Dale Amy
August 17, 2011

Horse Sense: Paul Svinicki says 8.8-inch diff lube temps can soar as high as 310 degrees in summer road-course use, far beyond the axle's anticipated operating range.

Road racers, open trackers, and roundy rounders-listen up. You're likely cooking your 8.8-inch rearend in its own juices. Drivetrains aren't anywhere near 100 percent efficient, and one of the byproducts of that inefficiency is heat. Though perhaps not an issue during the short duration blast of a quarter-mile car, sending the repeated high-torque loads of road-course or oval racing through a ring-and-pinion for extended periods of time can really turn up the heat in a rear axle, degrading the diff lubricant's ability to do its job.

Luckily, the answer may be as simple as a call to Paul's High Performance for one of the company's new diff cooler kits. This easily installed, $199 kit routes lubricant flung off the axle's ring gear through a pair of aluminum tubes that act as heat exchangers, and back into the outer ends of the axle tubes, where it cools further on the way back into the pumpkin, only to start the cycle all over again. Being basically gravity operated, there's no need for a pump and its associated wiring and plumbing.

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M5lp 0407 08 O Pauls High Performance Diff Cooler Kit Compression Fittings
Thread the remaining pair of compression fittings into the axle tubes-but not far enough to hit the axle shafts-again using some form of Teflon sealant.