Transmission clunk noise shifting park to drive or reverse - JeepForum.com
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post #1 of 12 Old 04-16-2021, 10:25 AM Thread Starter
jeeptome
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Transmission clunk noise shifting park to drive or reverse

Finally resolved clunking noise shifting park to drive or reverse on my brand new 2021 Jeep Grand Cherokee V6 Auto 4x4 Limited (8,000 miles).

When starting Jeep on flat ground I'd immediately put into reverse or drive after pushing start. I'd notice a muffled single "clunk" through transmission. Seemed intermittent at first. Then I noticed only happens if I push start and IMMEDIATELY shift out of park. If a way a few seconds for the gauges to come on, maybe 3 or 5 seconds, it never clunks. I bought the 2021 Jeep GC after owning a 1998 4Runner which I was use to sort of abusing. I love the 2021 GC, and after careful analysis, picked it over 2021 4Runner since I do more on road driving.

Issue solved, but I would interested to know what causes noise. Likely Jeep doing some quick programing check before starting. I'll have to check with dealer on GC clunk noise, even though I know how to stop it. Not really a big deal. Just don't be in such a spaz hurry to shift out of park. Use 3 to 5 seconds of my life to put seat belt on and catch my breath -- then shift out of park!


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post #2 of 12 Old 04-16-2021, 10:37 AM
ColdCase
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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.

I just got lost in thought. It was unfamiliar territory;
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post #3 of 12 Old 04-16-2021, 10:46 AM Thread Starter
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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.

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post #4 of 12 Old 04-20-2021, 08:50 AM
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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.
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post #5 of 12 Old 04-20-2021, 10:05 AM
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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.

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post #6 of 12 Old 04-20-2021, 12:53 PM
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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.

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post #7 of 12 Old 04-20-2021, 01:40 PM
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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.
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I just got lost in thought. It was unfamiliar territory;
Current: 2011 Grand Cherokee Overland V8, 2009 Liberty Rocky Mt V6
Previous: 2000 Grand Cherokee Laredo I6, 1979 CJ7 I6 Quadratrac
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post #8 of 12 Old 04-21-2021, 07:57 AM
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Quote:
Originally Posted by ColdCase View Post
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).
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post #9 of 12 Old 04-21-2021, 10:56 AM
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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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post #10 of 12 Old 05-01-2021, 07:38 PM Thread Starter
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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.

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post #11 of 12 Old 05-02-2021, 08:05 AM
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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.
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post #12 of 12 Old 05-02-2021, 08:30 AM
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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.

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