vacuum brake experinces

[shmed]

i did the change over and now im not sure if i should change back.
the brakes are alot harder to push on
they dont stop no where near as fast as the pm did
i cant get them to lock up at all no matter how hard i push.

how do the TA guys manage? did i miss something here?

 

[JACKH]

Something must be wrong... I switched a few years back and am very happy.

Did you use the vacuum brake pedal? Maybe the check valve is bad? What about your proportioning valve? Is it brass? I have a spare if you need it. Did you bleed it all really well?

Also, where did you get the parts from that you replaced everything from?

I have no problems with mine.. I can hold 10-11# boost at the line with the larger s-10 cylinders and still have great brakes at the end of the 1/4. I had to add an adjustable proportioning valve so that the rears would not lock up during normal driving.

Jack
Jack@Huisman.com

 

[shadow84]

hard pedal

you should recheck your installation? did you change the brake pedal to the correct one the right one for vacuum brakes has a different mounting point for the rod? also you should check that your booster isn't deffective!!!! (bad parts from a rebuilder no way!!)

i've been on vacuum brakes sinse jan with no hard pedal and they hold boost to 12 lbs.with stock cylinders shoes and aluminum drums

 

[shadow84]

booster test

engine off pump pedal several times till hard hold foot on pedal depressed start engine pedal should sink about an inch or so booster is good no sink bad booster

 

[John Larkin]

You can hold 12 psi. Now that's amazing; I can only hold 2. Shoes are adjusted all the way out, 3 clicks from locked up solid. The brakes themselves stop fine though the pedal feels like it goes a little deeper than the PM did. Shmed, I'm thinking your booster isn't up to par also.

 

[TR Custom Parts]

Vaccuum sucks! And that's a good thing. I would never go back to the PM. One less thing to worry about going wrong.

 

[shmed]

i used the pedal and booster out of the same car. 84 regal.
my prop valve is a brass one.
i bled it several times went thru 2 bottle of fluid.
i too have the s-10 rears

the rear shoes are new and the drums and all hardware
the fronts have new pads and calipers.

still have the original flex hoses though??

im lucky if i can hold 2-3 psi on the brake and thats with me pushing as hard as possible on the pedal.

ill go out and try the booster test and get back to you guys
thanks

 

[GNVAIR]

I converted mine over 2 years ago and have nothing but praise for it. It is phenominal the difference in power assist and the fact that I dont have to worry about all of the other things failing on the power master. I have held upwards of 10 lbs of boost on the foot brake.
Now another good point to mention is vacuum can vary depending where you tap in for the vacuum line to the boost. Never tap into the pcv line. To be honest, it should be tapped directly off the vacuum block.
Mine have gotten better since I installed the b body spindles and 12" rotors.

 

[Nick Micale]

Originally posted by GNVAIR
......Now another good point to mention is vacuum can vary depending where you tap in for the vacuum line to the boost. Never tap into the pcv line. To be honest, it should be tapped directly off the vacuum block.....

I have seen and heard this comment many times over the years and never understood why it was made?

Over 2 dozen vac conversions that I have done this way perform exactally like the many others I did changing the vac block. The measured value for vac is the same at a tap on the block or a few inches away where a tee would be inserted at the PCV.

As far as holding boost, it is a factor of the brakes shoes, drums, rotors, etc., NOT the type of power assist applied. If it does not hold boost after conversion, then air is in the system or something was not done properly.

 

[shmed]

i used the caspers aluminum block for the TTA.

tried the pedal test, about 2-3 pushes and it was hard.
the pedal sank a little once the car started. it didnt feel like an inch though

i have noticed the the brake lite will come on after using the brakes a few times or sometimes at start up.

the proportining valve is a brass one but its the same one i was using for the PM.

the master cylinder is from a 95 caprice remaned with the 1 7\8 plunger

 

[GNational86]

I converted my brakes two weeks ago and it is perfect. You might be running into a brake lining issue. It might take a while for those new drums and shoes to wear into each other. And you also put new pads on the front which will have to break in too. Just trying to throw some ideas at you.SeeYA Mike

 

[shmed]

thanks i better clarify a bit i did the swap beginning of the summer, thats when the pads and drums and shoes were also installed, i would hope to think there broke in now.
thanks again though
anyone else?

 

[GNVAIR]

Originally posted by Nick Micale
I have seen and heard this comment many times over the years and never understood why it was made?

Over 2 dozen vac conversions that I have done this way perform exactally like the many others I did changing the vac block. The measured value for vac is the same at a tap on the block or a few inches away where a tee would be inserted at the PCV.

As far as holding boost, it is a factor of the brakes shoes, drums, rotors, etc., NOT the type of power assist applied. If it does not hold boost after conversion, then air is in the system or something was not done properly.

Well Nick,
The main reason for this is that a leak in the pcv line could cause issues with crank case ventilation. Dont you think GM would have done the same thing on the TTA's rather than spending the money tooling up another vacuum block.
I am sure you will have a logical explanation, but I do remember on several other vehicles I have owned that tapping into pcv lines for power brakes caused some issues with operation of the brakes. Dont get all insulted, but I have used the TTA style block on all the cars I have done the way GM would have done it. Like I said, if GM could have save a few bucks, they would have tapped into the pcv line as well.

 

[shmed]

question, when i did the conversion, i used the pedal and the booster from a mid 80's gm, i used the MC from a 95 caprice.
could that little push rod be causing my problem?

 

[Chris Taylor]

I love my vacuum brakes.

The reason the vacuum block is used, is because of the ported vacuum. Using the vacuum block is the proper way to supply vacuum to the booster. Not the only way, but the proper way.

 

[GNVAIR]

As long as the pedal came from another vacuum brake equipt G body, you should be fine. I have an 86 Caprice master cylinder on mine because of the B body brakes (larger caliper pistons and 12" rotors)
You say you have a master cylinder from a 95 Caprice on there?
Do you have the B Body brakes or the stock brakes that came on your car?

 

[Red Regal T]

You said you were seeing a brake lite. I don't believe you should be seeing any lite. Maybe the master cylinder isn't up to snuff.

 

[shmed]

ya still using the stock brake set up.

maybe the master cylinder? is there any kind of test for that?

 

[GNVAIR]

The master cylinder could DEFINITELY do it.
The stock G body master cylinder bore is approximately 1"
The stock Caprice master cylinder is 1 1/8". You think 1/8" could make a difference? Trust me, it does as the calipers on the g body have smaller pistons than the ones on a B body. Try installing a stock replacement G body master cylinder (for vacuum brakes ofcourse) for the year of your particular car. I can almost guarantee that will solve your problem.

 

[shmed]

1\8 make a difference? i wouldnt think so, but ill trust ya on it.

question though, i woulda swore that i read on the turbo regal web site to get the master cylinder with the bigger bore?