HELP ME - Stock Brakes vs Vacuum, Why switch?

[GNregistry]

I would like to know why the vacuum brakes are better vs stock GN brakes?

I have brake problems and purchased Vacuum system.

Why do people switch and what modifications, pro's, con's of switching and what has to be done to replace vaccuum, I will not be doing it myself, but wondered is it small job, not sure how to explain what I don't understand.

I mean Buick choose the stock version of brakes for a reason... and vendors offer vacuum style. What work is needed? How much time is needed? How easy or difficult is it to replace stock brakes to vacuum brakes, and then if used while racing, what are the drawbacks, if any...

I hear the push for installing vacuum brakes...
Now I want to understand, is there a information out there to explain how it works and what is needed to convert...

Also, interested in new exhaust, stock dimensions, who has the best cat back exhaust, stainless steel vs aluminized, would like to install one time.

Using stock ideas, with TA49 turbo, for dependable street driver maxed to the limit... with out pushing engine into ground...

Brett
GNregistry@aol.com
920.279.5466

 

[BlackMetal]

The PowerMaster is an electrical motor used for brake assist and when the PM motor gets old or fluid leaks down into the motor, the 30amp fuse blows, and you'll be standing on the brake pedal with both feet trying to stop the car. When the fuse blows, you have zero brake assist, and your brake pedal feels like a rock. The high pressure accumulators also fail over time, which is usually when you'll see your red "brake" light start flickering on the dash, and before you know it you'll go rolling through a stop sign.

Remember that they went with vacuum brakes on the TTA cars, so ask yourself why they did that. Yes, they went with PowerMasters on the GNs for a reason, because it provides a lot of brake assist to stop a fast, heavy car, but for some reason they didn't continue it with the TTA. Maybe they already knew about the issues people would experience with a PowerMaster.

That's really the only reason. The PowerMaster provides decent brake assist and doesn' involve the hassle of more vacuum lines and check valves for a vacuum system, or a bunch of extra lines for a HydroBoost system, BUT the huge downside is that they fail unpredictably. 99% of the time that's why guys are converting their brakes.

I haven't installed a vacuum kit but it's pretty well known that the hardest part about the install is switching the brake pedal assembly. You can't use the PowerMaster pedal. So you have to lay upside down under the dash and break your back to change out the pedal. Some people suggest removing the driver's seat so you have more room to position yourself down there.

 

[GNVYUS 1]

I will do the best I can in a short amount of time.

The Powermaster when working is great, tons of line pressure and gets the job done.

If and when the Powermaster has an issue, you are dead in the water without any pedal to stop the car. At least with Vacuum there is some left in the booster to stop your car, failsafe goes to Vacuum.

Buying parts etc for the Powermaster is getting really expensive. Cost goes to Vacuum

Pontiac didn't use the Powermaster on the TTA ( GN motor ) and I wouldn't doubt their legal team and engineers had something to say about it.

There is a link on Turbo Regal Web Site with an install how to.

I personally don't think it's as cake of a job as others claim it is. I actually thought it was one of more frustrating jobs, maybe because it didn't add any power so my patience short to begin with.

 

[turbofish38]

The number one reason for upgrading to vacuum would be because of the lack of replacement parts to fix the current PM. What parts that are still available are super expensive. Most of us cut our losses from the get go. Dollar for dollar the vacuum is dead nuts relaible compared to the PM or hydraboost system.

Personally I think if you can bleed the brakes on a car than you can do the swap. Most of it is just time consuming parts R&R'ing anyway.

 

[turbo nasty]

Frekin price of the PM switches, pump motor, and accumlator could get you 3 vac conversions.
I did the swap and my pedal feel is higher and more trustworthy than the PM.

I can hold the exact same boost at the line as with the PM .....Im staying with it. Yeah the TTA has it so nobody can say a thing about Hydroboost and PM

 

[POWERBRAKEBOB]

Hydroboost Vs Vacuum Vs Powermaster

The Hydroboost unit bolts right on the firewall, and uses the same pedal as the P/M. Vacuum boosters need vacuum to work. They are rated to work with 20" of vacuum. A 231 engine with an overdrive trans produces little vacuum by itself, much less with a turbo. When the vacuum goes down from 20" to 15", the brake pressure drops by 1/2. When the vacuum drops to 10", there is little power brake assist, because the pedal ratio is not the same as a manual brake pedal. Disc brakes need 1200psi to work properly. The vacuum booster with low vacuum produces maybe 600psi.The Hydroboost needs no vacuum, because it runs off of the power steering pump pressure. At idle pump speed, the hydroboost will produce up to 2000psi to the calipers, with a great pedal feel. They can last up to 200,000 miles. Read hydroboost?....in the other posts.

 

[turbofish38]

Vacuum boosters need vacuum to work. They are rated to work with 20" of vacuum. A 231 engine with an overdrive trans produces little vacuum by itself, much less with a turbo. When the vacuum goes down from 20" to 15", the brake pressure drops by 1/2.

Where are you getting your figures from? Typical misinformation. First off we aren't talking about single diaphragm boosters here. This is the very reason for the advent of the dual diaphragm booster which 99.9% of us use. Those are tested at 15 inches. Second I dare you to tell me, better yet prove to me that my car has no brake assist at .001 inches of vacuum pressure let only 10,15 or 20 inches. Hey here's an idea for you. Why don't you buy a TR. Install a vacuum booster and provide us with some real life data. I'll put my GN on the line to back up my statements. What have you got to back up yours?


So what if the vacuum booster wont function under boost. How many of us drive with both feet on the pedal? All of the time? I've said it a few times. All you need to do is back off the gas,or close the throttle blade for a split second to bring the vacuum back up and every thing is normal.

 

[8AV8]

The Hydroboost unit bolts right on the firewall, and uses the same pedal as the P/M. Vacuum boosters need vacuum to work. They are rated to work with 20" of vacuum. A 231 engine with an overdrive trans produces little vacuum by itself, much less with a turbo. When the vacuum goes down from 20" to 15", the brake pressure drops by 1/2. When the vacuum drops to 10", there is little power brake assist, because the pedal ratio is not the same as a manual brake pedal. Disc brakes need 1200psi to work properly. The vacuum booster with low vacuum produces maybe 600psi.The Hydroboost needs no vacuum, because it runs off of the power steering pump pressure. At idle pump speed, the hydroboost will produce up to 2000psi to the calipers, with a great pedal feel. They can last up to 200,000 miles. Read hydroboost?....in the other posts.

You said"A 231 engine with an overdrive trans produces little vacuum by itself, much less with a turbo."


I know you are obviously an expert...so perhaps you can help me...I have vac brakes...

How is it that I can hold 12lbs of boost anywhere I want to?

And manage to stop the car on a track after running 125 mph...?

Perhaps I have MAGIC brakes...PM...Power Magic:biggrin:


If I bought your product could I stop better?

 

[turbo nasty]

He always says the same thing and the HB may work awesome....BUT

the TTA had vac brakes from the factory with the the 3.8 liter turbo/ GN motor.

Why did GM use such a unsafe setup on the TTA which shares the same engine as the GN??

 

[8AV8]

He said on one of these threads that it is because GM ran out of powermasters...I don't know though That would mean that there weren't any for warranty issues that may have come up.

Maybe GM just counted wrong....:biggrin:

I know my vacs work just fine. If you don't know how to launch one of these cars it doesn't matter what kind of brakes you have.

I even offered him and oppurtunity to use my car as the guinea pig for a test...

 

[Roger]

I tried the vacuum conversion. I hve friends with TRs that say they have no issues with vacuum. I had way too many issues with vacuum & wwent back to PM which I managed to get with a lifetime warranty, however, I was loosing patience having to use the warranty - not with the vendor (I find under dash work to not be appealing.

My vacuum conversion was based entirely on $ & the above mentioned Trans Am, however, I never located a TA vacuum 1 way valve & with all I tried I still continued to blow out the booster bellows. I believe Buick was prone to spend more $ than Pontiac. Still doesn't answer the question - why pm change from 85 hydroboost.

I'm happy with my upgrade/downgrade to 85 hydroboost.:smile:

 

[zeus87gn]

Brett,
I know this thread is a little old, but if I may offer my opinion...
Vacuum brakes are not an upgrade from a properly functioning PowerMaster.

It is impossible to make a vacuum system react faster than than P/M.
It has over 600psi ready the instant you touch the pedal.
A vacuum system has to build this pressure from vacuum (negative pressure).

The P/M has more reserve in the acc ball than a vacuum booster. Your typical vacuum booster (in excellent condition) has maybe 3 power assists left once you remove the vacuum (it's source of power). The P/M acc has at least 8, sometimes 9 power assists once power (electricity) is removed.

The problems (many previously stated) with the P/M are that they are high maintanence, expensive and difficult to diagnose.
GM also didn't give the warning light enough thought - but at least you have that.

I believe the root cause of the P/M problems are people (including the d@mn GM engineers who designed the thing) not knowing how to properly care for the P/M. GM never published a mantanence schedule, much less an installation and setup procedure (that I know of) and most likely mever gave it any thought that these cars would still be on the road so long after production.

If it matters, vacuum systems fail too.
I will agree that they are cheaper, but the P/M is my first choice.


Bob,
When are you going to become a proper vendor for this site?

 

[Roger]

I switched many years ago - $$$$, however, I had too many issues with the vacuum.

I went back to pm when they were available for $150, however, I'm pleased with the hydroboost. Hydroboost is expensive, but, no issues since the switch.

 

[mscalc]

My Vacuum Conversion kit should arrive on Monday. I am planning to install it next weekend. If you want to practice you can come put mine on:smile:

 

[tzque]

I swithced to vacuum and I have not looked back . My powermaster failed and I never wanted to test the waters again . I later found out it was a lack of regular brake maintence by the previous owner but I am not going back
Good luck on your conversion

 

[josefigue]

Dual Diaphragram Booster

To Mr.Eric Fisher:

Hi:In which donor car I can find a dual diaphgram booster for vacuum conversion?
Thanks

 

[Nick Micale]

He always says the same thing and the HB may work awesome....BUT

the TTA had vac brakes from the factory with the the 3.8 liter turbo/ GN motor.

Why did GM use such a unsafe setup on the TTA which shares the same engine as the GN??

Back in the late '80's I had a good working relationship with many of the engineers at the GM Proving Ground here in Mesa, AZ. These guys were doing evaluation and testing on the turbo [and supercharged] Buicks.

An obvious question was "why the Powermaster on these cars"? Their response was GM wanted to field test the electro-hydraulic brake assist on a limited run of production cars. The '86-87 turbo cars and some Buick station wagons fit this requirement.

The Powermaster was the fore-runner of GM's first ABS system, and the 1989 Cadillac has an ABS unit that looks just like the PM.

This is my "story", and I am sticking with it!:biggrin: