Nissan Xterra Aluminum Differential Cover Review

Xterra Racer preps for race

Oct. 15, 2007 By Dan Spalinger/Team Xterra Racing
Dave Blakely’s #3112 Nissan XterraRacer

In desert racing, as in life, the more you take care of the little things, the more the bigger things tend to fall into place.

This was the thinking behind Dave Blakely’s (owner and primary driver of the 3100 class, #3112 XterraRacer) decision to swap out the stock stamped steel rear differential cover for an aluminum one.

In preparing the XterraRacer for the August “TSCO Vegas to Reno” race, it became clear that every critical system in the truck would need to be in top shape for the Xterra to complete all 560 brutal miles that the course would cover.  Dave felt that one area that could be improved with a simple modification was the reliability of the Xterra’s rear differential. Operating in the Nevada summer heat (where ambient temperatures can easily reach 105+ degrees) and traveling at speeds nearing 100 mph, all the components and fluids in the rear diff would be subject to about as an extreme condition as any Nissan is likely to face.

Swapping out the stock stamped steel rear differential cover for an aluminum one will help keep the fluid temperature cooler.  Aluminum desipitates heat more efficiently than steel.

Though the XterraRacer (like all Nissan Xterras and Frontiers) came from the factory with a stock steel rear differential cover, Nissan has been nice enough to manufacture a finned, aluminum replacement diff cover.  Available at any local Nissan dealership, not only will this swap upgrade your Xterra diff but will also work with most Nissan Frontiers and Titans as well, given that all three models (in various forms) use the same rear differential housing.

As it is a factory replacement part, the finned aluminum cover is a direct fit with zero modifications necessary.  Installation is as follows, though these directions should not be considered comprehensive or a substitute for someone with hands-on experience.

1. Drain the gear oil by removing the drain plug on the center, bottom of the case.

2. Undo the bracket holding the brake line and then remove all the diff cover bolts.

3. CAREFULLY remove the original cover. Use a chisel to initially create a small gap between the cover and housing, then moving to a screwdriver/pry bar to work the cover the rest of the way off.

4. Clean the interior of the housing by washing all components with a very liberal amount of brake cleaner—using an entire can to do this is not uncalled for.

5. Using a single edge razor, scrape all the remaining gasket material off the housing where the diff cover sits.  Again, clean the area with brake cleaner.

6. Take the new aluminum cover and run a 3/16” bead of gasket maker around the inside of the bolt holes and set cover aside for 5-10 minutes to allow the gasket maker to set.  Re-install drain plug.

7. Carefully put the new cover in place without smearing the bead of gasket maker and insert one of the top bolts, allowing gravity to hold the housing down on the housing.

8. Proceed to install all the bolts by hand, then with your torque wrench set for 25 ft. lbs., start at the 6 o’clock position bolt and snug it down…then move to the 10 o’clock bolt and do the same…then to the 2 o’clock bolt and so on in this pattern until all are snug.

9. Once all are snug, then (moving in a circular fashion) torque each bolt down to spec.

10. Refill diff with gear oil through the fill plug on the middle of the cover.  Fill it until the oil runs out of the diff, then reinstall the fill plug.  Snug both drain and fill plugs down and clean entire area with brake cleaner.

11. (Optional) Grab a cold one and admire your new diff cover!!

In its first race after installing the new aluminum differential cover, the XterraRacer covered all 560 race miles with zero problems involving the rear differential.

The results for Team Xterra Racing?

Well, in its first race after installing the new cover, the XterraRacer covered all 560 race miles with zero problems involving the rear drivetrain and finished third in its class.  While the additional cooling the new rear diff cover provides may not have been the primary reason behind such a solid result, it certainly was one of the many “little things” Dave Blakely has done to ensure a shot at the class 3100 Best in the Desert season championship. Newsletter
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