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.

Leaf Spring Clean-Up

This morning I cleaned-up my rear leaf springs in order to assess their condition. I’m in the process of deciding whether to replace them or have them re-arched (or de-arched, as the case may be). The springs hold their arch well, so their is no need to add a leaf or anything like that.

Also, both springs are arched equally, so neither side is high or low, which would require correcting. Below, left is a shot of both springs lined-up; they are basically identical which makes it difficult to see the one in the rear. On the right I measured the distance from the floor up to the bottom of the spring where the mounting bolt is. The distance was 3 5/16″. I’m posting to the forums at 311s.org to see what height others are running. The competition springs lower the rear of the car a bit, so I may actually want to have these de-arched an inch or so. We’ll see.

After measuring I took the springs outside to wash them. Like everything else off the underside of the car, they were pretty filthy. I wet them down and wiped on some Simple Green.

I used a wire brush to loosen up some of the dirt and then scrubbed the springs with scouring pads and more Simple Green. I’ve found it important to continually wash away the dirt as it comes off the parts.

The bottoms of the springs (which are actually mounted upward on the car) were equally dirty.

But they actually came clean enough to read the part numbers on the springs. I cleaned up the edges the same way.

I was pleased at how nicely the leaf springs cleaned-up.

Rear End Disassembly

Today I tore down the rear suspension and removed the differential and rear axle. Progress!

Here are some pictures of the rear suspension before I began. The rear axle:

And a couple of close-ups of the right rear suspension components from the front and rear:

The suspension is held together largely by a plate that bolts over the axle and through the leaf spring, and also bolts onto the rear shocks. Underneath this plate are the five primary bolts that hold everything together.

The first order of business was to remove the wheels. I broke loose the lug nuts using a breaker bar 19 mm socket with the car resting on the ground. I then jacked-up the car and supported it using my heavy-duty jack stands under the rear part of the frame.

I finished removing the lugs using a socket wrench and the 19 mm socket, then carefully lifted the wheels off the lugs and pulled the wheels.

Here are a couple of shots of the brake drums and rear suspension with the wheels removed.

The weight of the wheel assembly caused it to drop down, stretching and placing tension on the leaf springs. I used the jack to apply upward pressure underneath the suspension plate, and placed another jack stand under the leaf spring to relieve this pressure. I applied enough upward force to raise the wheel assembly but not enough to raise the frame off the larger jack stands placed at the rear. I then jacked-up the differential, but not enough to raise the leaf spring off its jack stand, and placed a final jack stand under the differential. This ensured that no matter what I unbolted, I shouldn’t have anything heavy falling to the ground (or onto my lower extremities). Safety first!

The plate that all of the suspension components bolt to is held to the rear axle by two threaded u-shaped clips that bolt over the axle and through the plate. Four nuts hold these clips in place from underneath the plate. I removed all four of these nuts using a 15 mm socket. I tapped the clips from below using a mallet to get them free.

I removed the clips and then was able to pull the bumpstops off the axle.

Underneath, at the center of the plate is another nut that mounts on a threaded stud that protrudes through a hole in the leaf spring. I began to loosen this nut using a 12 mm socket and before it was off the plate came free and slid down the shock toward the ground.

Next I removed the nuts that secured the top of the shock. The nut was larger than my largest socket, so I used an adjustable wrench. With the nut removed I slid the shock and its bushing off the stud onto which it was mounted.

I then jacked up the differential about a half an inch (actually I just lifted it up using brute strength and raised the height of the jack stand) which raised the axle off the leaf spring.

I was then able to pop off the lower metal piece that bolted the leaf spring to the whole assembly, leaving the leaf spring mounted only to the frame at the front and rear.

At the rear the leaf spring is bolted to the frame by two bolts through a bracket. I unbolted the two nuts from the bolts using an 18 mm socket.

From the inside I then removed the bracket’s cover plate and from the outside I removed the bracket itself.

The leaf spring is the upper loop and is held to the frame by the lower bracket bolt through the lower loop of the scroll.

At the front there was a single bolt through the frame that mounted the leaf spring. I loosened the nut on this bolt using an 18 mm socket and then tapped the bolt out.

That released the leaf spring from the frame. I next removed the scroll-shaped hangers that mount the leaf springs in the rear. There was one bolt on the inside, which I removed using a 15 mm socket.

On the outside of the frame the scrolls were mounted by another bolt. I used a 15 mm ratcheting wrench on the nut and 15 mm wrench to hold the bolt.

On the passenger side only, later roadsters have a torque strut bar that helps to prevent the frame from racking when the car puts power to the wheels. I removed this, which is bolted through a bracket on the rear axel. I used a 19 mm socket and wrench to remove the bolt.

I unbolted the front of the torque strut bar the same way and pulled the bar off.

That concluded the disassembly of the rear suspension and I was able to roll the axle and differential away, leaving the naked frame.