Throwback Thursday: ATI’s Near-Bulletproof 4L85E Overdrive Automatic

Can you believe it’s once again time for another Throwback Thursday? Let’s do everything we can to make this day a good one. The arrival of the day after Humpday means another week is almost over. For this week’s look back, I thought we would check out an article published in December of 2016. Yes, I’m going back a few years, but the information is still relevant.

It was a long time ago when we published an article with help from ATI Performance Products discussing what the company does to build a great overdrive 4L85 transmission. The article, titled ATI’s 4L85 Offers Overdrive With Near Turbo 400 Durability was put together to let everyone know this four-speed automatic was a great upgrade for enthusiasts, as it can be just as strong as the venerable Turbo 400.

4L85E

Adding an overdrive to a classic is a great way to improve drivability. And when that improvement can also deliver a durable upgrade, what’s not to consider?

When most performance-oriented enthusiasts discuss automatic transmissions, the Turbo 400 is usually at the top of any list—and with good reason, It’s reliable, nearly bulletproof, and has earned a reputation as a go-to transmission in high horsepower applications. But Dave Caine of ATI Performance was quick to let us know that there is there something just as strong and reliable?

“We currently offer a 4L85E package that is rated to 1,000 horsepower (has been tested higher)” he states. “We are working on one that is rated to at least 1,500, and even maybe as high as 2,000 horsepower.” That means that for the average street guy and the guy that hits the track occasionally, the 4L85E is definitely an option worth checking out.

The stock 4L85E is conservatively rated to handle up to 460 lb.-ft of torque. That rating makes it the strongest (at the time of the initial writing) GM overdrive transmission produced. What’s great about it is, it easily accepts upgrades to make it a great choice for extreme power applications.

In the original article, we mentioned that in stock applications, the 4L85E lacks any real problem areas, and they are a perfect choice for most mildly-hot-rodded Chevys. Dave continues, “One thing I need to clarify is that we make a line of Turbo 400s that will handle over 3,000 horsepower, and the 4L85 will never get close to that. So, to be factual, the 4L85 cannot be built “just as durable” as the Turbo 400.”

4L85E

By having ATI build you a new 4L85E with these high-performance parts, you’re sure to have a transmission that can take virtually any punishment you can throw at it.

If you are trying to decide whether you want a traditional Turbo 400, or a 4L85 that gives you the overdrive capability, there are a few things to consider, like vehicle usage and transmission fitment. For instance, there are dimensional differences between the two, “The 4L85 is going to be bigger around the middle, longer, and even heavier,” Dave affirms. “The gearsets are interchangeable with little effort, so dropping to a 2.10-ratio is no big deal, and that’s what the most common option would be. We also make a special tailhousing and output shaft to shorten the 4L85 to get as close as possible to the length of a Turbo 400, but the transmission mount will still be in a slightly rearward location.”

We were curious about what ATI does to this new-age transmission to increase its strength, and Dave says, “Some of the items we change for increased strength are going to be the input and main shafts, aluminum direct drum, and heavy-duty center support assembly. We can also put any number of gearsets in there as well, depending on what the combination dictates. I’m guessing that most of your readers will be fine with the standard 2.48 and 1.48 gear set, but a common replacement is the 2.10 and 1.40 gears.”

There is a lot more interesting and what might seem surprising information in the original article, and to learn more, you really need to check out ATI’s 4L85 Offers Overdrive With Near Turbo 400 Durability. Check back with us often, as we’ll be sure to bring you more great tech you can use.

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About the author

Randy Bolig

Randy Bolig has been working on cars and has been involved in the hobby ever since he bought his first car when he was only 14 years old. His passion for performance got him noticed by many locals, and he began helping them modify their vehicles.
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