It was a good run. How long did your Ford C6 automatic transmission live? Ten years? Fifteen? After 20 years and 250,000 miles, ours finally slipped (pun intended) into mechanical unconsciousness.
We were lucky. Our C6 breathed its last gasp of tranny fluid pulling into the parking lot of the office instead of on some lonely trail on the edge of civilization. Now we’re aware that the risk of being stranded off-road with an automatic is always greater than with a manual transmission, but we’ll wager that most of you reading this either ’wheel a fluid-shifted vehicle or have one in your driveway. Plus, we’ve recently seen more purpose-built 4x4s using autos as well.
We’re not going to settle the auto versus manual debate here. In short, we decided against trying to retrofit an NP435 four-speed, and against all the modifying necessary to install a late-model auto overdrive (such as an E4OD) at this time. We just wanted the Bronco’s trusty C6 revived.
The Plan
Maybe “revived” is not a strong enough term—we wanted the tranny rejuvenated. We knew that gains could be had with a performance rebuild that included heavy-duty friction and band materials, valvebody modifications, and shift reprogramming, but, being 4-Wheel & Off-Road, we wanted more. We wanted big-time improvements in off-road capabilities. In 4-Wheel & Off-Road parlance, we wanted lower gears.
While we’ll gladly tear into a transfer case or a manual transmission, setting an automatic on our workbench is like NASA shuttling Ray Charles up to correct Hubble optics.
So, after flipping through a JET Performance Products catalog we knew the company had the tools, techniques, and technicians to handle rebuilding the C6, but we didn’t know if JET could also provide the lower cogs (see the sidebar “A Case for Lower Gears”) needed to satisfy the 4-Wheel & Off-Road gearing decree.
A phone call to JET’s Paul Darden gave us the answer: No problem. Wonderful device, the telephone. A few days later the Bronco was up and running with improved driveability, on-road and off. If your automatic transmission is on its last legs, read this story, then use your phone and JET to put the juice back into that juicebox.