Transmission Maintenance - Keep Your Transmission Cooler

An external trans cooler is cheap insurance for your automatic during particularly stressful motoring excursions. Like the advertisements say, heat is your transmission's worst enemy; B&M advises that typical operating temps for an automatic trans remain between 150-200 degrees F, with an ideal temp around 175. Since engine coolant temps are often higher than this, particularly on late-model vehicles, the small OE trans cooler in the radiator is barely adequate for high-performance or heavy-duty use. The B&M Supercooler is a complete kit that includes plumbing and mounting hardware in addition to the plate-type cooler.

An external trans cooler is cheap insurance for your automatic during particularly stressf

No matter what part of the country you find yourself in, summer is prime time for cruising, racing, or whatever you like to do with your "fun" cars. Of course, it's also the time for intense temps and lots of traffic. So, whether you're out on the racetrack or sitting in traffic trying to get there, your drivetrain is likely being subjected to its worst enemy: heat. We were made acutely aware of this during last summer's Hotchkis' Track Day. First, the tow vehicle (former Caltrans laborer, Project Jake) was brutalized over California's infamous "Grapevine": a stretch of the I-5 that traverses grades serious enough to concern even the most calloused truckers. Then there was the event itself, featuring long open-track sessions on Buttonwillow's rather fast road course--lots of fun, but also a serious workout for any vehicle when overly competitive motoring journalists are driving.

The instructions advise installers to plot cooler placement prior to beginning the installation to affirm that the unit can be mounted properly and that the fluid lines can be routed as directly as possible. This early Camaro has plenty of room up front to mount the cooler in front of the radiator. B&M considers this the ideal location, and classifies the cooler as having 100 percent of its potential efficiency like this. If there were an A/C condenser in front of trans cooler, efficiency would drop to 75 percent, and mounting the cooler on the engine side of the radiator drops efficiency to 60 percent.

The instructions advise installers to plot cooler placement prior to beginning the install

Vehicles intended for this sort of use are generally built with extra cooling capacity, and many have gauges, or at least warning lights, to keep drivers apprised if any of the vital fluids exceed safe temps, except of course, the automatic transmission fluid. This nearly universal oversight may be because trans temps are not a major concern on typical road-going vehicles, but all it takes are a few hot laps at a racetrack or an extended Second-gear hill pull with a loaded trailer to saturate the entire fluid capacity of the average automatic with heat. What follows is often disastrous and expensive.

So, after being reminded of these facts, we were motivated to upgrade the fluid cooling abilities of a few of our fleet. An external transmission cooler is a time-tested method of enhancing the transmission's cooling capacity and is relatively simple as well. Similarly simple is the practice of increasing total fluid capacity with a deeper pan. We went to one of the original sources of automatic transmission performance, B&M, and ordered a universal Supercooler kit and a cast-aluminum deep pan kit in the hopes that our automatics will be better equipped to survive the next heavy-foot episode.

Often, external trans coolers are plumbed so that they replace the stock in-tank radiator cooler, but most OE and trans cooler manufacturers recommend retaining the factory cooler, using the external cooler to increase the system's heat-transferring capacity. Proper routing passes the fluid through the radiator cooler first, then on to the external cooler before heading back into the transmission.
Often, external trans coolers are plumbed so that they replace the stock in-tank radiator
Here's another common mistake: cutting the steel hardlines for the factory cooler and sliding standard rubber fuel hose over it with hose clamps. Even with multiple clamps, this is bound to fail eventually as the pressure in these lines can reach the high side of 200 psi during extreme use (such as high-rpm racing). Once the fluid seeps under the clamped portion, the hose becomes lubed and slips off.
Here's another common mistake: cutting the steel hardlines for the factory cooler and slid
B&M provides brass fittings that thread onto the fittings on the factory cooler lines, providing a series of barbs to secure the hose connection. Similar male-ended fittings are provided to thread into the radiator.
B&M provides brass fittings that thread onto the fittings on the factory cooler lines, pro

Many veteran wrenchmen shun tranny coolers that are plumbed with rubber hose, usually because of all the hacksaw-and-fuel-hose jobs they've seen go awry. However, the B&M kit uses high-pressure hose coupled with the barbed fittings and high-quality stainless steel hose clamps to ensure positive sealing.
Many veteran wrenchmen shun tranny coolers that are plumbed with rubber hose, usually beca
The B&M kit comes with two options for mounting: Plastic "zip" fasteners to tie the cooler to the radiator or four universal steel brackets. We're going with the steel brackets so we can bolt the cooler to the outside of the radiator support, which in this case will make the plumbing a bit easier.
The B&M kit comes with two options for mounting: Plastic "zip" fasteners to tie the cooler
The zip fasteners are easy to use, but we have heard of radiator tubes being cut by the zip teeth in high-vibration applications where care was not taken to keep the two separated. The brackets can be cut and bent as needed, though ours fit pretty well out-of-the-box.
The zip fasteners are easy to use, but we have heard of radiator tubes being cut by the zi

Once the cooler is bolted up, all that remains is to slip the hose ends over the barbs on the cooler and fasten the clamps. B&M warns not to double-clamp any connections. Conveniently, we were able to route the lower hose under the radiator support and the upper hose through an existing hole, but we got lucky. You may need to create appropriate holes--don't force the hoses under, over, or through anything that may pinch or chaff them for obvious reasons. Remember, this stuff will be vibrating, if only slightly, but frequently.
Once the cooler is bolted up, all that remains is to slip the hose ends over the barbs on
While investigating ways to keep the transmission from deep-frying itself during road-course maneuvers, we found an additional means of keeping the fluid cool: a deeper pan. Increasing the capacity of the pan, and therefore the fluid capacity of the system, increases the system's ability to manage heat. The B&M deep pan for the GM 4L60-E adds a whopping 4 quarts of fluid capacity, plus its aluminum construction helps to dissipate heat, and B&M says it adds rigidity to the trans case as well.
While investigating ways to keep the transmission from deep-frying itself during road-cour
Before the filter can be installed, a special filter "spring" (also included in the kit) must be installed using one of the valvebody bolts. The instructions are specific about which bolt to use, and stress the importance of re-torquing the bolt to the factory 8-lb-ft spec. The spring is required to keep tension on the filter so that it doesn't vibrate out of its socket in the transmission pump.
Before the filter can be installed, a special filter "spring" (also included in the kit) m

Now's a good time to install a fresh filter, but the deeper pan requires the sump (which is the filter) to be positioned lower than it was with the stock pan. Rather than requiring a custom filter, the B&M kit includes an aluminum extension housing for the stock filter. It seals to the filter using a stock-type filter seal, included in the kit.
Now's a good time to install a fresh filter, but the deeper pan requires the sump (which i
The pan installs using new bolts (torqued to 12 lb-ft), which are included along with a new gasket. Be aware that the cast-aluminum pan may require trimming of the stock torque-converter cover for clearance. A bonus of the new pan is a drain plug, making future fluid changes less messy.
The pan installs using new bolts (torqued to 12 lb-ft), which are included along with a ne
A final bit of insurance comes from B&M's Trick Shift transmission fluid. Trick Shift is synthetic and we're told it has foam inhibitors, extreme pressure agents, and shift improvers. It's also said to handle heat more ably than standard trans fluid, so we're giving it a try. After pouring in 4 quarts, we started the engine, ran it through the gears, and checked the level, topping it off as needed. Make sure not to overfill the trans, as this can cause foaming, leading to other problems.
A final bit of insurance comes from B&M's Trick Shift transmission fluid. Trick Shift is s