitely going to check that now. I wonder if one of the retaining pins isn't in or something.... Could be binding in the same way.

Other thought i had is that I removed the rear spring isolators (to drop the rear end down a bit) and when the rear is off the ground the spring is kind of "loose" in there. Maybe it's binding when the car comes back down on it.

Thanks. Your post made me think of 2 key things to check :D

[Nick_V]

I had a similar noise that was driving me insane in my E36 (flame suit on). After throwing money at all the usual suspects (RTABs, CSB, guibo) to no avail, I eventually discovered a broken rear spring. That wasn't it either. Tore out some hair and decided to check the parking brakes. It seems that the initial impact of the spring breaking caused the spring retainers for the parking brake shoes to partially tear out of the backing plate. The hand brake still worked but apparently was binding randomly on that side, causing a violent bang. Took the guts out of that side, BOOM - no more noise.

[TobyB]

Disasterman says that there's a chunk out of your spider gears...

...but he comes from 2002land where diff spiders are notoriously weak...

t

[irish44j]

yeah gonna check the ujoints tomorrow. I did check the diff mount bolts and they were all a bit loose, so maybe that's it.

[bmwguy325is]

GIUBO and CSB were replaced less than 6 month ago. They have like 1000 miles on them tops.

Did you check the ujoints for binding issues. A bad ujoint can still make the CSB slap around. It also makes the noise right behiend the seats.
You may also check the diff make sure it has all the bolts and the bushing is good.

[irish44j]

How are your muffler hangers? When badly worn, the muffler can bounce up and into the trunk floor, and it's loud.

Just thought you should check that before you go crazy on a driveline rebuild.

My muffler and exhaust are actually secured even more than stock, with all new hardware. I made sure they were very secure since this car is a rallycross vehicle. Plus the muffler is not stock, and it's small and is several inches from anything. I've kicked it hard a few times from under the car and no noises or touching anything.

I don't get the noise in particular bumps, or places you would expect to hear exhaust banging around, and there is plenty of clearance....

hmm.

[irish44j]

Your GUIBO is failing..... had the same problem in my e30........

I get the exact same noise in the same place, wish I could help.

GIUBO and CSB were replaced less than 6 month ago. They have like 1000 miles on them tops.

[hwy84]

Starting easy...

How are your muffler hangers? When badly worn, the muffler can bounce up and into the trunk floor, and it's loud.

Just thought you should check that before you go crazy on a driveline rebuild.

[bmwguy325is]

Your GUIBO is failing..... had the same problem in my e30........

Its this and the center support bearing is going out. You need a drive line rebuild most likely.
What happens is that the ujoints go bad and then wear at the rubber parts of the drive line. The guibo goes cause of flex at the center support bearing.