Chuck Huber built this outstanding 1972 Jensen Interceptor Mark 111. The car was originally equipped with a Chrysler 440 V8, Chrysler 3 Speed 727 Torqueflite Transmission, and a Salsbury 4H Limited Slip differential.
The car’s drivetrain was later modified in 2017 at Phoenix Transmissions in Weatherford TX with a 4 Speed Overdrive GM 4L60E electronically controlled transmission, a HGM COMPUSHIFT Transmission Controller, a custom driveshaft, and the internals of the Salsbury differential was replaced with Dana 44 internals, to modify the rear-end ratio to be in line with the gearing of the modern 4L60E.
So the goals for the build were (in priority order)....
1) Get a reliable and robust overdrive transmission in his car (the Torqueflite was old technology, slipped during shifts, didn't kick down, and constantly poured fluid on the ground)
2) Provide high speed cruising at low engine RPM (shooting for a much lower cruising speed)
3) Increase performance as judged by "off-the-line" acceleration
4) Improve gas mileage
The 4L60E electronic transmission is a modern 4-speed automatic, with both overdrive and lock-up torque converter. The transmission is used by many GM products (Corvettes and Camaros, among other vehicles). In addition, he then added a "lower" gear ratio in the differential (going from a 2.88 rear end to a 3.54 rear end). This gave him incredible acceleration from a standing start.
Chuck could have addressed priority #1 by just going through and repairing his Torqueflite, but that would probably have cost between $1200 - $1800 and still left him with an antiquated 3 speed transmission. Priorities #2 & #3 are just the kind of thing a gearhead would want for his or her car. Priority #4 was the bonus item. Chuck was hoping to get ~16-17 mpg out of the upgrade (vs. the dismal current 11-12 mpg).
This project is one that would give him a much improved car, yet still stay within the spirit of the Jensen Interceptor - a high speed touring car - "The Gentleman's Express". Many things are being touched, and all for the better. He did 900 miles cruising at 3000 RPM on the way to Texas - then Chuck cruised back at higher speeds and lower RPMs. He wanted to take advantage of the power and torque that was available from his 440.
Chuck's 1972 Jensen Interceptor Mark 111 is a great example of the diversity of cars that have used a COMPUSHIFT transmission controller to get full electronic control of their transmission.
If you have a build that uses our COMPUSHIFT please be sure to send it in by replying to this newsletter.
If you are thinking about a 4L60E for your next conversion check out our 4L60E Controller.