The Best Ways to Keep Engines Cool - Rearend Cooling - Drivetrain

It's late July and teams are looking for the best ways to keep their engines as cool as possible. But with all the attention being paid to the motor, there is something at the other end of the car that can be easily forgotten, the rearend. Most of us will just put the gear in, fill up the fluid, and not think anything else about it. Later that year when we start going through the teardown process, we notice that the rear gears are pretty well burned up and need to be replaced. Even if you're only running 50 laps at your local short track every Friday night you might want to think about taking some steps to ensure that you don't overheat your rearend. Ultimately, it will save you money.

The rearend of your race car experiences a significant amount of stress and heat. Think about it, the rearend is responsible for accelerating a 2,200 to 3,400 pound race car forward by transfering the energy produced by the motor/trans to the rear wheels. Without the proper maintenance and, in certain cases, a system for keeping it cool, you'll considerably shorten your rearend's lifespan. I've seen many teams just accept the black and burnt smell when they drain the rearend oil as the norm. But trust me, this is a problem.

The problem will not only lead to a rear-gear failure, but it will also increase the wear on the parts inside the rearend. For instance, the ratchet springs in your locker rearend control how the power is distributed to the rear wheels. When these springs "go out" or wear beyond their usable life, it causes a car to be a handful to drive. Here's why-prolonged use and/or excessive heat will cause a loss of spring rate (the spring actually loses height). In that case, one of two things will happen under acceleration, either both sides will lockup together, which is exactly what we want, or one side will not lockup at all, which is a problem.

However, there is good news. There are some simple and easy steps to take to avoid being sidelined by an overheated rearend.

Inspect And Change The Oil
Regardless of whether or not you're going to change the gears, you should inspect and change the oil in your rearend each week. It's the simplest and most effective of steps, but with that being said it's the most commonly overlooked step as well. Other than completely taking apart the rearend and inspecting it, the rearend oil is the only thing we can inspect to see what is happening inside. If the oil comes out black and smelling awful, then you know that you have overheated the rearend. Inspect not only the color, but also pay careful attention to any debris build up. Specifically, how much debris is there? You'll more than likely see a little metal in the form of minute shavings. But you shouldn't see any pieces of metal larger than a pinhead. This would signal a problem in the rear. I always drain my oil into a clear container and then let it sit for an hour or before really inspecting it. The time sitting allows any foreign material to settle to the bottom of the container, easily spotted thanks to the clear glass jar.

Changing the oil weekly may seem like overkill, especially considering that rearend oil isn't the cheapest stuff in the world, but changing the oil weekly helps in reducing operating temperatures espcially in longer races.

Before I move on to the next item, here's a quick word about qualifying oils. Some manufactures have a qualifying oil specifically designed for rearends. Often found in the upper levels of racing, this lubricant is extremely thin and will help create a little bit of horsepower for qualifying. However, if you can't change the oil immediately after qualifying don't even try to use it for the race. These lubricants are designed for one- to two-lap runs and won't last for even a 20-lap feature.

Install A Rearend Cooler Don't think just because you run a quick-change rearend that you don't need a rearend pump to keep the oil circulating through a cooling reservoir. Tiger Rear Ends has a direct drive external pump that works off the gear shaft. The relatively small pump will circulate oil throughout the entire rearend. Tiger will even install it into the back of the gear cover for you.

Want to do it yourself? Since it requires machining, this is one of those instances where it's better left to the professionals.

Now the rearend cooler will act as a reservoir if it's mounted correctly which will constitute a relatively small increase in oil supply. If you choose to run a rearend cooler, the process of filling the rear with oil is relatively straightforward.