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The noise is not road speed related and it sounds like metal on metal thus gearbox on cross member must be the prime suspect.
A simple solution is to take two strips of tyre inner tube 1 inch wide and about 12 inches long. Fold the strip such that it forms a packer about 1 inch square- encapsulate it with Gorilla tape or whatever and after jacking up the gear box place it between the rubber and the mount frame then let the gearbox hold them in place.
See if it makes a difference. I had a similar sound a few years ago and the above fixed the issue- cheap and easy to implement.
Edit- found the photo
Thanks Fred, great idea (and photo!) I tried this today but its still clunking
Thanks Fred, great idea (and photo!) I tried this today but its still clunking
Todd.
Todd,
The more you can eliminate- the less it leaves to be the issue!
I seem to remember you checked the exhaust system as it passes by the cross member- those things can cause issues albeit I am not familiar with the exhaust system on the earlier models.. The noise sounds like some kind of random metal to metal slapping so whatever it is should leave some tell tale marks or so I would think. The only other thing I can remotely think of would be the Weissach bushing if that has failed badly but that is just a wild *** guess. I suspect you have not had chance to push the handling envelope yet. Have you checked the mounting bolts for the rear coilover?- that is an easy one to eliminate.
From this, can anyone guess what it could be? It doesnt do it if I lightly press the brakes (or hard of course ). I have visually inspected everything I can get access to around the rear (the noise is definitely coming from the driver-side rear (UK car)). I havent taken anything apart as I will need to replace bushes etc and that is a big job that needs planning out. I have checked every bushing/mounting/bolt I can see and extensively wobbled the exhaust.
Any help appreciated!
Todd.
Make another video but with the window up to eliminate much of the road noise.
Almost sounds like a blown shock that's just rattling up and down.
Have you unloaded all the wheels and rocked them at 12 and 6 and the 3 and 9? Check all the fasteners on the upper control from the engine side where it bolts though the fenders and the washers and nuts in the fender wells from the outside.
Are all the cv joint bolts torqued.
Based on the noise and the diagnostic driving videos, I'm frankly surprised whatever it is hasn't completely come apart and revealwd itself.
Someone here in 2015 posted about finding his flex plate with two corners broken off. He described the symptoms as "There is a noticeable vibration at 2800-3100 rpms along with a slight metallic rattle." Seems like I have seen the word "rattle" used in this thread early on.
Unfortunately not, I just created the exhaust and its all solid. I know its the obvious thing since I touched that last... but its solid. I've violently wobbled it and resolved any touch points. The knocking happens surprisingly easily (meaning I don't need to drive fast or go over big bumps) so if it were the exhaust I should be able to replicated at home
The more you can eliminate- the less it leaves to be the issue!
I seem to remember you checked the exhaust system as it passes by the cross member- those things can cause issues albeit I am not familiar with the exhaust system on the earlier models.. The noise sounds like some kind of random metal to metal slapping so whatever it is should leave some tell tale marks or so I would think. The only other thing I can remotely think of would be the Weissach bushing if that has failed badly but that is just a wild *** guess. I suspect you have not had chance to push the handling envelope yet. Have you checked the mounting bolts for the rear coilover?- that is an easy one to eliminate.
Hi Fred,
Yes totally, none of this is a waste of time as I keep solidifying the car.
Its not the exhaust, 100%
I havent pushed the car hard, no, and I've inspected all of the rear suspension - I assume that something making this type of noise would be loose to touch, but I have also levered with a crowbar, The top bolts for each strut are tight, Im tempted to remove the corner's coilover to have a look....
Make another video but with the window up to eliminate much of the road noise.
Hi Jerry, will do.
For info, I am unable to repeat in my garage by bouncing the car up/down... which to me implies its something to do with the unsprung components (wheel, hub, etc) and I have no way to replicate going over a bump.
Almost sounds like a blown shock that's just rattling up and down.
Have you unloaded all the wheels and rocked them at 12 and 6 and the 3 and 9? Check all the fasteners on the upper control from the engine side where it bolts though the fenders and the washers and nuts in the fender wells from the outside.
Are all the cv joint bolts torqued.
Based on the noise and the diagnostic driving videos, I'm frankly surprised whatever it is hasn't completely come apart and revealwd itself.
Hi Petza,
I have, but I'll do it again... its definitely at the rear/driver-side corner. Front suspension is all torque and double/triple checked..I dont' know how to check for a blown shock, if its easy I can remove the suspect....
Totally agree that whatever it is should have revealed itself by now (Im expecting a wheel to roll past me.... )
Someone here in 2015 posted about finding his flex plate with two corners broken off. He described the symptoms as "There is a noticeable vibration at 2800-3100 rpms along with a slight metallic rattle." Seems like I have seen the word "rattle" used in this thread early on.
I don't think its engine related, it happens at any speed/rpm in D or N, and is definitely from that rear corner.
Are the sway bar links in good condition and the bolts properly positioned in the rear the upper right side can hit the tank saddle if the bolt is installed opposite
Are the sway bar links in good condition and the bolts properly positioned in the rear the upper right side can hit the tank saddle if the bolt is installed opposite
Sway bars are old, but all seem firm, and the bolts are facing rearwards, so do not touch fuel tank.
From the sounds, Im assuming whatever is causing it should be loose enough for me to feel by giving it a good, strong wobble? Is there anything that sounds like that that can be tight to touch?
(thanks for the continued support - we will find this one!)
Last edited by Todd Gibbs; 07-11-2023 at 03:31 PM.
Is the rear crossmember loose? With negative force it moves, could be also the gas tank or battery.
Unfortunately no, all seems to be secure.
I just spent another hour under there, everything is solid. All bolts tight, all bushes (while old) are serviceable. Nothing is moving around (I tested all bushes with a crowbar).
When lifting up/down I can hear that damper sloshing more than any other... I wonder if it has blown and is rattling around? Is that possible? The top 3 mounting nuts are secure/tight. The central nut turns the entire shock/damper rod, not sure if thats normal...
07-10-2023, 04:02 PM
). I have visually inspected everything I can get access to around the rear (the noise is definitely coming from the driver-side rear (UK car)). I havent taken anything apart as I will need to replace bushes etc and that is a big job that needs planning out. I have checked every bushing/mounting/bolt I can see and extensively wobbled the exhaust.
