Keep Cool: A plug-and-play transmission cooler for the Chevy Trailblazer SS

Posted on June 29, 2015 by Jefferson Bryant in Tech, The Science of Speed with Scott Parker, Transmission/Drivetrain // 4 Comments

Heat is the single biggest killer of automatic transmissions. Part of the reason is that we ask a lot of these transmissions, especially when they are in a truck. Burnouts? Sure. Tow your buddy’s Impala to the shop? Sure. Donuts until you’ve gotten dizzy? Why not? And if you happen to have any 4L60E-equipped GM truck or SUV, then you are in the inevitable position of using a toothpick instead of a two-by-four. While GM did give it a steep first gear with trucks in mind, only the 4L80E – the electronic overdrive version of a TH400 – was meant for such heavy-duty tasks. For towing and gas mileage, the later 6-speed 6L80Es were a much-needed improvement.

The 2006-2008 Chevy Trailblazer SS was GM’s flagship performance SUV, so it was given an upgraded version of the 4L60E, known as the 4L70E, to sit behind the 395hp LS2. However, it is one of the most notorious killers of transmissions. When you are attempting to race and/or tow with this much weight, the little 4-speed doesn’t have a shot. I have high hopes of one day modifying my daily driven 2008 Trailblazer SS to surpass the Porsche Cayenne Turbo and other SUVs in factory trim at the very least. Of course it wouldn’t hurt to give some modified Jeeps a run for their money as well. Long before that ever happens, this painfully stock TBSS needs to be fortified in the critical areas. Step one was the aforementioned transmission.

At some point in the not-too-distant future this 90,000-mile truck will require a tranny rebuild, but for now I decided to add a cooler and cross my fingers. Thankfully PCM of NC offers a completely plug-and-play option for the Trailblazer SS that mounts behind the grille or the brake duct in the bumper. With dreams of boost, the bumper seemed the best option. Features of the kit include a high efficient stacked plate cooler design and high quality components. We clicked the upgrade button for the black braided lines, though the standard rubber lines will hold 250psi. The kit is complete with all the fittings, precut lines, brackets, and hardware needed for installation with a price tag under $300 (base price is $229.45).

Since I was without a shop or even a garage to work out of at the time, Kyle Miller at AntiVenom Racing was happy to lend a hand. Follow along with this simple, two-hour install that will keep a tranny in check.

PCM of NC, who specializes in Trailblazer SS parts and tuning, offers this complete plug-and-play tranny cooler package. The Brake Duct Mount Transmission Cooler (PN P-120011BL) comes as you see it here with the optional black braided lines and AN fittings. Even with this upcharge, the kit still costs less than $280. Braided stainless and an auxiliary fan are also available, as is a front mount kit.

To get started Kyle Miller of AntiVenom removed the plastic tabs and the fender liners via the pushpins and 10mm bolt.

The J-nut is installed, which will eventually help mount the cooler.

Teflon tape is applied to the fittings before screwing into the cooler.

5/8-inch bolts and flange nuts mount the bracket to the cooler.

Kyle drills a 5/16-inch hole that will serve as the mounting point for the upper side of the cooler. Bolting the cooler into place first helps locate and mark the hole (prior to drilling).

Using one of the smaller provided J-clips, the top of the cooler is mounted with a ¾-inch bolt.

The stock transmission cooler line is removed at the return (on the radiator) and replaced by the new braided piece.

Perhaps the trickiest part of the install is removing the factory supply line and connecting the new braided line just below the airbox.

This detailed diagram (notice the torque specs) is provided in the step-by-step instructions, which proved to be very helpful.

The last step is tightening all the bolts and fittings as well as zip-tying anything that might get caught or rub on a moving part. After that Kyle reinstalled the fender liner, topped off the trans fluid, and checked for leaks. From start to finish this took less than two hours and the truck performed flawlessly on a 2,500-mile trip up the east coast and back.

Sources: AntiVenom Racing http://antivenomefi.com/