Unsolved transmission issue driving me crazy

[rebel58]

Hello everyone. I need the help of people who understands how transmission works. I hear a clunk in my truck that the dealership cannot figure out why and they just say its “normal” but I don’t think any clunk is normal in a $65,000 truck.

I have a 2021 Ram 1500 Rebel with 5.7 etorque engine with 23k miles on it. When speeding up, there is no problems with the shifting, it shifts perfect and smoothly.

However, when slowing down and the truck downshifts from 4th gear to 3rd gear, the rpm stays above 1200rpm and if I hit the gas again when it is at 1200rpm, there is a huge clunk coming from the rear end of the truck.

If I don’t hit the gas when the rpm is at 1200, the rpm drops suddenly to 800rpm WHILE STILL AT 3RD GEAR and the truck kind of relaxes and cruises easily as if it was exhaust braking before it dropped if you know what I mean. Now, if I hit the gas AFTER it drops to 800rpm WHILE STILL IN 3RD GEAR, the rpm slowly rises WITHOUT A CLUNK and drops around 1200, then picks up again (without a loss in power) and rises like normal.

Can someone please help me figure out what is going on here? I took it to the dealership at least 5 times and left truckless for more than 15 days however they just brush me off and say it is “normal”.


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[Rick3478]

All guesswork of course, but I'll describe a few things, starting at the rear.
1) Loose suspension. Worn bushings make noise as parts shift and impact each other.
2) Differential backlash. Gears in the rear axle have a little bit of backlash, and when you transition from deceleration to acceleration there is a moment when the gear mesh transitions from the leading edges of gear teeth to the trailing edges, crossing a small air gap then colliding. It's usually more noticeable with manual transmissions where the loading and unloading is more rapid.
3) Worn universal joints add backlash to the drivetrain and make noise as the parts collide.
4) Driveshaft slip joint may pop or clunk as it sticks for a moment then slides when you transition from deceleration which stretches it to acceleration which compresses it, and this is a much-reported thing with these trucks.
5) Transmission yoke. The bolt that secures this part to the transmission main shaft has been reported to come loose in some cases and allow extra movement and backlash.
6) Clutch packs and gears in the transmission also have a bit of backlash. The noise from these is usually pretty well contained within the transmission case.
7) Torque converter lockup clutch. This doesn't usually make much noise, but it releases under computer control at some speed, letting RPM drop and truck becomes more "coasting" rather than "engine braking". I'm not sure what all gears this comes into play, but it might explain your RPM drop and pickup.

Some of these things are normal, some just annoying, and a couple can be dangerous. Checking for loose parts, lubricating, and checking fluid levels might be in order. Dealer should have already done that. I don't have a specific diagnosis, but maybe some of these ideas will give you a feel for what's going on.

 

[rebel58]

All guesswork of course, but I'll describe a few things, starting at the rear.
1) Loose suspension. Worn bushings make noise as parts shift and impact each other.
2) Differential backlash. Gears in the rear axle have a little bit of backlash, and when you transition from deceleration to acceleration there is a moment when the gear mesh transitions from the leading edges of gear teeth to the trailing edges, crossing a small air gap then colliding. It's usually more noticeable with manual transmissions where the loading and unloading is more rapid.
3) Worn universal joints add backlash to the drivetrain and make noise as the parts collide.
4) Driveshaft slip joint may pop or clunk as it sticks for a moment then slides when you transition from deceleration which stretches it to acceleration which compresses it, and this is a much-reported thing with these trucks.
5) Transmission yoke. The bolt that secures this part to the transmission main shaft has been reported to come loose in some cases and allow extra movement and backlash.
6) Clutch packs and gears in the transmission also have a bit of backlash. The noise from these is usually pretty well contained within the transmission case.
7) Torque converter lockup clutch. This doesn't usually make much noise, but it releases under computer control at some speed, letting RPM drop and truck becomes more "coasting" rather than "engine braking". I'm not sure what all gears this comes into play, but it might explain your RPM drop and pickup.

Some of these things are normal, some just annoying, and a couple can be dangerous. Checking for loose parts, lubricating, and checking fluid levels might be in order. Dealer should have already done that. I don't have a specific diagnosis, but maybe some of these ideas will give you a feel for what's going on.

Thank you so much for your detailed explanation. I will bring the truck to a transmission shop instead of the dealership.

One last question: Do you think this is normal? What’s weird to me is that the rpm stays around 1200 in 3rd gear for a whole second before a sudden drop to 800. None of the vehicles I owned did that before which makes me wonder.


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[HSKR R/T]

Sounds more like driveshaft/rear end issue and not transmission issue. At least as far as the clunk. Are you manually downshifting? It's may be in-between gears causing some of your issues with the RPMs and clunk as well

 

[rebel58]

Sounds more like driveshaft/rear end issue and not transmission issue. At least as far as the clunk. Are you manually downshifting? It's may be in-between gears causing some of your issues with the RPMs and clunk as well

No I’m not manually downshifting. It happens when I’m slowing down towards the red light and accelerate again when the light turns green while I’m in third gear. Or when I’m turning left/right on the street in third gear and accelerate again. It happens so many times during the day which bothers me. I can attach a video if that would make it easier.


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[23RAM]

Hello everyone. I need the help of people who understands how transmission works. I hear a clunk in my truck

There's another thread already in the general forum about this clunk...try a search to find it and maybe you'll find a solution?

 

[rebel58]

There's another thread already in the general forum about this clunk...try a search to find it and maybe you'll find a solution?

I have been searching online for months for a solition and I don’t know how to search for this specific clunk. Can you help me locate that thread?


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[23RAM]

I have been searching online for months for a solition and I don’t know how to search for this specific clunk. Can you help me locate that thread?

Searching "clunk rear" shows your post and this one:

Differential or Transmission Clunk

I picked up my Longhorn Tuesday night. So far I have less than 150 miles on it. Today driving home from work, I started hearing a clunk and can feel a slight jolt when starting and stopping in slow moving traffic (such as creeping your way up to a stop sign, waiting for your turn to go). I'm...

5thgenrams.com

 

[rebel58]

Searching "clunk rear" shows your post and this one:

Differential or Transmission Clunk

I picked up my Longhorn Tuesday night. So far I have less than 150 miles on it. Today driving home from work, I started hearing a clunk and can feel a slight jolt when starting and stopping in slow moving traffic (such as creeping your way up to a stop sign, waiting for your turn to go). I'm...

5thgenrams.com

Thank you!


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[6of36]

Have you had the recall performed? My brothers main complaint about his truck was the down shifting. 2021 Etorque engines got a recall for a software update. He got the recall, and it cured it, and increased his MPG by almost 3.

 

[rebel58]

Have you had the recall performed? My brothers main complaint about his truck was the down shifting. 2021 Etorque engines got a recall for a software update. He got the recall, and it cured it, and increased his MPG by almost 3.

I took it to the dealership 5 times in the past year and there was only 1 recall done which was about the tailgate. Other than that, no recalls performed.


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[6of36]

I took it to the dealership 5 times in the past year and there was only 1 recall done which was about the tailgate. Other than that, no recalls performed.


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There is a recall. From memory it was 87A, but that could be wrong. It was model year 2021, e-torque only.

 

[6of36]

37A. It's a software update. I found the old thread, where I made the same mistake, saying 87A.

 

[rebel58]

37A. It's a software update. I found the old thread, where I made the same mistake, saying 87A.

Is there any way I can check without going to the dealer if that recall is performed on my truck?


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[6of36]

Is there any way I can check without going to the dealer if that recall is performed on my truck?


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I think in the Ram app for your phone, there is an option. Either that or there is a website that you can punch in your VIN and see. Recalls.gov. That lists the recalls, not if they have been done.

 

[6of36]

safercar.gov | NHTSA

SaferCar.gov is now NHTSA.gov. You can search for vehicle ratings and do recall checks on vehicles, tires, car seats, and more.

www.safercar.gov

This one says it tells if it was performed.

 

[rebel58]

safercar.gov | NHTSA

SaferCar.gov is now NHTSA.gov. You can search for vehicle ratings and do recall checks on vehicles, tires, car seats, and more.

www.safercar.gov

This one says it tells if it was performed.

It says “0 Unrepaired recalls”. Thank you for your help though.


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