[TeleZL1]

I have noticed a couple of different times when I get in my car and start it, there is a quick "bump".

It has happened a couple of different times. Once I had pulled it into my drive to detail another car in the garage. It sat on a very slight incline for a couple hours and I did set the Ebrake. Got in it, hit the start button and BUMP.

Other time was the car was flat in the garage...got in to start it after not driving it for a few days and same thing. Its almost like its still partially in gear for a split second. There is no noise that I can tell and its not a hard bump but there is a definite little bump like someone barely tapped the rear end while parking.

I took it in to the dealership for my 1st complimentary oil change and asked them about it....they deemed it was probably the adaptive learning and its still learning how I drive and blah blah....

I'm not buying it. I asked them "So it doesn't know its in park?!"
Anyways, I didn't expect much from the service writers but I know its not normal.


Anyone else experienced this?

[jbp8653]

I have noticed this a few times as well.

[Can'tHave2MuchHP]

Electric parking brake? Is it the brakes? Or do you think it's trans related?

Sometimes after I park my performance cars, the first time I move them, they jerk, and I think it's the brakes that stick to the rotors if left wet. After the car moves an inch it's fine.

[Homey Da Clown]

Mine does it too. I have never used the parking brake.

[djfury05]

Mine does it too, no parking brake. Happens randomly no trend discovered.

[Busted43]

Haven’t noticed it on mine as of yet.

[TeleZL1]

Definitely NOT the brakes.

It’s a very quick jerk/bump from the drivetrain and it is random.

Glad it’s not just me but I hope it’s not a symptom of a larger long term issue.

[ninetres]

Lil over 2,000 miles. I’ve never had that happen on mine.

[6spdzl1]

I don't have the 10 spd in the Zl1 but do have the Ford version in my F150. Does the same thing every so often.

[kwav8r]

Just over 2K on mine, never experienced this either.

I use the parking brake about 50% of the time and turn it on before I turn off the car.

[Jmueller]

Hmm. I have over 6500 miles and I have never experienced this on my A10.

[thompstl1]

Mine does this too on occasion. To me, it feels like the drive clutches in the transmission engage momentarily, even though it's in park. Feels like it is slightly in gear, but in park at the same time. I've noticed my car moves just a bit when I feel this.
Hasn't gotten any worse and only happens sporadically.

[jasonfichter]

Originally Posted by thompstl1

Mine does this too on occasion. To me, it feels like the drive clutches in the transmission engage momentarily, even though it's in park. Feels like it is slightly in gear, but in park at the same time. I've noticed my car moves just a bit when I feel this.
Hasn't gotten any worse and only happens sporadically.

I was told that this can sometimes happen overnight when the fluid has time to drain back into the bottom of the transmission. During initial startup the clutches momentarily catch because there is no fluid on them. Once fluid is circulating the clutches slip as they should.

This is just what I have been told, sounds like that could be the case.

[thompstl1]

Originally Posted by jasonfichter

I was told that this can sometimes happen overnight when the fluid has time to drain back into the bottom of the transmission. During initial startup the clutches momentarily catch because there is no fluid on them. Once fluid is circulating the clutches slip as they should.

This is just what I have been told, sounds like that could be the case.

That explanation sounds exactly like what I'm feeling when the transmission "bumps". To support that theory, I've noticed when the car sits for long periods of time it's slow to "grab" going into reverse... waiting for the transmission fluid to be pumped from the pan into the torque converter and transmission.

Actually my Ford truck (F-150 with 6 speed auto) does exactly the same thing