I want to put an 8hp75 from a 2020 RAM in my 2017 Jeep Grand Cherokee. I know the current TCU is not compatible with my cars software. From comparing both TCUs I can see that physically they are both identical, the connections to the valve body and solenoids etc. Would it be possible to use the TCU from my 8hp70 in the 8HP75? Then tune for any differences in the shift settings?
VIN number has to be changed
TCM tune is quite different. Not a straight shot, but it is possible to work with it though
Last edited by DodgeBoy_8HP; 02-24-2025 at 08:21 AM.
DodgeBoy.
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If I'm using the original 70 tcm from my car then the VIN won't be an issue. So you think this would work if I apply the right tune from the 75 to the 70?
i tune way more cars than trucks but i think you will have problemsOriginally Posted by str77x
for starters you are going to be writing a 4x4 tune into a 2x4 os
also, there were huge changes between the 2015-2017 and 2018+ operating systems
for this reason i have different ways of tuning the different versions
(early and late)
hp tuners only writes calibrations... it will not flash a different os into the controller
if said controller is even compatible with os you want to flash
get ahold of jon sipple to confirm
or david starnes outta memphis tn
or bill at paramount
8HP75 is the next gen of 8HP70.
Uses a different method of operating the B Clutch amongst many other changes.
Also, solenoid placement in valve body is changed (different solenoid sequence) and oil ports in trans case are different so you cant just swap valve body/TCM.
Plug pins are same but you would need to update TCM OS in the vehicle to be compatible with the newer TCM.
Not sure how doable that is as have never tried to.
Thanks for the info, good to know about the solenoid position, did a bit of research and yes you are right, B and D solenoids are switched between Gen1 and Gen2.
wow wait what...
my dumb ass thought 75 was 4x4 version
did some research... i really oughta start a new thread for this but since tuna dude is here here it is:
it looks like the hp 70 was only manufactured until about the time when mopar started selling them lol
checks out, right?
so if the 75 is 2nd gen and is what zf has been building since around 2015 is that is what comes in a 2018 scat?
what about a 1320?
i thought the cars got 70's and the trucks 75
if 70 had been outta production since 2014 what comes in a 2019 1320?
Not sure why you think the 70 is out of production in 2014? My jeep is 2017 and has the 70 as standard. My car is AWD not 4x4 but that's nothing to do with the trans that's down to the transfer case. As far as I'm aware the 70nwas used in Jeep grand cherokee up till 2021, with the exception of the Trackhawk which uses a 95, and for some reason as I recently found out German Diesels version which used the 75 from 2017. A TCU from one of these 2017's would likely be the best option.
dodge/jeep did not manufacture your transmission
ZF Friedrichshafen AG did
and it looks like they quit making them years before your jeep was released
fkn mercedes rofl
I've seen the 8hp70 in Jeeps and Rams till at least 2019ish.
Then Ram went to 8HP75, not sure about the Jeeps and Dodge cars.
Maybe some later HP70's were built specially for Jeep/Dodge USA or they stock-piled em?
I have seen a 2017 build HP70 that was in a untouched stock 2019 SRT Jeep and did wonder where that trans had been hiding till it landed in the Jeep.
Also, sometimes when I try to get parts out of ZF Germany for later 8HP70's, they tell me the parts are only available through ZF USA.
Always thought that was kinda strange seeing as they did build it, but get around that issue usually by just using an earlier trans serial number.
no idea
fkn strange tho. all of it
curious how far down the list of operating systems the tcm in the 2019/2017 trans was?
what are the physical differences between a early and a late hp70?
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