727 to 518 swap thoughts....

[prophetdaniel2]

Totally plagiarized from another RV site:

Dodge 518 Conversion 
This is how to replace your three speed transmission with a 1995 back A518 overdrive transmission with a three wire connector (gas). A 518 transmission has a 31% overdrive and will produce a 30 to 40% increase in gas mileage on the road over a three speed transmission. Remember overdrive is only 3rd gear high range anyway. There are two wire 518 transmissions out there, these have a non-lock-up torque converter. With this three wire setup you have a four speed transmission plus a torque converter lock-up feature. The extra gear is 3rd high range. We've been asked this question for years, so I decided to put it down in black and white. What we're actually going to do here is control the overdrive and torque converter lock-up normally controlled by the computer using one vacuum and two oil pressure switch. Instead of using an electronic speed sensor and throttle position sensor we will use a mechanical / hydraulic / electronic speed sensor and a vacuum / electronic throttle position sensor. This will be accomplished with the use of three GM parts and some trick wiring. The Chevy and Ford guys make the swap to overdrive all the time, it's time for the Dodge people to have the same option. 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. This can be made to work with a diesel motor also with or without a vacuum pump and vacuum regulator.


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#1. The center wire on the transmission is the hot wire and the two other wires are ground wires for overdrive and the lock-up torque converter. The front wire is the overdrive ground and the rear wire is the torque converter lock-up ground. You can get a three wire female connector from a junk yard or buy one from us.

#2. Run a 12 volt fused wire that turns on and off with the key to the vacuum switch, then to the center wire on the transmission connector. This is a normally open vacuum switch that takes 7 inches or more of vacuum to shift into overdrive and lock-up the torque converter and 3 inches or less of vacuum to down shift and unlock the torque converter. Lets say you're in overdrive going 54 miles per hour at very light throttle, when you press on the throttle and the vacuum drops below 3 inches the transmission will immediately shift back to 3rd gear low range without lock-up or even a lower gear depending on the throttle position.

#3. At the governor pressure tap on the transmission install a tee fitting for two oil pressure switches. Say a 44 PSI oil pressure switch for overdrive and a 52 PSI oil pressure switch for the torque converter lock-up. Or any other combination of switches you may want. At light throttle the transmission will shift into overdrive at 44 MPH and the torque converter will lock-up at 52 MPH. The pressure switches go on the outside of the transmission case in the governor pressure port. It's located on the right side, at the upper rear of the main transmission case. The figures on the pressure switch will only be correct if you have a stock tire size and rear end ratio.

#4. Run a wire from the front pin on the transmission connector to the 44 PSI oil pressure switch and a second wire from the rear pin on the transmission connector to the 52 PSI oil pressure switch. Now at 52 MPH when you step on the gas the transmission will shift back to third gear and the torque converter will unlock at the same time. It can't get any easier than this.

#5. Install a toggle switch in the overdrive ground wire. When the switch is turned off you will have 1st, 2nd and 3rd low range, exactly like a 727 transmission with the same ratios. When the switch is turned on you will have 1st, 2nd  and 3rd gear low range plus 3rd high range. When the toggle switch is on the transmission will immediately shift into overdrive at light throttle over 44 miles per hour whenever it's in drive range on the gear selector. Once in overdrive the transmission will not come out of overdrive until the overdrive solenoid is turned off, or the vehicle speed goes below 44 miles per hour, or the vacuum drops below 3 inches. The only electronic parts on a 518 transmission are the overdrive and torque converter lock-up solenoids.

NOTE: People make this swap all the time, but I've never heard of anyone doing it correctly. They drive down the street flipping a toggle switch on and off at every stop. This setup works automatically.

NOTE: The way governor pressure works is 1 pound of pressure per square inch equals 1 mile per hour unless someone has changed the tire size, or rear end ratio, or governor springs and weights. The vacuum switch acts as a throttle position sensor and the oil pressure switch acts as a speed sensor.

NOTE: Use a lock-up type torque converter if possible, this could get you as much as 5% better gas mileage and the transmission will run much cooler. Running cooler will make the transmission last longer.

NOTE: You can also run the torque converter ground wire through the brake switch if needed.



I would like to do this someday.....if I can get a 4x4  under my rig

[John Eversoll]

Oh Danny Boy, da dee dee dee da de da .......  Never mind---

I had a tremendus thought.....

Why don't   you use the running gear from a ford bronco

Trans and front axels  That way you would have a 'Forge"

I ran the idea by a friend of mine that did stuff like that and I know that he himself

did a 67 dodge van with the gear from a bronco.. ran  great too.. I think he gave it to his son when he left for collage.  Still drives it too.

Later gater, John

[JerryT]

Hi PD2

I too have thought about engine/trans swapping in our Clippers. I was thinking that when the 440 gets tired(er) that one may want to do a Magnum 360 swap from a Dodge van. I think it would be nice to have factory engineered fuel injection,cruise control,high output motor four speed auto with lock up torque converter, ect.
The only pause that I have is will a Magnum 360 tote the load as well as the 440 does? I am almost certain that I would see a MPG increase and would bet that it would be around 3 MPG to about 10+. I think a Dodge to Dodge swap would be a project that I would tackle knowing that it would be bolt in with a bit of fabing. After writing this  I can see that to answer my own question all I need to do is buy a 360 Dodge van and load about 4 ton in the back and go for a drive

JerryT

[dave16131]

Sounds good but the 440 is externally balanced using the converter and harmonic balancer,so I would maybe add that your replacement converter should be matched to the original. Nice concept though, maybe someday

[pop427]

The trans cases are different bolt pattern. The torque converter always stays with the engine or balance problems.     Doug

[prophetdaniel2]

pop, i have found the adaptor already. availabe through jvxracing.com.....they have adaptors for any 727 based tranny...hehe.

[Horst]

Here's a youtube video of a guy that put a slick diesel engine into a Travco that used to have Dodge gas motor (440, 413, 318?) - a real nice mod.
http://www.youtube.com/watch?v=Vo11DG1nuGk

he has another video up too - search Travco Diesel on youtube  - not sure it wold fit in a Clipper - maybe some mods - and it could.

[pop427]

Prop, I'm sorry you did not understand my post. It was to let you know that the cases are different but the guts are the same. If you know someone with some trans knowledge he can switch the guts in about half an hour. Might be less hassle and cost less than an adapter kit. I worked for Chrysler for 9 years, went to their trans school and have rebuilt hundreds of automatic transmissions so I'm not blowing smoke. I'm very busy getting my race car ready to go to the Bonneville salt flats for speedweek next month and I should have taken time to explain better.  My Bad.

[Hank Jourdin]

Hey Dan-2 ,  When I built my motor I changed crankshafts for a steel crank verses the castiron arm. I also installed a full lockup converter with a Gearvendor Overdrive, 4:10 gears and  215/85R16 Trasforce Firestone tires which are a shade over 30 inches tall verses the 28" 16.5 wheels. I 'am dieing to get it on the road 2-1/2 years later.  I have it figured that it should run at aprox 65 mph a 2100 rpms, fingers are crossed for best gas mileage, hoping for 14 on the road. Hank Out!!