Cheap power brakes for electric car?

[bennelson]

Hey everyone,

As you may know, I am converting a car to electric.

One of the problems with an electric conversion, is that you lose the "waste by-products" of the gasoline engine, namely, heat in the winter and vacuum year-round.

I have seen that there are some electric vacuum pumps available through EV conversion places, but they are all very expensive.

What would really be needed to create vacuum for power brakes?

Could something like this work?
air suck pump



Doesn't say if it is AC or DC powered, but if it is DC, it would then just need some sort of simple control to turn it on and off at the right time.

Whoops, I just noticed, it isn't electric, but rather air powered. Does that mean I could hook up an air compressor tank to it and just have that aircompressor run while hooked up to house power, saving it in an air tank for later?

Would this work? Any other ideas?

[MetroMPG]

I would be looking into junkyard vacuum pumps from diesel cars. Maybe ask some of the TDI drivers here how their brakes work.

[MazdaMatt]

MUCH BETTER IDEA: Upgrade to a larger master cylinder and remove your brake booster. You will never lose boost, have better brake feel and lighten your car significantly by removing the part and not adding a vac pump.

[MetroMPG]

The FS has a discs/calipers upgrade from the 4-cyl car. Much easier to use than the 3-cyl setup without vacuum.

I've also heard that you can simply puncture the diaphragm in the booster reservoir (drill through it), and it significantly lessens the amount of pedal effort required. Not sure I totally buy that idea though - not enough to try it on the FS anyway (in case we ever want to add vac assist).

Ben: I can attest to the insanely hard brakes without assist in my '98 3-cyl.

[MazdaMatt]

drilling through you booster will kill your boost and increase your pedal effort as though you were eoc'ing and pumped the brakes till they were hard. If i were doing this, I would see absolutely no option besides replacing the MC with one that does not require boost. I will be doing that to my track-only car soon.

[MazdaMatt]

oh yeah, drilling a hole would also have the same result as a vaccuum leak... bad idea

[dcb]

a vacuum leak on an electric car?

[MazdaMatt]

a vacuum booster on an electric car? (see my point?)

Funny... new tech (EV) brings back old tech (properly sized MC with no booster!)

[dcb]

I'm all over the manual brakes suggestion. The booster on an ICE could probably be disabled without destroying it or causing a vacuum leak though. Just fish a bit of plastic wire through the check valve and block off the hose going to the engine perhaps.

edit: heck the check valve might be removable.

[dcb]

I did just did an experiment on a metro, when I pulled the hose from the booster there was a noticable noise of escaping air, so it seems likely that the check valve was external. I plugged the hose end removed from the booster (jammed in a round thingie of the right size) and took a test drive (no traffic, slow speeds).

Initially it felt pretty much like it does when the boost runs out. But I got a lot more confident with it as I used it. No problem locking up the tires, it just takes more pressure which legs have plenty of, especially in a panic I am starting to think a big problem with running out of boost is the sharp transition to no boost braking. If you never have boost it seems pretty manageable. More leverage wouldn't hurt though, and of course your mileage may vary.