vacuum vs powermaster

[Holdenbr]

My power master brakes had issues and I had zero brakes so after installing a new acumulator and still having issues I had vacuum brakes installed. That way at least if there are problems I will have something. I mean I had zero brakes when the powermaster went out. I would have had better luck throwing out a rock tied to a rope.
I haven't got to try them out since I am having other work done as well but what will they be like compared to normal power brakes. Also, will I have issues with vacuum since this is a turbo car?

 

[bison]

You won't have much if you lose the vacuum to the booster. A recent post revealed that a stalled car rolling down hill can get you in trouble really fast.


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[BEATAV8]

Yep it's all about having vacuum available. And a good quality valve to keep boost out of the brake diaphragm.

 

[robzombie]

P/M or hydro boost is still the better choice than any vac setup in my opinion in a boosted vehicle.

It was never offered with vac brakes for a reason.

BTW if the motor was still working than you probably only needed a pressure switch, unless the pedal was going to the floor that is.

 

[Nick Micale]

[QUOTE="robzombie, post: 3616607, member: 40932"....It was never offered with vac brakes for a reason.
...........[/QUOTE]

According to my technical contacts at GM in the 1980's there was a good reason the PM was used on the 1985 Regal station wagons and the 1986-7 turbo cars, and that was because management wanted an extensive field test of the PM system on a limited run of production vehicles.

The electric-hydraulic pump concept was to be the GM/Bosch first production version of an ABS which was to be introduced in a couple years on a few million cars and lots was at stake.

The 1989 Cadillac, and others GM's, had an ABS brake system and the heart of it is a PM electric pump/master cylinder.

GM and other manufactures used vacuum brakes on millions of turbo vehicles in the 1980s' and beyond with great success!

The big issue with a PM is not "will it fail', but "when it will fail"?

A PM failure will require as much, or more, foot pressure to stop the vehicle as a vacuum system.

 

[BEATAV8]

If the powermaster is kept clean and the owner pays attention to it, it will work great for years and years. But not many people pay any attention to it at all.

 

[whitehot1]

I've had both brake systems fail on a turbo regal ( PM, and Vacuum ) The cause of failure on the vacuum system was the little plastic one way check valve that goes directly to / on the brake booster i think that was just a defect valve.But i was still able to stop the car by applying more pressure to the brake pedal. Trying to stop the car with the PM failure was almost impossible pushing on the brake pedal was like pushing on the floorboard of the car, it happened twice on different cars. I was lucky no cars or anything was in front of me when it happened,it would not have turned out good.

I have done the vacuum brake conversion on a few turbo regals without any regrets on doing so. Best brake system for the money. And years of trouble free service / maintenance.

Here is a link for the vacuum brake system conversion if you should decide it is for you.

http://www.gnttype.org/techarea/brakes/Powermaster_to_vacuum.html

 

[TurboDave]

If the powermaster is kept clean and the owner pays attention to it, it will work great for years and years. But not many people pay any attention to it at all.

Very true!!! Unfortunately for the PM system in it's early years none of the Turbo Regal owners back then understood it at all, and like most other braking systems it was neglected and never received ANY attention or maintenance. They were doomed to fail just from ignorance and neglect.
The original accumulators and pressure switches were a weak link, yes. The switches were recalled and replaced, and eventually the newer accumulators (with the yellow ring, and wrench nut attached) were ever more dismal failures. But with proper maintenance even they lasted for several years.
Now we have the latest version of accumulators (the big ones) that vendors like Kirban sell, and it has proven to be a great piece! I haven't heard of a single failure since their inception quite a few years ago.

One of the simplest methods of maintenance that can help the PM live trouble free is a twice a year fluid change. It doesn't have to be more than simply sucking the old fluid out of the reservoir, cleaning it out with lint free rags and re-filling with fresh fluid. You need not go to all the trouble of bleeding out the entire system (unless of course you're a glutton for punishment).

Oh, I'm sure there will be occasional failures, even with the best of intentions. But like ANY mechanical device, things can happen.

Boy! if some of you guys knew what kind of braking and steering systems are being built into many modern day cars you'd probably never buy a new car again!

 

[pacecarta]

P/M or hydro boost is still the better choice than any vac setup in my opinion in a boosted vehicle.

It was never offered with vac brakes for a reason.
.

the reason wasnt that vacuum wouldnt work but more because they needed a place to test out the pm in a vehicle that was low production in case they had issues ..well they did
in 89 gm didnt repeat their same mistake ..they built the 89 TTA..with the lc2 motor and the brake system was ...vacuum ..and it worked just fine

 

[BEATAV8]

Also in 89 there were lots and lots of cars getting the powermaster III system. Regal, cutlass, Chevy. By then I guess it was a bit more dialed in.

 

[robzombie]

[QUOTE="robzombie, post: 3616607, member: 40932"....It was never offered with vac brakes for a reason.
...........

According to my technical contacts at GM in the 1980's there was a good reason the PM was used on the 1985 Regal station wagons and the 1986-7 turbo cars, and that was because management wanted an extensive field test of the PM system on a limited run of production vehicles.

The electric-hydraulic pump concept was to be the GM/Bosch first production version of an ABS which was to be introduced in a couple years on a few million cars and lots was at stake.

The 1989 Cadillac, and others GM's, had an ABS brake system and the heart of it is a PM electric pump/master cylinder.

GM and other manufactures used vacuum brakes on millions of turbo vehicles in the 1980s' and beyond with great success!

The big issue with a PM is not "will it fail', but "when it will fail"?

A PM failure will require as much, or more, foot pressure to stop the vehicle as a vacuum system.[/QUOTE]


The reasons you stated may be true but I still say that it [the PM] is a better system than a vac system in a boosted application. I've used both and the vac system comes up short in my book, but that is just my opinion.

Hydro boost is the best alternative if you plan on keeping the P/S which most don't in race applications [not street cars] and is more trouble free than the P/M.

If I ever ditched the P/M I would go to H/B for reliability as the only issues I ever had with that system were leaks due to blown seals in the M/C.

All systems will fail and the P/M gets a bad rap in this department. Like said TURBO DAVE there are now replacement parts available that make it almost bullet proof.

I'm still on the original motor and M/C as far as I can tell and only the switch and ball have been replaced, [by me]. I'd say that 28 years out of anything is pretty damn good. Especially since it was basically a prototype for early ABS systems according to Nick's buddy's.

 

[bison]

the reason wasnt that vacuum wouldnt work but more because they needed a place to test out the pm in a vehicle that was low production in case they had issues ..well they did
in 89 gm didnt repeat their same mistake ..they built the 89 TTA..with the lc2 motor and the brake system was ...vacuum ..and it worked just fine

They continued using the powermaster in other models as Nick stated. A more resilient design was used from 88 on.


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[Nick Micale]

Actually Rob, my preference over the PM, vacuum and hydro-boost is what I have on my race car - good old manual brakes with only foot-power assist, and Baer disks all around!

It is more reliable than any of them, and also has the best stopping power of all my Regals.

 

[1986 Buick GX1]

The "more resilient" PM III was used on the '89 and '90 Pontiac Turbo Grand Prix and according to the guys on the W- body forum they still sucked, still with no available replacement parts.

 

[robzombie]

Actually Rob, my preference over the PM, vacuum and hydro-boost is what I have on my race car - good old manual brakes with only foot-power assist, and Baer disks all around!

It is more reliable than any of them, and also has the best stopping power of all my Regals.

Sorry Nick, that doesn't count! I did point out that race cars are a different story.

If I had aftermarket brakes and a H/B or P/M I would have more stopping power than you do with a manual setup or at least less leg effort for same stopping power.
Apples and oranges comparisons don't count in this case as the OP is talking about factory parts and or interchange ability as I read it but I could be wrong.

I am glad that you are happy with your Baer setup and yes they make quality products. We should all upgrade the brake systems on our cars when we reach HP levels that were never intended to be in these chassis's on the street let alone track use.

 

[Nick Micale]

Sorry Nick, that doesn't count! I did point out that race cars are a different story.

I am glad that you are happy with your Baer setup and yes they make quality products. We should all upgrade the brake systems on our cars when we reach HP levels that were never intended to be in these chassis's on the street let alone track use.

Rob, I was somewhat, pulling your chain, but the race car is street legal with current registration and insurance, but not many creature comforts except for a muffler!

 

[robzombie]

Nick, I somewhat was doing the same. LOL

 

[BEATAV8]

I want to upgrade my disks and calipers.... want want want... Lol

 

[87-WE2]

I swapped my PM for vacuum. It works great. There's a video I posted on a thread here of it holding 12 psi on the foot brake. They do the job.

Hydroboost are also great. I have them on my two diesel pickups. The 2012's brakes are truly awesome. During a panic stop from 70 mph, you better be wearing sunglasses or your eyeballs will hit the windshield. I wish I had a carbon copy of this system on all of my vehicles. However, they are not without their issues either. My 2004's booster is failing and due for a replacement after 12 years of reliable service.


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