MAIN HOME PAGE > Technical Info TOC > Late B-Body Automatic Transmission to 4-speed Swap Information
Thanks to Bill Haigh who frequents the Mopar Mailing List (MML) for the information on this page.
This information is for converting '71 B-Bodies and am not sure how much it pertains to our Chargers but it worth a try My high school car was a '73 Charger SE with a 400 2bbl & automatic. It was tired & lame and I knew a 383 had more guts right out of the box, so I decided to go that route. Since I burnt up 3 automatics in my senior year (a few too many neutral gear drops) I decided to swap to a 4-speed. This is real easy if you have a donor car that has all of the parts. If you don't, it can take a lifetime of searching to find all the right stuff. I also helped a friend convert his '71 Road Runner to 4-speed and he got EVERYTHING he needed from a '73 Charger (318 4-speed) for $200. Here is a list of what you need: * Pedal assembly, complete with all brackets (especially the bracket on the left side of the clutch pedal & the clutch pedal switch) * Gas pedal (bent to the left to clear the trans tunnel) * Transmission tunnel * "Reverse" indicator light (goes in the dash) * Frame rail bracket for the cross shaft ("Z bar"). This is welded on, but a hacksaw, chisel & hammer, and about an hours time will remove one at Pick & Pull. A torch or Sawz-all is that much faster. * Transmission * Bellhousing * Shifter & linkage * All clutch linkage * FlywheelThe only part that is not a bolt-in is the bracket that goes on the frame rail. If you get a used one, cut off the frame rail around the bracket, then trim off the excess frame rail. You will notice that there is a metal tab on the bracket that sticks through a small slot in the frame rail. Most automatic cars I have seen already have this slot in the frame rail, so you simply drop the bracket in this and weld it in place. Real easy if the engine is out of your car, but it can be done with it in too.
Now the difficult part. You said your car was a 400 4 bbl. This is a problem if you are swapping to a 4-speed. Everything I have read says that a 400 with an automatic has a cast crank and is externally balanced but a 400 with a 4 speed came with a STEEL CRANK and was balanced differently. I do know 360's are externally balanced and their flywheels have a huge pie shaped section on the backside which is used for balancing, but the one honest 400 flywheel I have seen did not (which matches what I read about the steel cranks).
If you use your 400 automatic engine, you may have to use a 360 flywheel, but I would still highly recommend having the entire thing rebalanced (and unless you plan on tearing the engine apart, this would be out of the question).
Also, one more thing (famous last words). Not all automatic crankshafts are drilled for a pilot bushing. I found this out the hard way on my first 383. The easy way to tell is to stick your finger into the end of the crankshaft. If your finger goes in to the first knuckle, it is not drilled for a pilot bushing. If your finger goes in to the second knuckle, it is drilled far enough and you should be able to install a pilot bushing. Measure the inside diameter of the crank hole and compare it to the outside diameter of the bushing before you pound it in. The Dorman brand bushings that most stores sell nowadays are never the correct diameter.
Other than that, it is easy! :-) Let me know if you need more detailed info, you know I can ramble on for hours......Also, send this on to the MML if there are more people interested. BILL
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