2014 8 SP transmission problem

[Leiterterry]

Hello everyone;
First posting, I was driving from Nashville to Michigan. SP limit 75, doing 80 up those beautiful mountains. Transmission went to shift down, bam right out of the blue, it started to violently slam gears. And I had to slow down, now after this I slowed down, since then, I has been working great until it gets too hot, then it will kick out of gear.



Question: how reliable now is this transmission? Only 85000 miles on it. I would like to haul my 28 ft camper around to camp sites close to where I live in Michigan.
Thank you very much for having this great site.

 

[jws123]

What are your trans temps when it does this? It will say in the dash display.

 

[Leiterterry]

Thanks for replying, truth is, I don't know what the temperature was reading at the time. I will have to recreate, then check. Could I ask what in the meantime, what would your reply have been, if it was at a certain temperature? Thxs a lot.

 

[Leiterterry]

It is still very cold in Michigan

 

[caulk04]

I think the temperature related question is if it was malfunctioning causing it to overheat and shift oddly.

Regardless of outside temp, it should operate at 175-180 for driving unloaded.

 

[crash68]

Transmission went to shift down, bam right out of the blue, it started to violently slam gears. And I had to slow down, now after this I slowed down, since then, I has been working great until it gets too hot, then it will kick out of gear.

Watch the transmission temperature, if it is spiking higher than the coolant temperature the TMU on the side of the transmission needs to be replaced. The normal operation temperature for these 8spd transmissions is around 180° - 215° depending driving/ambient conditions.
There are very few reported problems with these 8apd transmissions.

 

[Leiterterry]

Excuse me.
What is a tmu and will the cost be considerable?

 

[Wild one]

Excuse me.
What is a tmu and will the cost be considerable?

Thermal Management Unit.It's the aluminium heat exchanger on the drivers side of the transmission.

 

[Leiterterry]

Thank you for that.
I feel very much that I know nothing about this transmission.
Thus, please excuse the question if it sounds stupid.
I have read that this transmission has heated fluid pumped into it.
My initial question was in regards to my transmission while traveling becoming so hot, that it would slam out of gear.
I read of a kit to bypass the heater, thus cooler fluid.
QUESTION: would your advice be to get it?
Thanks

 

[Wild one]

Thank you for that.
I feel very much that I know nothing about this transmission.
Thus, please excuse the question if it sounds stupid.
I have read that this transmission has heated fluid pumped into it.
My initial question was in regards to my transmission while traveling becoming so hot, that it would slam out of gear.
I read of a kit to bypass the heater, thus cooler fluid.
QUESTION: would your advice be to get it?
Thanks

Start reading about here. I don't want to ruin your day,but you might be looking at a new transmission,hopefully not though. When the 8 speed in my 14 went south,it did pretty well the same thing,wouldn't hold a gear on hills,and would slam itself down into 4th so hard it's almost knock the fillings out of your teeth. Do you know if the truck or transmission has ever been tuned?

RevMax 8 speed thermostat bypass

Hovering around 20 lately. I do still have the grill shutters. Also just for kicks I covered most of the trans cooler with a piece of rubber to test but it didn't seem to affect the temps. The trans cooler is so high that there doesn't seem to be much air directed at it through the grill anyway.

www.ramforum.com

 

[Leiterterry]

I don't think so

 

[Leiterterry]

My transmission does not seem to slam gears very often
, I have driven it for a hour or so, temp around 200 and slammed the throttle down and transmission worked very well. This transmission was covered by a warranty until I let my mechanic change the filter and he did not use dodge fluid it was a red color ,well anyway dodge voided the warranty

 

[Leiterterry]

Just out of curiosity, if I need to replace the transmission, what would that cost?

 

[jjjefferson]

I have a 2015 with the 8-Speed and experience similar. The first time it was slam-shifting from 2nd to 3rd. Ram replaced the Transmission Control Unit. That lasted a couple of months...then it did it again. They replaced the transmission. A couple of months later, it started overheating and hard shifting when the temps got above 210. I ended up installing a Bypass valve made by Caulk04 and it solved my issue. These 2014 - 2015 have more over heat issues than mentioned earlier...look on this and other forums.

 

[Wild one]

My transmission does not seem to slam gears very often
, I have driven it for a hour or so, temp around 200 and slammed the throttle down and transmission worked very well. This transmission was covered by a warranty until I let my mechanic change the filter and he did not use dodge fluid it was a red color ,well anyway dodge voided the warranty

Find out what he used for fluid,as that might be some of your problem.Suck it up and try doing a couple pan drop and drains using the Mopar fluid,and see if there's any change,it'll hurt your wallet,but it's cheaper then a new transmission.Also have him follow these instructions ,they're the factory instructions that came with my "brand new" not rebuilt 8 speed from the dealer. I don't know US costs,i'm in Canada,but my brand new 8 speed shipped out of Michigan,lol.

 

[Leiterterry]

Thank you for the info.

 

[Leiterterry]

What would it cost to have the transmission rebuilt.
What would it cost to buy new?
Thanks very much.

 

[Leiterterry]

Could I humbly ask where should I buy new at, dealer or maybe someplace else
Thank you

 

[smoothee]

Just out of curiosity, if I need to replace the transmission, what would that cost?

Don't know if you're set on new, but you can pick up a used unit for reasonably cheap. I got one with ~20k miles for $800 CAD for my 8 speed swap

 

[Atcer2018]

Could I humbly ask where should I buy new at, dealer or maybe someplace else
Thank you

There may not be anything catastrophic with your present transmission. The ZF 8 speeds have very good reliability but they are picky about fluid levels. You said your mechanic replaced the filter so that means 5-6 quarts of fluid were changed. Was it a compatible fluid? There are owners who have switched to Maxlife or Redline or Amsoil with much success but was the fluid the mechanic used compatible? The filter is integrated into the pan on these transmissions, did the mechanic make sure the sealing O ring between the filter and pickup tube was correct? Cavitation of the fluid will make shifts hard. Did the mechanic assure the proper fluid level? These ZF units have a wacky level check procedure, it’s not just add fluid till it spills back out, seal it up and you’re done. Incorrect fluid level will cause hard shifts too. You said Ram voided your warranty for the wrong fluid so there is a backstory to the transmission issue. Your current transmission may be fine with a couple hundred bucks worth of fluid, parts and maintenance.