Car Handling Issues at High Speeds: Rear-End Swerves and Knocking Sound – Seeking Advice!

[ioniamichael]

Problem #1:
At speeds above 70 km/h, when I press the gas pedal, the rear of the car veers to the right, and when I release the gas pedal, it shifts to the left.

Problem #2:
When I'm rolling slowly in traffic, in first gear, at speeds around 5-15 km/h, I press the gas pedal, and there's a knock. It's hard to pinpoint where the knock is coming from; sometimes it feels like it's under my left foot, and sometimes from the middle of the car.

I've replaced the right and left engine mounts, as well as the transmission mount (the long one attached to the bridge under the transfer case with four bolts in a row). I also replaced the bushing for the front axle near the left wheel.

The car is a 2006 model with a 3.7 engine. Any ideas on what could be causing this and where to look? Driving at high speeds and accelerating is really scary right now.

By the way, when I press the brake, the car doesn’t veer at all.
If I press the gas pedal smoothly at low speeds, there’s no knocking sound.

I suspect both problems might be related.

 

[Gyro]

Likely the rear lower control arms bushings.
Call your local Jeep dealer with your VIN# and see if the recall on the lower control arms has been done.
Could be a free repair/solution.

Gyro

 

[LibertyTC]

View this thread as well.
https://www.jeepkj.com/threads/rear-sway-when-i-stop-excelerating.70019/#post-755697

 

[ioniamichael]

Likely the rear lower control arms bushings.
Call your local Jeep dealer with your VIN# and see if the recall on the lower control arms has been done.
Could be a free repair/solution.

Gyro

Thanks a lot mate, I will uninstall one of them today and check the bushings.
And what you think about the knocks on the low speed ?

 

[DadOSix]

Problem #1:
At speeds above 70 km/h, when I press the gas pedal, the rear of the car veers to the right, and when I release the gas pedal, it shifts to the left.

Problem #2:
When I'm rolling slowly in traffic, in first gear, at speeds around 5-15 km/h, I press the gas pedal, and there's a knock. It's hard to pinpoint where the knock is coming from; sometimes it feels like it's under my left foot, and sometimes from the middle of the car.

I've replaced the right and left engine mounts, as well as the transmission mount (the long one attached to the bridge under the transfer case with four bolts in a row). I also replaced the bushing for the front axle near the left wheel.

The car is a 2006 model with a 3.7 engine. Any ideas on what could be causing this and where to look? Driving at high speeds and accelerating is really scary right now.

By the way, when I press the brake, the car doesn’t veer at all.
If I press the gas pedal smoothly at low speeds, there’s no knocking sound.

I suspect both problems might be related.

1 - rear bushings - lowers give the swerve on acceleration - deceleration - Just did these on my 04 (which btw, had already had the recall work done years back). Look at the link and info above us.

2 - The knock under your foot may well be the driveshaft from the transfer case to the front differential. There are 2 CV joints on teh shaft. Relatively easy fix, but a bear to wiggle the shaft down once you decide to service the joints.


A few tips - lying under the jeep, it is usually the rear-most joint that is bad. With the shaft out, I replace both. I never had a bad front, but to me it is like only changing 1 brake pad.

To best diagnose - pull the shaft out of the jeep and go drive. You wont hurt anything. Noise gone? Service the CV joint(s). Still there? Keep looking —- maybe the ball joint on the rear upper control arm, where we were discussing the A/D swap.

 

[KJowner]

The knock on acceleration or braking is usually the rear upper control arm.