Rear End Popping Noise

M4rk

M4rk

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Well since my previous thread has changed direction into an entirely new issue, I thought it would be better to just start a new thread.
Old thread RE possibly leaking half shaft seals: http://www.lincolnvscadillac.com/showthread.php?t=81839


Anyway, my current issue is a popping nose coming from the rear end, passenger side. The noise happens when braking, turning, straightening the car following a turn, or even when driving on uneven surfaces. To me, this suggests that it could be the subframe (searching points to other owners with the same symptoms under the same conditions), or perhaps (and hopefully) one of the control arms. The noise is only present when the outside temperature is warm, about >10C (50F). When it's cool outside, the car is absolutely silent. When it's nice and warm, the noise is very apparent, but difficult to hear from the outside.


I posted this picture of a cracked subframe bushing (passenger side) in my old thread:


DSC_2724-s.jpg



Some relevant information:

  • I attempted to tighten the bolt, but it is already very tight, way above the torque specs it seems.
  • While swapping on my summer wheels, I pried on the LCA's inner attachment point (closer to the front of the car), and was able to move the arms on both sides up/down slightly - is this normal behavior of the rubber bushings?
  • With the passenger rear wheel in the air, I checked for play with the 9&3 and 12&6 o'clock hand position test, but everything was tight
  • Also, sometimes when rocking the car side-to-side, I can hear a metal-on-metal clunk coming from the passenger rear side.
  • My toe links are infested with cancer
  • End-links replaced 2 years ago


Any thoughts, ideas, feedback, etc would be greatly appreciated, along with ways that I could attempt to diagnose this myself.

Thank you.
 
I had a rear end popping that was most apparent at full lock left or right. I went to have an alignment done and the dealer said one of my rear sway bar link was bad, replaced with new and no more noise. Sorry can't help with diagnosis.
 
I think it is your blasted bushing. The LCAs should have some wiggle when pried,but that cracked bushing is a big problem. If you want, get a couple of fairly thick plates (not electrical box flat blanks, I used lolly column end plates, two together), drill them out for that bolt, reassemble with the plates clamping down on your subframe steel outer bushing. If the noise goes away, you know what the problem is. When you take out the bolt, all of the inside of that tube it is holding down will fall out in shards. It is toast and the bolt is holding it together, but it is not securing your subframe corner.
 
milehighmikey said:
I think it is your blasted bushing. The LCAs should have some wiggle when pried,but that cracked bushing is a big problem. If you want, get a couple of fairly thick plates (not electrical box flat blanks, I used lolly column end plates, two together), drill them out for that bolt, reassemble with the plates clamping down on your subframe steel outer bushing. If the noise goes away, you know what the problem is. When you take out the bolt, all of the inside of that tube it is holding down will fall out in shards. It is toast and the bolt is holding it together, but it is not securing your subframe corner.
Click to expand...

Thanks for the info! I saw your thread/posts on the subject - I am afraid of removing the bolt in the even that the internals of the bushing fall out and I won't be able to assemble it back together safely. I plan to keep the car for a few more months, but I refuse to spend thousands of dollars on a new subframe. Up here in Canada, finding wrecked LSes doesn't appear to be easy. Even if I sourced a used subframe, it would surely take hours of work to have to swap done.

Is there any way I could test the bushing itself without removing the bolt?


JaredLS said:
I had a rear end popping that was most apparent at full lock left or right.
Click to expand...

Thanks for the tip. Unfortunately my problem is present regardless of steering angle. Of course, that would also be too easy.
 
If you do some fabrication, you can cut a piece of steel pipe to go to the subframe bushing mounting point, which should be perhaps 8 mm shorter than the overall height of the steel outer bushing, add the two plates (or, one thicker one) the bolt and you will have a restrained subframe at that corner. The steel inner pipe would act as a final depth of compression of the flexing of the steel plate, allowing the steel plate to hold the subframe firmly, and allowing your bolt to tighten to specification and stay tight. It's really a shame that the bushings are not replaceable, regardless of the fact that you would have to still be dropping the subframe to change them. That would beat having to purchase a USD$2000 replacement part.
 
M4rk said:
Thanks for the info! I saw your thread/posts on the subject - I am afraid of removing the bolt in the even that the internals of the bushing fall out and I won't be able to assemble it back together safely. I plan to keep the car for a few more months, but I refuse to spend thousands of dollars on a new subframe. Up here in Canada, finding wrecked LSes doesn't appear to be easy. Even if I sourced a used subframe, it would surely take hours of work to have to swap done.
Click to expand...

I found a used subframe on ebay for 140 with shipping. You should check ebay somebody should ship one to Canada. I would have the other parts checked. When my bushing went out i could see the crack and pulled parts of it off. Also mine only popped when starting from a light or stop sign. Being that you get popping from any motion have your other parts checked 1st. If you've looked at your subframe bushings and do not see any cracks then it's possible it might be something easier to fix.

(just saw the pic in other thread, doesn't look good, but you never know. Replace other bad parts first you might get lucky.)
 
Thanks for the information guys. I should really remove that bolt to see what the real deal is, but first I'll get the MacGyver fix ready to prepare for the worst.

@milehighmikey Since you have replaced your subframe, and presumably saw the bushing(s) from every angle, is there any way you could sketch its cross-section in MS Paint or similar? I would greatly appreciate it!
 
I can do even better. I can photograph the old subframe holes and also the good bushings from both sides. I should have something for you by tomorrow night. (Monday, 4/9)
 
Update!

I think I was able to capture the noise on my dashcam/GoPro. Even though it's perfectly audible from within the cabin, I never heard the (popping) noises reflect from the outside, so I gave the camera a try. This was the only occurrence in the entire original clip where you can hear anything out of the ordinary, namely the click-clack a the 2 second mark, later repeated in slow-mo. I spent about 10 minutes on the campus parking lot making circles in both drive and reverse and this is all I was able to capture, so I am a little disappointed.


YouTube Link (watch in HD!): http://youtu.be/8KcSrZICwx0


Tomorrow = Judgement Day as I will be taking the car to a mechanic to have it looked at :) I will be sure to post an update.
 
Update #2!

Took it to a garage this morning. The tech took it for a test drive, and of course there were no noises at all :rolleyes: They checked out the entire rear end and said it was all "nice and tight." Their suggestion: keep driving it until it gets worse or there is play of some kind.

I guess that's as far as I will go with this, as I don't want to start blindly replacing all the control arms in the back. It sure will be hella annoying this summer..
 
Ha, I told you it was nothing.. :shifty: Now drive down to toronto and shoot some photos with me dawg.
 
i occasionally (although havent heard it in a while) have a similar noise... Mine sounds like a snapped sway bar link and the swaybar is bouncing up and down... usually coming out of a turn.... sound similar?
 
G-RELL said:
i occasionally (although havent heard it in a while) have a similar noise... Mine sounds like a snapped sway bar link and the swaybar is bouncing up and down... usually coming out of a turn.... sound similar?
Click to expand...

Not sure. I can't even describe the noise properly lol. "Popping" comes the closest.. it's really weird. I'll try to actually record it soon. Stay tuned.
 
VIDEO UPDATE #2!

Few thousand KMs later, the noise has gotten much worse and is finally audible from the outside, and can be replicated when the trunk is unloaded or by pulling up on it. I am 99% sure it's the passenger rear LCA (rear ball-joint type bushing is bad). Ordering new arm - will update when I swap it in. :)


Lincoln LS Rear End Noise (Underside View) - YouTube
 
**Final Update**

After swapping out the suspected rear lower arm, the popping/clunking/creaking noises have completely stopped! As per the video above, the noisy rear ball-joint bushing was very worn. Turning it by hand I clearly felt the worn out areas as the motion was very rough.

I am glad this turned out to be something relatively minor, compared to the subframe bushing as speculated at first. Guess I will be keeping this car for a bit longer :D
 
Good to hear it wasn't the worst possible outcome as it so often can be. You had good rhythm in the first part of the video lol
 
Sweet. That noise would've definitely bugged me, not my dad though.
 
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