loud clunking from rear on fast right turns

[Pablo M]

1972 2002tii

Starting to test the car for longer distances, further than just my neighborhood, as I try to get it roadworthy.

Took it up the coast from my place on Pacific Coast Hwy. Freeway speeds. Generally went ok but on sweeping fast right bends, and right bends in the canyons, there was a loud clunking noise from the rear. Didnt notice it on left turns. Felt slightly violent and could have been from driveshaft/diff area.

Guibo and CSB were changed less than 1200 miles ago, BUT over 10 years ago. Appear tight and in good order though.

Diff bushings and transmission mount I put in a couple months ago and are brand new.

When I've been under the car in the past I checked the driveshaft for movement by hand, none evident.

 

What should I look at? What could be causing such a noise?

 

Edited March 1, 2023 by Pablo M
Added photos, clarified info

[Son of Marty]

First thing that comes to mind are the halfshafts or rear wheel bearings.

[Dudeland]

Do you have a rear sway bar?

 

[dlacey]

Exhaust hitting something?

[visionaut]

Worn stub axle and/or loose castellated nut..?

[Pablo M]

2 hours ago, Son of Marty said:

First thing that comes to mind are the halfshafts or rear wheel bearings.

Hmm, I can see that. How would I check that? When I was doing the brakes I checked the half shafts and wheels for play but they seemed solid. Try bay was just checking with my hands. Is there some better way to check?

2 hours ago, Dudeland said:

Do you have a rear sway bar?

 

Yes, factory bar. I had taken it off to do the suspension refresh (new shocks and springs). The bushings were dry rot like lots of other things with this car, but there wasn’t any play in the mounts that was obvious. 

2 hours ago, dlacey said:

Exhaust hitting something?

Someone mentioned that previously for another issue. Is the exhaust that bad haha? 
I checked it last time someone mentioned it and grabbing it and shaking it violently didn’t budge it. 

1 hour ago, visionaut said:

Worn stub axle and/or loose castellated nut..?

Stub axle? So not the half shaft itself as SoM mentioned? If the half shaft is bad it would be bad at the wheel right? If the stub axles bad it would be at the diff right? I do feel it more in the center. I’d suspect the csb if I hadn’t already checked that. 
wouldn’t a loose castellated but be obvious though? When I did the brakes they were on there pretty good, cotter pinned as well. How would I check any of these?

[Pablo M]

I'll get the car up on jackstands tomorrow and see if there's any evidence of things hitting each other, and subframe mount condition.

[2002iii]

3 hours ago, Pablo M said:

Someone mentioned that previously for another issue. Is the exhaust that bad haha? 
I checked it last time someone mentioned it and grabbing it and shaking it violently didn’t budge it.

Even with brand new exhaust mounts the exhaust is very close to the rear subframe. Definitely check your subframe bushings, if they flex and the exhaust moves they can touch.

 

Is your spare tire secured down?

 

Did you replace the motor mounts?

 

Check for tire rubbing on the inner fender well 

[Dudeland]

Wait, did you do the rear control arm bushings?  If you are in the twisties, then I would start there it would help in either case. 

 

 

 

[uai]

12 hours ago, Pablo M said:

Diff bushings and transmission mount I put in a couple months ago and are brand new.

Is the orientation of the diff bushings ok? 
Right Engine support bearing?
Rear axle bearings rubber ok?

 

[Mike Self]

If I had to hazard a guess: since it occurs only on right curves,, I'd suspect something on the right side in the car's rear axle...loose 275 ft/lb castle nut on the outer axle shaft, a loose or worn half shaft, bad right wheel bearing etc.  

 

I would also suspect that it if was a loose subframe, swaybar, exhaust etc you'd get a similar noise in a sweeping left turn...but that's just a (semi-)educated guess.

 

One more thing to test:  see if you get the noise in a sharp right turn--like at an intersection--taken with some elan.  No noise in a sharp turn may give you (and your readers) some additional insight and ideas...

 

mike

[beammmer]

Had this issue once, loose top shock mount. They were both loose so either which a way I turned clunking was present.  Maybe just the left one is loose or failed upper rubber mounting thingy.

Those unknown noises are really annoying.

Good luck.

Don

 

edit: And VERY satisfying when found and fixed

Edited March 1, 2023 by beammmer

[Mike Self]

1 hour ago, beammmer said:

Had this issue once, loose top shock mount. They were both loose so either which a way I turned clunking was present.  Maybe just the left one is loose or failed upper rubber mounting thingy.

+1 on that--great memory, Don.  I had a similar thump, but it occurred when going over bumps or unevenness in the pavement.  Couldn't find it, so finally had a friend drive the car while I sat in the trunk (on a residential street way back in our plat).  I had him first drive along with the left wheels on the unpaved verge, then the right.  When he did the right side, I could see the upper shock mount moving up and down under its rubber cap.  I tightened the upper mount and the noise was gone.  IIRC this was a year or so after installing new rear shocks, and I suspect the rubber bushings had collapsed a but under their load and thus loosened the upper mount.  

 

Certainly worth checking as it's an easy fix....

 

mike

[Pablo M]

15 hours ago, 2002iii said:

Even with brand new exhaust mounts the exhaust is very close to the rear subframe. Definitely check your subframe bushings, if they flex and the exhaust moves they can touch.

 

Is your spare tire secured down?

 

Did you replace the motor mounts?

 

Check for tire rubbing on the inner fender well 

I checked bushings and subframe does not seem to have any sloppy movement when "encouraged" with a big pry bar.

The exhaust does hit the underbody near the CSB. There are marks there and I can shake the exhaust to get it to hit. Don't know why it would only do that on right turns though.

Exhaust has new hangers at the back but it sits higher than the forward one so its doing nothing-whole exhaust hangs from the trans mount to the rear exhaust hanger. (Transmission mount is new IE urethane, trans exhaust hanger is original though)

 

Spare is not secured. Should make noise in either left or right turns if it were the issue though, I would think.

No, but motor mount (or perhaps only the left bracket) were done in 1999. I do have new mounts I need to install when I get some time.

Oof, forgot to check for rubbing. I'll check for that shortly.

 

 

 

11 hours ago, Dudeland said:

Wait, did you do the rear control arm bushings?  If you are in the twisties, then I would start there it would help in either case.

For sure they're needed, and original. They show signs of dry rot cracking. Taking a long pry bar to the control arm bushings I can't get them to move though, so no outward slop.

 

 

9 hours ago, uai said:

Is the orientation of the diff bushings ok? 
Right Engine support bearing?
Rear axle bearings rubber ok?

Yes, I installed new IE diff bushings and they're directional so only go on one way.

You mean right motor mount? No, mounts are original but I did buy new ones. Need to find time to install. Motor doesnt move much when idling so I don't think the mounts are bad, but they're old so very possibly.

Axe rubber? You mean the boots? They are not cracked open at all, but show surface cracking from dry rot/age.

 

 

8 hours ago, Mike Self said:

If I had to hazard a guess: since it occurs only on right curves,, I'd suspect something on the right side in the car's rear axle...loose 275 ft/lb castle nut on the outer axle shaft, a loose or worn half shaft, bad right wheel bearing etc.  

 

I would also suspect that it if was a loose subframe, swaybar, exhaust etc you'd get a similar noise in a sweeping left turn...but that's just a (semi-)educated guess.

 

One more thing to test:  see if you get the noise in a sharp right turn--like at an intersection--taken with some elan.  No noise in a sharp turn may give you (and your readers) some additional insight and ideas...

 

mike

I jacked the car up on jackstands and pulled the rear wheels. castle nuts don't look like they've been off the car in decades. No movement from vigorous testing by hand. I agree, if it were something not side specific like the subframe it would make some sort of noise in each direction, in theory.

Will have to test slow sharp right turns. From memory it did not make noise doing regular intersection turns, but I did not give it any speed there. I'll retest that and verify.

 

 

8 hours ago, beammmer said:

Had this issue once, loose top shock mount. They were both loose so either which a way I turned clunking was present.  Maybe just the left one is loose or failed upper rubber mounting thingy.

Those unknown noises are really annoying.

Good luck.

Don

Thanks. Shocks are new to the car (I installed them december, but they were lightly used). Rechecked the mounts and they seem tight and rubber feels newish.

 

 

---   ---- 

 

Thanks again for all your insights. I'll keep testing to see if I can pinpoint when noise happens and not. I have video of the bottom, with me turning the axles and shaking the  that I'll try to attach here in a moment. When I installed the diff mounts I also pulled the cover and redid the seal as it showed signs of long term seepage all over the diff. No evidence inside the diff of 'loose parts' either in the bottom of the diff or in the oil. Driveshaft feels tight in the CSB and guibo, not much play to speak of. Guibo was also installed in 1999 but only 1,000 miles ago. No visible signs of dry rot.

 

Video to follow...

[jgerock]

8 hours ago, beammmer said:

Had this issue once, loose top shock mount. They were both loose so either which a way I turned clunking was present.  Maybe just the left one is loose or failed upper rubber mounting thingy.

Those unknown noises are really annoying.

Good luck.

Don

 

edit: And VERY satisfying when found and fixed

That was Vintage 2009 correct?  Matthew Cervi and I rode in the back seat for a sound check of the noises. 🤷🏻‍♂️