Transmission issues after gear ratio swap

[loveracing1988]

So I had 4.44 gears installed into my 2014 2500 and everything has been going great so far since I had it done at the beginning of January.
However I towed my trailer for the first time yesterday and it didn't go that good. It's only a snowmobile trailer with a atv in it but since it is enclosed it is like towing a wind sail. The issue is if I tow in 6th gear without a speed drop it will kick down to 5th, then back to 6th and repeat over and over until I lock out 6th gear. If I tow in 5th gear any little hill the torque converter will unlock and rev up, get the speed and lock back up and repeat the process. It varies about 500 rpm from 2500 to 3000 rpms and acts like a cvt essentially. I am not too thrilled with it but my big fear is it causing damage. When I went out to get lunch today the check engine light came on and the codes were a input/turbine speed sensor fault and 5th gear ratio incorrect.
Has anyone who has done a gear swap had this happen or am I just lucky?
I have no idea if the two are related or not but I'm not sure how to really tell.

 

[AFMoulton]

Did you reprogram the computer for the new gears?


2018 Ram 2500 6.4L 4x4
Amsoil SS 0W-40

 

[loveracing1988]

Did you reprogram the computer for the new gears?


2018 Ram 2500 6.4L 4x4
Amsoil SS 0W-40

Yeah, I did before I left the shop. It's been driving fine for the last month but I haven't towed with it so I can't pinpoint when exactly it started.

 

[Bldrinker]

I put 4.88’s in haven’t programmed my computer and tow a big ass Toyhauler. 10k empty. Around 12-13k loaded depending on where we are going.
I mainly stay in 3rd and 4th gear going 55-65mph

not a single issue.

 

[loveracing1988]

I put 4.88’s in haven’t programmed my computer and tow a big ass Toyhauler. 10k empty. Around 12-13k loaded depending on where we are going.
I mainly stay in 3rd and 4th gear going 55-65mph

not a single issue.

I think if I were spinning 5000 rpms it wouldn't need to kick down in the first place. I'm spinning 2500 in 5th gear going 70, 4th gear was 3300 or so and I wasn't going to lock it into 4th

 

[mtnrider]

When you say you programmed it what exactly did they do? Just calibrate the speedo or actually change the gear ratio with AlfaOBD etc?


.

 

[NewBlackDak]

There shouldn’t be a anything to program in and HD unless you changed the tire size. The speed sensor is down the chain from the differential.


Sent from my iPhone using Tapatalk

 

[yoda]

I dont think its related to your gear change. I would focus on the speed sensor fault first.
The pcm uses the speed sensors to sense gear ratio faults.
If you have access to a scan tool. monotor input shaft rpm while wiggling related harnesses. Or try replacing the sensor. Go OE with the sensor

 

[AFMoulton]

How heavy is your trailer? And what are you pulling? 4.44 might not be enough to get into and stay in 6th gear.

4.88’s seem to be a sweet spot on these trucks.

@U&A have you had any issues with towing after going 4.88?


2018 Ram 2500 6.4L 4x4
Amsoil SS 0W-40

 

[yoda]

How heavy is your trailer? And what are you pulling? 4.44 might not be enough to get into and stay in 6th gear.

4.88’s seem to be a sweet spot on these trucks.

@U&A have you had any issues with towing after going 4.88?


2018 Ram 2500 6.4L 4x4
Amsoil SS 0W-40

Agreed it may not stay in 6th but what he is describing along with setting speed sensor and gear ratio faults, he has something wrong with his truck

 

[U&A]

At a minimum you need to make sure your gears and tire size are programmed into the truck.

That alone will affect the difference between the output shaft speed and the wheel speed.

If they are different it will possibly/eventually cause a problem.

The way I understand it is a gear change should not confuse the transmission IF you did reprogram for this. tire size included




Sent from my iPhone using Tapatalk

 

[U&A]

There shouldn’t be a anything to program in and HD unless you changed the tire size. The speed sensor is down the chain from the differential.


Sent from my iPhone using Tapatalk

Not 100% true.

They are supposed to relate the output shaft speed to the sensors at the wheels.


Sent from my iPhone using Tapatalk

 

[U&A]

How heavy is your trailer? And what are you pulling? 4.44 might not be enough to get into and stay in 6th gear.

4.88’s seem to be a sweet spot on these trucks.

@U&A have you had any issues with towing after going 4.88?


2018 Ram 2500 6.4L 4x4
Amsoil SS 0W-40

No issues at all.


O.P.
6th is not a towing gear anyway. Run in 4th or 5th on the highway and keep the RPM up. Hemi’s power curve showes it NEEDS to run up there close to 3,000if you want power of any kind.

I run 60-70 and in 5th when towing with my 4.88’s. Puts me between 2,700 and 3,500 If i need more i go down to 3rd

Let her scream


Sent from my iPhone using Tapatalk

 

[chris1126]

i changed my gears and tires and only reprogrammed for tires. havent had any issues myself. are you using tow/haul?

 

[loveracing1988]

How heavy is your trailer? And what are you pulling? 4.44 might not be enough to get into and stay in 6th gear.

4.88’s seem to be a sweet spot on these trucks.

@U&A have you had any issues with towing after going 4.88?


2018 Ram 2500 6.4L 4x4
Amsoil SS 0W-40

Fully loaded it is only 2000 or so pounds. Like I said it isn't weight it is wind that is the problem with this trailer. I would tow my 10k 5th wheel at 65 in 5th gear provided I was on flat ground and that was with the 3.73 gears, not I'm up about 400 rpms from that.
To the others yes I programed the gear ratio with alfaobd and set the tire sizes with my trinity.

 

[loveracing1988]

i changed my gears and tires and only reprogrammed for tires. havent had any issues myself. are you using tow/haul?

Tow haul didn't do anything

 

[yoda]

You need to fix your input/turbine speed sensor code first. I dont think your gear swap or tires has anything to do with this fault.
A flaky input speed sensor signal can cause gear ratio faults and will cause shifting issues.
The input/turbine speed rpm should read about the same as engine rpm in park.

 

[loveracing1988]

Turns out the overdrive clutch was on its way out the door. So I now own a 2020 3500 with a cummins and most importantly not the 68rfe. Pretty sad that I only got 75k out of the transmission in my 2500.

 

[U&A]

Turns out the overdrive clutch was on its way out the door. So I now own a 2020 3500 with a cummins and most importantly not the 68rfe. Pretty sad that I only got 75k out of the transmission in my 2500.

Congratulations on the new truck! Hope it all goes well and trouble free.


Sent from my iPhone using Tapatalk

 

[6.4LMegaMan]

Yikes. Sorry to hear your troubles. My valve body went out at 75k. On the bright side you now have a beast of a truck. Sucks you had to get it this way but don't look back and enjoy it.

Sent from my SM-N975U using Tapatalk