Violent Downshifts

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Sorcerer33

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Hi all, looking for comments on the issue. 44,500 km 2018 RAM 3500 with 15K of the 45K problem free towing a 34 foot 5th wheel -- so far... until a couple of weeks ago:

the violent downshifts happens under the following conditions:

When towing the trailer:
1) In tow / haul, deceleration under brake or exhaust brake at about 80kph
2) Out of tow / haul deceleration under brake or exhaust brake at about 50 kph
3) Smooth downshift if coasting to a stop up a slight gradient - no load on tranny
4) If using electronic shifter on the stalk to change gear still kicks me in the back...
5) Sometimes it happens when the trans downshifts on an uphill grade, I've experienced it between 4th, 5th and 6th.

Without the trailer:
Same conditions but the jolt is not as violent and seems to be mostly 3rd to 2nd and 2nd to 1st, however today on 2 occasions, the trans down shifted at the apex of a curve, I was going a little quickly and it sent the truck into a skid on a damp road. Nothing uncontrollable but the ditch was getting closer on the 2nd one !

With the trailer, the jolt seems like it happens at these downshifts: 6th to 5th, 5th to 4th.

Without the trailer; 3rd to 2nd, 2nd to first.

Sometimes it is a dull "thud", sometimes there is an accompanying metallic clang but its like being rear ended !

Comments and experiences appreciated, its going to the dealership next week and I'd like to be as informed as I can. I've had experience of the "there's nothing wrong" "there are no codes" and the clincer "They all do that".....
 

Daw14

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Have you had it serviced?
 
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Mine was doing something similar. Was happening in the midst of my dealer trying to solve an oil leak, which they never did after over a half dozen return trips. Anyway, they just kept clearing codes saying nothing was wrong when I’d pick it up from another failed oil leak repair. Finally it stopped shifting up from 4th and all of a sudden we have a bad transmission that’s juuuuuust out of warranty and $6500 to replace. So traded all dozen Rams for a dozen F250’s. My RAM dealer’s service dept (Cass Burch) is trash. The worst part is, I hate driving this F250. It beats me to death. I miss my ram, but will never have another one with this dealer.


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Iron Outlaw

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It’s a shame most dealers do not have very good techs. They are all part replacers and seems they struggle with any kind of diagnosis. When I had my transmission built an old guy did it who builds every thing that goes through his shop. He has three guys that remove and install and he rebuilds them himself. It was cool talking to him about what exactly went wrong with my unit to cause it’s failure. He told me what he changed to make it better and what parts were upgraded. Apparently some of the holes in my valve body weren’t machined correctly. This caused the fluid not to flow right and burnt the overdrives up. He modified them and my transmission has been better the last year since he built it than it was the five years before then.

good luck with the issue. I hope you can find out the problem under warranty. That’s why it is there but it seems a lot of dealers try to avoid issues if they can.
 

SeppW

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Which tranny does truck have? The RFE VBs are notorious leakers and create a host of shifting issues. I had similar issues and dealer experiences with the 66RFE in my Wagon and installed a Sonax reman VB and all is good. Not to say that would fix your issue. I have no experience with Aisin. Other than that, find another dealer or a specialty transmission shop that can troubleshoot the trans. The diagnostic fee alone could be worth it to take back to dealer and confront them, if still under warranty.
 
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Sorcerer33

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Which tranny does truck have? The RFE VBs are notorious leakers and create a host of shifting issues. I had similar issues and dealer experiences with the 66RFE in my Wagon and installed a Sonax reman VB and all is good. Not to say that would fix your issue. I have no experience with Aisin. Other than that, find another dealer or a specialty transmission shop that can troubleshoot the trans. The diagnostic fee alone could be worth it to take back to dealer and confront them, if still under warranty.
6 speed, 68 RFE I think. Just tried to find the build sheet (I factory ordered) but no luck.
 

SeppW

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6 speed, 68 RFE I think. Just tried to find the build sheet (I factory ordered) but no luck.

If you go to Ram Truck Web site and register for an owners account, it *should* pull up your window sticker at least, plus a host of other stuff, like dealer servicing, recalls, etc, etc. Tranny should be listed on that sticker somewhere.
 

RamCares

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Hi all, looking for comments on the issue. 44,500 km 2018 RAM 3500 with 15K of the 45K problem free towing a 34 foot 5th wheel -- so far... until a couple of weeks ago:

the violent downshifts happens under the following conditions:

When towing the trailer:
1) In tow / haul, deceleration under brake or exhaust brake at about 80kph
2) Out of tow / haul deceleration under brake or exhaust brake at about 50 kph
3) Smooth downshift if coasting to a stop up a slight gradient - no load on tranny
4) If using electronic shifter on the stalk to change gear still kicks me in the back...
5) Sometimes it happens when the trans downshifts on an uphill grade, I've experienced it between 4th, 5th and 6th.

Without the trailer:
Same conditions but the jolt is not as violent and seems to be mostly 3rd to 2nd and 2nd to 1st, however today on 2 occasions, the trans down shifted at the apex of a curve, I was going a little quickly and it sent the truck into a skid on a damp road. Nothing uncontrollable but the ditch was getting closer on the 2nd one !

With the trailer, the jolt seems like it happens at these downshifts: 6th to 5th, 5th to 4th.

Without the trailer; 3rd to 2nd, 2nd to first.

Sometimes it is a dull "thud", sometimes there is an accompanying metallic clang but its like being rear ended !

Comments and experiences appreciated, its going to the dealership next week and I'd like to be as informed as I can. I've had experience of the "there's nothing wrong" "there are no codes" and the clincer "They all do that".....


We're sorry to hear about your downshifting concerns. We would like to offer our assistance if desired! Feel free to send us a private message with your vehicle's make, model year, and mileage to get started.

Hannah
Ram Cares
 

SouthTexan

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Did you let someone borrow or drive your truck in the last two weeks?
 

rixter99

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FWIW, the RFE68 fluid dipstick is on the passenger side and the AISIN's dipstick is on the driver's side...
 

Robert Mc

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Hi, new member here.

I have an issue similar to Sorcerer33 so I thought I'd post my issue as well. It is similar in many ways but also different in some ways.

If I should make a new post I will but if it's okay to I'll post it here first.

I have a 2018 Ram 2500 w/ 6.7L Cummins and the RFE68 6 speed transmission. In February 2021 at about 50K miles I started to experience a very harsh downshift from 5th to 4th. I should also state that almost 100% of the time I am in Tow/Haul mode and use the Full-time Exhaust Brake feature. In town I also limit the transmission to a max of 4th gear so I don't lug the motor. It keeps it in a higher torque range and it drives much smoother. On the freeway I limit the transmission to 5th gear while I'm towing which is 95% of the time I'm using the truck. After it happened a few times I confirmed the issue by using the Driver Selectable Gear mode and limiting the truck to 4th gear. While decelerating it downshifted smoothly through the whole range 4-3-2-1. Then I used the DSG mode to allow the transmission to shift into 5th gear. During deceleration the transmission downshifted very harshly from 5-4 and then downshifted smoothly from 4-3-2-1. I repeated the testing using just the Tow/Haul Mode, just the Exhaust Brake Mode, and again with both the TH mode and the EB Mode engaged.

The transmission downshifted harshly from 5-4 in all modes but did so more harshly while using the combination of the TH and EB Mode. I took the truck in to the dealer for service and the tech confirmed the issue. They refreshed the computer and went through a relearn mode. The truck was under warranty but they charged me for the update saying it wasn't covered under. I balked at that but lost the battle. The transmission was fine for about 5 months and in until August 2021 at about 80K miles the issue came back. I made an appointment and took the truck in. They called and said the tech was not able to confirm my issue and asked me to come in. I took a different tech (the previous tech already went home) out for a test drive and on the first downshift the problem was confirmed. We went back to the shop and the Service Manager said they couldn't work on my truck since the transmission guy went home. (That was the tech that couldn't confirm my issue) and it might be a day or two until they could get to it. That didn't work for me since I use the truck for my job. I made a new appointment and said that was the day they could work on it.

I took the truck in for its new appointment and it still took them two days to service it. WTF?!!! They corrected the issue with another refresh and test drive. I told them I wasn't paying for the same thing to be done since they just did it. This time I didn't pay for the service. The transmission was working fine until last week, which was two weeks after they fixed it, and now it is doing the same thing.

Has anyone else had this issue and what do you guys think it might be and what is my recourse for getting it permanently fixed?
 
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WY-Dave

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I have had the same thing for quite a while, I have 45K miles on it right now.
Using Torque pro, I was able to see exactly what was happening.

When the EB is off, the downshift from 5th goes into 3rd, skipping 4th.
When the EB is on, the downshift from 5th goes into 4th and clunk.
It hits so hard at times, the tires will lock up and I get a screech (can't think of the right word to use).

Tomorrow I will have to see what only tow mode does. IIRC, it did not do it. (Checked this morning, in TOW it does not skip 3rd when slowing down by idle or braking and does give a slight bump)

For reference

CHRYSLER 68RFE RATIOS​

1st
2nd
3rd
4th
5th
6th
R
3.23 : 1​
1.84 : 1​
1.41 : 1​
1.00 : 1​
0.82 : 1​
0.63 : 1​
4.44 : 1​


BTW if you use TorquePro with the extended PIDS (https://drive.google.com/file/d/18CkJlaNAK3kr7jWknm3JzSOXp59bwoM4/view),
you have to change some settings for the 6-speed.
1631071270008.png

And for the Trans fluid temp use (Jeep Pre 2012)


my run with TorquePro
 
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Mbrigh3

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its your transmission. I had 2 replaced on my 4th gen before i dumped it.
 

Fast69Mopar

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Did you let someone borrow or drive your truck in the last two weeks?
I second this, @Sorcerer33, does anyone else besides you drive your truck? Do you have any kids who are driving age?

Chrysler uses adaptive learning to make
real-time adjustments based on your current driving habits. We use what's called a CVI or
Clutch Volume Index. In the TCM their is a list of CVI's for each clutch...

U/D (Underdrive)
O/D (Overdrive)
L/R (Low/Reverse)
2C (Second Clutch)
4C (4th Clutch)
R (Reverse)

Each CVI is the measurement of how much fluid it takes to apply a certain clutch. Each clutch has a standard range of what is acceptable for clutch application.

If a specific clutch has heavy wear or a leak the CVI will be elevated but each CVI can also tell us how the vehicle is being driven. When a truck is driven very easily with low throttle input it does not take alot of fluid to apply a clutch and hold that clutch from slipping. When a vehicle is driven hard or worked hard like when towing or racing or even just spirited driving the CVI will go up because it takes more fluid to apply a clutch and keep it from slipping under heavier loads.

Like the other poster asked about someone else driving the truck, if you drive it one way and someone else drives it another way, when you get back behind the wheel the trans can feel entirely different on the upshifts and the downshifts.

I'm not implying that this is your problem but it is a scenario that I see quite often being in the dealership.
 
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Sorcerer33

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Update . Only I drive the truck. Just finished a trip with the trailer and all is well. The dealer reprogrammed the computer and added the didn’t have the tools to diagnose the problem! Their SOP from Chrysler is 1) reprogram. 2) if the doesn’t work replace the valve body, 3) if that doesn’t work then replace the whole transmission.

I was shocked that the dealer had no diagnostic abilities and just changed parts out to try and fix an issue.

Thanks for all the comments but it seems Chrysler know there is an issue with these transmissions …..
 
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Sorcerer33

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Ps I asked the tech about CVI, that’s when he told me that they did not have the test equipment!!
 

John Sabatula

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2018 ram 2500 66rfe 30k miles mine seems to like to downshift while using the cruise control while going downhill, drives the tach up to 5k and revs up the engine. Anybody else's truck do this? Shut the cruise off it shifts into od and the tach drops to normal.
 

carmantl

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My 17 chassis cab 3500 with Aisin trans does the same thing. Really annoying. Haven't figured out anything to stop it, other than don't use cruise!
 
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