Cadillac Owners Forum banner

1 - 20 of 21 Posts

·
Registered
2004 CTS - 245K
Joined
·
253 Posts
Discussion Starter #1
Hi all,

I am continuing to have a thud noise from my drive shaft unfortunately. A little back story, I’ve changed my center bearing twice (thinking it was the issue) to no avail. Also changed my coupler on the drive shaft as well as my transmission mount to no avail. The sound only occurs when about 35 percent or more on throttle in certain conditions.

If turning left or right from a stop or low speed corner, after getting back on the on the gas it’s almost most guaranteed to “thud thud thud” we are talking a very hard thumping noise from a 0-15 mph. Sound appears to be right under the arm rest. Once momentum is gained no issues at all.. car drives like a dream. Certain 0-60 runs it sings and other times it does not and you’d swear it was perfect.

Corner accelerating is the only guarantee it will thud consistently. With that being said, I’m running out of ideas about to take it to a shop for diagnostics but before doing that I wanted to see if anyone had ideas or further thoughts?

I have read that engine mounts can cause this too? I am no expert on how to tell If they are bad however. I’ve attached this video
here which shows my engine moving while in drive foot on the brake and applying throttle. If anyone has experience to tell me if this is normal movement, it would be appreciated.

I can certainly attached the video of the sound it makes if that would be any help. I appreciate any help or thoughts provided. Thank you.
 

·
Registered
2007 CTS 3.6 >131k miles
Joined
·
701 Posts
The engine movement in your video does not appear to be bad. If you Google 'bad engine mounts' you can see that the abnormal movement is usually obvious.

Also, you mentioned the thump when you take off while turning...does your car have a limited slip differential?

A video of your situation would be helpful.
 

·
Registered
2004 CTS - 245K
Joined
·
253 Posts
Discussion Starter #3 (Edited)
The engine movement in your video does not appear to be bad. If you Google 'bad engine mounts' you can see that the abnormal movement is usually obvious.

Also, you mentioned the thump when you take off while turning...does your car have a limited slip differential?

A video of your situation would be helpful.
Hi Ryan,

thanks for checking the mounts video. I do have a limited slip differential, correct,

I replaced the oil a while back and used mobile1 fluid with “limited slip friction modifier included”. Here is a video of the sound, hopefully that helps.

the video makes the sound, sound higher pitch but in reality it’s a deeper hit sound in the car.
 

·
Registered
2007 CTS 3.6 >131k miles
Joined
·
701 Posts
I would think the LS additive already in the M1 is sufficient, and the fact that it also happens when you are going straight suggests some other issue.

i will ask my cousin later today for potential causes...he has a lot more experience than I do.
 

·
Registered
2004 CTS - 245K
Joined
·
253 Posts
Discussion Starter #5
I would think the LS additive already in the M1 is sufficient, and the fact that it also happens when you are going straight suggests some other issue.

i will ask my cousin later today for potential causes...he has a lot more experience than I do.
Thanks! Any thoughts or suggestions of things to check would be appreciated. I certainly don't mind checking. I'd rather not admit defeat and take it to a shop if I don't have to.
I really appreciate your time, thanks again.
 

·
Registered
2007 CTS
Joined
·
210 Posts
Have you checked the differential support bushing? It as been a problem for a few folks. Some have changed from rubber to poly, with help using the tool & bushing from Creative Steel.
 

·
Registered
2004 CTS - 245K
Joined
·
253 Posts
Discussion Starter #7
Have you checked the differential support bushing? It as been a problem for a few folks. Some have changed from rubber to poly, with help using the tool & bushing from Creative Steel.
I have not physically removed the drive shaft to check the bushings, but from what I can tell by hand it feels very solid.
I put a jack under it and applied pressure and not much movement either. Assuming they've been on the car for 245K without change, so it certianly wouldn't hurt to change them I suppose.
 

·
Registered
2007 CTS 3.6 >131k miles
Joined
·
701 Posts
I was also thinking of the differential bushing. If completely deteriorated, the front of the differential bolt will dance around within the sleeve during hard acceleration. However I would also expect a few thumps when you back off the gas. My bushing also felt tight when trying to move it with a jack but the top half was mostly gone! Here is an old thread (see my post #49 near the bottom with pics)
Replacing rear differential bushing on 2005 CTS 3.6

Also possible that other suspension parts are deteriorated or broken.
 

·
Registered
2004 CTS - 245K
Joined
·
253 Posts
Discussion Starter #9
Front suspension was replaced recently entirely including control arms, tie rods shocks, etc.
Back suspension hasn't been touched ever to my knowledge. Your bushing certainly was shot, I do not notice any issues letting off the gas in my case. Only mid acceleration.

At this point I would not be surprised if the bushing needed to be replaced as it's certainly had it's share of use, I just don't have any positive signs pointing to it saying that I am the problem. (yet)
I'm going to see if I can strap a go pro under the car somewhere and see if I can watch the rear differential dance at all under pressure.
 

·
Registered
2007 CTS 3.6 >131k miles
Joined
·
701 Posts
The go pro vid would be helpful. Hopefully this works and the cam doesn't drop to the road during the test!
 

·
Registered
2004 CTS - 245K
Joined
·
253 Posts
Discussion Starter #11
The go pro vid would be helpful. Hopefully this works and the cam doesn't drop to the road during the test!
The go pro vid would be helpful. Hopefully this works and the cam doesn't drop to the road during the test!
I managed to get a video of the rear differential today.
During the video I only got it to thump a few times on two separate runs.

It appears the drift shaft certainly moves a bit during accelerations, I am just not certain how much movement is normal.
 

·
Registered
2007 CTS 3.6 >131k miles
Joined
·
701 Posts
I was listening for the thump in the video but really couldn't tell when they occurred. I presume the microphone did not pick it up given the wind noise etc. Was the thump loud inside the car during these runs?
 

·
Registered
2004 CTS - 245K
Joined
·
253 Posts
Discussion Starter #13
I was listening for the thump in the video but really couldn't tell when they occurred. I presume the microphone did not pick it up given the wind noise etc. Was the thump loud inside the car during these runs?
AT 48 seconds on that run inside the card a loud noticble thump noise for a few thumps. Unfortunately as mentioned no sound in the video :(
 

·
Registered
2005 Base CTS work at Pullen solenoids Glass Factory for 36 and a half years
Joined
·
170 Posts
Check your front wheel bearing hub assembly by jacking it up and then spinning the wheel and seeing if you can just shake it back and forth a little bit also when you have one side jacked up but the other side on the ground grab the wheel front and rear and see if there's much movement, if there is that's usually an indication of a tie rod and after that grab it top and bottom and see if you get much movement, if you do that's generally a ball joint. Make sure one side is still on the ground when you do this. Link to wheel bearing hub assembly:

Roy
 

·
Registered
2004 CTS - 245K
Joined
·
253 Posts
Discussion Starter #15
Thanks Roy! all seems to check out there. Also Thanks to Ryan for assisting.
I have good news and bad news to report. The good news is I have a video of the drive shaft shaking vioelntly (It;s no longer just in my head lol) the bad news is I don't know whether it would be the center carrier bearing or if it is the rear drive shaft bushing that would cause this.. Thoughts anyone?

Sorry no sound, but if you watch at the video you will see a few real good violent wobble back and forth.
https://youtu.be/JINTzn9QRq0
That is what is causing the thumping sound for sure. Now just to figure out what would be causing that drive shaft to be that bad during heavy acceleration?

Thanks again to all involved.
 

·
Registered
2007 CTS 3.6 >131k miles
Joined
·
701 Posts
Wow! That is a lot of movement. It's hard to tell from the video whether the most movement is at the front or back of the shaft. Given that you already changed the bearing twice, I would lean toward the rear bushing. However, I have not seen one wobble this much with a bad bushing. Could be more going on inside the diff than just the bushing.
 

·
Registered
2004 CTS - 245K
Joined
·
253 Posts
Discussion Starter #17
Went out to remove the drive shaft support bushing and the metal casing surrounding the bushing seems to heat welded itself to the casing of the differential. When chizzling away unfortunately broke apart and now will be replacing the differential lol.

So now 200 dollars in for a new (used 89K) differential and while I am at it, going to throw a OEM / AC delco center support bearing on and two new flex disc. If it still does it after that, I am going to live with it.

Two questions for anyone that may know, how will this impact my balance having a new differential?
Second question, do I need to take my rear wheel bearing out to get to the CV join axle that's connected to the differential currently or is there a easier way.
 

·
Registered
2007 CTS 3.6 >131k miles
Joined
·
701 Posts
That is awful! I hate when things end up costing a lot more than I plan for! At least the replacement unit is only 200 (+ the other items that will now be new...

If it still vibrates after the replacement I would suspect the driveshaft.
 

·
Registered
2005 Base CTS work at Pullen solenoids Glass Factory for 36 and a half years
Joined
·
170 Posts
Make sure you replace as many bushings as you can from either revshift or creative Steel.

Roy
 

·
Registered
2005 Base CTS work at Pullen solenoids Glass Factory for 36 and a half years
Joined
·
170 Posts
I'm probably going to buy the complete revshift bushing kit for mine:


Roy
 
1 - 20 of 21 Posts
Top