Last Updated:12/23/01

POWER BRAKES
Note: This page was created in reference to my Jet 007 Omni conversion.  My Civic EV was factory equipped with power brakes, so I simply added a GM pump as described below.  Unfortunately, after about two years the pump died.  Since then, every replacement pump I have been able to find in salvage yards has been dead.  The sad truth is the pumps are just about impossible to find in working condition anymore.  I ordered a rebuilt one from an auto parts store, and when it arrived it had been damaged in shipping.  It turned out to be the last one they had in the system.  No more were available.  Since then I have fitted the Civic with a Thomas pump and switch as is used on most conversions.  These are available from many EV parts suppliers.  See http://geocities.datacellar.net/MotorCity/Downs/4214/links.html#EV Parts

Last Updated:11/26/98

My car was not originally equipped with power brakes, as most modern cars are. I wanted that feature (3400+ pounds is hard to stop), so I installed a power brake booster and the matching brake pedal. Since power brakes require a source of engine vacuum, and electric motors have no vacuum source, another method had to be found.

I was told by an EVer in Michigan to locate an electric vacuum pump from a Chevrolet Cavalier Cadet. It seems GM had a problem in the early 80s with the J-body cars equipped with the 1.8L engine. They didn't produce enough engine vacuum at idle to maintain the power brakes. What GM came up with was a 12 volt automatic vacuum pump. This was exactly what I needed for my car.  I later found the same pump on an '87 Volvo sedan.

At my favorite self serve salvage yard I found an '84 Cadet. The vacuum pump was mounted inside the driver's side front fender in front of the wheel, inside a black plastic shield. The easy way to find it was follow the vacuum hose from the booster down the fender and to the pump. The pump was made to hang under a horizontal surface. The connections were very simple,  just three wires: 

  • Red to the 12 volt positive of the battery (through a fuse) 
  • Black to ground or the 12 volt negative of the battery. 
  • Black with a white stripe to 12 volt positive from the ignition switch. 
There were two hoses. One is the vacuum source for the brake booster and the other is the pump exhaust. This originally vented into the air filter housing, but since EVs don't have one, I vented mine into an '84 Ford Escort emission air pump muffler.

The pump will produce 22 inches of vacuum. It automatically cycles on when the vacuum drops to 12 inches. It takes mine 11 seconds to pull the vacuum back down to 22 inches.  I don't use a vacuum tank, it doesn't seem to need one.



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