The Dodge Challenger Message Board

Hey guys. I am new to the board. My name is Wes and I have a 70 RT/SE clone. It has a 440 magnum with a 727 tranny and a 323 gear ratio. I am building my car up for a very powerful street/strip combo. I have a guy that will build my 440 into a 500 with 670hp. I plan to put a dana 60 posi rear end in it and all new suspension and stearing components. I will run bigger tires in the rear, but not much bigger than stock. My question is this, what tranny/rear end gear ratio combo should I run in order for it to run decent on the highway? Is there a 4 speed automatic that will bolt onto my 440? I heard Ford has an AOD that will work. I am not too sure what is out there. Got any advise guys?

500MAG wrote:Hey guys. I am new to the board. My name is Wes and I have a 70 RT/SE clone. It has a 440 magnum with a 727 tranny and a 323 gear ratio. I am building my car up for a very powerful street/strip combo. I have a guy that will build my 440 into a 500 with 670hp. I plan to put a dana 60 posi rear end in it and all new suspension and stearing components. I will run bigger tires in the rear, but not much bigger than stock. My question is this, what tranny/rear end gear ratio combo should I run in order for it to run decent on the highway? Is there a 4 speed automatic that will bolt onto my 440? I heard Ford has an AOD that will work. I am not too sure what is out there. Got any advise guys?

Yes, there are 4-speed automatics that will fit . The drawback is that they are too weak .

My best suggestion is that you order an overdrive unit from Gear Vendors for instance. Read all about the installation here:

Part 1: http://challenger.mpoli.fi/forum/viewto ... =9182#9182

Part 2: http://challenger.mpoli.fi/forum/viewto ... 0062#10062

Part 3: http://challenger.mpoli.fi/forum/viewto ... 0769#10769

Tranny tips can only be got via the introduction of silicone into the...Aw, forget it..bad joke.

love that but that would be totally lost abroard

Look at the A518 series of Chrysler overdrive transmissions.
Contrary to popular belief they are not weak, and why should they. They are your basic everyday run of the mill 727 with an overdrive unit on the back.
They've been known to take 700+ ftlbs of torque and 600+ horsepower from the diesel boys. I've also got a customer that is putting together a 70 'Cuda Clone, with a fuel injected Aruza HEMI that has a dyno sheet showing 675HP, and he is putting the A518 behind it. So much for the weak theory.
You'll need to find any early one (with the hydraulic style governor), and you'll need to make up a new driveshaft, new crossmember (agrumentive, as some say no to the crossmember modification), and you may have to massage your floor pan to fit the overdrive unit. You can also look at the elctronic version of the A518, but that will require you to figure out the wiring etc. Not an impossible task, but more difficult for sure.
What I'm seeing is more and more late model overdrive transmissions of all types being put in the older vehicles. I was at a car show this past summer, and I bet that over 50% had fuel injected engines with matching overdrive transmissions behind them. The one fellow I had a laugh with, owned a 1938 Oldsmobile, with a 572 **** engine, a 4.10 Dana rear end, and GM's 4L80E Electronic transmission. He claimed that on the highway, and maintaining posted highway speeds, he made about 15 MPG.
Enjoy the old body styles guys, but don't be afraid to embrace the new technology.
Merry Christmas to all.
transman

transman wrote:Enjoy the old body styles guys, but don't be afraid to embrace the new technology.
Merry Christmas to all.
transman

Merry Christmas to you too (and all others)! Thanks for sharing all your know-how.