Vacuum brakes conversion

[8AV8]

The pressure when you apply brakes goes to the front brakes thru one line, the rear brakes thru another. While pushing the brakes you hit the LL switch which locks the pressure into the front brakes ( you actually cut into the front brake line to install the LL solenoid ). Since there is no solenoid cut into the rear lines, the rear brakes release when you let off of the brake pedal.

Its kinda like you pinch the front line while there is pressure in it with a switch.

Its easier to burnout because there is no brake pressure on the rears at all.

Clear as mud?

I don't recall the wiring. I used the Hurst LL with the Hurst install kit and had everything I needed for the job, except the double flare tool. You can bend the lines (SLOWLY) by hand and when you get them like you want them, take the lines to any mechanic and let him flare your ends.

If you really want to hold boost for racing, adjust the rear shoes out tight and have a rough turn cut on them.

 

[MIB]

FWIW. I still will not convert my VB car back to PM or HB. I think every car is different. I have a lumpy solid roller, big motor and a large turbo on my 9 sec street car. I do have wilwoods on the front and 11" drums in the rear. Like I said before it stops very well even with the skinnies. I do have a brake proportioning valve installed in the floor of the car so that I can adjust the front to rear bias. I have the utmost confidence that my car will stop in a hurry. It stops like a race car should, in a hurry. I would love to try a HB but why spend the extra cash and change my set-up that works, unless it's free .

 

[jdpolzin]

I have the LL solenoid installed already. So, basically you do let off the brakes afte pressing the LL button?? Otherwise the pressure will still be at the rear wheels.

 

[8AV8]

I have the LL solenoid installed already. So, basically you do let off the brakes afte pressing the LL button?? Otherwise the pressure will still be at the rear wheels.

yep...if you got it on check it out.

 

[TURBOPOWERED68]

Makes me think about that vacuum conversion again.....

Jim

I wanted to skip the Vac. brakes and got to HB.

1-But you loose an electric motor and you are toast Example GNX #258
2-I lost my acc. belt on the astro and at once lost the Steering and brakes.
3-now Vac. in my opinion don't belong in a forced induction car.
No Vac. no Brakes.

It’s a tuff call
Chose your poison.

 

[Robbie-87plz]

Out of those three, I know that the HB offers a reserve. Does the other two have such a reserve, for a last ditch effort in stopping the car?

 

[zeus87gn]

Out of those three, I know that the HB offers a reserve. Does the other two have such a reserve, for a last ditch effort in stopping the car?

With the PowerMaster, you have 9-10 more times you can press the pedal and still have power once the unit malfunctions. Problem is that you don't know when the unit malfunctions except for the brake light (if it works) and by that time you only have about 5 pedal presses left. Not much warning, but it's better than nothing. Unfortunately inherent to the design.

 

[TURBOPOWERED68]

Out of those three, I know that the HB offers a reserve. Does the other two have such a reserve, for a last ditch effort in stopping the car?

My astro is a 1995
may be a newer design.

i felt the belt go and my wheel got rock hard then i pressed the brakes and it felt worst with no reserve nothing just a stiff pedal i was lucky i don't tailgate because if i did it would not have been pretty.
Remember this is what happened to me in my Van.

 

[Robbie-87plz]

I've lost my powermaster and it happened at 50 mph. Good thing I wasn't tailgating either. That made me go to vacuum, with that, I could be boosting then hit the brakes, made me a better driver I guess.

With my Cobra, it has a reserve accumulator, which stores the aforementioned 70% initial reserve pressure. Did your Astro van have the reserve accumulator?