Front Suspension Assembly

I spent today putting the front suspension assemblies together. The front suspension consists of a wheel spindle that has upper and lower ball joints bolted to it, which are each in-turn bolted to upper and lower A-arm assemblies. The ball joints act as pivots and the arms bolt to the front-end of the frame, with the springs and shocks, which go in between the arms, regulating the compression and rebound of the suspension.

I assembled each side basically in four steps. First, I put the spindle arm and stub axle together. Second I assembled the lower A-arm, and third I assembled the upper A-arm. Finally, I attached the arm assemblies to the spindle assembly, creating the completed front suspension assembly.

Below I document the assembly of the front left suspension. I began with the wheel spindle. On it will eventually be mounted the hubs, rotors, and wheels.

Over the spindle was mounted a caliper-adapter plate, which had two forward-facing holes onto which the brake calipers bolt. Then, over the adapter plate is a shield that acts as a backer plate for the brake rotors.

However, it was much easier to bolt the ball joints onto the backside of the spindle before bolting those components onto the front. Here is a shot of the back of the spindle, where the upper and lower ball joints mount.

I bought sets of used but excellent condition upper and lower ball joints on ebay. For the uppers I paid $140 and the lowers I paid $150. New ball joints are very expensive, and these used ones are in much better shape than my old ones. All of the new ball joints came with new rubber dust boots. Below left are the lowers and uppers.

I began by pushing the upper ball joint onto the top of the spindle. The downward-facing bolt-shaft was fastened to the spindle by the castle-nut, which I twisted on and then tightened using an 11/16″ socket.

After tightening the nut down I installed a 1/8″ x 1 1/2″ cotter pin and bent it back to prevent the nut from backing off the shaft.

The lower ball joint went on upside-down relative to the upper. I tightened down the castle nut and installed another cotter pin.

My “new” upper ball joints came with new grease zerks, but the lowers did not. I installed a new 45-degree zerk into the lower balls using a 5/16″ box wrench. I actually bought a complete set of new grease zerks for the car, also on ebay, for around $30.

As mentioned above, it is easier to install the ball joints as a first step because I could access the castle nuts for tightening much easier than I could with the other pieces mounted to the spindle.

So, with the ball joints mounted to the back of the spindle, I layered the caliper adapter and backer plate back onto the front of the spindle.

There were a total of four bolts that connected those parts to the spindle. However, the top and bottom bolts connected directly into the spindle, whereas the right and left bolts go through the spindle and bolt into another part. Consequently I installed the top and bottom-oriented bolts first, so that they would hold these three pieces together and oriented correctly. The powdercoating layer made the caliper plate a tight fit around the edge of the spindle, but the bolts pulled the two pieces together nicely.

On the back of the spindle assembly is a steering knuckle bracket, which bolted to the spindle and has a forward-facing hole through which the steering linkage rods connect. This enables the steering wheel to rotate the suspension assembly to turn the car. The knuckle brackets are not interchangeable from one side to the other. The shaft from the steering linkage rods will only fit through one end of the bracket because the hole through which is mounts on the bracket is tapered (wider at one end than the other). The knuckle bracket should be oriented in such a way that the wider end of the hole is facing downwards, because the steering linkage rods mount up through the brackets on the car. Two longer bolts fed through the right and left holes in the front of the spindle assembly and threaded directly into the knuckle.

After tightening down all four bolts that held the spindle assembly together, I torqued each of them down to 35 pound/feet.

Here are a couple of pictures of the inner and outer sides of the spindle assembly.

 

The second step, after putting the spindle assemblies together, was to assemble the lower A-arms. Below is a picture of the pieces that constitute one of the lower A-arms. It is important to note that not all arms are created equal. Each A assembly contains one straight arm and one angled arm. I went back to the pictures of when I took the front end apart, and realized that the straighter arm is oriented towards the front of the car with the A-arm assembly upside-down, as it is connected to the car. The straight arms also have a tab (faces downwards) and a slot (faces upwards) onto which the front anti-sway bar mounts. Keeping the arms in the appropriate positions and even matching the same spindles back to their corresponding arms made everything go together more smoothly.

The first thing I did after laying out the pieces was to install the spindle into the arm pieces. First I slipped on the new dust boots, which I bought for $1.55 apiece from Nissan (part #54539-04200).

The spindles threaded onto the arms and I tightened them down by hand.

Then I turned my attention to the spring plate, which is the triangular piece that mounts into the center of the lower A-arm. The plate has a center disk bolted into it (the shock plate) through which the shaft of the shock absorber bolts. Also, the triangular plate itself supports the bottom of the spring.

The powdercoating must have worked its way into the bolt holes, because I found it necessary to chase the threads with a 1/4″-28 tap to get the bolts to thread.

I added the new bolts through the shock plate and tightened them down very firmly using a 7/16″ socket.

The spring plate mounted to the arm pieces with four bolts; two on either side. In order to get the holes to line up and force the spring plate up into the arm, I used a large screwdriver as a lever through the upper right pair of holes. After prying downward on the screwdriver to align the holes on the opposite side, I slipped one of the bolts through to lock the plate into position. I then tightened down the nut on that bolt and worked the other bolts into place. I used a 9/16″ socket on the bolt and a 9/16″ wrench on the nut.

Finally I torqued all of the bolts down to 30 pound/feet.

I added a pair of 45-degree grease zerks at either end of the spindle, using a 5/16″ wrench to tighten them down. That completed assembly of the lower A-arms.

The third step was to assemble the upper A-arms. The upper A-arms bolt onto the upper ball joints and also connect to the frame just above and behind where the shocks and springs mount to the frame. I began by installing new dust boots (part #54541-04100 from Nissan, priced at $.59 each) on the ends of the upper A-arm spindles.

Then I put the spindle onto the stamped A-arm piece in order to thread the metal bushing pieces onto the spindle.

I started the bushings onto both ends of the spindle and hand-tightened them roughly equal amounts. When installing the bushings I was sure to replace the lock-plates that have tabs that bend down onto the bushings to prevent them from backing off the spindle. I used my impact wrench with a 1 1/8″ impact socket to alternate tightening the two end bushings down until they were tight.

The uppers were fairly simple to assemble.

I completed the assemblies by adding new grease zerks to the bushings.

The fourth step was to bolt the upper and lower A-arms onto the spindle assemblies, through the ball joints. This would complete the front suspension assembly.

I began with the lower A-arm assembly. It mounted on the lower ball joint and was held in place by four bolts. The little arms on the base of the ball joint fed into the triangle-point of the A-arm. I used a mallet to persuade the ball joint to go into place.

Once I got the first of the holes to align, I tapped a new bolt through to hold that position. Then I worked the rest of the holes into alignment by further tapping the ball joint back. I inserted the remaining three bolts from below.

Before installing the nuts on those bolts, I had to drop on the bumpstop. Because I will be installing competition front springs that will lower the front-end by an inch or so, the stock rubber bumpstops would be too large. They would come into play much more frequently at the lower ride height, each time causing a temporary but disconcerting loss of traction. The Bob Sharp Competition Manual suggests cutting down and shaping the stock bumps to about half their original height. I elected to replace the stops with new urethane bumps from Energy Suspension. I bought these, which were around 1 1/2″ tall, from Summit Racing (part #ENS-9-9103) for $8.50 for the pair. They are also available in red : ).

The new bumpstops had a threaded shaft that was a bit larger in diameter than stock bumpstops. In order to mount them on the bumpstop bracket I had to tap the hole using a 7/16″-20 tap. That enabled me to screw the new bumpstops onto the brackets.

Underneath the bracket I added the bolt onto the shaft and tightened it down using a 14 mm socket on a long extension.

The new bumpstops mounted very firmly to the old brackets.

So I dropped the bumpstop assembly over the lower ball joint/lower A-arm bolts and then put on the new nylock nuts. I torqued the bolts to 17 pound/feet using a 1/2″ socket in the torque wrench.

Here is a shot of the assembly after attaching the lower A-arm and prior to installing the upper A-arm.

The upper A-arm simply mounted over the upper ball joint, and was attached using four bolts that threaded down into the ball joint’s arms. The hole in the top of the upper A-arm enabled the ball of the upper ball joint to protrude through and allowed for access to the grease zerk in the ball joint. I torqued these bolts down using a 1/2″ socket to 17 pound/feet.

That completed the front end suspension assembly. The next step will be to bolt each side onto the frame.

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