Strange rocking and knocking coming from rear of car

[Shambosley]

So I've been searching everywhere to find someone with the same problem which leads me here to the professionals.

What's happening is, if I accelerate hard from a stop, something feels like it's rocking from side to side in the rear end followed by a "knock, knock, knock" back there and almost as if it follows the driveshaft to the front because there will be a tiny squeak in the front sometimes when this does happens. Only does it when taking off hard but has done it when stopped on a hill and applying torque to the rear end when taking off.

This all started after trying to do a little burnout forgetting about TC being on, since it's my first car with it, and I heard a pop in the back. Continued to drive home and nothing seemed wrong until I realized what it took to bring the problem to the surface

Im not very technical with all the parts of a car, but jacked up the rear end on the diff and checked u joint in the middle as well as where the driveshaft mounts to the diff and where the input splines go into the tranny. Everything was tight with no play other than a tiny bit in the middle at the DS carrier brace.


Not sure what to really check when under there or which bushings to check but i did notice one of the rear diff bushings is cracked a little and found a strange fluid on the side of the gasstank across from what I believe to be the subframe bushings shown in attachment. This fluid is on both front bushings of the rear subframe

https://youtube.com/shorts/vtjK2RqjQVc?feature=share

Wish I knew how to mount some sort of camera under there to resimulate and capture the problem, so I tried to be as descriptive as possible. Any help is much appreciated

[strat61caster]

Describe the rocking more please, like there’s an item moving or like the whole car is shifting?

If it’s less of a knock and more like a tick I’m going to guess it’s time for new axle nuts.

If you take it to an alignment shop they can hopefully diagnose and tighten something that’s loose as part of a standard alignment.

I’ve dumped the clutch hundreds of times, I doubt you broke anything and more likely something has just shaken loose on a 10+ year old car. Don’t forget to check the interior of the car for any items rolling around behind your seats or in the trunk.

[Shambosley]

Originally Posted by strat61caster

Describe the rocking more please, like there’s an item moving or like the whole car is shifting?

If it’s less of a knock and more like a tick I’m going to guess it’s time for new axle nuts.

If you take it to an alignment shop they can hopefully diagnose and tighten something that’s loose as part of a standard alignment.

I’ve dumped the clutch hundreds of times, I doubt you broke anything and more likely something has just shaken loose on a 10+ year old car. Don’t forget to check the interior of the car for any items rolling around behind your seats or in the trunk.

I sure wish it was something as simple as axle nuts but something is definitely moving underneath. Feels like, from what I guess would be the whole driveshaft rocking underneath the car back and forth from right to left or left to right which makes a knock or banging sound in the rear until I ease off and let everything settle under there. Feel it only in the rear but it is accompanied by a tiny squeak in the front sometimes, which makes me feel like it's the drive shaft rocking.


I'll also hear that same squeak in the front only, if I go over a little hill where it's like the car is on two different planes(levels), like a motor mount squeaking or something.

Thanks for your reply

[Turdinator]

Could you make a video of the noise?

[Shambosley]

Originally Posted by Turdinator

Could you make a video of the noise?

I'll see If I can figure out a way to capture a sound or video. I try not to let it happen if can, because I'm afraid something is gonna break lol

Also I'm not 100% sure it's originating in the back, kind of hard to tell. Motor could be moving and shaking the driveshaft back to the rear.

In the mean time, any recommendations on how to easily check the motor mounts on a manual?

[soundman98]

i would check the rear diff. almost sounds like it's come loose from it's mounting points.

but it would still be surprising that you managed that-- i just left t/c off today, got stuck in the wrong lane behind a surprise-left-turner. at that point i was irritated, and traffic wasn't easing.. i clutch-dumped 1st at about 5k, and then slammed/chirped 2nd at redline(i've learned that people don't mess with someone making obnoxious car noises, otherwise, i would've gotten honked at)... my car is still holding together fine...

[strat61caster]

I’ve done that literally hundreds on times without issue.

[Shambosley]

Originally Posted by soundman98

i would check the rear diff. almost sounds like it's come loose from it's mounting points.

but it would still be surprising that you managed that-- i just left t/c off today, got stuck in the wrong lane behind a surprise-left-turner. at that point i was irritated, and traffic wasn't easing.. i clutch-dumped 1st at about 5k, and then slammed/chirped 2nd at redline(i've learned that people don't mess with someone making obnoxious car noises, otherwise, i would've gotten honked at)... my car is still holding together fine...

Gotta say, I really love how optimistic you guys are here, I always assume the worst. I'll get under there start throwing a wrench to all the diff bolts.

[norcalpb]

Originally Posted by Shambosley

Gotta say, I really love how optimistic you guys are here, I always assume the worst. I'll get under there start throwing a wrench to all the diff bolts.

How did you jack up the rear of the car? If it was by the diff, and it didn’t move, I’d say the bolts should be properly tightened.

A video would be really helpful. Almost sounds like when I had my busted transmission mount.

[Shambosley]

Originally Posted by norcalpb

How did you jack up the rear of the car? If it was by the diff, and it didn’t move, I’d say the bolts should be properly tightened.

A video would be really helpful. Almost sounds like when I had my busted transmission mount.

I did jack it up by the diff and it didn't move. I actually just captured a video of the sound, what's the best method of sharing it here?

https://youtube.com/shorts/vtjK2RqjQVc?feature=share

I checked the tranny mount to the best of my ability and nothing obvious stood out. I also have a white line tranny mount bushing that I have yet to put in. Maybe it's time so I can really get in there and see if anything is wrong there.

[Shambosley]

Originally Posted by Turdinator

Could you make a video of the noise?

https://youtube.com/shorts/vtjK2RqjQVc?feature=share

[Shambosley]

Also just noticed when I turn the AC on a here a knocking at the bottom of motor between motor and tranny. Think maybe a mount up there broke?

[Shambosley]

So I got under there today, specifically looking at the engine mounts and I've noticed that they are not mounted to the subframe, Is that normal? The mounts threaded bolts that go through the subframe don't have any nuts on either of them. Videos I've watched shows them removing a 14mm nut.

[soundman98]

that would definitely cause a clunking sound!