Drivetrain and half shafts

We finally got the custom half shafts in last week and just installed them. They look so beautiful. We needed to get them built for a couple of reasons: the amount of torque that is being transmitted is too large for the originals to handle and the originals no longer fit because they are too short and don't have the proper ends for the differential.


Here the new half shafts are connected. Now when we spin the wheels, the motor spins!!


The old half shafts (top) are really worn out and rusty. The new ones (below) look nice and fit perfectly.

Battery Box

One of the most critical components in any hybrid or electric vehicle is the batteries. We decided to use a total of 90 3.2 V 90 amp hour LiFePO4 batteries made by ThunderSky to power our vehicle. This should give us an all electric range greater than 60 miles.

The batteries take up a lot of space, almost as much as the original engine, transmission, and radiator. The only place we have to put all of these components is under the hood.

We created a battery box that will hold the batteries on two levels and allow for easy access to the lower level. The complete box just barely fits inside the space that was allotted so we had to modify the bumper slightly to make it fit by trimming some excess plastic from the inside of the bumper.


This photo shows the rough lower level before it got welded into the car.


Now the lower level is complete with half the batteries installed.


Now the top level is complete and ready for wiring.

Mounting the Motor Controller

Once we had the large beast (400 pound electric motor) in the vehicle, we needed to place the motor controller in the car. We decided on placing it behind the driver, where we had plenty of space.

Design and Manufacturing of the Support Bars

The team is getting ready for a long and hard-working session...


The steel bars were properly sized, cut, and welded to the frame of the vehicle.

Sizing and Placement of Components

After most of the cuts on the chassis were made and the differential assembly was ready, the team proceeded to make some rough mock-ups of the motor and inverter.






After the electric motor was delivered, a mock-up of the coupling between the differential and the motor was placed between them.

(Christophe take another look at the assembly)

The differential coupling was designed with simplicity in mind. After the mock-up was built in a CNC router, the stress analysis was executed and the piece outsourced to a nearby professional machine shop.

Differential Assembly

The original Haldex LSD of the TT was removed from the powertrain since it was not designed to handle the high torque of the electric motor (more than twice) and the final gear ratio was too high for out single-gear powertrain.

(Original differential of the TT Quattro)

After some careful research (based on a simulation done at the laboratory), we knew we needed a differential capable of handling up to 500 lb-ft with a final gear ratio between 3:1 to 3.2:1. It turns out that a 1998 BMW E32 differential suited our needs.

(BMW differential placed inside of the subframe)

Since the differential had to be placed at an angle, the top bar of the subframe assembly was trimmed, and a new rear support was made.



A stress analysis (Von Mises) for worst-case-scenario was performed and proved well below the maximum strength of the steel.

First Cuts on the Chassis

Once the car was moved to an area where hot work was permitted, the first cuts to remove some of the sheet metal in the trunk compartment were done.


Look at Christophe (gray t-shirt)... he knew there was no ticket back once the first cut was made...



After the spare-tire well was cut, some rough markings indicated the areas to be trimmed. Caution was taken so no parts of the shell affecting the subframe supports (or any other important structural items) were unnecessarily cut.


(we also made a cardboard mock-up of the AC motor and inverter)

(Peter making a cut with the grinding wheel)

(Keith making some fire)

Preparing the Chassis for the New Powertrain

Having finally just the "shell" of the vehicle, the entire rear end of the car was stripped from most of its sheet metal so it could accommodate for the electric motor and differential.

(The complete rear subframe was taken out of the vehicle)


Peter is removing some hoses in order to remove the gas tank.



(Yep, that was one of the holes for one of the fuel pumps)


This video shows how light the shell of the car was... Just a handful of people could lift the car and put it over some dollies.

Engine and Transmission Removal

After just a few days of having the car delivered, most of the interior of the car, doors, hood and trunk lid were removed.



Next, the removal of the engine and transmission followed.


Peter (blocked by the crane), Chistophe, and Keith work in the removal of the engine.


After a few hours of struggle, the transmission was finally separated from the clutch...


A few days later (and many, many man-hours) the complete front end of the car was dismantled.