Another New Guy with questions.

James that is a great looking car!



RedFish and Bob, a few years ago I would have absolutely agreed with you on the gear ratio.

What changed my mind was the 37 Dodge. During the initial mock-up of the truck I was planning on a 727 and a rear-end with around a 3.20 gear. From experience with the Gen 1 HEMIs and with the old tech including carburetor(s), ignition and the cams I’m fond of, the sweet spot for cruising is normally around 26-2900 RPM at 75 MPH. At the time I hadn’t picked up a rear end yet, but had a B Body Dana 60 sitting around I had been trying to sell. The reason I hadn’t had any takers on it at what I was asking was primarily because it had 4.56 Gears in it. I ended up deciding that as the 37 Dodge was strictly going to be a toy that wouldn’t travel too far from home what the heck I’d throw in in the Dodge with an OD transmission.

I ended up using a 46RH. OMG if you have never driven a street car with 4.56s, it is a RIOT. The 46RH has a .69 overdrive ratio resulting in the effective ratio being 3.14:1. With 28 inch tall tires 75 MPH is around 2800 RPM right in the engine’s sweet spot. 4.30 Gears will effectively be 2.96 and of course RPM will also be effected by the tire size I use, so a might play with the gear ratio a little bit.

Now all that being said, I’ve been looking at what’s involved to install a 46RH in an A body. At this point it doesn’t look like a show stopper as long as my back will let me crawl in and out under the car to the measuring, fitting and welding ( a kit for the trans mount would sure be nice).

I do have a plan B, I still have a builder small block 727 sitting in the back shed which should eliminate the trans mount modifications, and I would be back to looking at a 3.20 ratio.

On a side note, the 2 thing that are critical with the deep gears are drive shaft balance (fortunately there’s a good drive line shop close by) and pinion angle.