Toyota Rear-Axle Beef-Up

The Toyota rear axle is a... 

   

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The Toyota rear axle is a versatile unit. With the wide array of upgrades and options available for it, customizing it to your needs is easy. Also, the stamped steel housing easily accepts welded components such as track bars or link mounts.

Toyota truck and 4Runner rear axles are plenty tough in stock form, but there are a number of upgrades available that can make them even tougher for hard-core users. In a previous article ("Toyota Axle Beef," June '99) we discussed fortifying front axles. Here we'll discuss the other end of your Toy, and a few pieces in between.

Basically two versions of 8-inch rear axles have been used over the years. Production rear axles through the 1985 model year (those with a straight front axle) measure 55 inches flange to flange. When Toyota changed to IFS in 1986, its engineers widened the rear axle to 58 inches to match the wider front suspension.

Along with widening the axle, Toyota engineers also increased the tube diameter from 65mm to 80mm in diameter, and increased the drum-brake size. The axle shafts were lengthened 1.5 inches per side, but the third members are completely interchangeable between the early and later years, through 1995 when Toyota changed the axle for the Tacoma.

The differentials that came in turbo-engine-equipped trucks, or in V-6 trucks, contain four spider gears as opposed to two spiders on the four-cylinder versions. This is often not significant as lockers or other traction aiding devices are added, replacing the stock carrier. However, the V-6 third-members do carry beefier ring-and-pinion gears than the four-cylinder ones.

Stock Toyota axle ratios have varied over the years, as shown in the following table. Not all gears shown were available in each specific year from 1985 to 1994. Ratios varied based on engine, tire size, and transmission configuration.

The wider version rear axle...        read full caption The wider version rear axle is three inches wider overall, flange to flange. The difference can be seen between these two versions of the housings. Note the distance from the perch to the flange on the end. Perch separation on both axles is the same. This allows the axles to easily be swapped, and is a simple bolt-on procedure. Parking brakes can be connected using the cable from the newer axle.	The narrow axle uses 10-inch...        read full caption The narrow axle uses 10-inch dual-servo drum brakes (right), while the wider axle uses 11.6-inch leading/trailing brakes. Pad surface is about 25 percent greater on the larger ones, with this additional size intended to compensate for some of the self-energizing action that is lost due to the change to the leading/trailing design. Flange sizes and bearing cups make the brake systems adaptable to either axle type. However, the drum-center holes differ in diameter.	All rear Toyota truck and...        read full caption All rear Toyota truck and 4Runner axles use beefy 30-spline axle shafts. These are the same size as heavy-duty Dana 44 or standard-duty Dana 60 axles. The large bearings used can easily handle oversized tires for many miles.
The third members used in...        read full caption The third members used in the four-cylinder and V-6/turbo vehicles (right) are interchangeable in the axle housings, but differ internally. The carrier from the four-cylinder vehicles uses two spider gears, while the V-6/turbo version uses four spiders. Additionally, the V-6/turbo version uses larger bearings, a stronger carrier, and a slightly beefier ring-and-pinion gearset.	Stock Toyota axles use U-bolts...        read full caption Stock Toyota axles use U-bolts mounted with the nuts on the bottom, protruding through stamped steel plates. Converting to this U-bolt flip kit from All-Pro Offroad will increase clearance under the axle ends by about an inch. All-Pro also provides new weld-on lower shock mounts to replace the ones removed when deleting the lower spring plates.	Rear axleshaft failure is...        read full caption Rear axleshaft failure is not that common, but can occur on trucks used for hard-core 'wheeling. Front Range Off-Road Fabrication now offers a complete full-floater conversion kit for Toyotas. This conversion increases load capacity and axle strength because the axleshaft itself no longer supports the weight of the vehicle. Using stock front locking hubs makes flat-towing easier as all four axles can be fully unlocked.

Many rockcrawlers with early-model narrow-track axles have opted to swap in the later wide-track axles to widen tire stance and prevent the inside face of the rear tires from rubbing on the frame rails under extreme articulation. Swapping to the newer axle is a bolt-on affair.

In any case, Toyota rear axles are versatile and reliable performers. With the wide availability of aftermarket beef-up parts, and a number of stock interchange options, you can set up your truck or 4Runner to tackle the four-wheeling you do.