It could be normal, or you could have a marginal transmission. There could be a very slow servo leak and the narrow passages makes for a bit of time to build pressure. When you first start, there is no pressure, and shifts are sloppy. Then it will thump when the pressure is high enough to squeeze the clutches. Its more complicated with all the software control nuances, but thats typically the situation. It also could be a little slow releasing the parking pawl.

One reason we recommend that when shopping used, to start cold, and see how it shifts.

 

Wow. Thanks ColdCase! Very interesting details you provided. I bought Jeep new with 9 miles on OD. Yeah could be normal, as happens when I shift out drive IMMEDIATELY after pushing start. Was curious if anyone else had this, thus proving "normal" design behavior of trans? Or, I'm just hyper driver. I'm due for service, so I'll find out what Jeep says. Thank you again.

 

Just FYI - Ours does the same (2020 WK2 Limited, 3.6, Offroad Pkg w/Air Suspension). I have not had it checked out by the dealer, but it does seem to happen when you start quick and immediately shift into Drive or Reverse. I also wondered if it has something to do with the all the things ColdCase mentioned as well as the brakes. I feel like the 'clunk' seems be coming from the rear of the vehicle, but it def. could be the tranny itself. The brakes have the hill feature where it locks them when on an incline. I wondered (no proof) if somehow the brakes are locked at start-up somehow and don't completely release even though you take your foot off the brake pedal. Like you, I know I can eliminate it mostly by taking a bit more time when starting and pulling out of the garage, but I forget sometimes and get quickly reminded with the jolt and clunk of whatever it is.

 

I believe that is what's called an "undocumented feature". Another way to get it to clunk every time is to put the parking pawl under a load like parking on an incline without first setting the parking brake. My '17 does it and every other WK2 I've driven.

 

I've noticed the Jeep has an initial "high idle" start up that lasts for a few seconds as compared to my other vehicles. If I start up and immediately shift into gear during the high idle it will lurch due to the higher rpm's and occasionally hear a clunk. I always wait for the idle to stabilize before shifting into gear.

 

If you have ELSD, like the trailhawks do, it can thud a bit as it switches from the parked position to running position. Just another variable.

 

Mine has this and I noticed yesterday just on start up, no gear selection and still in park, that there was a little 'thunk' as if the rear end was releasing. Not sure if that was the ELSD or the brakes releasing. Parking brake was not on and on flat ground (garage).

 

I have same behavior as OP. If I'm late for something, jump in, start, and throw it in reverse to get out of garage....I get a decent clunk. As OP also noted, if I wait even just 5 seconds before taking it out of park there is no clunk.


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Of note. It is not the parking brake. I thought at first it was how i was using it, but does not matter flat ground, hill, brake, no brake. Something in the trans with needing the computer or like Cold Case stated with the fluid needed to build up for 3-5 seconds. Have not got to dealer yet. Soon.

 

My 2020 Limited does this when first started and the idle is high as well, but my 2019 300 does not, even though they both have the same V6 and auto. It can't be good for the trans to slam into gear like that. Will get it checked out at my next service.

 

i think it has to with at start it does idle up its waiting to go from a base setting to what its reading. at say 1200 rpms going into gear its going to be a harder shift. What you are hearing is all the slack in the drive train as it goes from 1200 right to idle and its not moving, clunk.

 

Sooooo. Finally took JGC to dealer who said if I’m pushing start and IMMEDIATELY putting into drive or reverse within less than 3-5 seconds, certainly will get a thud, especially in morning cold or if sitting awhile. Could vary. The trans fluid and fluid pressure need a few seconds to normalize. Said not electronics but mechanical, and typical operation really on most any vehicle trans — one should not jam into gear from park the instant they start the ignition, which I did with my 1998 4Runner I abused and that this new Jeep replaced after 250k miles.

Then I took Jeep to to my regular small mechanic shop who has taken care of all my cars over the years, and he said same — wait a few seconds after hitting start. He did add that I should be putting on my seatbelt first anyway, relax, and I should take car of myself first, not to mention the Jeep! Lol. Case closed. 😀

 

Sooooo. Finally took JGC to dealer who said if I'm pushing start and IMMEDIATELY putting into drive or reverse within less than 3-5 seconds, certainly will get a thud, especially in morning cold or if sitting awhile. Could vary. The trans fluid and fluid pressure need a few seconds to normalize. Said not electronics but mechanical, and typical operation really on most any vehicle trans - one should not jam into gear from park the instant they start the ignition, which I did with my 1998 4Runner I abused and that this new Jeep replaced after 250k miles.

Then I took Jeep to to my regular small mechanic shop who has taken care of all my cars over the years, and he said same - wait a few seconds after hitting start. He did add that I should be putting on my seatbelt first anyway, relax, and I should take car of myself first, not to mention the Jeep! Lol. Case closed. 😀

Yes, I think that was the consensus here - normal behavior for millions of automatics. Glad you got an official answer and no repairs needed!

 

Dealer told me this was normal for my 2020 GC. However, my 2019 300 Limited which has the same V6 and 8 speed trans does not does this. It side easily into reverse.

 

There are production variances. Some leak down more than others and the adaptation parameters could vary from model to model.