Attn vaccum brakes users

[turbobuickman]

If you run vaccum brakes, make sure you put clamps on ALL the vaccum lines! Today I took the GN out for the first time this season, went for a quick blast up to 100 on the local four lane hwy, only to find out that I had just blown the vaccum hose off the brake booster Thank god the road was empty, it took me a good quarter mile to stop (downhill).

 

[turbofrank]

Good point i also learned that lesson.

 

[TR Custom Parts]

Wonder if it is possible to actually blow the fitting right out of that grommet in the booster??

 

[Red Regal T]

Probably not. I'm sure we would have heard. I never had a hose blow off but I do have nylon ties on the vacuum line.

 

[bruce]

Just another reason to do something like this:

http://www.t6p.com/forums/showthread.php?t=5967

Note, everything has a barbed fitting on it, and can easily be hose clamped. Unlike the oem vac block.

 

[POWERBRAKEBOB]

VACUUM

HMMMMM... NO BOOST PRESSURE GOING UP A VACUUM HOSE IN A HYDROBOOST

 

[bruce]

Re: VACUUM

Originally posted by POWERBRAKEBOB
HMMMMM... NO BOOST PRESSURE GOING UP A VACUUM HOSE IN A HYDROBOOST

Ya, just no brakes, if it fails.

 

[Geoff87]

Originally posted by BuickGn Boosted
Wonder if it is possible to actually blow the fitting right out of that grommet in the booster??

I blew the plastic check valve once. The entire front came clean off...

Probably a defect though, Back then, I was only running around with 17#'s of boost.....

 

[POWERBRAKEBOB]

hoses

I'm not sure what you mean by "it just fails". The hydroboost has an accumulator that stores high pressure for three stops with power brake assist after the pump stops turning. If you are still at speed after three brake applications (?), then the hydroboost has one steel push rod pushing against the other on thru to the master, just like a vacuum booster does when the vacuum is used up. The Powermaster has an accumulator that stores three to five applications, and then the pressure switch tells the pump to replace the pressure in the accumulator. If the pump is worn, it cannot generate the 2400 psi into the accum. and shut off the motor switch. That's when the red light comes on and stays on, or the motor runs EVERY TIMEyou apply the brake. You know what the brake pedal is like when the Powermaster pump is weak, the pedal is hard, but does not fail. As a power brake rebuilder for 55 years, we have rebuilt any and every vacuum power brake unit there is, going back to the twenty's. We ahve a vacuum test bench to test them, and can watch the pressure output drop on the guage as the vacuum drops. It's not a secret. We actually sold and installed many delco vacuum brake conversions in our own shop, but the customers were never really satisfied. The hydroboost can and does stop 14,000lb trucks. They can last 200,000 miles with clean oil, and can easily power a car, with or without 4 disc conversions. We have intalled them on 572 chevys, 540 hemi's, and cars with 1000hp.

 

[POWERBRAKEBOB]

hoses

I'm not sure what you mean by "it just fails". The hydroboost has an accumulator that stores high pressure for three stops with power brake assist after the pump stops turning. If you are still at speed after three brake applications (?), then the hydroboost has one steel push rod pushing against the other on thru to the master, just like a vacuum booster does when the vacuum is used up. The Powermaster has an accumulator that stores three to five applications, and then the pressure switch tells the pump to replace the pressure in the accumulator. If the pump is worn, it cannot generate the 2400 psi into the accum. and shut off the motor switch. That's when the red light comes on and stays on, or the motor runs EVERY TIMEyou apply the brake. You know what the brake pedal is like when the Powermaster pump is weak, the pedal is hard, but does not fail. As a power brake rebuilder for 55 years, we have rebuilt any and every vacuum power brake unit there is, going back to the twenty's. We ahve a vacuum test bench to test them, and can watch the pressure output drop on the guage as the vacuum drops. It's not a secret. We actually sold and installed many delco vacuum brake conversions in our own shop, but the customers were never really satisfied. The hydroboost can and does stop 14,000lb trucks. They can last 200,000 miles with clean oil, and can easily power a car, with or without 4 disc conversions. We have intalled them on 572 chevys, 540 hemi's, and cars with 1000hp.

 

[bruce]

Re: hoses

Originally posted by POWERBRAKEBOB
I'm not sure what you mean by "it just fails".

If you're reling on line pressure to stop the car, then in the event of a failure, with the low leverage pedal that the PM uses, you won't be able to really stop the car.

Since you want to talk about 572s, Hemi's etc., why don't most racing applications use Hyrdo's, if they're just that great.
I don't recall seeing one on any of the Professional Classes of race cars. They all seem to be using Manuals. Maybe they're just all wrong. When your racing, well, IMO, you want the absolute most reliable system for stopping the car, even in failure mode.

 

[POWERBRAKEBOB]

BRAKE SYSTEMS

I'm not sure what you mean by "fail" All of these systems use dual master (front and rear) separation. Total failure could only be caused by oil being poured in the master. The powermaster is a 1.250" bore cyl. Our hydroboost uses a 1.125" master. It is easier to push in the event of pressure failure from the pump, using the same pedal as the powermaster. Has anyone had their p/s pump fail on the highway? Maybe. Speaking of FAILURE, some of your guys have blown the vacuum hose off of the vacuum booster under boost. That is EXACTLY why Buick did not install vacuum boosters on turbocharged cars. The term GRAND NATIONAL was actually a race series. They did not use vacuum boosters in that race series. I'm still don't understand why the close mindedness about the hydroboost. When those cars came out in 1983, Buick installed HYDROBOOSTS from the factory. No one that owns one of those cars complains about them. As far as 572's and 540 Hemi's, there is no pro class for them to run in. They are strictly testosterone machines, for the street There are actually some guys using the h/b for drag race cars, and we have sold them. It will set the line lock hard, as disc brakes are hard to lock. The very serious drag cars use trans brakes to snap the driveshaft on the start. The G.N. guys like to stand on the brake and the throttle at the same time and watch the boost guage go up. If you blow the vacuum hose off at the line. the car won't hold at all. The vacuum check valve is just a thin flap of rubber that wasn't really designed to hold pressure, and will eventually be forced inside the vacuum booster.

 

[bruce]

Re: BRAKE SYSTEMS

Originally posted by POWERBRAKEBOB
I'm not sure what you mean by "fail" All of these systems use dual master (front and rear) separation. Total failure could only be caused by oil being poured in the master.

Has anyone had their p/s pump fail on the highway? Maybe.

Speaking of FAILURE, some of your guys have blown the vacuum hose off of the vacuum booster under boost.

That is EXACTLY why Buick did not install vacuum boosters on turbocharged cars.

The term GRAND NATIONAL was actually a race series. They did not use vacuum boosters in that race series.

I'm still don't understand why the close mindedness about the hydroboost. When those cars came out in 1983, Buick installed HYDROBOOSTS from the factory. No one that owns one of those cars complains about them.

As far as 572's and 540 Hemi's, there is no pro class for them to run in.

The G.N. guys like to stand on the brake and the throttle at the same time and watch the boost guage go up. If you blow the vacuum hose off at the line. the car won't hold at all.

The vacuum check valve is just a thin flap of rubber that wasn't really designed to hold pressure, and will eventually be forced inside the vacuum booster.

In order,
Fail:
To cease functioning properly: The engine failed.
In this case, blowing a hose, losing a serpentine belt.

Yes.

One individual that didn't bother using a clamp on the line, and one with a check valve, that failed.

While Buick didn't, Pontiac did. I also believe the Turbo Sunbirds had vacuum boosters.

That's what I said. They used manual brakes, with no power assist.

No one complains?. You're now stating as fact that there's never been a compliant?. Hmmm
Maybe, your the only hyping them, since that's your business. BTW, what did you say a Hydroboost system costs?.

So then, are we to assume, that you also haven't sold any to any Pro Stock, NEXTEL, F1, LeMans Series, Sprint car, old Can-Am racers?.

Blowing a hose off, is a possibility with your system also. Ones vacuum, the other oil's down the track. Have you documented you claim of the check valve failing in such a manner?. I would have thought that GM would have thought of something like that, when they used a vacuum booster on the 89 TTA.

So that's how, the GN Guys, stage, gee, what a concept.

BTW, one other item, is with the higher assist the less *feedback* there is. Are you familiar with the term threshold braking?.

BTW, do you have a data log, of a Hydroboost equipped GN (stock weight, only braking improvement the hydroboost), stopping?.
If so, I'll go out and log a 80->0 *panic* stop, and we'll compare numbers, OK?.

Up for the challenge?.
I'll also gladly get it notorized, if that's a concern on your part.

 

[POWERBRAKEBOB]

BRAKE SYSTEMS

WOW! I'm not here to wrestle, but present logical facts from a professional point of view, and I have presented all types of brake systems and their differences. Buick used what they used from their enginering point of view, and their turbo experiences. Buick tried a cost cutting measure, or an experiment with the Powermaster, and in the long run (10-20 years) it has proven to be troublesome. The hydroboost, even when worn, still works, they just leak when the seals shrink due to overheated or dirty (20 year old) p/s fluid. Actually we are doing a stopping distance test at Fontana Raceway under the controlled testing of Street Rodder magazine. The street rodders love big cams, which in turn have low vacuum. They are are also limited for space. They have been using a chinese "mail order" 7" vacuum booster for years and are fed up with not being able to stop. Street Rodder will test a 40 Ford's stopping distance using the mail order brake, and then we will convert the car to Hydroboost, and run the stopping distance test again. The results will be published. We would LOVE to do a stopping distance test against any vacuum brake you have. We have done those in our shop, WITH vacuum pump assist, and I drove the cars for a week. The results were only "O.K." but nothing exciting. In California, you don't have a 1/4 mile to stop. It's a chariot race here just to go to work. If anyone in this forum has a car that currently has a vacuum booster, or willing to run their vacuum boosted car against a hydroboosted car, we are up for it. As they say, "When the green flag drops..."

 

[bruce]

Re: BRAKE SYSTEMS

Originally posted by POWERBRAKEBOB
As they say, "When the green flag drops..."

As I offered, if you can access a PM'd stock braked GN, and data log, a few panic stops, we'll compare notes.

If you're so confident in just using line pressure has no down side, include some time stamps on the data logs, and do say, 5, 70->0 panic stops in a row. That is if you really think being able to absorb heat isn't an issue.

 

[POWERBRAKEBOB]

LINE PRESSURE

O.K. We have been building high pressure, sensitized power brake systems for the handicapped for 40 years. Some are quadrapalegic. They are so weak, their hand is velcroed to the steering wheel. A hand control is fitted to the steering column We can and have built modified vacuum power brake units, sometimes adding two truck hydroVACS on the frame to be activated by the firewall booster. The hydroVAC needs 200-300 input to create 1200-1600psi output. The firewall booster has, say, 1000psi available to provide input to the hydrovacs. We can modify the control valve in the firewall booster to make it easy to open. The quad only rests his hand on the hand control to stop a heavy van. NO 17" wheels were used, no 13" rotors were used, these were stock vans and wheels. All done with line pressure. These systems were capable of tearing the lining off the shoes, "with only pressure" We also added a 1000 cu.in. vacuum tank, and sometimes a vacuum pump to make surethere was always vacuum available. Anyway, as it relates to the GN's the issue is vacuum. Vacuum power brake units need the most possible vacuum you can get to provide stopping power for a fast car that came with downsized brakes. Actually the GN has exactly the same brakes, Calipers, rear axle, etc., as as S10. The GN is heavier and faster. The power of a vacuum booster is measured by the square inches of diaphragm area times the inches of vacuum. The delco dual dia has approx 100 sqin of dia area. The difference of 20in. of vacuum versus 10 in of vac. multiplied by the suface area is half. Below 10" of vacuum, down even more. The hb can put out its power even at idle pump speed. The only time a turbo motor can pull a vacuum is when the motor is at high speed, and the throttle snaps shut. Not easy with an overdrive. There is no high piston speed to pull against a closed thottle, especially with a 231CI engine. I believe the TTA came with a vacuum pump. There were also two vehicles built by GM called the Typhoon and the Syclone. Basically GN's as a S10. I'm checking, but I think they came with Hydroboost. You are certainly entitled to your opinion, but I deal with these situations 65 hours a week for the last 38 years.

 

[bruce]

Re: LINE PRESSURE

Originally posted by POWERBRAKEBOB
O.K. We have been building high pressure, sensitized power brake systems for the handicapped for 40 years.

Your dodging the issue, we're not designing systems for the handicapped here.

I'm glad you like what you sell, but, you've overstated your case. There is ALOT more to a braking system then just increasing the power assist to get it to work, correctly.

So, do you have a stock GN with a HB at your disposal?. After all that's what we're talking about, well, at least when being on topic.

 

[POWERBRAKEBOB]

DODGING

NO DODGING HERE. You contend that vacuum power brakes are superior on a turbo charged car. Buick doen't agree. You said high pressure won't work, I disagree. You feel that manifold pressure into a brake vacuum hose, and manifold pressure into a plastic check valve is a superior idea, I disagree. There have been brake failures with manifold pressure into a vacuum booster. The handicapped example I gave is to show that vacuum power brakes are very powerful, IF you have vacuum. A fuel injected, small cubic inch, turbocharged, overdrive automatic engine has very little chance to build 20" of vacuum quickly. This forum is full of people that have brake systems they feel are not the equal of the car, and how it should be, especially with modified turbos, bigger cam, etc. The Powermaster has it's faults, well documented here. That leaves vacuum boosters, IF YOU HAVE VACUUM, or Hydroboosts. Many Hydroboosts installed 32 years ago, are still on the job, stopping heavy trucks. Vacuum works fine, on a stock Regal. By the way, what business did you say you are in?