Ben Nelson's Electro-Metro Build thread

[dremd]

you could try an add a 12 volt motor to a tdi vacuum pump.
I don't know what the volume is; but the supra also has a vacuum pump factory ( located under the cruise module on turbo cars). Any luck reversing the aquarium pump?
Does anybody know enough about brake boosters to convert them to run on pressure ( iknow wild)

[bennelson]

Reversing the aquarium pump was easy. I just pulled the little bit of paper off the bottom and goo-ed in a fitting designed to go onto the airline into the air intake on the pump.

The aquarium can only pull about 4 of whatever units is on the vacuum gauge. I would imagine the units is inches of mercury, right? It goes from zero to about 30.

[bbjsw10]

Originally Posted by bennelson

The aquarium can only pull about 4 of whatever units is on the vacuum gauge. I would imagine the units is inches of mercury, right? It goes from zero to about 30.

Yeah inches of mercury. And 4 inches is really low to try and use for brakes.

What about going to a junk yard and getting a convertible air pump and instead of hooking up pressure side. Put a fitting in intake side of that pump and use to vacuum air out of booster. I got one for $10 awhile back and it will put a hickey on your hand.

You would have to find a vacuum switch to shut it off though. I tried looking with no success.

[bennelson]

Well I ended up going to the auto parts store and just buying a replacement caliper unit.

It was $50 for the whole thing - brand new, and all put together.


I lubed up the new slidey bolts..


Then put together the piston and brackety thing, and installed the brake pads.

I tried bleeding the brakes with one of those hand pump vacuum things rented from the auto parts store. It didn't work very well.

Then I took the car out for a test drive. When I got back and opened the hood. I realized I left the brake fluid cap off! I couldn't find it anywhere! I biked back down the street looking of both sides trying to find it. (3 miles round trip!)

When I got back, I found it almost instantly, under the hood, where it slid way back behind the battery. At least I found it!!!

The brake was still leaking fluid and the pedal was soft. I had my wife pump the brakes while I was looking up under the car. The fluid was oozing out from around the banjo bolt. Turns out that there are two washers that come with the kit, which I put on the two bolts that come with the kit. That's not where they go. The two washers BOTH go on the banjo bolt which is NOT part of the kit.

Once I figured that out, I was able to pull all the bolts out and swap the washers around. This time, I had my wife pump the brakes while I bled them. Worked WAY better than the stupid hand vacuum pump and with two pushes of the pedal, there was no more air in the lines.

Now when I drove, the brake pedal felt nice and firm when pressing down.

Yea! Car is starting to get close to becoming something half-safe! Next, I installed a switch in the wire that runs power to run the controller. That way, I can turn the DC motor controller on and off from inside the car. Before, I was just disconnecting a spade connector directly on the controller under the hood.

I also rigged up my multimeter to sit inside the car and read the total battery pack voltage. No, it's not an ammeter, but seeing how voltage drops when under load is at least an indicator of power usage.

I went for a little test drive and everything seemed to work fine.

Then I got ambitious and decided it was time to head towards town, a few short miles - to the gas station!

Yes! I couldn't resist going straight to the gas station and NOT buying gas. Plus, this place was a car-wash too, and the car was dirty. I got the fanciest car wash I could that didn't include an "underbody blast"!.



Here I am NOT buying gas.



My baby all clean and shiney!

[Tango Charlie]

Originally Posted by bennelson

...Then I took the car out for a test drive. When I got back and opened the hood. I realized I left the brake fluid cap off! I couldn't find it anywhere! I biked back down the street looking of both sides trying to find it. (3 miles round trip!)

When I got back, I found it almost instantly, under the hood, where it slid way back behind the battery. At least I found it!!! ...

That's called a Reverse Hallucination. As you know, a regular hallucination is when you see something that's not really there. A reverse hallucination is when you don't see something that is there.
It's good to know I'm not the only one that has 'em.

That white rim is growing on me. Are you going to paint the others?

[Clev]

Ben.

Check the EVDL for specifics, but I know that many small diesel pickups, as well as some GM econocars from the 80's, had a vacuum pump you could drive with a 12V motor. Might be able to find those at your local junkyard. I don't think anybody has successfully built one from a compressor.

[bennelson]

Originally Posted by Tango Charlie

That white rim is growing on me. Are you going to paint the others?

Check all the angles of the car. One rim is white, one is blue, and two are rust.

I think the white one looks a lot like a boat trailer tire. Not so bad though. The best suggestion I have heard so far is to paint them a metallic graphite color.

Something that would match the color of the lettering on the back of the car could look really nice.

[MetroMPG]

OK, so Ben: you've ben driving around on 48v with a 300A limit, correct?

Have you been going in 2nd gear or 1st? (You said you don't have the shifter hooked up.) Any point in asking what you think of the performance?

[bbjsw10]

Originally Posted by Clev

I don't think anybody has successfully built one from a compressor.

That is all a vacuum pump is. A compressor pulling the air on intake side. A pump is a pump. If it will pump to 25psi it will vacuum to 25 psi. The only difference is the switch instead of psi it is inches of vacuum.

EDIT: Found a guide for making a vacuum pump for under $50 just replace that compressor with a convertible top compressor. And presto instant vacuum pump. Homemade Vacuum Pump

[johnmyster]

Shultz's "fulcrum move" (I also suggested it earlier) may be worth looking into. Sounds like it would be easy to source a vacuum pump, but a simple fulcrum move and brake pedal arm bend would keep the SIMPLE factor up, and the ELECTRICITY useage down. It's worth a shot, especially if your junkyard can source you a brake pedal assembly.