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DRIVESRT.COM
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Discussion Starter #25
I had the TCM and PCM flashed, however the downshifts with the transmission in street mode, are still pretty noticeable, and lurches my head forward slightly almost as if i tapped the brake slightly.
 

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Discussion Starter #27
The clunk is pretty violent lurching the car forward no matter how hard i put my foot on the brake, its almost as if its taking away all the driveline slack.

What really bothers me is when coasting to a stop or braking to a stop with the transmission in street mode, I can feel the rough downshifts everytime im driving casual.

I just had the TCM/PCM flashed with the latest software, but no change in the rough downshifts so far, or the large lurch forward when putting it into "D".
 

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Is the replacement fluid a different part# than what was originally in the diff?
Nope, just looks like they added the friction modifier.

On a side note, Star case started to see if they'll approve another driveshaft and maybe rear differential. I think the carrier bearing is not so good.
 

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Nope, just looks like they added the friction modifier.

On a side note, Star case started to see if they'll approve another driveshaft and maybe rear differential. I think the carrier bearing is not so good.
Ok thanks. From the new TSB it looks like they're just draining/refilling all the fluid.

Star case huh? Hope they get it figured out. FYI 1200 miles 2017 is dead quiet
 

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The other thing to keep in mind is if you are on a grade and not using the parking brake. There will be increased stress on the parking pawl if your car is tilted up / down when moving from P to R/D after being parked / stopped.

If you're parking on a grade, apply the parking brake (with regular brakes applied) before you release the regular brakes after shifting into park, and release the parking brake (with regular brakes applied) before you release the regular brakes when shifting out of park into R or D to remove the weight of the car from resting entirely on the parking pawl.
 

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Hey folks... I noticed this sound today on my 2017 A8 Charger Hellcat.

If I just sit in my driveway and engage D or R, I get a clunk. I don’t even actually have to move... just makes the clunk as I go from D to R or vice versa. Car drives fine otherwise, but this doesn’t sound right at all.

I’ve got 5700 miles of town and highway driving and 3 trips to the track. I also have the DSS Aluminum driveshaft and stock rear end.

Has anyone confirmed for sure what resolves this? An active TSB?
 

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Thanks... need to find the right place to take it.

I'm very weird about who I let look at anything to do with engine or transmission.
 

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Apparently there is a TSB for this, but I'm not sure it it's active for 2017 cars.

I also have the Aluminum DSS. It was recently installed. Need to make sure all is good with that.

Worst case I could have problem with rear end gears or transmission.
 

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I had this issue with my HC. Ended up being the driveshaft bolts that attach it to transmission. They worked loose and had to be replaced because mechanic said they are like head bolts and stretch when tightened.
 

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I've got a little clunk, sounds like a driver side half shaft cv joint, hasn't gotten any worse but probably should get it checked out.


Sent from my SM-N920T using Tapatalk
 

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I've got a little clunk, sounds like a driver side half shaft cv joint, hasn't gotten any worse but probably should get it checked out.


Sent from my SM-N920T using Tapatalk
Mine only happens once when the transmission and driveshaft change torque direction when engaging R or D, and happens at a dead stop just same as when moving. It’s all about the change in torque direction occurring through the main DS. So this tells me it has nothing to do with the wheel DS, but more likely the transmission, DS, or rear end.

If your clunk occurs when moving while turning one direction or another, that gives different clues and may tell you one of your half shafts has issue.
 

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I had this issue with my HC. Ended up being the driveshaft bolts that attach it to transmission. They worked loose and had to be replaced because mechanic said they are like head bolts and stretch when tightened.
Man this is what I am hoping it is! I just had the new one-piece DSS installed and ran an entire weekend of one-mile races last weekend, and the clunknshowed up the day after it ended. Racing was all soft launch on street tires on airport runway (unprepped surface). Only thing the newly installed DS saw was lots of speed, start and stop. So I think Force-caused damage to anything should be unlikely based on what I was doing, and I am really hoping it is just new part needing to be re-torqued.
 

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Just doing my service to the community and reporting back and confirm root-cause... was indeed loose driveshaft bolts.

Pause and “clunk” when engaging into drive or reverse was just loose DS bolts... was the large ones that torque to 70 lbs. they seem to have backed out some since installation. If it happens again I’m going to go nuts on them with thread-lock.

This happened about 1 month after DSS Aluminum install. One trip to drag strip and one weekend at Texas Miles is what loosened ‘em up.
 
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