Connecting the Vacuum Pump

I have a small reservoir that I made out of PVC pipe with end caps and PVC glue. I drilled and threaded the holes and then installed the pipe fittings with teflon tape. My pump initially takes 20 seconds to evacuate my little reservoir at which point it shuts off. I get two brake applications and then the pump comes on again and shuts off in about 12 seconds. I gave it a leak down test and it came on again 12 minutes later so I know I too have a leak. It should hold vacuum indefinitely...right?..or at least longer than 12 minutes. I suspect that my leak is occuring at the teflon tape on the fittings because I am using new booster hose and "full circle" clamps that are on very tight. I also have two new check valves I installed but still same problem. Im thinking that I may get rid of the teflon tape and use epoxy to seal the fittings to see if this helps. How did you affix the brass fittings to your reservoir Kiwi?
BTW...how to do you post the pics within the text like you do?...mine show up as thumbnails.

On a side note people...you want to use real brake booster hose. It has a thicker wall so it will not collapse under vacuum and adversely affect your brakes.

You're not a post-whore? Oh go on, admit it! You can't resist it!
LOL

Ok, I covered everything in PVC cement glue stuff and now it's going fine. I pressed the brake, got the vacuum pump motor going, waited for it to reach vacuum, then timed how long before the motor kicked in again.

Thirty minutes later I got sick of waiting. I guess that means the leaks are gone!
Here's a picture in glorious full size.


You can see the master cylinder (bottom right), the vacuum canister (behind the front grille) and the vacuum pump (in the black box behind the left headlight).
I fear my vacuum tank isn't big enough though as whenever I put my foot hard down, the motor kicks in. If I press the brake lightly it's ok but realistically the motor's going to kick is fairly often. I don't have room for a bigger canister yet either.

I'm proud of the way the vacuum pump is tucked away in a box. It brings the noise level of that little pump down HEAPS! It's a quiet little thing now.

Maybe later I'll install a large mega-tank behind the lower front grille. Still, it's one thing done off my list!

P.S. Maybe your images are too big so they automatically get thumbnailed? I reduce all my pics to 640x480.

mattW said:

why do cars use a vacuum for brake assist and not pressure?

Click to expand...

Mostly because vacuum is a readily available resource that all gasoline engine develop without additional equipment. It’s drop-dead simple and very cheap to implement.

The vacuum servo (booster) on a power brake system is a fairly simple device which places vacuum on both sides of a diaphragm when the brakes are at rest. When you press the pedal, atmospheric pressure is allowed to enter one side of the diaphragm, allowing the vacuum on the other to "suck" the diaphragm (and the master cylinder push rod) in, assisting in applying the brakes.

Vacuum assist has been around so long that it's become the default for brake servos, even in diesel vehicles which need a mechanical pump driven from the crankshaft to develop vacuum.

Systems exist that do use other power sources, notably some that activate ABS brakes, but the vacuum servo is cheap and simple, and will likely be with us as long as there are throttle plates in ICE engines.

Kiwiev, thank you for the info. I have heard that the Thomas vacume pumps are very loud. I'll keep watching ebay until I find a quieter pump.
I found the 5K throttles on two ele sites. around 80.00 each thats about 60.00 more then they are worth but I'll buy 2 anyway. Hows the weather down your way? We were getting hit with storm after storm for a while there-until people actually called into the alternate media and told of the tanker planes -seeding the air were spotted off the coast of the western USA by more then one person--then all the sudden the weather got better. (www.infowars.com has the weather modification story if your intrested) Now we are having nice weather here in the northern area of Idaho just 30 or so miles so of the Canadian border. They chemtrailed today so we will have to stay at home tomorrow, (as I have 3 hepa filters in my home) -otherwise its nice here as we have mountians all around us! Its like living in Alaska again. Nothing like snow caped mountians to cheer you up. Are you in the USA or Aus?
neogeogray