Transmission (lack of) maintenance and failures…tip of the iceberg?

[OnTheReel]

Lately I’ve seen several TRXs with transmission failures, most before 100k miles. The frequency of these type posts online seems to be picking up as these trucks age and get some miles on them. Aside from the active threads here, search “transmission” in the main Facebook group and you’ll many recent examples.

None of these owners have mentioned any maintenance done previously and since the manual doesn’t recommend any, it’s likely they were untouched.

We can’t know how many of these could have been saved but there are two things you can do to improve your chances. And all too often these solutions are presented only after you’ve already had issues and it’s too late. So consider this a friendly reminder.

Regular service. The advertised “lifetime fluid” is a self-fulfilling prophecy and should read “lifetime of the factory powertrain warranty”. Beyond that, good luck.

On mine, I did a pan drop and additional drain and fill at around 25k. Beyond that I am targeting regular 25k mile spill and fills, basically refreshing with 4-5 quarts of new fluid each time. When you get the hang of this it really doesn’t take much longer than an engine oil change.

Fluid capacity: 9.5 quarts (dry)

OEM pan/ filter assembly: 68261504AA

OEM Mopar fluid: 68218925AB

Aftermarket fluid alternatives:

Ravenol 8HP. This most closely mimics the OEM fluid in composition.

https://www.ravenolamerica.com/passenger-car-products/atf-fluid-ravenol-8hp-fluid/

Red Line D6. I am currently using this in a Jeep 8HP, great shift quality. PAO/POE blend, good oxidative stability and shear resistant.

https://www.redlineoil.com/d6-atf

Amsoil Signature ATL (blue). Popular option and great quality product.

https://www.amsoil.com/p/amsoil-signature-series-fuel-efficient-100-synthetic-automatic-transmission-fluid-atl/?

HPL ATF Green CC. Running this in my TRX with great results. Similar to the D6 in formulation but green in color instead of red, so its usage won’t be obvious to a dealer.

https://www.advlubrication.com/coll...tic-transmission-fluid?variant=41597446226113

Overall if you change it on a decent schedule it doesn’t much matter what you choose. Just changing it is the important part!

Manage temperatures. Once you have the fluid changed, you can give it (and the transmission) a longer life by keeping it cool. The stock TBV is an absolute joke with a pinhole sized outlet and a thermostat that opens too late (when it opens at all). The Mishimoto TBV is cheap, easy to install and keeps temperatures right where they should be for optimal shift quality AND transmission life.

https://www.ebay.com/itm/226725743267?

https://www.ram-trx.com/threads/mishimoto-transmission-thermostat-preliminary-review.24229/

Just some things to consider…

 

[Two]

Thanks for yet another helpful and informative post.

 

[FULLTHROTTLERICK]

MAKE THIS THREAD A STICKY! Great info as always!

 

[Louk]

How different from the trackhawks and durango hc is our trans? I assume it’s more robust than the one in the charger/challenger?
Have those vehicles also experienced trans issues?
Is the extra weight of the trx causing these issues?
zf8 speed is an extremely common trans, curious why in the trx only it would be having these problems.

 

[atljar]

I belive you can buy the trans pan gasket, bolt kit and filter separately. No need for the entire pan. Can save some costs there!

 

[Psifer]

How different from the trackhawks and durango hc is our trans? I assume it’s more robust than the one in the charger/challenger?
Have those vehicles also experienced trans issues?
Is the extra weight of the trx causing these issues?
zf8 speed is an extremely common trans, curious why in the trx only it would be having these problems.

The only difference in the TRX transmission is the tail housing adapter. Besides that, the internals of the 8HP95 are the same for the Trackhawk, DDHC, and TRX. The TRX uses a completely different transfer case that is much more robust.

 

[Two]

How different from the trackhawks and durango hc is our trans? I assume it’s more robust than the one in the charger/challenger?
Have those vehicles also experienced trans issues?

Don't know about Durangos, but the Trackhawks have a built in fuse, in the form of a transfer case.

 

[DrVoddka]

Bump

 

[R6Snods]

How different from the trackhawks and durango hc is our trans? I assume it’s more robust than the one in the charger/challenger?
Have those vehicles also experienced trans issues?
Is the extra weight of the trx causing these issues?
zf8 speed is an extremely common trans, curious why in the trx only it would be having these problems.

It is the same transmission from the trackhawk and durango hellcat, the 8hp95. This is supposedly an update of the 8hp90 from the challenger/charger hellcat with some reworked internals to handle more power, for which I've seen multiple different quotes for torque capacity. Keep in mind, this transmission is made by Chrysler under a license from ZF for their 8HP design. It is in theory the same one used in BMW's, Audi's, etc, however its susceptible to Chrysler manufacturing and design tweaks (A clutch backing plate sticking/uneven contact).

If you look at the trackhawks they have been having problems with the transmission as well. Quite a few e-clutch drum failures and stuck in gear issues that the TRX has been having. The challenger hellcat, specifically the demon and widebody variants have also had their fair share of transmission issues. All of these models have 1 thing in common, tractionl. Ever see a regular hellcat full throttle launch without wheel spin? Me either. That wheelspin keeps the torque on the transmission clutches lower and keeps them cooler and the fluid barrier between them happier. With the TRX there's 100% traction all the time. So from a launch the clutches are subjected to all 650ft.lbs from the engine making them mesh (slip) more which gets them and the fluid super hot. If you factor in the weight of the TRX under normal driving, it requires either more torque to get the truck to move in a similar speed, or a longer amount of time with a similar amount of power as a charger/challenger. Either one subjects the clutches and the fluid in the trans to more heat. More heat, less viscous the trans fluid is. Too low of a viscosity and the fluid flows out from between the clutch discs and that's when you get severe wear and possibly warping of the discs causing the sticking in gear.

I can say after changing the trans fluid in the TRX the fluid was much more degraded and contaminated with clutch material after 27k, than my challenger hellcat was with 70k miles, both having never been changed prior to those points. Also while switching out the mishimoto thermostat, the new fluid is already showing signs of wear and degradation (dull opaque grey) after about 8k miles. This fluid has never seen temps above 180* according to the dash so I support @OnTheReel 's plan to change the fluid after 25k miles. (MILD RANT ALERT) This blatant bullshit marketing idea from RAM that the transmission fluid is lifetime is as accurate as it is a pathetic business model. The fluid will last 100% the life of the transmission, as you'll change the fluid when you change the transmission out after its failure. Then don't authorize dealership rebuilds, just make them slap in a new one at twice the cost. This is not unique to the TRX, this is every 8HP variant in Stellantis's lineup, but to see this same mentality applied to a 700 hp supertruck as it is to a 3.6L dad wagon is beyond disappointing. Further proof that the engineering/marketing scales are tipped in the wrong direction at Chrysler; hopefully this is something Tim can address.

Back to the topic at hand, what can we do to help our trucks? CHANGE THE TRANSMISSION FLUID AND KEEP THE TRANS TEMPS DOWN. Both have been said multiple times in multiple threads and at this point I think I'm going to change my screen name to it so I don't have type it in a reply. Pick your flavor of fluid even if its factory 8 & 9 speed fluid, and change it every 20-30k miles. Put an aftermarket TBV on it or bore out the stock unit to keep the temps in check. And for the love of god, DO NOT TURN OFF TORQUE MANAGEMENT if you're going to get a transmission tune.

 

[FULLTHROTTLERICK]

It is the same transmission from the trackhawk and durango hellcat, the 8hp95. This is supposedly an update of the 8hp90 from the challenger/charger hellcat with some reworked internals to handle more power, for which I've seen multiple different quotes for torque capacity. Keep in mind, this transmission is made by Chrysler under a license from ZF for their 8HP design. It is in theory the same one used in BMW's, Audi's, etc, however its susceptible to Chrysler manufacturing and design tweaks (A clutch backing plate sticking/uneven contact).

If you look at the trackhawks they have been having problems with the transmission as well. Quite a few e-clutch drum failures and stuck in gear issues that the TRX has been having. The challenger hellcat, specifically the demon and widebody variants have also had their fair share of transmission issues. All of these models have 1 thing in common, tractionl. Ever see a regular hellcat full throttle launch without wheel spin? Me either. That wheelspin keeps the torque on the transmission clutches lower and keeps them cooler and the fluid barrier between them happier. With the TRX there's 100% traction all the time. So from a launch the clutches are subjected to all 650ft.lbs from the engine making them mesh (slip) more which gets them and the fluid super hot. If you factor in the weight of the TRX under normal driving, it requires either more torque to get the truck to move in a similar speed, or a longer amount of time with a similar amount of power as a charger/challenger. Either one subjects the clutches and the fluid in the trans to more heat. More heat, less viscous the trans fluid is. Too low of a viscosity and the fluid flows out from between the clutch discs and that's when you get severe wear and possibly warping of the discs causing the sticking in gear.

I can say after changing the trans fluid in the TRX the fluid was much more degraded and contaminated with clutch material after 27k, than my challenger hellcat was with 70k miles, both having never been changed prior to those points. Also while switching out the mishimoto thermostat, the new fluid is already showing signs of wear and degradation (dull opaque grey) after about 8k miles. This fluid has never seen temps above 180* according to the dash so I support @OnTheReel 's plan to change the fluid after 25k miles. (MILD RANT ALERT) This blatant bullshit marketing idea from RAM that the transmission fluid is lifetime is as accurate as it is a pathetic business model. The fluid will last 100% the life of the transmission, as you'll change the fluid when you change the transmission out after its failure. Then don't authorize dealership rebuilds, just make them slap in a new one at twice the cost. This is not unique to the TRX, this is every 8HP variant in Stellantis's lineup, but to see this same mentality applied to a 700 hp supertruck as it is to a 3.6L dad wagon is beyond disappointing. Further proof that the engineering/marketing scales are tipped in the wrong direction at Chrysler; hopefully this is something Tim can address.

Back to the topic at hand, what can we do to help our trucks? CHANGE THE TRANSMISSION FLUID AND KEEP THE TRANS TEMPS DOWN. Both have been said multiple times in multiple threads and at this point I think I'm going to change my screen name to it so I don't have type it in a reply. Pick your flavor of fluid even if its factory 8 & 9 speed fluid, and change it every 20-30k miles. Put an aftermarket TBV on it or bore out the stock unit to keep the temps in check. And for the love of god, DO NOT TURN OFF TORQUE MANAGEMENT if you're going to get a transmission tune.

Great rant my man!

Is that really the only difference between OEM TBV and Mishimoto? Im tempted to just bore the factory one out so its 1 less thing they can point to if and when my next transmission fails during my extended warranty period.

 

[R6Snods]

Great rant my man!

Is that really the only difference between OEM TBV and Mishimoto? Im tempted to just bore the factory one out so its 1 less thing they can point to if and when my next transmission fails during my extended warranty period.

The stock and mishimoto thermostats are both 160*. The mishimoto unit has a slightly different bypass setup than the stock unit as well but I dont know its effects on flow. Here is what they look like side by side on the cooler side.

 

[84 Sheepdog]

Guess I'll finally be installing the PPE bypass that's been sitting here collecting dust this weekend. LOL In regards to the fluid change, I seem to remember these transmissions being a pain to get the level right, something about it needing to be on a lift and run through the gears to get the level right. Is that correct? I might just take it to the dealer for that job if so.

 

[2026TRX]

Guess I'll finally be installing the PPE bypass that's been sitting here collecting dust this weekend. LOL Seem to remember these transmissions being a pain to get the level right, something about it needing to be on a lift and run through the gears to get the level right. Is that correct? I might just take it to the dealer for this job if so.

I haven’t done mine yet but I found this super helpful.

 

[2026TRX]

I know he used the red Amsoil ZF8/9 speed ATF in this video but do you guys think the blue Amsoil would flow just as good cold as shown in the video? I would feel better about the cooler I ordered knowing I had the Amsoil in there that was pouring like cough syrup at -50F vs the Mopar that looked like a rock hard green slurpee at the same -50F. Cold flow test starts at 6:26

 

[R6Snods]

Yes. Better than the red according to the tech sheet. The red has a pour point of -63*F and the Blue has a pour point of -85*F.

Not sure why he has the Fuel-Efficient blue bag but is pouring the red bag multi-vehicle ATF, other than maybe that's all Amsoil offered 4 years ago.

 

[LouDogg]

@OnTheReel What are your thoughts on just flushing the system with new fluid?

 

[OnTheReel]

Keep in mind, this transmission is made by Chrysler under a license from ZF for their 8HP design. It is in theory the same one used in BMW's, Audi's, etc, however it’s susceptible to Chrysler manufacturing and design tweaks (A clutch backing plate sticking/uneven contact).

Couldn’t agree more with your overall sentiments and appreciate your insight. Just a little footnote…as far as I know our transmissions are actually manufactured in Germany by ZF. At least going off the window sticker and ZF casting on the transmission above the TBV.

Most if not all of the 8 speeds built by Chrysler under license here in the US (like the 850RE) are going behind Pentastars. And even those seem to be pretty good considering they don’t get maintained much either.

The main observation from my ATF sample, like you saw with yours, was just how damn filthy it was. This type of particle load (mostly from run in I presume) should not be left alone for too long. Because eventually you get a wear-snowball effect, in addition to this “trash” dispersing throughout the transmission and collecting in areas you don’t want it, like the valve body.

Left long enough and/or run hot enough and you also run into issues with additive depletion and oxidation until the fluid no longer has characteristics needed to function properly. Mine was OK in that regard because I did bypass the TBV early on and save it some stress.

 

[OnTheReel]

@OnTheReel What are your thoughts on just flushing the system with new fluid?

I’ve never been a flush guy if that’s the question. I dump and I fill. Do it enough times and the % of original fluid remaining is down to an inconsequential amount.

I’ll type out exactly how I do the service later. I do take a few liberties to streamline the process and bypass need for a lift. In my opinion this is one of those things that gets over-complicated beyond reason, and the fact that I haven’t ever lost an 8 speed maintaining them my way backs that up!

 

[LouDogg]

I’ve never been a flush guy if that’s the question. I dump and I fill. Do it enough times and the % of original fluid remaining is down to an inconsequential amount.

I’ll type out exactly how I do the service later. I do take a few liberties to streamline the process and bypass need for a lift. In my opinion this is one of those things that gets over-complicated beyond reason, and the fact that I haven’t ever lost an 8 speed maintaining them my way backs that up!

What would be the procedure to drain and fill? I ask because Mopar's transmission service procedure has a ton of steps.

 

[R6Snods]

@OnTheReel I see the same ZF stake on mine and the Germany origin on the window sticker so they must have got this batch straight from ZF, or a Stellantis plant over in Germany. It would appear that the 8HP75 is still made in Kokomo, IN and the base TorqueFlite (8HP40?) being manufactured between the 2.

Is that analysis of the first oil change? If so how many miles? Hopefully that iron is from the gears and not the steels.