Knocking from rear when coasting?
Thread Starter
Teching In
Joined: Apr 2006
Posts: 2
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Knocking from rear when coasting? I have a 2002 WS6 (stock) with 70 000 km and I'm getting a knocking noise coming from the rear end, usually when I'm coasting to a stop. It doesn't happen always or consistantly, but sometimes it's pretty loud. It seems to happen when the car isn't being "engaged" (accelerating or given gas) - just when coasting or cruising without giving it much gas. When I am coasting to a stop, the knock will slow down in time with the speed of the car, slowing down as the car slows. Once stopped, there is no noise.
I've had it looked at twice now, U-joint checked, etc... I had a mechanic ride with me, and he said it was something to do with the differential in these cars. He told me about another Trans Am that they had looked at with the exact same problem, they replaced some stuff in the rear and it was actually worse...
This can't be normal - it's annoying as hell, and people riding with me are like "what is that noise?"
Has anyone heard of or experienced something similar? I still have a few months of warrantly left - I think they just don't want to bother unless I'm paying for it...
I've had it looked at twice now, U-joint checked, etc... I had a mechanic ride with me, and he said it was something to do with the differential in these cars. He told me about another Trans Am that they had looked at with the exact same problem, they replaced some stuff in the rear and it was actually worse...
This can't be normal - it's annoying as hell, and people riding with me are like "what is that noise?"
Has anyone heard of or experienced something similar? I still have a few months of warrantly left - I think they just don't want to bother unless I'm paying for it...
On The Tree
Joined: Apr 2006
Posts: 162
Likes: 1
From: Boring Ohio
A couple things, my car did the same thing, it was actually brake pads, if it comes when you lightly apply the brakes its probably the pads fitting loosely in the brackets, if its always there brakes or not then I'd be looking towards side gears in the differential.
TECH Regular
Joined: Jan 2004
Posts: 496
Likes: 0
From: GARDEN GROVE, CA
Mine has been doing this for the last 25k miles after having the rearend rebuilt for the second time in 6 months. It hasn't gotten worse and I have come to live with. I did a burnout once to see if I was painting two tires strips and I am.
Originally Posted by noisy
I have a 2002 WS6 (stock) with 70 000 km and I'm getting a knocking noise coming from the rear end, usually when I'm coasting to a stop. It doesn't happen always or consistantly, but sometimes it's pretty loud. It seems to happen when the car isn't being "engaged" (accelerating or given gas) - just when coasting or cruising without giving it much gas. When I am coasting to a stop, the knock will slow down in time with the speed of the car, slowing down as the car slows. Once stopped, there is no noise.
I've had it looked at twice now, U-joint checked, etc... I had a mechanic ride with me, and he said it was something to do with the differential in these cars. He told me about another Trans Am that they had looked at with the exact same problem, they replaced some stuff in the rear and it was actually worse...
This can't be normal - it's annoying as hell, and people riding with me are like "what is that noise?"
Has anyone heard of or experienced something similar? I still have a few months of warrantly left - I think they just don't want to bother unless I'm paying for it...
I've had it looked at twice now, U-joint checked, etc... I had a mechanic ride with me, and he said it was something to do with the differential in these cars. He told me about another Trans Am that they had looked at with the exact same problem, they replaced some stuff in the rear and it was actually worse...
This can't be normal - it's annoying as hell, and people riding with me are like "what is that noise?"
Has anyone heard of or experienced something similar? I still have a few months of warrantly left - I think they just don't want to bother unless I'm paying for it...
TECH Addict
Joined: Nov 2005
Posts: 2,379
Likes: 2
I've got 2 torsen's in 2 different camaro's and have not heard anything as long as the 10 bolt is intact.
If the gears were going or had some damage to the teeth, the sound will happen regardless of the action and will be louder on acceleration/decelleration.
If the carrier is making noise aka "the rusty screw sound" it WILL be loudest during turns as that's when the worm gears in a torsen will be moving the most. You will hear this effect the worst making a sharp turn very slowly, especially in reverse.
Bearings will make a whining sound that will change pitch according to the speed of the vehicle. No load tends to be the loudest while under load, the sound "may" get quieter.
Loose brake pads will make a good squeel usually when "lightly" applying the brakes. Check for uneven brake wear, unusual brake marks on the discs.
For any kind of "knocking" noise, I'd have a look at the amount of play you have with the rear. Check axle side play and any movement up/down/left/right that indicated some bearing wear, check differential gear play between the pinion and ring, check if there is any pinion movement forward or backward, up or down. Check the differential races and see if there is movement left or right of the differential itself.. Lastly, check your suspension, it could be as simple as a swaybar bushing or end link breaking off. Inspect your lower control arms, the shocks, the springs for any unusual wear/movement.
If its not any of those, maybe a loose exhaust rattling around in back. hanger may have come off/broken allowing the muffler to bang around a bit or the intermediate pipe to knock around.
If the gears were going or had some damage to the teeth, the sound will happen regardless of the action and will be louder on acceleration/decelleration.
If the carrier is making noise aka "the rusty screw sound" it WILL be loudest during turns as that's when the worm gears in a torsen will be moving the most. You will hear this effect the worst making a sharp turn very slowly, especially in reverse.
Bearings will make a whining sound that will change pitch according to the speed of the vehicle. No load tends to be the loudest while under load, the sound "may" get quieter.
Loose brake pads will make a good squeel usually when "lightly" applying the brakes. Check for uneven brake wear, unusual brake marks on the discs.
For any kind of "knocking" noise, I'd have a look at the amount of play you have with the rear. Check axle side play and any movement up/down/left/right that indicated some bearing wear, check differential gear play between the pinion and ring, check if there is any pinion movement forward or backward, up or down. Check the differential races and see if there is movement left or right of the differential itself.. Lastly, check your suspension, it could be as simple as a swaybar bushing or end link breaking off. Inspect your lower control arms, the shocks, the springs for any unusual wear/movement.
If its not any of those, maybe a loose exhaust rattling around in back. hanger may have come off/broken allowing the muffler to bang around a bit or the intermediate pipe to knock around.
trust me on this,i been down this road.its the torsen and its completely normal.every used fbod i drove with 25k+ i drove had the same noise.you might not notice it but its there in all of them.when i showed the salesman how to make the noise in a used 20k miles z28 he said WTF is that!i'll bet if you coast @ 20-30 mph and turn the steering wheel slightly to the left or right it will knock like heck.sure test that its the torsen.i even paid to install a auburn and sure enough the noise was gone.
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Originally Posted by noisy
Okay, so if it's normal, then that's good news...
What are my best options (if any) for getting rid of the noise? What's an 'auburn'?
What are my best options (if any) for getting rid of the noise? What's an 'auburn'?
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Staging Lane
Joined: Dec 2005
Posts: 71
Likes: 0
From: Portland OR
When I bought my 98, I had the same fears because I noticed after a few trips that there was a funny noise. The best description I found on here was it sounds like "Marbles rattling around in a coffee can."
It doesn't seem to have any side-effect, and many of the experts think its normal. I agree that there's no point wasting 2k trying to fix something that might not be a problem. There will always be someone willing to spend your money.
...But then again, I dont trust any mechanics or dealerships.
It doesn't seem to have any side-effect, and many of the experts think its normal. I agree that there's no point wasting 2k trying to fix something that might not be a problem. There will always be someone willing to spend your money.
...But then again, I dont trust any mechanics or dealerships.
Registered User
Joined: Aug 2016
Posts: 1
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I bought a 2006 chrysler 300 in March. About 2 months ago it started making a knocking noise when I brake at a slow speed. Like when I'm going 15-20 mph and then touch the brake. If I press hard on the brake the noise stops. It will also do it when I let off the brake to leave a stop sign. Any ideas ?
mine has a torsen diff and mine doesnt make a peep when driving or coasting.. although when I take off from a dead stop I hear a clunk if I give it moderate gas..
pretty sure thats the old U-joints (never replaced I dont believe)
pretty sure thats the old U-joints (never replaced I dont believe)
TECH Enthusiast
Joined: Jul 2007
Posts: 563
Likes: 0
From: Central,NJ
My Torsen had a knocking noise as well when slowing, would also pop once in a while on moderate (no spin) launch.
Bobby, your 300 may have a loose brake pad or a warped or even a cracked rotor causing the noise.
Bobby, your 300 may have a loose brake pad or a warped or even a cracked rotor causing the noise.
Joined: Nov 2001
Posts: 34,648
Likes: 2,574
From: Schiller Park, ILL Member: #317
Welcome back to 2006.
FWIW, I've owned three torsen rears, two of them brand new, and they all chattered under certain low rpm coasting conditions. As stated 10 years ago above, that is very typical of the Torsen. To the responder with the '98 car, your issues are different as you have an Auburn which does not chatter in this way during normal operation (unless something is wrong with it.) But as you posted 10 years ago, I'm sure you've got those issues sorted out by now.
As for the new member who brought this one back from the grave, your 2006 Chrysler 300 is apples to oranges here, you'd be better off asking on a Mopar forum that's more specific to these cars.
Time to put this decade old thread to bed.
FWIW, I've owned three torsen rears, two of them brand new, and they all chattered under certain low rpm coasting conditions. As stated 10 years ago above, that is very typical of the Torsen. To the responder with the '98 car, your issues are different as you have an Auburn which does not chatter in this way during normal operation (unless something is wrong with it.) But as you posted 10 years ago, I'm sure you've got those issues sorted out by now.
As for the new member who brought this one back from the grave, your 2006 Chrysler 300 is apples to oranges here, you'd be better off asking on a Mopar forum that's more specific to these cars.
Time to put this decade old thread to bed.
