Many of us who have owned older vehicles have had one or more with front drum brakes. While drums can be made somewhat effective with high quality shoes and some careful tweaking, front disc brakes are far better performers, especially if you've increased tire size and weight.
Drum brakes also have several disadvantages. Under heavy use, they may be prone to brake fade as the iron drum expands and wants to move away from the brake shoes. Drum brakes also tend to retain water and mud, and are not as self-cleaning as disc brakes are. That means, for those of us who venture into the dirty stuff, a disc system is typically the better option.
Early Toyota Land Cruiser models came with drum brakes on all four corners. Fortunately, they were dual-piston units up front and were driven with a vacuum-boosted master cylinder. But, they remain troublesome, so an upgrade to front disc brakes using OEM Toyota parts is a wise modification to any fully drummed 'Cruiser. To do so requires a visit to a variety of parts bins to pick and choose some components from several years and models of Toyotas. The OEM parts can be sourced from Toyota, auto parts stores, or from salvage yards. Along with the disc brake swap, we'll also get stronger outer axles (Birfields), knuckles, steering arms, and locking hubs.
Our first order of business was to get the front axle on jackstands and accessible to disassemble the aged axle drum assemblies. Here we'll detail the swap procedure and the parts we used to complete our front axle upgrades.
Here’s what you get with the...
Here’s what you get with the early Land Cruiser models. We performed the work on a 1970 FJ55 model, but the conversion is typical of Land Cruisers of this era. Removing the drum reveals these are double piston drum brakes. Note the early ’Cruiser locking front hubs. These will also be replaced along with the wheel hubs.
With the drum off, disassembly...
With the drum off, disassembly started with the removal of the front hub assembly, spindle nut, wheel hub, and bearings. Next, the stock front spindle and complete brake backing plate was removed along with the outer-most brake line. Then, the axle shaft assembly could be pulled free of the axle housing.
The tie-rod end, top steering...
The tie-rod end, top steering arm, and lower knuckle cap were removed, which allowed removal of the closed knuckle after the felt seal assembly was unbolted from the backside of the knuckle.
The last items to be removed...
The last items to be removed from the axle housing were the inner axle seal, plus the upper and lower knuckle bearings. The races can be tapped out using a steel rod or similar tool. This completed the teardown of the front axle housing to prepare for the upgraded components.
There are 16 taper rollers...
There are 16 taper rollers in each knuckle bearing. Ones that are badly worn will have an impression of each roller worn into the surface of the race. One of our races was deeply grooved, making the knuckle movement a bit notchy.
Here are most of the upgrade...
Here are most of the upgrade parts needed to complete the conversion on one side of the axle. Along with the major parts, a lot of hardware is needed to assemble the swap. A complete, salvaged Toyota mini-truck axle may be a good place to start to gather all the little odds and ends.
The early ’Cruiser outer axle...
The early ’Cruiser outer axle shafts (right) are about 1.11 inches in diameter and have six coarse splines that mate with the locking hub. Newer ’Cruiser, or 1979-to-1985 mini-truck outers (left), were swapped in and are about 1.24 inches in diameter with 30 mating splines at the hub.
The replacement truck Birfields...
The replacement truck Birfields were well packed with synthetic grease and the original inner axle shafts mated to the new outers using new retainer rings on the inner shafts.
The bell of the truck Birfield...
The bell of the truck Birfield is just a bit too large to slide into the Land Cruiser outer axle housing.
A grinder was used to remove...
A grinder was used to remove a little steel at the top and bottom of the outer housing ball. When doing this, periodically check to see when the Birfield will slip into the housing. Once slid in past the outer flats, there is ample room for the Birfield within the ball.
With the ball ground to allow...
With the ball ground to allow entry of the Birfield, and then cleaned, it was time to install the inner axle seal and new felt seals for the backside of the knuckle. It’s a good idea to check the ball for excessive rust pitting on the exterior surface. We’ve seen badly pitted ones restored to smoothness using J-B Weld or similar fillers. New knuckle bearing races were tapped into the balls using a brass drift.
Toyota inner axle seals have...
Toyota inner axle seals have been known to leak, especially when subjected to harsh off-road use. Marlin Crawler offers their Ecoseal heavy-duty inner axle seals with dual sealing surfaces that maintain a better seal to the inner axle, even when the shaft is slightly misaligned with respect to the seal. The exterior surface also incorporates an outer Nitrile sealing ring. These were installed in our axle housing.