Front Wheel Hub Disassembly

This afternoon I disassembled the front wheel hubs, which included the axle and wheel bearing assemblies, the brake rotor and wheel hub assemblies, and the brake caliper assemblies. The hydraulics in the brake cylinders will certainly need attention. I actually tried to do this work last weekend, but didn’t get anywhere as I was unable to get enough leverage to break loose the large bolts that mount the calipers to the wheel hubs.

Here is a picture of the wheel hub as I left it after I removed it from the car, during the front end disassembly. Note the odd shape of the assembly; neither side is flat and the piece is designed to rotate, which made gaining leverage to loosen bolts very difficult, even with a breaker-bar.

In order to lay the hub flat, I stacked up some 2x4s so the disk (on one side) and caliper (on the other side) could rest at different heights. This enabled the axle to sit up off the floor and the inside of the hub to rest relatively level. In order to get the leverage I needed, I used my new impact wrench, bought on sale for half price at $40 from Harborfreight this week.

I used a 3/4″ impact socket to loosen and removed the caliper mounting bolts. The caliper was still tight on the rotor, so I used a 3/8″ socket in my socket wrench to loosen the four cylinder bolts.

The caliper assembly was still firmly in place, so I flipped the hub over to loosen the four bolts on the other cylinder.

That allowed the caliper assembly to come loose, but I noticed that I’d missed a bolt that attached the hub plat to the small junction block where the rubber brake line feeds the hard line at the caliper. I removed this bolt using a 1/2″ socket and 1/2″ wrench to hold the nut while I loosened the bolt.

This enabled me to slide the caliper assembly free from the hub.

Brake fluid reaches the caliper via a rubber brake line, that attaches to the hard (steel) brake lines further upstream toward the brake pedal. Stomping on the brake pedal forces a plunger into the master cylinder, mounted on the firewall, to push brake fluid into the brake lines and down towards the calipers. This fluid flows through the rubber line and back into hard lines that directly feed the wheel cylinders mounted on either side of the caliper. The fluid forces the wheel cylinders (and brake pads) to clamp down on the rotor, which slows the vehicle.

There were two separate hard lines on the caliper assembly, one feeding fluid to each of the cylinders. I began by removing the line that fed the external cylinder from the internal one. I used a 7/16″ wrench to removed the fittings.

After loosening the fitting on the external cylinder, the short section of brake line came free.

Then I flipped the caliper over and removed the fitting from the inner cylinder. This enabled me to remove the hard line, soft line, and junction block assembly from the caliper.

This left the caliper-cylinder assembly. I plan to remove the cylinder, perhaps have them re-sleeved, rebuild the hydraulics, and clean up the calipers, but not today.

Next I returned to the wheel hub. The rotor and hub are pressed together. On the inside of the hub is an arm assembly that connects to the upper and lower ball joints, which bolt into the suspension arms. This arm assembly has the short front axle length that feeds through the rotor/hub piece and wheel bearing. The wheel hub and rotor spin on this axle and the car’s wheels bolt to the hub. There are four inner hub bolts that I removed using a 5/8″ box wrench. I had to tap the wrench with a mallet to break some of these bolts free.

I then pried off the outer axle cap using a flat-head screwdriver. It came off without much trouble after prying in different spots around the edge.

Through the “castle bolt” on the end of the axle was a cotter pin, which I straightened and removed using needle nose pliers.

I was able to remove the castle bolt without using my 1 1/8″ socket, because it was loose enough to turn by hand. Hence the reason for the cotter pin, which prevents the hub and wheels from flying off the car!

With the axle bolt off I was able to separate the hub assembly from the axle arm assembly. I slide the wheel bearings out of the hub.

There is a retaining plate on the inside of the rotor which bolts into the axel arm. The plate is connected by two sets of two bolts, with locking plates that have tabs to prevent the bolts from backing out. I pried back these tabs using a flat head screwdriver and then loosened the bolts using a 9/16″ socket.

I removed those bolts, one of the short and one of them longer, and then removed the other pair of bolts above those.

Then I removed the plate from the axle assembly, freeing up the arm onto which the steering linkage mounted. Below right is a close-up of the axle assembly with the upper and lower ball joints attached.

On the face of the axle was a mounting plate for the caliper. With all of the bolts out I could tap this plate off using a screwdriver to wedge between the two pieces.

I spent a bit of time doing a first cleaning of all the parts, which were some of the most greasy I’ve pulled off the car. They will need another cleaning prior to giving them a new finish, replacing the wheel bearings and seals, mounting new rotors, and rebuilding the cylinder hydraulics.

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