Tech Video: Street Muscle Magazine Covers TCI’s 4X Transmissions

Looking for a transmission that can handle inflated horsepower numbers and tall gears at the track while still being flexible enough for highway cruising? Well, it’s a common issue these days. Traditionally, people might opt for a built TH400 with some type of bolt-on overdrive unit. But, events like Power Tour and Drag Week have made people aware of the limitations a three or four-speed transmission, sans overdrive, have. Enter, TCI Automotive. The hot rod loving people over there have sought to answer the call for anyone willing to put their rides through a grueling week of drag racing and highway torture testing or those just looking for more flexibility out of a street car.

Rather than go for low-hanging fruit and pump out another TH400 in an already saturated marketplace, TCI figured they’d tackle something a bit more challenging on their end but better for the end-user. They elected to develop a 700R4-based trans with the TCI 4X. That means the transmission covered in this video is perfect for anyone looking to upgrade to a transmission that is not only stout while possessing overdrive, but doesn’t require an electronic transmission controller either.

We installed TCI’s 4X Four-Speed Transmission For Non-Gm, Non-Electronic 700R4-Based cars. This one happened to go into a 1970 Mustang Fastback. While the transmission we installed is capable of standing up to 750 horsepower, the 351ci Windsor sitting between the framerails of our pony likely falls way short of that.

If we were planning on sticking with the stock powerplant, TCI does sell the same transmission with the same bell housing and accessories that are made to withstand a more mild 550 horsepower. However, in a moment of clarity we were thinking ahead – one of the rare times we exercise foresight – knowing we want to eventually breathe some new life into our Mustang, we made our selection. Below is a list of everything our 4X Package came with.

Package Includes:

  • Transmission “Base”
  • SFI-Spec Bellhousing
  • Flexplate
  • Transmission Cooler
  • Dipstick
  • TV Cable
  • (3) Gallons Max-Shift™ Transmission Fluid

With all of those items included in these ready-made kits, it really takes the guesswork out of installing a GM transmission into a non-GM application, like ours. The installation went relatively smoothly. The only part that caused us to scratch our heads for a moment was when it came time to install the transmission cross member. We ended up having to place a call to TCI and they hooked us up with a universal unit – the factory cross member, unsurprisingly, didn’t work with the GM-based transmission. (See what we mean about our foresight.)

Nevertheless, the installation went as planned after that. The only thing left to do was figure out what we were going to do with the exhaust since what we had in place would no longer work with the new cross member placement – something to consider for your own project. We ended up fabricating some flanged exhaust dumps right after the header…It was loud! Luckily, it’s only temporary until we can get this thing to the exhaust shop.

After spending some time behind the wheel it was apparent the transmission we had just installed was vastly superior to the stock C4 Ford transmission we replaced. The shifts were more firm and made use of a closer ratio gear set. And, of course, it did much better on the highway as well. While the factory rear end still sports the granny-highway gears, the tachometer was loving the low cruising RPM. It just hummed along…albeit at an ear-shattering decibel level. Fortunately, we didn’t have to do any tuning so that negated the need for any electronic controller – our job was done.

Of course, if you are after something that gives you a bit more tunability, they also make a 4L60E-variant that allows the user to fine-tune shift points and firmness. TCI’s 4X line of transmissions are available for a whole host of applications; small and big block Chevy, Mopar, and Ford – all ranging in acceptable horsepower output.

For more information on the kit we used and every other application, check out TCIAUTO.COM.

Article Sources

About the author

Vinny Costa

Fast cars, motorcycles, and loud music are what get Vinny’s blood pumping. Catch him behind the wheel of his ’68 Firebird. Chances are, Black Sabbath will be playing in the background.
Read My Articles

Hot Rods and Muscle Cars in your inbox.

Build your own custom newsletter with the content you love from Street Muscle, directly to your inbox, absolutely FREE!

Free WordPress Themes
Street Muscle NEWSLETTER - SIGN UP FREE!

We will safeguard your e-mail and only send content you request.

Street Muscle - The Ultimate Muscle Car Magazine

We'll send you the most interesting Street Muscle articles, news, car features, and videos every week.

Street Muscle - The Ultimate Muscle Car Magazine

Street Muscle NEWSLETTER - SIGN UP FREE!

We will safeguard your e-mail and only send content you request.

Street Muscle - The Ultimate Muscle Car Magazine

Thank you for your subscription.

Subscribe to more FREE Online Magazines!

We think you might like...



Classic Ford Performance

Street Rods

Classic Chevy Magazine

Street Muscle - The Ultimate Muscle Car Magazine

Thank you for your subscription.

Subscribe to more FREE Online Magazines!

We think you might like...

  • Classic Ford Performance
  • Street Rods
  • Classic Chevy Magazine

Street Muscle - The Ultimate Muscle Car Magazine

Thank you for your subscription.

Thank you for your subscription.

Street Muscle - The Ultimate Muscle Car Magazine

Thank you for your subscription.

Thank you for your subscription.

Loading