Build 6R80 Six-Speed Autos For 7-Second Runs With These Billet Bits

Build 6R80 Six-Speed Autos For 7-Second Runs With These Billet Bits

We are living in a golden age of internal-combustion performance. In the Ford world, the Coyote engine platform ushered in a whole new level of performance. Often, however, it is the automatic transmissions behind these engines that allow the latest 5.0-liter engines to reach their full potential.

It is a very exciting time for the 6R80 transmission. — Bret Lasala

While the latest 10-speed automatic garners a lot of headlines these days, its predecessor — the 6R80 six-speed automatic — is farther along in the aftermarket development process. Thus it can be enhanced to support performance levels that factory engineers never dreamed it would have to withstand — like 7-second, 3,600-plus-pound street cars.

After witnessing numerous 6R80 failures in ultra-high-performance applications, Brett LaSala sought out two billet pieces from Bluestreak Performance in Australia to strengthen the six-speed auto — a billet First gear one-way clutch ($1,200) and a billet forward planetary ($1,200). After the intermediate shaft, which also has an available billet replacement, these are the two parts that will fail next. (Photo Credit: Bret LaSala)

Many chasing those performance levels eventually swap to a Brand X transmission, but Brett LaSala has shown that just isn’t necessary. He runs a fortified 6R80 six-speed auto in his 7-second 2013 Mustang GT, a.k.a. the Snot Rocket.

“I am an ambassador for this trans, and I’ve been testing and pushing it for so long now,” he added. “My friends call me the ‘6R80 President.’”

Early on that was an easy administration to be part of, as the 2011 Mustangs ran some amazingly quick times with the stock six-speed auto in the tunnel. Some cars ran into the 9-second zone without touching the trans. However, stock always has its limits.

The First gear one-way clutch (sprag) is a replica of the stock piece made of much stronger billet steel instead of the sinter-forged stock piece. Also the clearances of the mechanism have been lowered as much as possible to take the huge amount of play out that the stock piece has.

“A bone-stock 6R is very tough,” Brett explained. “The intermediate shaft is the first part to fail at around 700-800 wheel horsepower. This part has been available for years now. After 1,000 wheel horsepower you will start to see the forward planetary to fail and the first gear sprag, which is even more pronounced in heavier cars.”

While his transmission didn’t fail as he started to push the envelope, Brett knew that his trans was on the edge and performance was suffering. He is a trained transmission tech, so he realized it was time to head off any problems and prep for the future.

A billet replica of the sinter-forged stock piece, this stronger First gear one-way clutch features tighter clearances than the stock unit, which further reduces the chance for breakage.

“My background with 6R80 Mustangs started with my car in 2014. I installed a CPR turbo kit and was racing the car a lot. As we started to push the stock engine and trans to 800 wheel horsepower my tuner Sai Li and I started to notice some of the shifting was not as we wanted it. So, I ordered Exedy Clutches and a billet intermediate shaft. This would be my first 6R80 build and the start of a very exciting venture with this transmission,” he explained. “I have had transmission training in the past through Mercedes Benz as I am a 12-year, Master Certified Mercedes Benz technician. So I built my trans and continued to push my combo. At this point I was building all my friends transmissions for their cars. I proceeded to build an engine and crank up the power. We got my car at this point to a best of 8.21 at 169 MPH. Now a couple years later I have been building 6R80s for the Mustang community all over the country and have seen many failures come across my bench.”

Along the way to becoming a 6R80 guru, Brett began to see a couple of the usual suspects when people did push the envelope a bit too far.

“Seeing many failures of the first gear one-way clutch (sprag) and forward planetary and wanting to push my car future and add more power I got in contact with Daniel Otway of Bluestreak Performance in Australia, as he has already been in development of the planetary for his personal car,” Brett said. “Within a month he sent me a billet planetary and one-way clutch to test in my car. I immediately installed it and went to the track. We turned my car up as much as possible and started getting very aggressive with trans tuning and converter lock-up. The results were outstanding. My car, at a 3,650-pound race weight, went 7.93 at 176 MPH and has now had over 90 8.1x-second passes and faster on this trans with zero failures.”

The result is that Brett now incorporates these parts into his transmission builds and offers them for sale to those who want to fortify their own six-speed automatics. Either way your transmission should be strong enough for almost anything you have in store.

Born of building his own 6R80 transmission, Brett LaSala has become a go-to builder for big-power six-speed owners. The typical rebuild includes upgraded friction materials, steels, and a billet intermediate shaft. These start at $2,000, but if your are pushing four digits, you’ll need to add the upgraded First-gear one-way clutch and a billet forward planetary.

“Now that we have my car in the sevens and with no trans failures, we are going to be adding more power and see how far it can go in an actual 3,650-pound street car,” Brett enthused. “It is a very exciting time for the 6R80 transmission. As there are aftermarket controllers now and swaps are possible. You can truly have the best of both worlds — a perfectly stock driving street car with six speeds and a lock-up converter that can go the track and run 7-second passes all day long with no issues.”

Even better is the stronger transmission will still behave like the stock transmission when the tuning calls for it, so you can run it worry-free even if your ’Stang doesn’t run sevens. For more on these billet-bolstered 6R80 six-speed automatics, you can reach out to Bret via email or his Facebook page.

About the author

Steve Turner

Steve Turner brings decades of passion and knowledge in the world of Ford performance, having covered it for over 20 years. From the swan song of the Fox Mustang to the birth of the Coyote, Steve had a front-row seat.
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