Part Eleventy-Hundred of Our 1969 Bronco Build
Part 4 or 5: Who’s Counting? Not Me!
Sadly, our Early Bronco project has been languishing. That's for a few reasons, and not all are worth going into during this tale of Bronco construction. The main reason for this rig resting idle is because of our personal indecision as it comes to what transmission to run in the Bronco. Generally we are all for manual transmissions, but we also enjoy a good automatic every now and again.
The Bronco came to us with no transmission, but in its former life it had an NV4500, and before that an NP435. Despite this, for whatever reason we've decided this particular iteration of this vehicle needs an automatic. And sometimes making a solid decision eludes us. We've contemplated everything from the venerable and original Ford C4 and beyond for this project. We eventually shied away from the C-4 because of the Bronco's relatively deep 4.88:1 axle gears. Those combined with a healthy BluePrint 306ci Bronco Edition small-block engine would make for fun, albeit quick runs up to about a maximum of 55 mph. We'd like to occasionally drive faster than that, so the idea of a C4 was dropped in favor of an auto with an overdrive.
Enter Ford's AODs, AODEs, and 4R70W (these are the evolution of Ford small-block automatic overdrive transmissions), and more recently we've also learned more about Ford factory offerings with multiple speeds.
So with lots of information on what is possible to bolt between our small-block BluePrint engine and our freshly rebuilt Ford Dana 20 we've finally made a decision and have a fresh Ford 6R80 transmission from Performance Automatic in hand. The reasons are many. The Ford 6R80 is a beefy unit, rated to 590 lb-ft of input torque as it is one of the transmissions designed to live behind healthy V-8s in Ford's more modern SUVs and trucks. That also means it has some beneficial ratios for our usage. First gear is a deep 4.17:1, and the transmission has not one, but (count 'em!) two overdrives, the first at 0.87:1 and the second at a tall 0.69:1. Couple that with our T-shift Ford Dana 20's 2.46:1 low range and it should make for good crawling off-road as well as keep the 4.88:1 axle gears spinning fast on the highway while in two-wheel drive.
Adapters are a yes front and rear with this transmission because it never came with an early Bronco Dana 20, nor was it ever found behind a small-block Windsor Ford V-8. Lucky for us, Advance Adapters has a 6R80-to-Early Bronco Dana 20 adapter and a crossmember (the company is working on a shifter for this combo), and Performance Automatic makes adapters to fit a small-block Windsor V-8 to a transmission and torque converter designed to bolt to a late-model modular Ford V-8 engine.
Add in an electronic transmission controller, and with any luck the BluePrint Bronco Edition 306ci V-8 will haul our Bronco down the road and trail—once we get to wiring the rig, that is. For now, here's the mechanical action of bolting in an engine, adding a transmission, and bolting on at T-case.