Front Disk Brake Conversion with Mini Truck Parts

This page is a step by step instruction based on how I converted my front axle to the mini truck disc brakes.  In reading many other instruction pages and postings on the TLCA e-mail list I put together what I thought was the best of all the options. 

Index

Parts List
Tools List
Supplies List
Mini Truck Dissassebly
Birfield Separation
Land Cruiser Dissassembly
Birfield and Axle Prep
Axle Housing Prep
Assembly

Parts List

The first step is to collect all the necessary parts.  Although I did this over the period of a year it would take only a short amount of time to collect them all at once.  The table is a list of parts I used in my swap.  I purchased all new wheel bearings, knuckle bearings, and tie rod ends because all of these were worn out on my cruiser. 

Rotors and Calipers: 

In order to upgrade the original mini truck disks to a vented setup I used 1981 Land Cruiser rotors and 86-88 Toyota truck IFS calipers.   Please see Jack Alford's article to see more details.

Steering Arms:

When I bought my mini truck axle for parts it was missing the steering arms.  This turned out to be a blessing in disguise because I found out throught the TLCA e-mail list that the 1981 steering arms fit the mini truck knuckles.  This meant I could use my original tie rod ends which are stronger than the mini truck arms. 

Tool List

You will need an number of tools to complete the swap.  The following table shows what tools I used.

Supplies

Mini Truck Dissassembly

1. Remove the brake lines from the calipers and unbolt the calipers.
2. Remove the end caps from the hubs and remove the snap ring from the end of the birfield. 
3. Remove the 6 nuts that hold the the hub on and remove the 6 cone washers using a punch if necessary to loosen them.  Remove the hubs.
4. Remove the outer spindle nut, lock washer and inner spindle nut.  The hub and rotor can now be removed. 
5. Remove the 6 spindle bolts.  The spindle and backing plate can now be removed.
6. The birfield and axle can now be removed.   Turn the birfield until the flats line up with the top and bottom of the axle housing.
7. Turn your attention to the back of the knuckle.  Remove the 8 small bolts that hold the seal plates on.  Once the seal plates have been removed remove the felt seal and rubber wiper seal.
8. Remove the 4 nuts on the steering arm and loosen the 4 cone washers.  Remove the steering arm and shims underneath.  Keep the shims together and with the arms for future reference.  Some tapping and prying may be necessary to remove the arm.
9. The knuckle can now be removed by tapping the upper knuckle bearing downward against the race and then rotating the knuckle downward away from the top bearing.  If the knuckle doesn't free up the lower bearing cap can be removed. 
10. The seals left on the axle housing can now be removed.

Birfield Removal

Now for the fun.  There are several methods for removing the birfields from the axle shafts.  None of these are simple and easy. 

1. Pipe over axle - using a pipe slightly larger than the axle and longer than the axle shaft butt it against the inner race of the birfield and pound the other end against a very hard surface.  I had no luck with this method.
2. Home made press with pipe - using a 2" schedule 40 pipe and a coupling thread the coupling as far down on the threaded end of the pipe as you can.  Now slide it on the axle and against the inner race of the birfield.  The pipe must be cut with enough room to clamp the axle in a vice with the shoulder of the splines against one end of the vice and the pipe against the other side.   Then using two pipe wrenches loosen the coupling pressing the birfield off the axle shaft.  I was able to get this to work on the mini truck axles with tack welds on the axle to keep it from slipping in the vice.  I had no luck however, on the original birfields.
3. Torch - This can only be done on the old birfields that will not be used again.  Use a cutting torch cut the birfield in half right where the cylindrical section ends.  Make sure the area around the open end of the birfield is clear of people and flammible materials.  When the torch first cuts through the casing you will get a substantial fire ball from the grease.  Be careful not to head the end of the axle shaft too much.  When one end of the birfield is removed remove the snap ring from the axle end and remove the rest of the birfield. 

Land Cruiser Dissassembly

1. Set the front end on jack stands and remove the wheels.
2. Remove the brake lines from the wheel cylinders.
3. Remove the end caps from the hubs and remove the snap ring from the end of the birfield. 
4. Remove the 6 nuts that hold the the hub on.  Remove the hub.
5. Remove the outer spindle nut, lock washer and inner spindle nut.  The hub can now be removed. 
6. Remove the brake shoes and springs.
7. Remove the safety wire and the 8 spindle bolts.  The spindle and backing plate with wheel cylinders attached can now be removed.
8. The birfield and axle can now be removed.   Turn the birfield until the flats line up with the top and bottom of the axle housing.
9. Turn your attention to the back of the knuckle.  Remove the 8 small bolts that hold the seal plates on.  Once the seal plates have been removed remove the felt seal and rubber wiper seal.
10. Remove the 4 nuts on the steering arm and loosen the 4 cone washers.  Remove the steering arm and shims underneath.  Keep the shims together and with the arms for future reference.  Some tapping and prying may be necessary to remove the arm.
11. The knuckle can now be removed by tapping the upper knuckle bearing downward against the race and then rotating the knuckle downward away from the top bearing.  If the knuckle doesn't free up the lower bearing cap can be removed. 
12. The seals left on the axle housing can now be removed.
    
    
    Complete dissassebly of the old Land Cruiser Parts
    
13. Remove the knuckle bearing races from the axle.
    
    
    Most likely your knuckle bearing races will be damaged like this
    
14. Remove the axle seals in the end of the axle housing.
15. Now seperate the axle shafts from the birfields.

Axle Shaft and Birfield Prep

Birfields - Once the mini truck birfields have been seperated from the axle shafts they should be taken apart and inspected for wear.  To dissassemble the birfield tilt the inner race until you can remove one of the balls.   Repeat 5 times to remove the remaining balls.  Now tilt the inner race 90 degrees from its normal position and turn it until it comes out of the birfield.   Thoroughly clean all parts and inspect them for wear.  If any part of the birfield is significantly worn you are better off replacing it.  Once you are satisfied with the inspection reassemble the birfield in the reverse order of dissassembly.  Be sure to use lots of moly grease

To avoid ever having to seperate birfields from the axle shafts again I used the Marlin Tack.  This involved placing a couple of small tack welds on the start of the splines that go into the differential.  This prevents the axle shaft from sliding too far into the differential which was the job of the snap ring that holds the axle in the birfield.  This means you no longer need the snap ring allowing the birfield to slip right off the axle without any pressing, banging, cursing, etc. 

Axle Housing Prep

1. The truck birfields are slighly larger than the original birfields so the opening in the end of the housing needs to be opened up.  Using a 4" grinder remove about a 1/16" from the bottom lip of the axle housing between the outside and the lower knuckle bearing opening.  Don't forget to stuff a rag into the axle tube to keep metal shavings out of the axle housing.
   
   
   The area that needs to be ground can be seen here. 
   
2. To find out if enough material has been removed take the axle and birfield and slide them into the axle.  The birfield needs to slide all the way into the housing. 
3. Install the knuckle bearing races in the housing.
4. Do not install a new axle seal into end of the housing until you have aligned the knuckle housing with the axle.

Assembly

When everything has been cleaned, and inspeceted you can begin the assembly.

1. The first step is to align the knuckle housing with the axle.   If you are following the factory manual you will see you need a special tool to do this.  Through the list and old issues of Toyota Trails I found an alternate method for aligning the knuckles.  John Normile wrote an article in the January/February 1995 on how to build your own alignment tool and use it.  This tool uses a dial indicator and a machined plate with two dowel pins. 
   
   
   Using John Normile's  alignment tool to align the knuckles to the axle housing.
   
   1. Using the old knuckle bearing shims as a first guess, assemble the same number thickness of new shims on the knuckle.  Be sure to use the largest shims you can in assembling the pack.  Assemble the shims and the lower bearing cap and secure with the four nuts.  Install the lower bearing on the housing using no grease.  
   2. Place the upper bearing onto the race in the axle. Be sure to leave it dry as well.
   3. Asseble the housing on the axle pivoting about the lower bearing.   Install the steering arm and tighten the four nuts.
   4. The first thing to check is the bearing preload.  Turn the housing back and fourth to check the preload.  Using the fish scale attach it to the steering arm and measure the force it take to move the housing.  It should take 4-5 lbs to keep it moving.  Add or remove shims from the top or bottom to get the correct preload.
   5. Once the preload is correct you can proceed with the alignment.   Check the position of the knuckle housing at the top and bottom using the alignment tool.  Take half difference between the two readings and add that thickness of shims to either the top of bottom depending on which side is lower or higher. 
   6. It will take many iterations to get the housing centered. 
      
      
      '72 vs '81.  There are two differences in these arms.  The bolt pattern and the stud sizes.
      
2. Once the housing is centered pull the housing off one last time, install the the axle seal in the axle housing.
3. Next place the wiper seals on the axle housing in the following order:
   1. Felt seal
   2. Metal keeper
   3. Rubber seal
4. Pack the knuckle bearings with grease and install the knuckle housing with shims. Torque the 8 nuts to 70ft/lbs.
5. Where the wiper seals contact the axle housing apply a thin coat of oil or grease.  Now install the rubber seal followed by the metal ring.   Make sure there are no wrinkle in the rubber seal.  Then place the felt seal and seal flange halves.  Bolt the flange halves down with the eight small bolts.  
6. Now take the axle and birfield assembly and insert them into the housing.  Remember to line up the flats.  Pack the housing plenty of gease.
7. Now install the gasket that goes between the the knuckle housing and the backing plate, the backing plate, the spindle gasket, the spindle and the hub seal flange.  Tighten the 6 spindle bolts to 34 ft/lbs.
   
   
   Backing plate and spindle assembly
   
8. Hub Prep - If you have not already assembled the rotors on the hub this is the next step.  Install new wheel bearing races at this point in the hub.  Now pack the wheel bearings.  Place the rear most wheel bearing in the hub and install the spindle seal in the hub. 
9. Place a small amount of oil on the hub seals and install the hub on the rotor.  Install the large flat washer and then one of the spindle nuts.   Tighten the nut to 43 ft/lbs and rotate the hub/rotor back and forth to distribute the grease.  Loosen the nut and retighten to 35-60 inch/lbs.  Install the lock washer and then the second nut.  Tighten the second nut to 58 ft/lbs. 
10. Next install the locking hub housing.  If you did not use the Marlin Tack method install the snap ring at the end of the birfield.  Install the locking hub cap. 
11. Install the brake pads in the caliper and install the caliper on the knuckle housing. 
    
    
    Completed right side
    
12. Install the small hard brake line and flex line.  To see more information on brake lines go to the MC and Lines page.
13. Install the tie rod end in the steering arm and tighten to 67 ft/lbs.  NOTE:  This is a good time to check your front end alignment.
14. Install the wheels and bleed the brakes.
15. Carefully Test the brakes for leaks and operation.

Sources:

Tool Help by John Normile, Jaunuary/February '96 Toyota Trails

Mike (Cruiser_man)'s LandCruiser Disc Brake Conversion with Toyota 4x4 Mini-Truck Parts

Rod LaHaise's LandCruiser Disk Brake Conversion

Jack Alford's  79-85 Solid Axle Toyota 4x4 Vented Brake Rotor Swap

Randy Burleson's and Chris Geiger's  'Marlin Tack' Inner Axle Retainer

I would also like to thank Roy Bates for his machine shop services making the alignment tool.

Last Updated:  02/16/09
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