Category Archives: Chrysler Transmission

Chrysler A618/torqueflite

So one of my friends here in town decided to go truck pulling and hit me up for some transmission advise and service. sounded like fun so i am game. well, the first thing anyone should do when getting into new projects is to do some research so you have some fucking clue what the hell to look for and what you are working with upon innitial disassembly.

Back in trade school, we had to disassemble/reassemble a chrysler 777 tranny as part of a rebuild class. to be honest that was about the only time i spend on a chrysler production tranny for several years. hell i am an oldsmobile guy . back 8 years ago i teamed with my friends at bottom bulb racing to chassis and fab up a 71 duster for bracket racing that is still running today. this is where i got into the chrysler stuff again and along with it: the torqueflite 727. these are a very popular drag race and motor sports tranny. i have gotten into a few of these in recent years but there simply isn’t the demand for them like the GM transmissions.

Unlike the gm transmissions that have two or 3 major lines/designs of transmissions that changed over the years, chrysler pretty much based all their trannys off the same initial concept torqueflite tranny that debuted in 1956. to look at all the variations would be like looking at the family tree of my great great grandfather from sweden who had 14 kids-who all had 14 kids-who had…..well you get the point. inherantly all the chrysler trannys from the one in my dodge dakota-to the one behind the cummins-to a 904 from the late 70’s-to a 727 from 1969 all share some similar characteristics: and all of em have undergone numerous design improvements and changes.

The A618, later 47RH (hydraulic controlled governor pressure) and 47RE (electronic controlled governor pressure), is a heavier-duty version of A518. It was used in trucks and vans starting in the mid-1990s. While currently used with some internal changes when coupled to the 5.9 L Cummins Turbo-Diesel and the 8.0 L V-10 applications, it’s still a 727 with overdrive and stronger internal parts. It has an input torque rating of 450 lb·ft (610 N·m).

Gear ratios:

1 2 3 4 R
2.45 1.45 1.00 0.69 2.21

 

95 and earlier trannies (designated –rh)

The earliest version of the RH trans did not have a lockup converter. In 94 a lockup converter was introduced to the RH. Even though the RH is designated H, overdrive (and when present TC lockup) use solenoid(s) to turn on and off hydraulic fluid pressure to actuate these functions. These functions are controlled in an on-off electrical manner in a RH tranny.

The 94 up trans with lock-up has a place in the trans for the lockup solenoid and has fluid passages that do not exist in the earlier non-locking 74RH. A problem with these on the diesel applications is the converter clutches in the 47RH will not handle high throttle or engine braking.

96-up trannies (designated –re)

Were also not true electronic trannies, in that 1-2-3- shifts are still hydraulic controlled. They DID however – rather than use a cable to set throttle position control like they did in the –rh trannies – decide to use a PWM (pulse width modulated – a sort of digital control signal) to operate a pressure control solenoid in the valve body. This is not simply an on-off solenoid, it controls a variable pressure and REQUIRES a PWM driver to control it.

So at this point we are dealing with a 95 year truck with a modified 5.9L cummins…..with a shitload of boost. so i next need to establish if i have the original tranny or not in this truck, then find the appropriate core to begin with to make life A LOT easier for the rebuilder-yours truly. this should be a fun side project so stay tuned!