Rear Suspension Assembly

Once the rear differential was mounted properly, we started on the rear axles and suspension. This consisted of installing the lower a-arms, axles, spindles, tying in the sway bar and attaching the brake lines. The upper a-arms came pre-installed with the car.

The process wasn't too eventful. We installed the lower a-arms with little fuss first, followed by the axles, then the spindles, then brake hoses.

A few notes:

• Move the sway bar up and out of the way - or attach it to the upper a-arm first thing. If you completely install the axles and the swaybar is pointed below the axle on the left side of the car, the swaybar won't be able to swing up into position.
• In order to tighten the rear-most lower ball joint on the rear spindle, the caliper must be removed.
• When installing the axles, reach into the differential and situate the c-clip in the center of the hole. This will go a long way towards ensuring there is little binding when installing the axles.
• If necessary, tap the end of the axle with a block of wood and mallet to fully seat it. See the pic at the end of this post to view how far in the axle should go.
• Be sure to align the cotter pin holes for each ball joint in a way that will allow you to insert the cotter pin once installed.
• Note that if fully inserted into the hub (without a wheel installed), the wheel bolts will hit the hub. This will cause the hub not to rotate fully, making you think that something has gone awry with the differential, causing at least one full night of sleeplessness.

Here is a pic of the rear end pretty much fully assembled. We'll put the gas tank back in next. Note the red bushings near the bottom of the frame. To the best of our knowledge, those are used for a live rear axle set up and are not utilized with an IRS setup.

We currently do not know to where the wire on the right of the picture connects. The other end is not connected to anything and is not labeled.

Headlight Installation

This weekend, we switched gears a bit and moved to the front of the car to install the headlights. The kit comes with a pair of Hella lights, which should do a great job of lighting our way once installed.

The installation was fairly straight forward. The most difficult part was tightening the nut on the underside of the shock upright. Note that you'll need to remove the front shocks that you had probably previously installed.

On the underside of the head lamp, where the mounting stud comes out, take care to ensure the stud is seated correctly. The stud has a square end that fits down into the housing. If this is not seated correctly, you wont be able to create enough tension to hold the lamp assembly upright.

Tightening the nut on the underside of the upright gave us fits. We taped up the connector pins and routed the wire pigtail through a Harbor Freight impact socket. The socket had a hole drilled in the side of it from the manufacturer. We stuck a phillips screwdriver in that hole and used it to turn the nut to tighten the assembly down. We were able to get it fairly tight. See the pic above.

For reference, the order of assembly looked like the illustration on the left. (I'm quite pleased with how my illustration turned out, but note the flat washer at the bottom may have been a lock washer instead.)

Once each light was mounted, we slid the pigtail through the upright, body and into the engine compartment. We untaped the pigtail and slid the pins into their proper slots in the supplied connectors.

Progress On Rear End

With the Subaru differential in hand, along with the rear differential mount kit, we were ready to make an attempt to install it in the car. The first order of business was to remove the OE studs that helped secure the differential in its donor car, as the Birkin would use bolts to mount the aluminum mounting plate.

There was some concern that the thread of the stud would not match up to the thread of the bolts supplied with the Birkin. After pulling one of the studs out, we found we were safe. (We make it sound easy - they are held in by loctite and may require heat. If you take heat to it, be sure to remove the brown vent from the top rear of the differential or it will melt.)

After both studs were out, we mounted the rear differential mounting plate with the supplied bolts. You can see the mounting plate to the right - the pic was taken when the studs were still installed in the diff. Notice the position of the plate. The side of the plate with the spacers face the rear of the car. Also, it's important to note that when you bolt the plate to the rear of the differential, the little spacer (shown on the bolt there) will go in between the differential and the aluminum mounting plate. The washer will go on the outside of the aluminum plate.

There is another plate that mounts to the bottom of the diff, which is held in by four long bolts, some brass bushings and some nuts. This is visible in the pics below.

Here, we have taken the cover off the center console, which is held on by several small 8mm nuts/allen screws. I would think it to be impossible to mount the differential without removing this piece. We're test fitting the lower mount to get an idea of how the differential will fit into and mount to the chassis. We found that the routing and mounting of the two fuel lines and electrical running to the back of the car would not allow for proper mounting of the diff. At all. Not. Even. Close. We snipped the majority of the cable ties holding these lines together and drilled out several of the rivets holding them to the frame and chassis. Once free, we massaged them into a shape that would accommodate the differential. Note that the notch in the back of this lower mount should face rearward, as it coincides with a flange on the diff itself.

Edit: There was really no need to drill out the rivets and go to the trouble we did. After mounting the diff, adding additional spacers in the rear and jumping through a bunch of hoops, we discovered four extra bolts and four extra spacers for the lower front mount of the diff. The spacers were about 1/2" long and went between the frame and the front diff mounting plate. Once in place, all the lines fit fine and everything went together well.

At this point, it was necessary to hook up the rear brake hard lines to the soft lines, which came attached to our rear hubs. The clearance between the hard lines and the bottom of the diff is minimal, but the hard lines can be bent a bit to ensure they don't actually touch the bottom of the diff.

With the fuel lines out of the way and the brake lines attached, we mounted the lower mount on the differential and lowered it in the car. It was easier to attach the lower mount to the diff first, as opposed to attaching the lower mount to the car first. Here is the diff mounted in the car.



Here is a pic of the hard lines under the mounted differential. The bolt holding the rear half of the lower a-arm (to the right in the pic) will interfere with the soft brake line, but the brake lines need to be mounted before the differential - at least to get them in the correct location.

We got the rear suspension together as well. More on that with more pics later.

Progress On Front Suspension

Note: To avoid having to remove the front shock assembly, install the headlights before proceeding.

Manned with the Birkin Assembly Guide, we made some progress on the front suspension, which consisted of attaching the upper and lower A-arms, dampers, knuckles, calipers and end links.

The kit a-arms went in with a bit of persuasion. The manufacturing tolerances seemed fair so far.

After snugging everything up, we checked for any excess play at the mounting points and were prepared to add extra washers where necessary, per the guide's instructions. There turned out to be no need, as everything had very little play - one side tighter than the other. We're figuring that the tight tolerances were due to the new bushings and would loosen up slightly once on the road.

The dampers slid in without a hitch. Our chassis came with machined aluminum washers and spacers as a placeholder where the top and bottom of the dampers mounted. We retained the washer within the top mount to occupy the small amount of play present. The bottom damper mounting tabs were fine. The dampers allow for height adjustment which will be handy when corner weighting the car once fully assembled. *Please note that despite everything looking great at this point, you'll need to remove the top mount of each damper to install the headlight assemblies later on.

Next were the knuckles, which came as a unit, complete with bearing, hub and rotor installed. The top and bottom ball joints slid into the knuckle and we snugged everything up. The beefy Wilwood style calipers bolted easily into place and our Hawk pads slid into position.

We ended up being short the otter tie rod ends. Evidently, Dick has them in the mail. So as soon as they show, the front suspension will be ready to rock!

The Birkin Has Arrived

It's here! Dad (Ken) drove down to pick the Birkin up from Dick Brink and the folks at Texas Motor Works. It actually fit in the back of the van! After making some space in my garage, we set up some Harbor Freight saw horses in which to rest the car. With the help of an engine hoist and my lovely wife, we had the bare-bones car in position.

Much to our (my) surprise, many of the components were already in place. On the front end, the steering rack and sway bar were in place. The entire car was plumbed with hard brake and fuel lines and the pedal box was installed. The dash and wiring were in place, save for the instruments and the fuel tank and cargo tray were installed. This ought to be easy, right :).

We have most of the components on-hand, including the 2.0 Ford Duratec engine and a rear differential from a Subaru WRX, so here's to a smooth assembly.