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Hard Downshift on Power Wagon

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mtbgordon

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Noticed while the truck was downshifting from 5-4 or 4-3 that I occasionally get what I describe as a "clunk". Whether the transmission is cold or up to temp this occurs. I have 35s on the truck and did not program yet as the AEV part is on BO. Had this occur before the tire upgrade as well. Wondering if anyone else had this occur.

Again, this only occurs while I am braking and the truck is downshifting.
 
mtbgordon said:
Noticed while the truck was downshifting from 5-4 or 4-3 that I occasionally get what I describe as a "clunk". Whether the transmission is cold or up to temp this occurs. I have 35s on the truck and did not program yet as the AEV part is on BO. Had this occur before the tire upgrade as well. Wondering if anyone else had this occur.

Again, this only occurs while I am braking and the truck is downshifting.
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Yep. Have the same thing. I also have 35s, but reprogrammed tire size with Alfaobd.

The 5-4 is worse than the 4-3. I seem to notice it more under heavier braking. I just chalked it up to the ever-learning transmission, or the need for a software update.

In our 1500 I experienced the same thing. The dealership updated the TCM software and it fixed the hard downshift problem. I am just too busy / lazy to drop the powerwagon off at the dealer.
 
I just had this same issue fixed. I was having the hard downshifts from 5-4 mainly. The problem is common with cross leakage from the valvebody or solenoid pack. It is a known problem for the RFE trans. I just installed a remanufactured sonnnax valvebody with solenoid pack. I have the 6.4 with 66RFE. It came as a complete unit with upgraded pistons, springs, gaskets,seals and accumulator plate. After install I had to have a relearn process done a qualified shop. Has to be done with a scan tool that most people do not have laying around and also are not certified to operate. This is a universal unit for the rfe transmissions but you can get other brands. I believe even the 68RFE for the diesels will work as they are all the same. If you are able to do your own transmission fluid change then it is a simple do it yourself job. Other than the relearn process.
 
Well looks like you have the 5th gen 8 speed and I have the 4th gen 6 speed but maybe the same issue.
 
Dealership picked up my Power Wagon on Wednesday. Test drove it and was able to replicate my concern. PCM updated, ESC recall completed, checked fluid level, and made sure clutches were aligned. Not sure how they would check that. They noticed that it wasn't as bad when the transmission warmed up more. They claimed that it is how that transmission is. So for now it is at least noted. Will see how things go as the miles/years progress.
 
The 2019+ Heavy Duty RAM trucks with the Hemi (including the PowerWagon) use the ZF8HP75 transmission, which is perhaps the best automatic transmission ever produced in terms of smoothness, shift quality, and shift logic. The 35" tires might be creating the issue, but I'd also make sure the driveshaft u joint is good, which can clunk on a downshift. Otherwise, something is probably wrong.
 
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