Hello everyone. Is anyone getting a thumping noise with rattle in the right rear of the vehicle when going over depressed manholes or ripples in the highway? I mentioned this problem on another post that was specifically for a noise in the rear passenger area. Some thought the noise was from the rear passenger door. My noise occurs when the wheel drops with a normal thump but something rattles along with the thump, like something is loose in the trunk or under the vehicle. I checked many places, including the fuse box, spare tire etc. and have even added pieces of foam to parts of the plastic inner fenders but nothing has stopped the noise.

I’ve been to the dealer several times and they do not think the noise is caused by the rear door since there is no TSB on the CTS for that. They think it may be just a normal thing related to the lower profile 18’ wheels. I told them the noise never occurs on the right side so how could that be.

The dealer checked all TSB’s on the 08 CTS and found nothing related to rear suspension noise. I’m starting to think that the noise may be related to a shock absorber or differential but the dealer disagrees.

Is anyone else experiencing this? I have FE2 suspension with RWD and no sunroof, build date 1/08. I have folding seats but they seem OK. I love the car but this is very annoying in an otherwise very quiet car. I have no other problems.

check your exhaust. if the steel hangers on the piping or muffler are slightly bent, the exhaust may be hitting the suspension. not experience with the CTS, but experience with right rear "suspension' rattles. If you can get the car in the air, pry-bar the rubber exhaust hangers and see if you get a noise.

Thanks Ngiardina. The dealer checked under the car and said everything seemed tight. I'm not sure if they tried a pry bar on the exhaust pipping.

Thanks Ngiardina. The dealer checked under the car and said everything seemed tight. I'm not sure if they tried a pry bar on the exhaust pipping.

You might check the rear stabilizer bracket. At 585 miles my car a problem like yours but with a much more severe noise problem. I could actually see the right rear stabilizer broken bracket from near the wheel well after looking back and forth on the left side to see as difference. Dealer repaired in minutes after getting the part (which took 4 hours).

Thanks PJL. Will check mine.

MFG Bulletin Date: 20071001
Component: POWER TRAIN: DRIVELINE: DIFFERENTIAL UNIT
Bulletin Summary: LOOSE REAR DIFFERENTIAL BOLT - NOISE ON CERTAIN 2008 CADILLAC CTS. *NJ
Date added to datbase: 20080109



Could be the above?!

Mine is in the shop for this as we speak. Dealership called yesterday and said they are replicating the problem but have not been able to diagnose it yet.

They asked to keep the car over the weekend. I said that's fine, I don't want it back until it's fixed.

I will update when I know what the problem was.

I hope you get an answer. Is your dealer checking the differential as suggested by Da Thrilla above?
I had mine in to the dealer (Faulkner, Phila area) for another test drive yesterday. The service writer at least recognized the noise this time but did not have any idea what it was other than it is definitely not from the right rear door. The dealer had my car for a day about 6 weeks ago but did not hear or understand the noise. They only visually checked the rear suspension.

FYI:
I found out that the rear differential noise bulletin covered only 48 earlier production vehicles according to the GM Inside Line unless there was another more recent bulletin. See excerpt below:

"PRODUCT FIELD ACTION ANNOUNCEMENT
THIS PROGRAM IS IN EFFECT UNTIL OCTOBER 31, 2008.

General Motors is announcing Customer Satisfaction Program 07271 today. The total number of vehicles involved is 48. Please see the attached bulletin for details.

LOOSE REAR DIFFERENTIAL BOLT - NOISE ON CERTAIN 2008 CADILLAC CTS. *NJ

Dealer called me yesterday.

Said that they isolated the noise to the right rear shock absorber. They called the GM Technical Assistance center who said there was a bulletin out for this and advised them to in fact replace both rear shocks.

They ordered the parts yesterday, should be in Monday, I should get the car back Tuesday.

I'll let you all know if it took care of it.

Thanks FG3. Will be looking forward to the results. Let us know the name of your dealer if you can.

Hello everyone. Is anyone getting a thumping noise with rattle in the right rear of the vehicle when going over depressed manholes or ripples in the highway? I mentioned this problem on another post that was specifically for a noise in the rear passenger area. Some thought the noise was from the rear passenger door. My noise occurs when the wheel drops with a normal thump but something rattles along with the thump, like something is loose in the trunk or under the vehicle. I checked many places, including the fuse box, spare tire etc. and have even added pieces of foam to parts of the plastic inner fenders but nothing has stopped the noise.

I’ve been to the dealer several times and they do not think the noise is caused by the rear door since there is no TSB on the CTS for that. They think it may be just a normal thing related to the lower profile 18’ wheels. I told them the noise never occurs on the right side so how could that be.

The dealer checked all TSB’s on the 08 CTS and found nothing related to rear suspension noise. I’m starting to think that the noise may be related to a shock absorber or differential but the dealer disagrees.

Is anyone else experiencing this? I have FE2 suspension with RWD and no sunroof, build date 1/08. I have folding seats but they seem OK. I love the car but this is very annoying in an otherwise very quiet car. I have no other problems.
Correction: Above should read noise never occurs on left side!!!

I have the same problem, 4 trips to dealer and they tell me they can't fix it. email me if you like, posting here is unbelievably slow.

I have the same problem, 4 trips to dealer and they tell me they can't fix it. email me if you like, posting here is unbelievably slow.

information that helps the community should be posted publically.

Well the dealer called today. They apparently ordered the wrong parts. New shocks are supposed to be in tomorrow. We'll see.

Hopefully they get it right. I keep thinking I'm going to end up with FE2 shocks up front and either FE1 or FE3 shocks in the rear. Ugh.

It's a shame I don't have more confidence.

Again, I'll keep you all updated.

Thanks for the update, FG3. I know what you mean by "not having coonfidence". Let's hope your dealer get's it right this time.

Update: Dealer ordered the wrong parts again.

So now, they used the stamping on the shocks taken off of the car to order the new ones.

Hopefully will get the car back tomorrow now.

Don't buy those guys any ice cream cones......I would hate to see them poke an eye out.........

information that helps the community should be posted publically.
Have you not noticed it takes days to get a post up here lately? That's why I asked for email, I didn't have another 3 days to blow trying to post here. I have a lemon lawsuit pending and that's not something I want to discuss publically. Last I checked Private Messageing is still ok here.

Any update on a fix for this problem?

Yes. sorry for the delay.

Well they got the new rear shocks on and they didn't fix the problem.

Cadillac told them to check the bushings where the shock mounted to the lower control arm. Apparently the bushing on the right side was very loose and the one on the left was not.

They tried to order new bushings, but they are not available as a separate part, they are part of the control arm assembly. Of course the control arm assembly was not inventoried anywhere so they were told it could take up to 2 weeks for the parts to come in. They are going to be replacing them on both sides.

I got my car back on Thursday 4/24/08. It still makes the noise and the dealer is waiting on parts.

I'll let you know when I have more info.

Frank

Thanks again FG3. I'm sorry to hear the shocks didn't solve the problem. I have another appointment with the dealer on Monday. I told them about your experiences. If I have any luck getting this issue resolved, I'll post here.

Let me know what happens Monday... again sorry for the delay in reply - I've been traveling and kind of out of the loop on a lot of things.

I'll be giving my dealer a call on Monday to find out the status of those parts.

Thankfully they acknowledge the problem and have some speed bumps on their lot where they can duplicate it.

Frank

Just called my dealer to check on the status of the parts. Got the left one in, but not the right one yet.

My service advisor also told me that he's had a second car come in with the exact same problem. For some reason, I was glad to hear it...

Frank

Thanks for the update Frank. I left my car at the dealer today. They gave me a loner and are going to hook up sound recording equipment to help isolate the noise. I gave them the information about the control arms and they checked the availability just in case they need one. They said the right side arms were available in Tennesse. They did not check for the left. They also said they would keep the car for a few days.

Jim

My dealer called today and had me pick up my car. They said they think they isolated the problem to a bushing that somehow attaches the shock to the stabilizer bar or control arm. They said there is a bulletin on it. I do not have all the details other than that the bushing is not available at this time. They will call me when they find one. I hope this will eventually resolve the issue.

Well at least we're getting a consistent story. I was told the same thing... see post #21 in thread.

Now we just wait for the parts and hopefully it will be resolved.

I'm a bit concerned my dealer may be trying to get a bushing that is part of the control arm as you reported in post #21. The service writer said they ordered the control arm at my suggetion but that they needed a separate bushing. I think your dealer may be correct since they have been working on this longer.

I am dealing with the same issue. It was fixed for a short period of time, I think. My folks at my dealership have been quite patient with me while trying to figure this out. There was one "ride" where they actually had a tech riding in the trunk and found that the cap on the strut was missing.

The most recent find is that the panel that separates the rear window and the rear passenger doors is bouncing a bit. It is held in place by one clip near the top. They put some foam behind it and that stopped it.....for awhile. What I think happened after that was that the foam slipped when the panel came loose...........or at least that's what I am surmising. Check it out. It makes ME crazy, and now I my drivers window makes a noise when it opens all the way if I just hit the button and open in in express mode. Does yours do that? FYI, I have about 7,000 miles on mine.

I think my dealer (Faulkner, Phila) may have finally solved the noise in my rear suspension. They replaced a F-Knuckle assembly in the right rear that had a loose bushing. The part no is 15775072. They ordered it last week and it came in a few days later.

I hope this works. I did not hear the noise on the way home from the service dept. I also hope this info can help others with this problem.

Jim

Great to hear auraph!

I got a VM yesterday from my dealer letting me know my parts are in. I just need to get my car in to have them replaced.

I'll let you know if it took care of mine as well.

Frank

2008 CTS with 4,000 miles and have the exact same problem. What was the final fix and do you now the technical service bulletin?
Thanks

Bump - I have the same problem. The dealer replaced both rear struts and the noise came back after a day. Is there a fianl resolution to this issue?

I had what I believe was the same issue. I would hear a thump from the back right corner of the car. When I first heard the noise, I stopped the car to close the trunk as it sounded like the trunk was partially open. The dealer initially thought it was the air pump bouncing in the trunk. This did not solve the problem, but they did on the second visit. They found that there was a problem with the bushing in one of the knuckles in the right rear suspension. They replaced the knuckle in May. This immediately solved the problem and it has not returned.

Since this thread has been resurrected, I guess I should let you all know that replacing the bushing back in May did fix my issue once and for all...

Frank

Hi all. I noticed the same noise coming from right rear wheel area a few weeks ago and brought my car in on 7/30/08. They determined it was the right rear shock bushing was loose in the knuckle (whatever that means!!!). They replaced the knuckle assembly (Part # 15775072). My car was not ready until 8/6/08 because they said this part was on back order. Now I understand why, looks as though many others may be experiencing this same issue. My car has 3000 miles.

Maria

Yes the fix worked. My car has been noise free since the fix in May. See my post above from 5/14 for the the F-Knuckle replacement part number. I do not have a bulletin number.

Mine turned out to be a loose headrest rail in the passenger side rear seat back. Even though the headrest doesn't move, the rail was loose. Try lowering the rear passenger seat back and hitting it with your fist. That should replicate the noise if that is it.

Yes the fix worked. My car has been noise free since the fix in May. See my post above from 5/14 for the the F-Knuckle replacement part number. I do not have a bulletin number.

Who was your advisor at Faulkner? I have the same problem and go to Faulkner. Don't want to get the run around.

Thanks

My advisor at Faulkner in Trevose, PA was Larry. He should remember this repair since I was in four or five times from March till May till the issue was resolved. He was very patient with me.

Jim

I had the same exact problem. The first time I brought it in they replaced the rear stabilizer shaft links. The part numbers are 25964513 and 25964514. This did not fix the problem so I brought it back. The second time they replaced the rear wheel F-Knuckles left and right. The part numbers are 15775071 abd 15775072. This fixed the problem and the noise is gone. I should also mention that I have the FE2 suspension and all wheel drive.

Paul Nowak

Thank goodness for this thread. I have been dealing with this exact same problem since January. I just forwarded this link to my dealership and hopefully this will solve it once and for all.

Have you not noticed it takes days to get a post up here lately? That's why I asked for email, I didn't have another 3 days to blow trying to post here. I have a lemon lawsuit pending and that's not something I want to discuss publically. Last I checked Private Messageing is still ok here.

In addition, private messages are not intended to deprive the Community of valuable information or experiences which could benefit the entire group. Please do not use private messages if the content of the message can be helpful to others.

http://www.cadillacforums.com/agreement.html

I had the same exact issue with my RWD CTS with FE3 suspension. I took it into my dealer 4 times for the issue before they fixed it by replacing the knuckes on both rear wheels.

The printout from the dealer referenced a tech service bulletin. I can get you the TSB number if need be.

The printout from the dealer referenced a tech service bulletin. I can get you the TSB number if need be.

Please post it as my dealer is making no headway after 3 visits. Thanks!

The printout from the dealer referenced a tech service bulletin. I can get you the TSB number if need be.

Please post it as my dealer is making no headway after 3 visits. Thanks!

My service printout reads as follows:
"OWNER STATES OF A THUD TYPE NOISE COMING FROM REAR OVER BUMPS
INSTALL SOP
CHECK OUT AND HEARD NOISE COMING FROM BOTH REAR KNUCKLE ASSEMBLIES BULLETIN 08-03-09-002
REPLACED LEFT AND RIGHT REAR KNUCKLE ASSEMBLIES
NE 93 E4760 1.1
OLH 1.1 LEFT SIDE"

It was all done under warranty, but took a few weeks for the parts to come in (like 6). It took them 2 days to get it fixed, but I must say I am more than happy with the result. NO NOISE on bumps!!!!!!! Good luck.

Here is the text of that service bulletin - my VIN is much earlier than the range shown, but going to look for the source of the noise in this area anyway before I go back to the dealer. Thanks for helping!

#08-03-09-002: Clunk Noise Coming >From Rear of Vehicle When Driving Over Bumps (Replace Affected Rear Suspension Knuckle) - (Sep 22, 2008)
Subject: Clunk Noise Coming From Rear of Vehicle When Driving Over Bumps (Replace Affected Rear Suspension Knuckle)
Models: 2008 Cadillac CTS
Built From VIN Breakpoint 80162159 through 80195175

________________________________________

Condition

Some customers may comment on a clunk noise coming from the rear of the vehicle when driving over bumps.

Cause

This noise may be caused by contact between the shock absorber and the suspension knuckle. This contact occurs when the knuckle to shock absorber bushing becomes unseated from its position.

Correction

Inspect for contact and replace the rear suspension knuckle, if necessary. Do not replace the lower control arm, rear frame, shock absorber, stabilizer shaft links or any other rear suspension components.

Check the shock absorber lower bushing in the rear suspension knuckle on both sides of the vehicle. Inspect for contact between the shock clevis bracket and the knuckle (2). If the bushing appears to be loose and contact is occurring, replace the knuckle.

Parts Information

Part Number Description
15775071 Knuckle, Rear Suspension (Left)
15775072 Knuckle, Rear Suspension (Right)

Warranty Information

For vehicles repaired under warranty, use:
Labor Operation Description Labor Time
E4760 Knuckle Assembly, Rear Wheel (Right) -- Replace Use Published Labor Operation Time
E4761 Knuckle Assembly, Rear Wheel (Left) -- Replace
Note: For alignment times, refer to operation E2020 and add the applicable times to regular labor hours.
GM bulletins are intended for use by professional technicians, NOT a "do-it-yourselfer". They are written to inform these technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions, and know-how to do a job properly and safely. If a condition is described, DO NOT assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See your GM dealer for information on whether your vehicle may benefit from the information.
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