1983 Porsche 911 SC Targa

Thursday, December 29, 2011

Fixing Up the Car – Gear Shift Bushings

Over the last few weeks I’ve been enjoying the 911 under gasoline power. I want to have a performance reference to compare against once the car is under electric power. I also want to identify and make as many repairs as possible before starting the conversion.

I love the feel of the manual steering. It is more precise than any other car I’ve driven. The acceleration is terrific too. Adding to the exotic feel of the car, the pedals are hinged at the bottom, so shifting and braking are different than I am accustomed. What I hate is the smell that fills the garage, a mixture of oil and exhaust, which reminds me of an old pickup truck I once owned. There is also the feeling of uncertainty as to if the car will start up on any given attempt. Maybe the starting battery is getting weak. These will soon be non issues.

So far the repair list is small – minor looseness in the shift pattern, the car only has duplicate keys, different keys are required to open the door and operate the ignition switch, flimsy interior door handles, damage to the interior door panels from oversized stereo speaker installation, and a cigarette/12 volt outlet with intermittent power outages.

I will be keeping the stock transmission. The electric motors that meet my application requirements and my price range do not have a wide enough torque band to use with a fixed gear ratio. So the electric motor will be mounted to the transmission along with the flywheel and clutch. The car will shift much like a manual car, with a few noteworthy differences. At a stop the motor will not be spinning. With one foot on the brake the entire time, you could put the car into gear and release the clutch and the car will not move until you release the brake and press the accelerator. This means there will be no clutch slipping like on an internal combustion engine (ICE) as you try to coordinate releasing the clutch and pressing the gas pedal to get the car moving. Also, the electric motor does have a wider torque band than the ICE. A lot of electric car owners report starting the car in second gear, and leaving it there until up to 40 MPH (65 km/h). They shift to third for higher speeds.

While clutch usage will be reduced, it will still be used. To tighten up the shift pattern of the gear selector, I replaced the four bushings in the shift linkage. Pelican Parts sells them in a kit for about $23 USD. It looked like three of the bushings had been replaced recently, but the fourth and most difficult to access bushing was in poor condition. The result was a significant improvement in how the gear box shifts.

Rear Shift Rod Coupler and Bushings

The front shift rod bushing on the left was in
poor condition.  The others were OK.

Tuesday, December 20, 2011

Project Beginning

I have wanted an electric car for a long time. Over ten years ago, I used an electric truck on a summer job working with the college grounds crew. This was the perfect application of an electric vehicle – frequent start and stops, lots of torque during starts up hill, quiet, no exhaust, and super reliable. Then I discovered that there are suppliers that sell parts for converting a vehicle to electric. I was excited. The plan was to convert a small pickup truck, because this frame could carry the weight of the batteries, some 2000 lbs of golf cart lead acid storage, without overloading the vehicle. But I just couldn’t seem to fit this dream of a project into my budget.
Now that I’m finally able to do my conversion project, a new battery technology has emerged that makes it practical to convert smaller cars. Lithium Iron Phosphate (lifepo) chemistry stores more energy in a battery that weighs less and takes up less space than lead acid. The small pickup truck has been dropped for a small sports car – a 1983 Porsche 911 SC. I like new technology.
The steps of the project include:
  • Fix up the Porsche 911
  • Remove the internal combustion engine and supporting components (exhaust, gas tank, radiator) 
  • Couple an electric motor to the transmission
  • Secure between 48 and 56 batteries into the car
  • Mount the controller and accelerator position sensor. The controller goes between the battery pack and the motor, and controls how much voltage and current is delivered to the motor
  • Install a battery charging system
  • Stop buying gasoline

Soliton 1 Controller

Warp 9 Electric Motor

Manzanita Micro Battery Charger
Calb Lithium Iron Phosphate Battery Cell