COMPUSHIFT Sport the perfect match for Mike Drennan's 4L60E!

COMPUSHIFT Sport the perfect match for Drennan's 4L60E!

Read below the story of Mike Drennan and his '72 Chevelle. With a background in electrical engineering and working as a defense contractor Mike did his research before deciding on a HGM COMPUSHIFT Sport to control his 4L60E transmission. Mike says he has seen lots of high-end military-spec hardware and the HGM products were as high quality as he'd ever seen.

"My name is Mike Drennan. I graduated from the U.S. Naval Academy with an electrical engineering degree and went on to serve in the Marine Corps as an air defense officer for twenty years. I then spent another twenty years working as a defense contractor and civil servant supporting the Marines. I retired in 2016 while living in the Northern Virginia area. The rat race of living near Washington, DC lost its appeal after I retired, so my wife and I made the decision to move to the beautiful countryside outside of Chattanooga, Tennessee.

I started drag racing as a hobby in 1982. I had a great time racing, but decided to “hang up my helmet” after doing it for 25 years. It’s hard to get hot rodding and wrench turning out of your blood, so when the chance came up to buy a ’72 Chevelle that needed restoration, I took the leap. When I got the Chevelle in 2007, it was painted red and didn’t have a front end on it. It took me a year working nights and weekends to get it ready to hit the streets. It was originally powered by a 396 BBC backed with a TH350 transmission and a 10 bolt rear end. When the 396 wiped a camshaft lobe after 5 years of driving it, I dropped in a GM Performance Parts 454HO engine. I have enjoyed taking the Chevelle to cruise-ins and car shows and just getting out and driving it.

“Long Hauling” a Hot Rod Power Tour (HRPT) has been on my bucket list for a long time. When it was announced that the 2018 HRPT was coming through Chattanooga, I signed up. I completed the 2,000+ miles of the 2018 event with no issues. However, I learned that the trip would have been more comfortable with air conditioning and an overdrive transmission. Prior to the 2019 HRPT, I installed a Vintage Air AC setup in the Chevelle. I couldn’t afford an overdrive transmission upgrade at the time, so I swapped the 3.55 rear gear for a 3.08. The 2019 event was a lot more relaxing with these upgrades and I again long hauled the entire event with no problems.

The higher rear gear was great on the highway, but definitely changed the performance characteristics of the Chevelle. The 2020 HRPT was cancelled, so I decided to use the time (and $) saved from that cancellation to install an OD transmission and a lower rear gear. After much research, I decided to install a beefed-up 4L60E transmission. My Chevelle started life with Malibu trim, but I’ve incorporated almost all of the SS upgrades over the time I’ve owned it with the exception of a 12-bolt rear end. Used 12-bolt rear ends for Chevelles are bringing major dollars these days, so for less money I decided to go with a Quick Performance 9” with a 3.50 gear in place of my 10-bolt. As an aside, my first drag car was a ’72 Monte Carlo. The only thing I broke more than once while racing the Monte was 12-bolt rear end. Once I installed a 9” rear end in the Monte, I never had another driveline problem. So, going with the 9” in my Chevelle seemed like a sound decision. With the low first gear in the 4L60E, I didn’t see a need for a anything lower than a 3.50 gear in the new 9” rear.

With the decision to go with the 4L60E, I needed to come up with a transmission controller. After moving to Tennessee, I worked part-time for a couple of years at Honest Charley Speed Shop in Chattanooga. My boss at Honest Charley had been a writer for Hot Rod and Car Craft magazines in his previous life. When I asked him for advice on a controller, he gave me the names of two gentlemen who had been tech editors for the magazines. I contacted them and they both graciously shared their experiences with the various brands of transmission controllers they had used in their professional and personal lives. In the end, they both told me the HGM COMPUSHIFT controllers were the best they had used. After comparing their experiences with my own research, I decided to give HGM a call.

My first call to HGM was answered by Mike Hoy. Mike readily discussed all aspects of the COMPUSHIFT Sport controller and answered every question I had. I took the leap and ordered the controller and an Acculink TPS Kit. A few days later, the box arrived from HGM. Talk about impressive! The fit and finish of the controller, the TPS, and the associated wiring harnesses were impeccable. Much of my career was devoted to the research and development of command and control systems for the military, so I’ve seen lots of high-end military-spec hardware…the HGM products were as high quality as I’ve ever seen.

Drennan COMPUSHIFT

The hardest part of the COMPUSHIFT Sport controller installation was deciding where to install it. I eventually chose to install it under the passenger seat so that I’d have no problems with the Bluetooth connectivity. The instructions provided with the controller were clear and the wiring was straightforward. I did have a minor problem with calibration of the TPS, but a call to HGM provided a solution immediately. Using the Bluetooth interface makes setting up the controller a breeze. After inputting some simple info like gear ratio, tire size, and vehicle weight, I was ready to go. I was amazed by how well the transmission operated with the baseline HGM factory controller settings. As Mike Hoy mentioned to me, they have established the baseline controller settings based on years of experience with electronic overdrive transmissions. Although every aspect of the transmission is adjustable via the Bluetooth interface, I have yet to change any of the HGM factory settings and the Chevelle is a true pleasure to drive.

Most of the time, you only hear and read negative reviews about products. I’m proud to say that I believe I made the right choice for a trans controller and I am totally satisfied with the products I purchased from HGM. HGM’s products, customer service, and technical support are world-class."

If you need a 4L60E transmission controller, 4L80E transmission controller or have another transmission needing a controller then HGM has you covered. Head over to our “configurator” page and we will ask you a few questions about your build. You’ll then see the exact components and pricing you need for your vehicle.

Go to the HGM Configurator for your detailed quote.


Check Out HGM's Product Range


COMPUSHIFT Sport and Pro

  • App Programmable via Bluetooth from your smart phone or device.
  • IP65 Rated for dust and water resistance.
  • Delivered with a full set of plug and play cables.
  • Engineered and Manufactured in the United States.

COMPUSHIFT Transmission Controllers



Paddle Shifters

Transform the experience of shifting your electronic automatic transmission:

  • Get the fastest shift time possible - faster than any mechanical manual or floor shifting automatic.
  • Finishes include: Brushed Aluminum, Polished Aluminum, Brushed Black, Polished Black
  • DIY installation with full instructions.