Hi, I was wondering about retro-fitting my 88 Ram 250 with a 4 speed OD auto trans?
Did one exist for this chassis that would swap in semi-easily with say a driveshaft and cross-member swap?
If yes, what model and year etc?
Thanks!
Nobody?
Its not a terribly difficult swap, but there are a few things to be aware of. The trans will basically bolt up to any Smallblock Mopar engine (318/360 in the 80s) if you use the correctly weighted torque convertor or flexplate. The 360 is externally balanced and has to have a weight on the convertor, the 318 does not. People put these transmissions behind big-block v8s in muscle cars, too, but that requires an adaptor plate and significant modification.
Beyond that, there's the issue of the crossmember that supports the tail-shaft. The 4-speed is fatter in the tailshaft area (that's where the O/D was tacked onto the A-904 to create the A-500, or onto the A-727 to create the A-518). You may also have to massage the floorpan to clear the fatter tailshaft, although with a ram truck it should be minimal. IT gets pretty extensive for the folks that put these transmissions in Darts, Valiants, and Barracudas, less-so for B-bodies, not much difficulty for C-bodies, and virtually no problem for trucks.
And finally, there's control of the lockup convertor and O/D. In the vehicles that originally came with an A-518 or A-500, the computer would engage the locking TC and the O/D at the correct times. You CAN control both with simple toggle switches that you operate manually, but the danger is that if you improperly engage lockup or leave it engaged upon coming to a stop, you can overstress and damage the lockup clutch. Except for the very heavy-duty versions of the 518 that went behind the Cummins or the V10, the lockup clutch is not meant to handle a great deal of torque because the computer always disengages it when a lot of torque is demanded from the engine. There are aftermarket controllers intended for retrofitting these transmissions to muscle-cars that work it all automatically based on throttle position and manifold vacuum, so it would be best to consider that option.
Its not a terribly difficult swap, but there are a few things to be aware of. The trans will basically bolt up to any Smallblock Mopar engine (318/360 in the 80s) if you use the correctly weighted torque convertor or flexplate. The 360 is externally balanced and has to have a weight on the convertor, the 318 does not. People put these transmissions behind big-block v8s in muscle cars, too, but that requires an adaptor plate and significant modification.
Beyond that, there's the issue of the crossmember that supports the tail-shaft. The 4-speed is fatter in the tailshaft area (that's where the O/D was tacked onto the A-904 to create the A-500, or onto the A-727 to create the A-518). You may also have to massage the floorpan to clear the fatter tailshaft, although with a ram truck it should be minimal. IT gets pretty extensive for the folks that put these transmissions in Darts, Valiants, and Barracudas, less-so for B-bodies, not much difficulty for C-bodies, and virtually no problem for trucks.
And finally, there's control of the lockup convertor and O/D. In the vehicles that originally came with an A-518 or A-500, the computer would engage the locking TC and the O/D at the correct times. You CAN control both with simple toggle switches that you operate manually, but the danger is that if you improperly engage lockup or leave it engaged upon coming to a stop, you can overstress and damage the lockup clutch. Except for the very heavy-duty versions of the 518 that went behind the Cummins or the V10, the lockup clutch is not meant to handle a great deal of torque because the computer always disengages it when a lot of torque is demanded from the engine. There are aftermarket controllers intended for retrofitting these transmissions to muscle-cars that work it all automatically based on throttle position and manifold vacuum, so it would be best to consider that option.
Thank you!
I believe that the A500 was introduced to the Ram 250 Van in 1989, sound right?
It looks like ithe A500's gearing is good for the the van's rear gear (roughly 2.70, 1.50, 1.00, 0.70).
I do know that there's a lock-up converter in my 88's 3 Speed auto, so perhaps it's ECM will control the A500's as well?
Should I assume that there's also a TV Cable of some sort (Throttle Valve Cable to control pressure)?
So hopefully the swap only needs: A500, crossmember, driveshaft, and TV Cable assembley?
Thanks again for your help!
Maybe... I'm a little foggy on the very early days of the 4-speeds. My involvement with them came after the Magnum 318 and 360 came out with MPFI and full electronic drivetrain control circa 1992.
Nope. The A904 (and its HD A998 and A999 versions) had a fully hydraulic lockup control. The transmission operated entirely independently of any external control other than the kickdown/throttle position linkage. Driveshaft speed (determined by the governor) and input torque (implied from the throttle position linkage) determine the shift points, hydraulic pressures, and lockup point. Now the early A-500 *may* be the same way as far as lockup is concerned- you'll have to find someone who knows more about it in particular than I do.
Its a rigid linkage on Mopars prior to the Magnum series engines. It runs from the carburetor (or TBI) down to the transmission. There are two general versions- one with 3 semi-straight linkages coupled by bellcranks, another that is a single rigid bar in applications where there is room for it. The early Magnums use a cable from the MPFI throttle body, later ones went to increasingly electronic controls of everything until the A-500 and -518 were phased out completely in favor of 100% electronic transmissions with the arrival of the 4.7 and 5.7 v8 engines.
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