Small Pop in the Rear During Acceleration

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regiment1

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Hello, all

For the last few weeks, I have noticed the following. I didn't find similar issues with a search, so wanted your opinions on it.

During light acceleration from a stop, when the transmission makes it's first shift, there is a little click or pop from right behind the passengear rear seat. It may be coming at a level just above the door armrest, but just behind the passenger (my 10 year old thinks that's where he hears it from when he rides back there).

It's a small click, not a loud noise at all. I have to listen for it. I don't feel anything in the accelerator, handling is unaffected and acceleration is normal. It happens about 3/4 of the time.

I had the shocks replaced two years ago, and they mentioned the need for new end links at some point.

I welcome your suggestions!
 
Sounds more like a trans mount than a rear link. I have a rear link that has to be replaced and what I get is popping over bumps.
 
I thought the same on the links, too. I was trying to think what would be torqued (or "un-torqued") when the transmission shifts.
 
I've had a number of trans mounts fail over the years, and the 1-2 shift is the one that puts the most torque on the mount. As the failure... glllrowss (spoken like Ricardo Montalban as Khan explaining the ceti eels)... the other gears will start to cause noise on the shifts.
 
So, I've been listening to this more closely. It seems like it is coming right behind and at the level of my son's right shoulder - he's around 54 inches tall. Wouldn't a transmission mount cause a sound under the back seat? Looking at the suspension diagrams, the only thing I see around that level are the bolts holding the top of the shock. Everything else at the top of the suspension seems to be around the passenger's hip level.
 
Check your subframe-to-body mounts. They go bad eventually but I dont think they sell them anywhere.
 
Sound can travel around in funny ways. If the trans mount is the issue, it is very easy to find. Jack the back of the car up and put it on jackstands, or back it on a ramp, then use your jack on the rear of the trans. If the trans lifts off the cross member at all, it is defective.
 
I am going to take it in to the shop when I'm back in town on Friday.

The sound now is happening more frequently, and it is not when the shift occurs. I can make it happen about 2/3 of the time if, from a complete stop, I hit the accelerator quickly. The sound happens immediately. Then it will happen again if I let off the accelerator right away.

When I say "hit the accelerator quickly" I don't mean mashing down the pedal. I just push the accelerator a moderate amount, but in abrupt fashion. Like you would do to quickly turn left in an intersection to beat the red light.
 
That's about where the top shock mounts are. Maybe when the shop put in the new ones they forgot a nut? Didn't get it seated right and now it's worked loose? I'd expect the shocks shifting around a bit would do something like this, and accelerating from rest would torque them since the only other mount is the lower control arm.
Failing control arm bushings or subframe mounts would exacerbate the problem.

IIRC, the only holes from the passenger compartment to the rear underside is at that location, so any sound from down there would funnel up that way. Especially if the shock isn't seated right. ;)
 
If it isn't the trans mount, have the engine mounts checked as well. Could be the shocks, but a noise that happens mostly on the 1-2 shift like that says powertrain mount to me. If it's a shock mount, you should be able to recreate the sound by pushing hard on the fenders to make the car go up and down. Good luck.
 
I'd vote for center driveshaft bearing. When mine failed it sounded like someone banging on the floor just behind the console. Only made the noise when accelerating hard from low speeds in low gear (I have a manual). As it got worse it would occur at lighter accelerations.
 
So the mechanic drove it several times, got it on a lift after each drive. They could hear the problem but couldn't find the issue.

e told me I'd probably just have to wait for it to get worse.

But the guy absolutely refused to let me pay him for his time. They probably spent a couple of hours on it. He said just to be sure to have them do the repair when it's time. Stand-up guy.
 
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