what is dif. between stock brake system and vacuum
- Thread starter bryguy
- Start date
blackbuick87
Senior Member
- Joined
- Mar 11, 2002
One uses engine vacuum to produce power for the brakes, the other is strictly hydraulic and uses a pump and motor.
Wide range of opinions on which is better
Wide range of opinions on which is better
Red Regal T
Senior Member
- Joined
- May 24, 2001
I'D SAY IT'S 100 TO 1 IN FAVOR OF VACUUM. YOU HAVE THE PEOPLE WHO WILL SPARE NO EXPENSE AND EFFORT TO HAVE A POWERMASTER..... AND THE PEOPLE WHO HAVE VACUUM...........AND FORGET ABOUT IT! 
The Reject
New Member
- Joined
- Dec 17, 2002
How much does it cost to convert to vacuum?
blackbuick87
Senior Member
- Joined
- Mar 11, 2002
I dont know John, I have heard a lot of complaints about not being able to build as much boost after the conversion.
I dont think you are in to drag racing a lot, but for someone that is it makes a big difference.
I am not for or against it because I have not tried vacuum. Just letting the original poster know it is not all heaven
For a daily driver it seems like the way to go to me though
I dont think you are in to drag racing a lot, but for someone that is it makes a big difference.
I am not for or against it because I have not tried vacuum. Just letting the original poster know it is not all heaven
For a daily driver it seems like the way to go to me though
Red Regal T
Senior Member
- Joined
- May 24, 2001
I SELL EVERYTHING YOU NEED FOR $100.
DRAGRACING AT THE STRIP WHERE THE NEED TO BUILD 8 TO 10 LBS OF BOOST AT THE LINE, CAN BE HANDLED BY ANYONE THAT WANTS TO, WITH VACUUM BRAKES. HOWEVER, IT'S TRUE, PERSONALLY I DON'T REALLY CARE THAT MUCH ABOUT THE ABILITY TO BUILD 10 LBS OF BOOST AT THE STARTING LINE.
I'M REALLY ADDRESSING THIS FROM A "COST" POINT OF VIEW. EVENTUALLY, ALL TRs WILL HAVE VACUUM BRAKES. I THINK MY ESTIMATE OF 100 TO 1 IN FAVOR OF VACUUM BRAKES IS REALLY CONSERVATIVE.BoostedBug
Contents Under Pressure
- Joined
- Oct 1, 2002
I know of one that won't ever have them...I have 2 more spare Powermaster Units on the way and I am stock pileing parts everyday for them. I like how they work and the uniqueness of having them. We all know the vacuum brakes work great but why be common?
I bought my Limited as I did not want a run of the mill car. These cars are unique and i want to keep mine that way.
My buddy Mike McCoy offered to send me a complete vacuum setupto me for some work I am doing for him. I asked him to just send me a powermaster unit instead.
Do have a question though on the vacuum brakes....How well do they work when you are under boost conditions? How about if the motor stalls?
I bought my Limited as I did not want a run of the mill car. These cars are unique and i want to keep mine that way.
My buddy Mike McCoy offered to send me a complete vacuum setupto me for some work I am doing for him. I asked him to just send me a powermaster unit instead.
Do have a question though on the vacuum brakes....How well do they work when you are under boost conditions? How about if the motor stalls?
BoostedBug
Contents Under Pressure
- Joined
- Oct 1, 2002
What I was getting at was with the powermaster setup if the motor shut off and you still had power form the battery you still had your normal brakes.
Vacuum Can
There was a post recently where someone was attempting to plumb in a vacuum canister... store a little more vacuum... to increase the overall capacity. I wonder if this would overcome the reported problems of power braking at the line under boost? (With no other changes?)
NOTE: Some PowerMaster users complain about holding the cars at the line as well.
Alternatively, vacuum pumps can be added. (Although you are now approaching the cost of a remanufactured PM unit at this point.)
Back to the topic:
I've never had a PowerMaster (PM) last longer than 3 years. I've always used the GM factory PM replacement units at $700-800 a pop! I have never had much luck with them. When they fail, it can be sudden and scary. The best one I had was the original and it was the only one that lit up the brake light and gave me a warning before it died.
Vacuum brake boosters can fail suddenly as well. A simple check-valve leak or a line popping off under boost can kill the power assist. Just make sure all related vacuum lines are clamped, and service the check valve and lines on a regular schedule. They are cheap!
On the other hand, many on the board swear by the PM, so it is not all one sided. However, many are reluctantly realizing that the PM's are getting very expensive to maintain. It is now at the point where it is less expensive to replace the entire unit using with one from AutoZone/Cardon than it is to replace the 2 most failure-prone parts: Accumulator and Switch! I can't see this deal as lasting forever, either.
Bottom line is, the vacuum brake setup is (Arguably) the best daily driver system. It is a more reliable, simple, costs less to maintain, it does work in turbocharged systems, and in my experience, the braking performance has improved since I did the conversion.
I, personally, would be happy to see that vacuum booster under the hood of that 86! Replacing the brake pedal is a bitch! If you can, have the old powermaster provided in a box. They might be worth something to the collector in about 15 years!
There was a post recently where someone was attempting to plumb in a vacuum canister... store a little more vacuum... to increase the overall capacity. I wonder if this would overcome the reported problems of power braking at the line under boost? (With no other changes?)
NOTE: Some PowerMaster users complain about holding the cars at the line as well.
Alternatively, vacuum pumps can be added. (Although you are now approaching the cost of a remanufactured PM unit at this point.)
Back to the topic:
I've never had a PowerMaster (PM) last longer than 3 years. I've always used the GM factory PM replacement units at $700-800 a pop! I have never had much luck with them. When they fail, it can be sudden and scary. The best one I had was the original and it was the only one that lit up the brake light and gave me a warning before it died.
Vacuum brake boosters can fail suddenly as well. A simple check-valve leak or a line popping off under boost can kill the power assist. Just make sure all related vacuum lines are clamped, and service the check valve and lines on a regular schedule. They are cheap!
On the other hand, many on the board swear by the PM, so it is not all one sided. However, many are reluctantly realizing that the PM's are getting very expensive to maintain. It is now at the point where it is less expensive to replace the entire unit using with one from AutoZone/Cardon than it is to replace the 2 most failure-prone parts: Accumulator and Switch! I can't see this deal as lasting forever, either.
Bottom line is, the vacuum brake setup is (Arguably) the best daily driver system. It is a more reliable, simple, costs less to maintain, it does work in turbocharged systems, and in my experience, the braking performance has improved since I did the conversion.
I, personally, would be happy to see that vacuum booster under the hood of that 86! Replacing the brake pedal is a bitch! If you can, have the old powermaster provided in a box. They might be worth something to the collector in about 15 years!
BoostedBug
Contents Under Pressure
- Joined
- Oct 1, 2002
Or you can sell it to me now! I wonder why GM didn't put the vacuum brakes on these cars from the start?
On to how long they last...Ask Hyper on this board, He has had his from 88 with the same Powermaster on it, new accumilator but the same powermaster....
On to how long they last...Ask Hyper on this board, He has had his from 88 with the same Powermaster on it, new accumilator but the same powermaster....
Powermaster systems are trick, unique, and work regardless of manifold vacuum or pressure. These are self-sustaining systems and you have full power assisted brakes with the engine off and the key on! (As long as the battery has enough juice!) If I thought they were reliable, I would still have one on my car!
I am toying with the idea of following up with someone elses idea regarding adding a vacuum canister to store vacuum. This, in theory, would store enough vacuum for several brake applications even if the engine stalled or was under boost. It all depends on how well the check-valve and vacuum diaphram in the booster maintains the seal.
My current setup gives me one assisted brake application after I shut the car off. (Within 30 seconds). I have tested from a 10 PSI blast to a panic stop... No worries, I can lock them up if I want! Others have complained about this panic situation, but I have to believe that if this does not work, the check valve or the grommet that it presses into is leaking under boost and allowing the vacuum to bleed of too quickly (or pressurizing the brake booster)
The engine should also be capable of generating a 16 to 18 in/hg vacuum signal. Camshafts play a big part in this! If you have a cam with increased overlap, you either need a PM or a vacuum pump.
I am toying with the idea of following up with someone elses idea regarding adding a vacuum canister to store vacuum. This, in theory, would store enough vacuum for several brake applications even if the engine stalled or was under boost. It all depends on how well the check-valve and vacuum diaphram in the booster maintains the seal.
My current setup gives me one assisted brake application after I shut the car off. (Within 30 seconds). I have tested from a 10 PSI blast to a panic stop... No worries, I can lock them up if I want! Others have complained about this panic situation, but I have to believe that if this does not work, the check valve or the grommet that it presses into is leaking under boost and allowing the vacuum to bleed of too quickly (or pressurizing the brake booster)
The engine should also be capable of generating a 16 to 18 in/hg vacuum signal. Camshafts play a big part in this! If you have a cam with increased overlap, you either need a PM or a vacuum pump.
Red Regal T
Senior Member
- Joined
- May 24, 2001
AS LONG AS POWERMASTERS ARE WORKING, THEY WORK GREAT. MINE LASTED FOR FOUR YEARS AFTER PURCHASING MY RED T IN 1998. PROBLEM ARISES WHEN THEY MALFUNCTION. IMHO, THEY COST TOO MUCH TO FIX. GM PROBABLY DIDN'T WANT TO WARRANTY THEM ANYMORE AND WENT TO VACUUM ON THE TTA.
BLACK6PACK
1 sec reaction King
- Joined
- May 24, 2001
I had to replace the original PM on my car when it hit 200,000 miles and was 12 years old. The OEM unit on my car is now 4 years old and works fine.
I like the PM and my car is only driven to cruise-ins and the track, so it isn't a daily driver.
I like the PM and my car is only driven to cruise-ins and the track, so it isn't a daily driver.
granitestategn
Gettin' there
- Joined
- Jul 30, 2002
I bought my GN new off the dealer's lot in late 87. Didn't have a problem with it until 98. Accumulator crapped out. Put a new one in from the dealer for $105. That fixed the problem until last year when the Powermaster motor started going. Bad part is, when they fail, you're screwed! Mine was blowing fuses a lot. I switched to vacuum and have not had any problems. I used a reman. master cylinder and a new dual diaphragm booster. The biggest pain was getting the pedal from a salvage yard. I have not had ANY experiences yet where the vacuum brakes did not work reliably to stop the car. Having driven cars with the vacuum power brakes discharged (while flat towing, engine off) and having driven a GN with a dead Powermaster, it seems like it was a LOT harder to stop the GN. Does anyone know the relative size of the pistons in the Powermaster master cylinder and the size of the piston in a vacuum brake master cylinder? Maybe that has something to do with it.
turbofrank
Well-Known Member
- Joined
- Nov 4, 2002
PM all you need is to have a failure at the wrong time. I had two. One in front of a dealer and the other taking the car to have trans repaired . the third time switched over no more standing on the pedal and not looking back.BoostedBug
Contents Under Pressure
- Joined
- Oct 1, 2002
Everyone change over to vac brakes...Sell me you powermaster units!
BoostedBug
Contents Under Pressure
- Joined
- Oct 1, 2002
Seeing how that ol powermaster was just something to worry about I will give you $35 and pay shipping on it....Let me know...
