Differential Prep & Paint

Today I did the rust repair and final painting of the differential. The first thing I did was to give it a quick final cleaning using Simple Green to remove and grease on the surface from handling and working with the differential case since I last cleaned it. Prior to introducing and water I replaced the fill and drain plugs, the breather, and taped off the axle openings to keep water from getting inside.

Before painting I used an acid etch to brighten up the aluminum front of the differential. I used an Eagle One Mag Cleaner which is designed for rough-finish aluminum wheels. I donned my safety glasses and heavy rubber gloves (this is acid, after all) and sprayed the aluminum liberally.

Per the instructions, I waited thirty seconds while the acid did its etching on the aluminum, which caused a fairly vigorous foaming.

Then I washed it off very thoroughly with water.

Then I turned my attention to the rest of the differential. The case itself had several rough areas where the original paint had worn off and surface rust had set in. I had previously used a wire brush to remove and loose material. Before painting, I sealed the remaining rusty areas using Eastwood’s Rust Encapsulator product, which is supposed to seal in rust and neutralize its ability to deteriorate any further. I bought a quart can for $19 and applied it using a regular paintbrush.

There was a lot of rust around the edges of the axles, presumably from the finish being chipped by rocks and stones kicked-up by the tires. I painted over all of those areas with the encapsulator.

There was also surface rust around the welds at the rear of the “pumpkin,” which I painted over.

I rotated the differential to point down so I could access the areas underneath, and completed sealing over all of the rust areas.

After allowing the Rust Encapsulator to dry for four hours, as recommended by the instructions on the can, I prepared for the finish coat of paint. I masked off the aluminum part using heavy-duty foil and some painter’s masking tape. You can tell Thanksgiving is on my mind already!

Then I removed the plugs. The paint I used is Eastwood’s aerosol Chassis Black, which was $13 for the can.

I applied two coats, waiting 20 minutes between coats.

Then I rotated the differential up again in order to apply two coats to the areas I had missed.

After allowing the paint to try for several hours, I moved the differential into the garage to dry over night. I removed the masking from the aluminum area.

Overall I’m pleased with the results, particularly compared to the way it looked when I pulled it off the car.

Exhaust Manifold Coating

Today I painted the exhaust manifold using a high temperature coating from Eastwood Company that is designed for exhaust components. This product is meant to have the appearance of new cast iron, which is the material the Datsun manifold is made from. My manifold had already been coated in a white material, so this should restore a more “stock” appearance.

Prior to painting I cleaned the manifold again using Simple Green to remove and dirt or grease on the surface.

The product I used is rated for up to 1200 degrees and cost about $15 for the can, which was enough to thoroughly coat this manifold.

I sprayed on one coat and then did a second coat after an hour.

Here is the final product. After the paint has dried somewhat the effect dulls to more of a cast iron appearance.

Misc Parts Cleaning

This afternoon I cleaned up some miscellaneous parts that were laying around the garage. Some of these will be rebuilt, some painted, and some eventually sent off for powdercoating or plating. I used Simple Green and scouring pads.
Here are some body-frame clips and the bracket from the differential onto which the emergency brake mounts.

Here is the driveshaft and the two steering columns.

And here are the front hubs, wheel spindles, and calipers.

Rear Wheel Hub Removal, Part II

Two weeks ago I was removing the rear axles from the differential and had trouble getting the left axle free–it was stuck in place. I learned a trick from Dave Kaplan on the forums at 311s.org that solved that problem. Here is the stubborn axle in place. I tapped it with a rubber mallet to no avail. A slide-hammer should work, but I didn’t have one on hand.

So what I did was this: replace the brake drum on the hub, only put it on in reverse (inside-out if that helps). Then put the lug nuts on and tighten them down only a couple of turns.

What I don’t have a picture of, because I had to use both hands and therefore put the camera down, is what I did next: grab the drum at three and six o’clock and push it in and then pull it back out so it taps against the lugs. Repeat a few times and it is a homemade slide-hammer. After just a few pulls the stubborn axle came right out.

Here are shots of the inner axle backer plate with the wheel bearing and collar and the differential’s axle housing, which still holds the inner oil seal inside.

Rear Wheel Hub Removal, Part I

This evening I started removing the rear wheel hubs so that I can clean-up and re-build the rear brakes.

I started by simply pulling the brake drums off. With the wheels removed from the hubs, there was nothing mechanically holding the drums in place. The drums were aluminum and finned.

Here is the hub after the drum was removed. On the right I began to pull the brake shoes off. They are spring-loaded and I first tipped on shoe forward and off its mounting point.

Then I freed the other end of the shoes from its mounting point and popped the shoe assembly free.

Here is a shot of the hub after the shoes were removed.

The hubs have a backer plate that bolts directly to the rear axle. I removed the four bolts that make this connection using a 1/2″ socket.

With those bolts removed the hub came free, with the half-section of axle attached! Apparently the wheel hubs need to be backed off the inner end of the axle.

Both the hub backer plate and the end of the axle case had shim/gaskets on them. Below left the rear wheel bearings are visible up against the backer plate.

I will need to have the bearings pressed off in order to get the brake assemblies off the axle. That is something for another day.

Draining the Differential

I drained the oil from the differential in preparation for disassembling the rear wheel hubs and axle. Fist I propped the differential up on my jackstands, to provide better access to the plugs. Having spent an hour yesterday and another hour this afternoon cleaning it, the diff looked pretty nice at this point.

I started by removing the breather, using a 5/8″ socket.

On the right rear of the differential are a fill plug and a drain plug. It is always a good idea to ensure that the fill plug comes out prior to removing the drain plug and draining the differential. I used the drive of my 1/2″ drive socket to loosen the fill plug.

I removed the fill plug and then positioned my oil pan underneath the differential in preparation for draining.

Then I removed the drain plug: first using my 1/2″ drive breaker bar to gain some leverage and break it loose, then using the socket wrench with no socket, then spinning it off the last few turns so I could catch it in my hand.

Then the oil drained out of the differential. It smelled a little sour, but I suppose that is normal.

I lifted the axle up on each end in order to drain as much of the oil as possible. I will replenish the differential oil after I’ve done some work on the rear brakes. I don’t know what all the fuss is about–it is easy to change the differential gear oil, all you have to do is remove the rest of the car from the diff first!

Emergency Brake Arm Removal

This afternoon I removed the emergency brake assembly from the rear of the differential and then gave the diff a second cleaning. The e-brake assembly consisted of an arm that spanned the two rear brake drums and would apply pressure to the brakes if the lever in the car was pulled. The e-brake cable, attached to the handle in the car, attached to a bracket on the right side of the differential. I began at the wheels and worked my way in.

Starting on the right side, I unscrewed the Philips head screw that held the spring tensioner to the brake cylinder.

With the screw loose the small tab could slide outward towards the wheel hub, relieving the pressure on the spring.

On the right side the arm was attached to the brakes by a pin which had a cotter pin through its bottom. I pulled the cotter pin and then worked the retainer pin up and out of the arm.

This allowed me to disconnect the right e-brake arm from the wheel hub.

On the left side was a similar set-up. I loosened the spring screw, and removed the spring from the hub. Then I removed the cotter pin and tapped the retaining pin free using a nail-set and mallet.

That freed the left e-brake arm from that hub.

Just right of center, the two arms that activate the left and right rear brakes came together on a pivoting arm; this is where the emergency brake cable came in. I removed this mechanism next. First I pulled out the cotter pin below the mechanism and pulled off the retaining washer.

Then the piece slide of a bracket mounted onto the differential case.

In order to slide the assembly off the differential, because the left arm fed through a small loop on the diff. I had to remove the spring assembly from that end in order to pull the arm back through the loop. I removed the mounting screw and then pried the retaining bracket back to get the spring piece off the arm.

Then I removed the rubber cushion from the inside of the loop an order to slide the left arm through the loop and off the differential.

The center linkage for the e-brake mounted to a bracket on the differential. I removed this by taking out the two bolts using a 1/2″ socket.

After removing the emergency brake linkage from the rear wheel hubs and differential, I spent another hour cleaning the differential. More Simple Green and a good scrubbing with some #2 steel wool pads made it come remarkably clean.

Front Wheel Bearings, Removal from Hubs

This morning I removed the seals and inner bearings from the front wheel hubs. It took some effort, but I want to replace those seals and the bearings with new ones “while I’m at it.” The first step was to remove the bearing grease seal from the inner surface of the hub. It is a rubber gasket with a metal ring that helps it maintain its circular shape. The seals fit tightly into the inner circumference of the hub. I began by prying the seal outward using a flat head screwdriver, working may way around and around.

After going around a number of times, the edge of the seal began to come proud of the inner face of the hub. I was eventually able to grab its edge with a pair of pliers and pull it out. Easier said than done.

With the seal removed, the inner wheel bearing fell out.

The bearings were accompanied inside by a metal ring, known as a race, inside of which they rotated. The races are held tightly in place on the inner hub surface by friction. I had to pound them out of the hub. The outer race was the smaller of the two. I used a screwdriver and a mallet to pound it out, alternating from the right to the left side with my blows. Eventually it worked its way out.

The larger outer race was not as easy. Luckily the inner circumference of the hub is larger than the outer, so I was able to fit my pickle fork into the wide inner edge of the hub. The fork applied pressure to both opposing edges of the race simultaneously, so I could move the whole race with one strike. I used my 3 pound sledge hammer (and safety glasses) on the fork and the race came out willingly.

Differential, Clean-Up

This afternoon I pulled the differential out of the garage and started on it. It clearly was in need of a good cleaning. My plan for the rear end is to leave the differential gears alone and just address the rear brakes, grease seals, and wheel bearings. This afternoon I spent around an hour cleaning off much of the years of dirt, grease, and grime.

Here is the differential as it was when I pulled it off the frame:

I removed the hard brake lines that connect to the right and left rear brake cylinders from the junction with the soft rubber line above the center of the differential. I used a 7/16″ open wrench to loosen the hydraulic fittings after spraying on some Liquid Wrench. The lines came off without much trouble.

I removed the line on the left side in the same manner.

Here are the brake lines removed.

Then I spent a full hour cleaning the differential and axle case. I used some Simple Green, a wire brush, and a lot of scouring pads. Much of the dirt came off and revealed that the black paint on the differential is actually in pretty good shape. There are some surface rust areas, but nothing to be overly concerned about.

Front Brake Caliper Disassembly

This morning I took apart the hydraulic cylinders from the front disc brake calipers. The cylinders mount on each side of the caliper and hold the brake pads, which they squeeze together on the rotors in order to slow the wheels.

Here are the assembled calipers prior to taking them apart.

Each cylinder was mounted on the caliper by four bolts, one at each corner of the cylinder. I removed these bolts using a 3/8″ socket in my socket wrench. The bolts were not torqued down very tight at all.

With the bolts removed the cylinder was still attached, so I used some persuasion in the form of a few taps from the rubber mallet and some prying with a Flathead screwdriver.

In short order the first cylinder came free.

The brake pad had a groove from the center out to one of the narrow edges. A pin on the cylinder slid up into this groove to hold the pad to the cylinder. I slid the pad off.

Then I repeated the same operation to remove the cylinder on the opposite side, beginning with the bolts.

On the rear edge of the caliper was a keeper plate that I removed. It was held in place by a single bolt, which I removed using a 10mm socket and wrench. I then just slide the plate back and off the caliper.

The calipers I plan to clean-up, address any rust, and re-paint using a high-temperature caliper paint. The cylinders I will have re-built. I am thinking of sending them off to Whitepost Restorations in Virginia, who will completely sandblast, refinish, re-sleeve, and replace hydraulic components in brake cylinders. They quoted me a price of $80 per cylinder to fully overhaul each one, which adds up for four brake cylinders. But hey, stopping is pretty important. Whitepost also offers a lifetime guarantee, so I would never have to pay to have my cylinders re-built again. I haven’t completely decided to go that way, but I am leaning pretty heavily in that direction.