Specs, Options, And Upgrades
Toyota pickup axles are renowned for their light weight, low cost, and high strength. Although they don't offer the ground clearance of portal axles or the massive ring gear of a Corporate 14-bolt, these axles are popping up under a wide variety of vehicles beyond Toyotas, including Jeeps, Samurais, and buggies, because of the features mentioned above. As good as they are from the factory, like most components they can still benefit from advances made in the aftermarket.
Stock Front Axle
Toyota used a solid front axle in the '79-'85 pickups and 4Runners. All of these axles were 55.5 inches wide from wheel mounting surface (WMS) to wheel mounting surface and came with solid front disc brakes and closed knuckles with Birfields. These axles also came with push-pull steering and a torque-rod bracket welded to the housing. They use the same 8-inch third member and 1-5/16-inch axleshafts as the rear axle, simplifying part swapping. The Birfields are 30-spline at the hub, and the inner axles are 27-spline at the Birfield end and 30-spline at the differential end. Earlier axles had no trussing on the long side, but over the years Toyota increased the size of the truss under the housing until eventually it spanned the long side of the housing by 1984.
Front Axle Upgrades
By far the weakest link in Toyota axles are the stock Birfields. These joints have limited angularity and are prone to cracking with the steering at full lock and power applied. Long's Enterprises developed Longfields that address all of the factory shortcomings. The latest generation of Longfields are 30-spline from the differential to the hub and are made from chrome-moly. The inner race is machined from 300M and is smaller than stock to add thickness to the outer bell. In addition to the strength, Longfields are able to provide a much tighter turn radius than stock Birfields due to their tapered design.
Aftermarket Birfields used in conjunction with stock axleshafts can transfer the weak link to the splines where the shaft mates with the Birfield. Poly Performance sells chrome-moly inner axleshafts that do not neck down like the stock shafts and which eliminate the need for a C-clip to retain the axle.