This has been a dreaded project since I first thought of this project. Here’s the problem – modern cars have power assisted brakes. The power assist is provided by a brake booster that’s mounted on the firewall and attaches to the master cylinder. The power comes from a vacuum in the power booster – that vacuum is created by the gasoline engine. I no longer have one of these.
My first thought was to just leave the braking system as is and press the brake pedal real hard to stop. I read online that this is a very bad idea because you will have to press impractically hard to get the vehicle to stop. A couple of other sources recommended removing the power booster, attaching the master cylinder directly to the firewall, and shortening the rod between the brake pedal and the newly relocated master cylinder. Still others in the EV community use an electric vacuum and attach that to the original power booster so you have a braking system that functions the same as it did with the gas engine in it.
The problem with removing the power booster and mounting the master cylinder right to the firewall is it’s a pain to do. I got in there and detached the brake lines from the master, pulled the master off, removed all the bolts holding the power booster in and tried to remove the booster. There are still 5-10 different brake/fuel lines in that area and the power booster is nestled in behind all of them. This makes taking it off very difficult.
The problem with buying an electric vacuum is twofold. First, it costs money – generally a couple hundred dollars. I’m trying to keep this on some sort of budget. Second, it takes energy to run the vacuum which in turn would reduce the range of my car. This will not do.
I return to the first option. Leaving everything as is and pressing real hard. I bolted the power booster back on, re-attached the master cylinder, and reconnected all of the brake lines to the master. I put the car up on the lift, put the car in neutral, gave the front tires a spin and had my brother press the brakes all the way to the floor. The drivers side tire locked right up. I tried to turn it but couldn’t do it while he had the pedal in. I asked him how hard he was pushing and he said may 25% more than he normally would. That seems very acceptable.
I mosied on over to the passenger side of the car and did the same. The front passenger wheel stopped as well. Only this time when I tried to turn the wheel while the brake pedal was in, it turned with very little effort. This is not good.
I checked the brake fluid, checked the lines between the master and the caliper on the passenger side and it all looked copasetic. I bled the line on that side at the caliper to make sure I didn’t have any air caught in the line. There wasn’t any air in there, and still it would not “lock up” when we did our test. Frustrated I put the car up on the lift again to poke around and see if something wasn’t glaring out at me.
There was. The two brake lines that go to the rear of the vehicle were leaking like a sieve. There was even a small puddle of brake fluid on the shop floor. At first I didn’t think this would be much of a problem, but after checking around with some folks it made more sense why it would. The hydraulic braking system is a closed system, and must remain closed to ensure proper pressure to all parts of the system.
There wasn’t any more time to get to work on replacing the brake lines last weekend. With some luck, and some help, I can get those two lines replaced this weekend. We’ll see how it works out.