I've been learning more about transmissions in diesel school and torn into a few big powershift CAT transmissions and some big Allison Automatics. Its really neat to see the engineering in those things and have learned about mechanical and the newer electronic/solenoid transmissions. My potentiometer controller went haywire(TPS went haywire years ago so i did a POT conversion) in my truck the other day and I lost overdrive. luckily I had another one in the truck that I just hadn't put in yet but I got to thinking and why do we have an electronic Overdrive if the rest of the truck is mechanical??? The newer vehicles or trannys have a TPS that will tell the whole tranny when to shift with the solenoids but on our trucks have a TPS to control only the OD? I got to wondering why didn't they just keep them mechanical throughout with a mechanical Overdrive and be able to shift 1,2, and 3 on the column so we it would not go into Overdrive when we didn't want it to instead of using an electronic push button switch?

I know the whole electronic stuff was new back then and were they jut trying to convert things over slowly and one thing at a time to see how well it worked or what? It woulda made more sense to keep it mechanical and not have to deal with the faulty TPS that only had one single function. Or was it just the convenience of an electronic push button to lock it out of OD? Or did Overdrive transmissions require electronic components?

I've just gotten curious about this the last few days cuz the TPS can be a hassle sometimes and i'm not much of a fan of electrical things. I could be completely wrong on some of this and correct me if i'm wrong, I just like to learn new things or find out why things are the way they are?

also another side note: what runs the newer dodge trannys, say the 47re? is it just a TPS or is it tied into the computer and other things as well? cuz I was thinkin if you could get it to run with just a TPS then could we convert them to run in our trucks without a standalone controller or manual valve body?

 

Bump. Anyone have any ideas?

 

I'd assume easier for one cheaper and plus instead of the trans guessing at the load being put on od it knows where the throttles at and at how fast its moving and makes a calculation from there to be in od or not to be in.

 

The RE's are computer controlled.

The only "mechanical" OD tranny used in a truck would have been the 700R4 used in Chevys but that was vacuum actuated.

The electronics are easier on the end user.

 

The 47RE is basically the same except it used electronics to create the governor pressure, rather than a mechanical gov. That way they can have different shift points for different loads/ situations. Basically, the computer can alter the vehicle speed signal the valve body sees, making it shift sooner or later.

 

The 47res are controlled by the tps, opss and vss the biggest problem running an re is the electronic gov, if you use a rh you don't need to worry about a tps just put it on a toggle switch, or you can run it off the gov pressure port with a switch,

the newer trucks with the re's all the tps is for is od,everything else is mechanical, its when you get into trans with shift solenoids is where the electrical gets more complicated.
Like i said earlier (which i guess i didn't read your whole post) the main reason for the tps is for load control for od,

 

There are plenty of hydrulic and mechanical dodge overdrive just in gas aplications.

 

how are you building your 47rh?

 

Ok I guess that makes some sense. I was just kinda curious and got to thinking why did they do this? When I had tps issues.

So in a way we could build a controller or get a 47re to work in our trucks? With out spending a bunch of money on a controller? Is all the electronics in the valve body or is there a way to swap 47rh parts into an re to make it mechanical again? I just know how hard the 47rh is to find since they only came in 2 years. I luckily snagged one for a screaming deal and found out it had a billet input already in it after I got it so that was even better. It would be nice to be able to run an re in our trucks if it was simpler cuz they are much easier to find and they have the steel planetary rather than aluminum i've heard.

My 47rh is gonna be built by a smaller up and coming diesel shop, but the owner is a great guy and his trannys are well known along with hos other work. I built some things for him so he told me he'd build my 47rh if I paid for the converter. So im just waiting on the funds for the converter. Then its gonna get a nice build, a custom triple disk converter he has built buy a local company, the billet input is already in it, then it'll get upgraded/added clutch packs, his own custom valve body that he says he runs lots of pressure with, and other billet internal goodies, and maybe a trans pan. It should be a good build for my truck. I've been in some other trucks with his trannys and they scream. His p pumped 24 valve held up to over 1000hp with his built 47rh. So im excited. I got everything to swap it over but the flexplate and maybe the front driveline. I was gonna go with a 2nd gen flexplate but he convinced me to go with a billet flexplate since im pulling now.