47rh transmission swap

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srt cummins

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My brother has his 1990 cummins 2wd with an auto. Max speed is 60 mph so he got a 47rh transmission. What all is needed to make this work? Any info will be helpful
 
Something else is up if he can only get to 60, but anyways...
You'll need a 2nd gen block plate and starter. The flex plate is the same. You'll need a slip yoke for the rear and the 3 pin electrical connector to control O/D and lock-up. I think finding a driveshaft from a 2wd O/D 1st gen would save some work, but I didn't do it that way. Since it's a 2wd, you'll need a long shaft 31 tooth speedometer gear. I bet you'll have to grind the frame to give the starter some room since it should be the short frame. I controlled lock-up and O/D with switches, but there's other ways to do it.

That's all I recall needing. 3.07s and a 47RH make for a fun cruiser
 
It can go over 60 but the rpm's are so damn high the truck runs great. Thanks for your help this truck is just a cruiser don't pull trailers anymore.
 
I'm very interested in what it takes to get the OD and lock up to function as if it was in a factory truck. I have a trans and have been thinking of doing this swap on my 90' model 4wd.
 
I prefer the switches for lockup and OD. Comes in handy and with a stock motor, or less than 400hp it will be helpfull in the hills or towing anything.
 
RonA said:
I prefer the switches for lockup and OD. Comes in handy and with a stock motor, or less than 400hp it will be helpfull in the hills or towing anything.
Click to expand...

I agree. I think O/D can be controlled with a pressure switch, but I'm not sure how lock-up could be automated.
 
might be able to run 2 pressure switches off the gov port. one for od and have it kick od in around 45 mph and then the second one lock up around 50mph which you'd want to hook a pressure gauge up and see exactly what the gov pressure is at those speeds....I may be missing something though also...
 
you wont have to grind nor cut the frame unless your motor mounts are old and or shot. put new ones in with my conversion and it doesnt touch the frame at all....
 
powerchoke-eatr said:
you wont have to grind nor cut the frame unless your motor mounts are old and or shot. put new ones in with my conversion and it doesnt touch the frame at all....
Click to expand...

Do you have a tall frame or a short frame? I cannot see how I could have enough room down there get everything to fit with out doing something to the lip of the frame on my 2wd.
 
i thought the same thing but it doesnt touch. i mean its close but like i said i got all new motor and tranny mounts as well so im sure that helps keep off the frame. in fact just had to take my starter off the other day and no rub mark or anything on it.
 
The only thing I really see a problem with is the 4 in exhaust and the cross memeber, I don't think the front drive shaft is gonna clear all that but haven't really held it up there and looked. Maybe someone else else done the swap could post a couple pics up...
 
Will a 47rh tcm plug in or what needs modified to hook it up. I'm not a fan of flipping switches to shift to overdrive and lockup every time. I have a 92 I'm doing this swap on
 
revolutiondsl said:
Will a 47rh tcm plug in or what needs modified to hook it up. I'm not a fan of flipping switches to shift to overdrive and lockup every time. I have a 92 I'm doing this swap on
Click to expand...

I am not aware of anyone completely automating the process. O/D would be easy because you can controll it with a pressure switch. O/D pressure is proportional to speed, if I recall correctly. If you T'd the O/D pressure port, I suppose you could set up O/D to run off the same pressure port for lock-up.

Just my$.02, there's probably better ways
 
PATC 46RE 47RE 48RE Transmissions, Performance Transmission A518, 518

They also make a kit that takes the DIY out of it for about $250 more

PATC 727 to 518 Conversion Kit

Click here for 727 to 518 swap wiring diagram.

#727518. With these four parts you can convert your 727 transmission to a 518 overdrive transmission with locking torque converter. What this kit does is makes a 518 transmission shift without a computer. Lets say you drive an average of 400 highway miles per week, at that rate you could save as much as $1000.00 per year on gas, not to mention the 31% reduction in RPM. Your new 518 will have automatic shifts into overdrive and lock-up, no toggle switch needed. Now with adjustable vacuum switch. The instructions are at the bottom of this page. (11-25-06. I just saw this kit on the Internet by the copy cat competition for $1654.00.) Cost $85.00
Qty 12345
Overdrive 44 MPH48 MPH
Converter Lock-Up 50 MPH52 MPH

IMG_0750.JPG


Here's the other kit

PATC 727 to 518 Deluxe Conversion Kit
#727518DK. This is the fully electronic no vacuum needed deluxe kit for the 727 to 518 swap. Made for diesels without vacuum and big cam gas motors with low vacuum. Comes with two governor speed sensors, throttle position sensor, electronic control unit, carburetor bracket and a shift solenoid pigtail. It is 80% pre-wired. What this kit does is makes a 518 transmission shift without a computer. Can be made for a non-lock-up torque converter for $18.00 less. Cost $325.00
Qty 12345
Overdrive 44 MPH48 MPH
Converter Lock-Up 50 MPH52 MPH

_DSC3698.JPG
 
Last edited:
What does a TCM from a 47RH need to see to operate. Speed (governor pressure ) and TPS ?
 
revolutiondsl said:
What does a TCM from a 47RH need to see to operate. Speed (governor pressure ) and TPS ?
Click to expand...

It needs output shaft speed (rh has no governor pressure sensor), throttle position, 12v +, and ground, and the center terminal in the 3 prong connector needs 12v + normally supplied by the TRANS relay
 
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