Harsh 2-1 downshift, "Jerk" or "bump" upon coming to a stop

[QwikKota]

Mine does not do that. I can barely tell when it downshifts coming to a stop sign. I wait until it shifts down and the truck comes to a complete stop to take back off as the 2nd gear roll is sluggish with 3.21 gears. I'm curious as to what gears people have that are getting the herky jerk?

 

[1500canoe]

Mine does not do that. I can barely tell when it downshifts coming to a stop sign. I wait until it shifts down and the truck comes to a complete stop to take back off as the 2nd gear roll is sluggish with 3.21 gears. I'm curious as to what gears people have that are getting the herky jerk?

3.92 - mostly as other people have said might happen, mine has largely quit doing this on its own, or I've subconsciously changed how I decelerate to prevent it.

 

[Dusty]

Don't jump to conclusions on this issue. It may not be a transmission problem. There are three things that usually cause this complaint.

1. Those with the 32 gallon gas tank will occasionally feel a thump just after the vehicle comes to a stop, or just after roll out. This occurs when the tank is between 1/4 and 3/4 full.

2. Later 4th gen Ram 1500s with the 8-speed use a three piece drive shaft. The first section connects the transmission to a center mounted carrier bearing. The aft section is really two separate pieces. This section is fluted to allow the shaft to collapse and expand eliminating effects of rear axle wrap during starting and braking, as well as compensate for travel arc changes when carrying loads in the bed. It is also intended to reduce sympathetic noise from oscillations, MDS vibrations, and road conditions telegraphing through the driveshaft assembly. If the rear section is binding, you will feel the effects through the drivetrain (at vehicle rollout the rear section will shorten slightly, then when stopping the rear section will lengthen slightly). This feels like a rough downshift or rough clutch engagement at rollout. As someone else noted, GM trucks can suffer from the same condition.

3. The Ram 8-speed 8HP70 (Hemi) and 845RE (Pentastar) transmissions are modified versions of a ZF design (845REs are assembled by Chrysler, 8HP70s are made by Chrysler and ZF). The shift algorithm firmware/software is developed by Chrysler. As with almost all FCA autos nowadays, these are fully adaptive, 'learn' transmissions that change shift schedules dependent on driver input. While there have been several PCM flashes to address this issue, there is also a known problem with valve bodies. If this problem is intermittent, it can be more likely be a valve body issue. As in my case, this symptom has NOT been an issue on my vehicle all winter long. Now that warmer temperatures have returned, so has this problem.

Best regards,
Dusty

2014 Ram Big Horn 1500 Quad Cab 2WD, 5.7 Hemi, 8HP70, 3.92 LSD, factory dual exhaust, 20” wheels. Now at: 076517 miles.

 

[Nuke71]

2013 SLT Crew Cab 5'7" Box, 3.55's 90,000 KMs

Mine does this as well. Same as above, only in warmer temperatures, no issues in the winter although maybe harder to tell/feel on snow covered roads.

My question is, is there any long term damage happening to the transmission?

 

[iLLeStEyECoN]

On the truck, I have noticed it happens most often when you aren’t braking hard enough to stop it. If you brake incredibly soft, or let off the brake just as it goes from 2-1, it won’t do it. The other option is to brake harder. I’ve been alternating between the two options and I almost always avoid it.


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[four bye]

Bizarre fix for me. I brought my 14 Ram into the dealer about this issue 3 times, and the first time they found the trans. low on fluid, topped it and made no difference. The second and third time they made excuses that this was normal with these transmissions, I responded with they were full of sh*t! One day while pulling my car trailer I noticed the trans. wasn't having harsh down shifts, and after disconnecting the trailer it did not have one harsh down shift for about 5 or 6 months. So now when the trans starts acting up I just pull the trailer around the neighborhood and I'm good to go for another 5 months. I guess if you don't have a trailer you're pretty much screwed. I'm sure it has something to do with fluid pressure, but it's still bizarre.

 

[Dusty]

2013 SLT Crew Cab 5'7" Box, 3.55's 90,000 KMs

Mine does this as well. Same as above, only in warmer temperatures, no issues in the winter although maybe harder to tell/feel on snow covered roads.

My question is, is there any long term damage happening to the transmission?

From what I can tell, complete transmission replacements are extremely rare. I was told that in our Chrysler zone, only four transmissions were replaced between January 2017 and March of this year. Keep in mind there are only a handful of field replaceable spares for the 8-speeds. There is no field rebuild program. If the problem is not a filter, tranny pan, lines, or valve body, it's a new transmission.

Best regards,
Dusty

2014 Ram Big Horn 1500 Quad Cab 2WD, 5.7 Hemi, 8HP70, 3.92 LSD, factory dual exhaust, 20” wheels. Now at: 076560 miles.

 

[Dusty]

Bizarre fix for me. I brought my 14 Ram into the dealer about this issue 3 times, and the first time they found the trans. low on fluid, topped it and made no difference. The second and third time they made excuses that this was normal with these transmissions, I responded with they were full of sh*t! One day while pulling my car trailer I noticed the trans. wasn't having harsh down shifts, and after disconnecting the trailer it did not have one harsh down shift for about 5 or 6 months. So now when the trans starts acting up I just pull the trailer around the neighborhood and I'm good to go for another 5 months. I guess if you don't have a trailer you're pretty much screwed. I'm sure it has something to do with fluid pressure, but it's still bizarre.

Your problem could be the rear driveshaft binding. Try backing up at a good but safe speed and lay on the brakes. Do this a few times and see if it makes any difference. If it does, it's likely the driveshaft.

Best regards,
Dusty

2014 Ram Big Horn 1500 Quad Cab 2WD, 5.7 Hemi, 8HP70, 3.92 LSD, factory dual exhaust, 20” wheels. Now at: 076560 miles.

 

[iLLeStEyECoN]

From what I can tell, complete transmission replacements are extremely rare. I was told that in our Chrysler zone, only four transmissions were replaced between January 2017 and March of this year. Keep in mind there are only a handful of field replaceable spares for the 8-speeds. There is no field rebuild program. If the problem is not a filter, tranny pan, lines, or valve body, it's a new transmission.

Best regards,
Dusty

2014 Ram Big Horn 1500 Quad Cab 2WD, 5.7 Hemi, 8HP70, 3.92 LSD, factory dual exhaust, 20” wheels. Now at: 076560 miles.

We used to have to get all kinds of higher level techs involved when we had to replace a motor or transmission at my dealership when I was a tech, starting with StarTech (I think this was the name, this was almost 10 years ago) and a very lengthy documentation process. It was not easy.

Anyway, I stand by this not being an issue seeing as THREE straight 8 speeds that I have owned have all done the same exact thing, my Scat Pack being the worst.


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[four bye]

Your problem could be the rear driveshaft binding. Try backing up at a good but safe speed and lay on the brakes. Do this a few times and see if it makes any difference. If it does, it's likely the driveshaft.

Best regards,
Dusty

2014 Ram Big Horn 1500 Quad Cab 2WD, 5.7 Hemi, 8HP70, 3.92 LSD, factory dual exhaust, 20” wheels. Now at: 076560 miles.

Thanks Dusty, I'll give it a shot.

 

[gofishn]

As others have mentioned, my truck did it too. Horribly so. then, over time as truck learned my driving habits AND as I slowed down to a stop, it pretty much went away.

every once in awhile, it still wakes me up but not often.

 

[LarryA]

2107 Crew cab Hemi with 3.92 rear end. Bought my truck new May of 17, and at ~ 300 miles started doing hard 2-1 downshifts as I came to a stop. Took it to the dealer and was told the transmission was still in learning mode. I did not believe them for a minute and was expecting it to become a problem. A few months later (maybe 1,500 miles?) I realized it was gone. So there maybe some truth to the transmission learning ones driving style.

However I also think there must be some variability here too as other have taken other steps that seems to have resolved the issue.

Best of luck!

 

[RammerHarder]

What i`ve found (after owning 3 of the 8-speed 8HP70 transmissions in the 1500 RAM), i traced it down to the torque converter unlocking VERY late in its programming, in MOST cases, and its mostly noticed after a full complete stop....THUMP!!! When i use the +/- gear selector, dropped down into 8th gear, no more THUMP when i stop. Once i`ve hit the +/- back into "D" mode, i can repeat the THUMP at every stop. I haven't tried TOW/HAUL mode because i see no need to. But if some of you fella`s wanna try it, go for it and report back here to let us know what happens when you tried it. I will bet that in TOW/HAUL mode, its going to do the same UN-THUMP as the +/- method i tried. I believe the TOW/HAUL mode, when used, it partially unlocks the torque converter. I wont say this will work for everybody, its just some things i`ve been trying after owning 3 of these RAM1500 trucks with the 8HP70 transmissions.

Those that know the 8HP70 transmissions inside and out, know, that chrysler designed the software to keep the torque converters locked up for as long as possible, for efficiency & mpg reasons. Until chrysler re-write`s the software for the RAM from 2013 to 2018, 8-speeds, or comes up with a flash update to unlock these torque converters sooner, rather than later, this THUMPING issue will NEVER completely go away. I now own a brand new 2018 sport, it thumped for the first 500 miles, it has decreased since new, but i can make a severe thump happen, by coming to a VERY aggressive stop. Whats happening there is, the suspension/driveline is loading against the transmission as it slams the gears down into lower gearing.

When you drive a BMW that has the ZF 8HP transmission, there is NO THUMP whatsoever... its chryslers programming causing this little demon thumping.

PS: those that keep beating the dead horse of the gas tank thumping, thats a different horse of a different color, its NOT the same issue as the transmission 2-1 thump.
That theory HAS BEEN debunked, and several times, on many different RAM truck forums.

 

[mtofell]

My 2014 2500 6.4 Hemi with the 66rfe does it so bad it will actually cause the rear wheels to skid. However, the only time it does it is when I'm doing the engine braking by holding down the gear selector on my column shifter and it selects 1st as its "target". That usually only happens if I'm going under about 40. Otherwise, it picks 2nd and all is well. If I go to second and then to first all is fine. It's just the 3-1 jump that makes it act up. Of course, my dealer has been zero help. I just live with since I can just avoid it. For what these trucks cost it is pretty amazing there are so many problems with trannys across many different types/lines of Rams. I guess someone has to graduate at the bottom of their engineering school class.

 

[Dusty]

Thanks Dusty, I'll give it a shot.

I should also add that the thump issue went away completely on my truck for a month or better (about 4.5k miles) after I disabled the Hill Assist Mode. But it wasn't permanent and the symptom later returned, although not quite as bad.

Best regards,
Dusty

2014 Ram Big Horn 1500 Quad Cab 2WD, 5.7 Hemi, 8HP70, 3.92 LSD, factory dual exhaust, 20” wheels. Now at: 076574 miles.

 

[magic280z]

The problem is getting FCA to admit there is a problem. I just had my truck in for recall and warranty work. This was one the issues I wanted them to fix, but if there isn't a code update their hands are tied. One of the service managers even said the bump when stopping is a common complaint on alot of their cars not just Ram's. He didn't say if it was an 8-speed issue, but since that is their primary transmission now probably a good assumption. The responsibility becomes on the owner calling customer service and pushing the issue. BTW FCA this is really the opposite of good customer service.

On a side note I have had a pretty good experience with my local dealership service department. Well at least the dealership I go to. I would consider 4 dealerships local < 30 minutes. One of those nobody has anything good to say about. Then at least two more < 60 minutes.

I've had issues with my local Triumph service department that has steered me away from brands without service options.

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[CostaRam]

2011 RAM 1500 with 6 speed tranny and 62K miles
about 2 weeks ago: coming stop sometimes jerk and bang, mostly when tranny is "cold" (+/- 70C)
while tranny in neutral will not jerk and bang
last 10 days: almost always while breaking slowly to stop jerk and bang, not only when tranny is "cold"
now: almost always while shifting first and second down or up will lead to jerk and bang
CEL is not on
tranny oil is right level
only while shifrting between frst and second gear

Will try change filters and oil, but think it's only a waste of time and $$$

Any suggestions?

Chris

 

[PoMansRam]

Does anyone with the Pentastar and 8HP45 in their Ram 1500 report this issue? Seems to be Hemi and 8hp70 for what ever reason.

Like mentioned above, I have owned part time 4x4's in the past where a driveshaft slip yolk could cause this thump/bang if the splines in the slip yolk were not kept greased properly.

 

[JohnnyMac]

Does anyone with the Pentastar and 8HP45 in their Ram 1500 report this issue? Seems to be Hemi and 8hp70 for what ever reason.

Like mentioned above, I have owned part time 4x4's in the past where a driveshaft slip yolk could cause this thump/bang if the splines in the slip yolk were not kept greased properly.

I had a Chevy that did this and my Tacoma does it if I don't keep the driveline greased up.

 

[PoMansRam]

I had a Chevy that did this and my Tacoma does it if I don't keep the driveline greased up.

We had some Isuzu Rodeos and Troopers in the family that would do this. I forget what grease I used. It was years ago, but it was a thick red grease that worked wonders for these driveshaft slip yolks.