TECH BULLETINS

The installation process for a hub can differ depending on what generation it is.

Generation 1 FWD Hub

1. Inspect all components for signs of fatigue or damage. Any irregularities could possibly cause premature failure, so replace if there is any doubt.
2. The axle nut needs to be loosened while the vehicle is still on the ground. The old nut should never be re-used. Never use an impact gun on the axle nut.
3.  To avoid damage to components, be sure to use the proper tools to remove any component.
4.  Clean the bearing area hub to assist with smooth insertion. A light coating of lubricant can be applied to help ease the insertion.
5.  When press-fitting the bearing into the knuckle, be sure to apply pressure only to the outer ring. When pressing the hub into the inner ring, force must only be applied to the inner ring and the hub, not the outer ring. The inner ring must always stay in the same orientation as the outer ring. Applying force to the wrong part of the bearing could severely damage the balls and raceways. You can check for any damages by rotating the bearing to see if it turns smoothly. Press-fitting only locks the bearing radially. In order to lock it axially, install a snap ring where it is required.
6.  Manufacturers recommend replacement of the CV Joint boot after 60,000 miles.
7.  Lightly lubricate and then carefully align the splines of the CV shaft with the splines of the hub and pull the axle yoke into the hub and seat against the bearing. Install a new axle nut and fasten it using the specific torque nut for that application. With the vehicle on the ground, do a final fastening to the OEM torque specifications. For specific mounting instructions, Alltech suggests to refer to the vehicle manufacturer’s service manual for that model.

Generation 2 FWD Hub Assembly for Rear Application

1. Lift vehicle and remove rear wheel(s). Remove axle nut. Alltech suggests replacing the axle nut.
2.  If equipped with disc brakes, remove disc brake caliper from back plate and disc rotor from hub
3.  If equipped with drum brakes, remove brake drum from hub and disconnect brake pipe from wheel cylinder.
4.  Disconnect ABS speed sensor if equipped.
5.  Remove hub-mounting bolts. Remove rear brake shoes, stabilizer bar or other components that may interfere with hub removal.
6.  Remove hub separating axle hub and bearing if needed.
7.  The installation is done in the reverse order. Make sure the mounting surface is clean and check to see if other components have any damage or irregularities. Use torque specifications as recommended by that vehicle’s manufacturer’s service manual.
8.  Two piece axle and hub assemblies may need to be pressed apart.
9.  Some models equipped with ABS tone rings may require the tone ring to be switched over from the old hub unit to the new hub unit.

Generation 3 FWD Hub Assembly for Front Application

1.  Lift vehicle and remove front wheel(s) and remove caliper to set it aside.
2.  Remove brake disc rotor. Remove cotter pin and axle nut. Alltech suggests that the axle nut be replaced.
3.  On models equipped with ABS, disconnect sensor connector.
4.  Using a steering linkage puller, loosen the upper arm ball joint nut. If a toothed rotor is quipped, it is very important to be careful not to damage the ball joint. Shift knuckle to outside to maintain clearance between hub mounting bolts and drive shaft.
5.  Remove hub mounting bolts. Remove front hub assembly. Check the components for any damages or irregularities.
6.  The installation is done in the reverse order. Make sure the mounting bolts are installed to the manufacturer’s torque specifications. Alltech suggests the use of torque specifications as recommended in the vehicle’s manufacturer’s service manual.

1.0 Unrestricted Apply and Release
Stroke the master cylinder piston(s) through full stroke five times and allow return by the internal spring(s) force to the original position after each stroke. The piston(s) must move smoothly throughout the full stroke and must completely return to the original position within 5 seconds on the fifth stroke by the force of the piston return spring(s).

2.0 Venting
Set up the master cylinder on a mounting plate and adjust push rod to allow piston(s) to return to normal release position. Apply 30 psi ± 1 air pressure to the outlet port(s). Bore venting will be indicated by noticeable airflow from the vent port(s) into the reservoir.

2.1: Advance the piston(s) a minimum 0.200 inch and again apply 30 psi ± 1 air pressure to the outlet port(s). Observe that no perceptible air flows from the reservoir vent port.

3.0: Applied Leakage
3.1 Pneumatic: Mechanically restrain the piston(s) a minimum of 0.200-inch stroke to ensure that the vent port(s) is (are) closed. Apply 30 psi ± 1 constant air pressure to the outlet port(s). Cap reservoir(s) with a pressure measuring device(s) mounted through the cap. Stroke the pistons once to full stroke at no more than 0.250 inch per second and then allow the piston to return to the starting restrained position. Observe reservoir pressure(s) after stabilization for 30 ± 1 seconds. The reservoir pressures shall not exceed 1.0 psi increase.

3.2 Hydraulic: Attach bleeder tubes with check valves to the outlet ports and fill assembly with clean brake fluid. Curl tubes into the reservoir(s) and immerse open ends below the fluid level. Stroke the master cylinder through full design stroke until bubble-free brake fluid flows in the bleeder tubes. Observe fluid displacement and piston return with each stroke. Pistons must move smoothly and return by the return spring force to the original position within 5 seconds.

3.2.1 Low Pressure: With the assembly installed on a mounting plate, use the push rod to build 20 psi ± 2 pressure. Hold the push rod in the applied position and record pressure after a stabilization period of 15 to 20 seconds and again after 30 ± 1 seconds. The maximum pressure drop between readings shall not exceed 1 psi.

3.3 High Pressure: Replace low pressure measuring device with a high pressure gage and bleed system. Advance the push rod to build 1000 psi ± 100 pressure. Hold the push rod in the applied position and record pressure after stabilization period of 15 to 20 seconds and again after 30 ± 1 seconds. The maximum pressure drop between readings shall not exceed 50 psi.

3.4 Physical Strength: With assembly mounted as specified in Applied leakage test advance the push rod until reaching 3000 psi ± 150 gage pressure. Hold for 15 ± 5 seconds. Failure is indicated by abrupt drop in pressure, leakage or rupture.

3.5. Reservoir Seal: Plug all outlets and reservoir vents. Mount the master cylinder in an inverted position. Inspect the master cylinder for leakage.

4.0: High Temperature Durability
4.1: Displacement load cells connected to the master cylinder outlets shall provide for a gradual pressure climb not to exceed 50 psi until the primary port passes the compensating port.

4.2: Mount the master cylinder filled with brake fluid to the recommended level in the working position. Stroke at 60-80% of stroke length at a rate of 1000 ± 100 cycles per hour and a pressure output peak of 1000 psi ± 100 Discontinue stroking at the end of 70 hours continuous apply/release cycling. Inspect the master cylinder for leakage.

4.3: Repeat hydraulic applied hydraulic leakage test section (3.2:)

5.0: Cold Temperature Operation
Mount the master cylinder filled with brake fluid at the recommended level into the freezer. The displacement mechanisms shall be the same as for section 4.0. After bleeding the system, place leak trap at entrance to master cylinder bore and commence lowering the temperature within 18 hours to –40 to –45 °F. After a four-hour conditioning at test temperature begin stroking at 60-80% of stroke length, a rate of 250 ± 25 cycles per hour, and a pressure output peak of 1000 psi ± 100.

5.1: Repeat hydraulic applied hydraulic leakage test section (3.2:)

6.1: Examine the fluid and cylinder parts for evidence to indicate imminent failure of the cylinder upon continued usage in the vehicle.

Step bore master cylinders are more difficult to bench bleed than conventional master cylinders. They use an internal valve called a quick take-up valve that traps air causing difficulty in bleeding. Step bore master cylinders also have a larger primary bore, which takes longer to refill while bench bleeding.

The preferred method of bleeding a step bore master cylinder is to use a brake syringe such as the BrakeBest master cylinder bench bleeder tool part number10-5000MCB. To bench bleed using this tool, the first thing you want to do is mount the master cylinder in a vise by clamping on to the mounting flange. Make sure the mount is level and avoid clamping under the casting body, since that could damage the bore. Next, place a drain pan under the master cylinder to catch any fluid that is expelled during the bleeding process. Then, remove the protective caps in the primary brake line port and fill the reservoir with fresh, clean brake fluid, at least halfway. Draw some fluid into the syringe and then purge the air from the syringe. Starting with the primary in-line in the reservoir, inject brake fluid until clear, non-aerated fluid flows from the primary brake line port. Then, refill the syringe, purge the air again and inject the fluid into the primary brake line port, till no air bubbles are visible in the reservoir. Do the same for the secondary in-line and secondary brake line port and complete the install following your OE-approved service manual.

If you don’t have a syringe available, you can still do a traditional style bench bleeding procedure, which requires stroking at the piston and is much more time-consuming. There’s a slight variation between bleeding a step bore master cylinder and a conventional master cylinder. So, pay close attention to the process.

Again, mount the master cylinder in a vise by the mounting flange. THE MASTER CYLINDER BODY MUST BE LEVEL Then, install the supply plugs into the primary and secondary brake line ports of the master cylinder and fill the reservoir halfway with fresh, clean brake fluid. Using a blunt tool, depress the piston using a short stroke of an inch or less and hold for 20 seconds. This will allow air trapped in the valve to rise into the reservoir. Make sure the stroke doesn’t exceed one inch or else you could damage the seal. Keeping the piston depressed is the key to getting all the trapped air out of the quick take-up valve. It’s important to wait at least 30 seconds between strokes, to allow the larger primary bore to refill the fluid. Repeat as necessary, until no air bubbles are visible, and the piston travel is less than 1/8th of the original stroke. Finally, complete the install following your OE approved service manual