Manual Shift option wears out transmission

[jac04]

I'm not sure about these, but many transmissions of the past actually ran higher line pressures when manually shifting, meaning less slipping of the clutches and bands.

I occasionally use manual mode, but only for upshifting. I find in manual mode that the shifts are much quicker and 'firmer'. So, there is definitely something different going on in manual mode.

Sponsored

 

[aprez27]

Correct me if I'm wrong but aren't brake pads cheaper than transmissions?

 

[BourbonRunner]

Isn't the transmission used in the JL/JT the licensed version of the German transmission that is produced in a Stellantis factory?

More or less, yes. 850RE/Torqueflight 8 is a licensed version of a ZF box built in Kokomo that originally debuted in the BMW F01 V12-powered BMW 7 series.

It is found in a ton of BMW, VAG, Tata and Stellantis vehicles in various forms. As far as modern transmissions go it's one of the most reliable and widely found out there. Ineos puts it in the Grenadier with BMW's now legendary B58 and B57 motors.

Which is why a lot of us think that OP's downshifting as described may have been a component in its repeated failures.

 

[ShadowsPapa]

Isn't the transmission used in the JL/JT the licensed version of the German transmission that is produced in a Stellantis factory?

Yes

 

[Maximus Gladius]

If the OP has been through four transmissions, it seems clear that he's using it in a way that most other owners don't, and that the designers never intended.

I’m on #4, so I’ve only gone through 3 but #1 was destroyed by glycol contamination, I never got to use #2 as it was faulty out the door and replaced and FCA engineers looked it over and agreed with the warranty replacement with #3. So technically, I’ve only had #3 as a perfectly working transmission that had a whine in first and second gear from day one and up to the last lab report alerting to change the oil and filter.

Driving habits are what they are. Is this transmission so fragile that life expectancy isn’t much more than 100k when driven carefully? Heck, my neighbour drives an older RAM with 430k kms on it with no issues. Now, I know it’s a different beast so we aren’t comparing apples to apples but come on 100k and Chrysler washes their hands of this.

This 3rd transmission wasn’t dead when I brought it in and showed the dealership the report and the shop Forman heard the whine noise. The whine remained the same from day one. What alerted me to an issue was the oil analysis saying maintenance was needed on a transmission Chrysler doesn’t want anything done to it.

So in this case, the tranny was changed out while it still worked.

 

[Maximus Gladius]

Correct me if I'm wrong but aren't brake pads cheaper than transmissions?

Yes they are.

 

[SoK66]

Now that’s a pretty bold statement to make and post this thread saying it but now that I’m just past 4000k kms on my warranty replaced 4th auto transmission, …I decided to try driving this one a little differently to see if the manual shift feature, (I used a lot only for slowing down) had a significant roll in bringing about my third transmission’s demise and pump failure at only 32k kms.

As it was becoming apparent that the third transmission was experiencing problems and noted by the oil analysis lab to change the oil and filter because the IRON wear was too high, I had much time to critically think what could possibly be causing it’s failure. The 4th tranny was put in and I decided to not use the manual shift to assist in slowing down (which my brake pads benefited from) greatly and I wanted to see what impact this would have on the transmission in the wear department.

The first oil analysis proves the transmission is healthy right out of the gate and the second report was done at 3950k kms, pretty much at the same kms the third transmission report was done and we can see a HUGE reduction in wear not using the manual shift.

I’ve thought long and hard about this and the numbers don’t lie. Cause and effect law applies here and we can see this. I’ll be pulling samples and getting analysis reports at the same times as the third transmission to see if this theory holds true.

My conclusion is this 850RE transmission should not use the manual shift feature for slowing down if we can see expedited wear as a result. Now that said, I would use it if I’m coming down a mountain pass and I don’t want to burn the brakes out so there’s times it’s needed but it was far to easy for me to use it often in the city to slow down. It’s a cool feature so I used it. But I have also been able to not use it and be ok too. I figure brake pads are cheap andI’m still on my first pair at 80k kms.

(first image is 4th tranny)
(Second image is 3rd tranny)

We have five Gladiator Sport Max Tow automatics in Jeep tour service here and in Moab. We use the manual mode regularly when descending steep grades to prevent overheating of the brakes and have had no issues whatsoever with the transmissions. Something isn’t right with your setup, I’d be looking at transmission cooling, fluid type, something.

 

[ShrimpHappens]

Correct me if I'm wrong but aren't brake pads cheaper than transmissions?

EXACTLY.

Either way, kinetic energy of the vehicle is being reduced by converting it to heat energy. What do you want taking all that heat: pads & rotors or a transmission?

 

[Hootbro]

On 4th transmissions and what, 2nd engines also?

You are a statistical anomaly on a Pareto chart that would draw scrutiny.

 

[cranbiz]

So, you had one transmission that had glycol contamination, one DOA and now one that has whined since day 1 and now shows high metal levels in the fluid.

None of these sound like manual shifting caused your problems. Might it be the wear is caused by the whine and not manual shifting?

Sounds more like bad QC / bad luck more than anything else.

 

[ShadowsPapa]

EXACTLY.

Either way, kinetic energy of the vehicle is being reduced by converting it to heat energy. What do you want taking all that heat: pads & rotors or a transmission?

That energy is simply being transmitted by the transmission, the energy is lost through the engine, used to spin against compression.
Think about what you are saying- that same energy already went through the transmission.. through .to make it go to begin with.


I also note he said #3 had a whine from day one! Likely it already had problems and it wasn't necessarily the downshifting.

 

[Mav4x4Chris]

I can't see manually downshifting being what killed the transmission. I do it in my 4L60E Chevy all the time (for driving like a teenager purposes) - and if it hasn't killed that POS it surely can't hurt one of these 8 speeds

Though - I also can't see myself dicking with the shifter in an automatic constantly to do what the brakes can do. But I digress.

 

[ShrimpHappens]

That energy is simply being transmitted by the transmission, the energy is lost through the engine, used to spin against compression.
Think about what you are saying- that same energy already went through the transmission.. through .to make it go to begin with.


I also note he said #3 had a whine from day one! Likely it already had problems and it wasn't necessarily the downshifting.

Sure, it's ultimately the engine working against compression to slow the vehicle, but the transmission is being engaged to do this. And due to friction, this generates heat in the transmission. I think it is a bad idea to intentionally and routinely perform an unnecessary action that results in extra heat in a transmission.

It's one thing to use the transmission to help the brakes from time to time, but it's a different thing to consistently use the transmission as the brakes.

 

[KevinC]

On 4th transmissions and what, 2nd engines also?

You are a statistical abnomily on a Pareto chart that would draw scrutinty.

If it weren't for bad luck, he would have no luck at all!!

The internet don't lie, but something doesn't pass the smell test.

KevinC

 

[Maximus Gladius]

On 4th transmissions and what, 2nd engines also?

You are a statistical abnomily on a Pareto chart that would draw scrutinty.

Yes, second engine and on my 3rd power steering pump.

First engine consumed coolant at 1 + ounce/1000km. FCA engineer, NORM wasn’t concerned and not fixed. Not my fault for bringing it to their attention. Insurance paid for the replacement of #2 engine. After receiving the new engine and drove it 1500km and dropped the oil, discovered engine install tech made a mistake and topped up the oil to 12L.
I’m currently watching my reports but still see high IRON numbers with low kms. (Engine runs beautifully, can’t ask for better) - but still out of my control and I don’t baby it but I also don’t drive it like a teenager, nor like a Sunday grandpa.

The power steering pumps- well, after 2 quitting on me (not my fault) and the third one put in, all is great.

Sponsored