vacuum vs hydroboost

[Lee Thompson]

Powerbrakebob

I have an 85 with the HB and would not trade it for all the vacuum or PM out there. I have a tech ? for you. If I convert the top of my eng. to make it same as an 87, do you have a pully to switch the HB to serpentine? Disregard the negative post, some people know everything. Reminds me of some of my friends who are engineers---if they didn't think of it, it is not a good idea. The TR world is small and quit honestly some of these people embarrass me with all their petty bitching. Thanks for your time.

 

[John Larkin]

I can't comment on hydro since I have never used it. It is an intriguing setup and I believe it works fine. I did perfect my vacuum conversion and am very happy. The breakdown of parts is:

New NAPA master cylinder, the critical part
Used but good power booster (had vacuum in it at the j.yard) & pedal
Vacuum T in the PCV line with stock vacuum filter before the booster, route the hose under the coilpack
S-10 rear wheel cylinders
Long shoes on both shoes in rear
Adjust parking brake to fully engage hard with 3 clicks only
Gravity bleed all wheels at once for an hour

I held 10psi not trying hard on cold street tires in my driveway. It could have built higher but I stopped. It works when you do it right.

 

[bruce]

The TR world is small and quit honestly some of these people embarrass me with all their petty bitching.

Did you notice how he disappeared when asked about his claims of liability?.
How about when he made the claims, and when asked to document them, he didn't?.
Not to mention the items he *tells* us about what GM was thinking.

If you want to believe everything anyone ever says, fine, but what you call petty to some are serious issues to others.

Not to mention for the $900 he charges for just the M/C (HB setup), one can put together a true high performance braking system. ie 12" rotors front and rear, and a system that in the event of failure, you can still stop the car.

If someone wants to run a HB, fine, but, IMO, there's no HARM in giving them all the **TRUE FACTS** to make an informed choice.

 

[bruce]

Bruce, I read all 4 pages of that link you posted and couldn't find anyone who had HB ,and had bad things to say about it . Am I missing something? Whats a spool valve. Why does that make them unsafe

Google
Hydroboost Spool Valve
first entry seems to pretty well cover it.
http://www.babcox.com/editorial/bf/bf030542.htm

Look at the pics, and you'll see the Spool valve is the real controller of a HB, and that it's not directly connected to the pedal. It can self apply, or not release, just as a matter of design. For a truck at low speeds, while that's bad enough, but for a car, at high speeds, the situation can get really ugly really fast.

BTW, while they offer a *light* pedal, that means you actually have less sensorary *feel* about how the system is really working.

Not to mention that for a high performance car, without antilock, with the higher assists, generally it's much harder to do any threshold braking.

 

[vader87]

I have been reading posts for about an hour now. I know we are talking about TRs, and I am new, but if I may, I would like to tell you what I think about the hydroboost braking system. I have a 79 CHerokee (about 5000 lbs)with 37 inch tires and I converted it to a hydroboost system from a 1978 Caddy Eldarado along with the rear caliper setup. While using the vacume setup, I had a terrible time stopping. I had to brake hard once and the front tires did not lock but rears did. WHAT A RIDE! Anyway after the conversion, my Jeep will stop on a dime, well maybe a quarter. I know this is a totally differnet situation but I THINK the hydroboost setup is the way to go. Only down fall that I have experienced is if the engine dies, which happens a lot during 4 wheeling, you have to stand on pedal. I am running a vacume setup on my 87 GN and I can only hold 3-4 pounds of boost also. I hope we can a solution (cheap) for this topic soon. My 60fts suck!

 

[at7we2]

thanks Bruce

thanks for taking the time to post in this (and the many other) thread. while I don't have *any* experience with the hydroboost system or a vacuum conversion, I agree 100% with your point-making methodology.

fwiw, I've stayed with the PM setup on my current and previous GN's. I've thought about the vacuum conversion and may still go that route at some point, but so far the only PM problems I've had were cured with either new accumulators or new switches.

Like you said, the GM engineers decided to go with the vacuum setup on the '89 TTA. As far as why they switched back and forth, I don't pretend to know, but I *speculate* they developed and utilized the PM system in an effort to improve certain characteristics of the brake system but later determined that it was really a trade-off and not worth the additional expense and complexity.

Rob

 

[turbofish38]

Its kind of funny because when I bought it I was under the assumption that it would also have the rear disc brakes like all the other 99-up body style Silverados and Sierras. It turns out that '04 was the last year for that. Some research found GM had lots of reliability issues with the discs and hydroboosts on the 1/2 ton trucks. I found an article online that GM teamed up with Bosch engineers to design a new braking system for the '05's. The end results are finally a braking system that is over engineered. The brakes on my '05 are over kill with 13" front rotors, 12" rear drums, dual piston PBR calipers and an enormous master cylinder and booster.

You can still get 4 wheel disc on 05-06 GM trucks. It depends on the GVWR of your model that determines whether you get 4WDB. Most 4 door stubby box 1/2 tons have the rear drums. Purely a hit and miss if you'll have problems like you have read about. The early 4WDB had issues but they are pretty much worked out on the new trucks. The 90-05 Astro/Safari uses the HB. Some years are a mix between the two types. IMO I think it has to do more with how much space there is to package a PB set up. They didn't put PM or HB on the TTA because it was PAS that did all the proto and production work on the TTA. If they knew thet were going to build more than 1500 of them they would have put the PM on it.

Personally I prefer the PM or HB over vacuum. As was pointed out it is just plain cheaper to convert to vacuum. I have never had problem building boost with any of the three types of boosters. The HB on the hot air Rivs works better than the vacuum on the NA POS ones I drive. There is a technique to building boost and launching with the vacuum. Just ask any TTA owner. With the VB on my GN I have no problem power braking past 15# with out the tires breaking loose. If you cant than you have problems whether it is in the tune of your engine or problems in your brake system.

 

[Red Regal T]

The only guys who make all the noise against Hydroboost are you and Mr Red Regal T. He sells used Regal vacuum boosters for his gas money, but if the car is involved in an accident, will he be LIABLE for used brake systems on someone else's car? Do you or he design brake systems? Do you know more than the engineers at Buick? Are you or he in the brake business? Would you really step up and tell us what business you are in? If the brakes work so well on These cars, why is the subject constantly on this FORUM? The BRAKES ARE FAILING ON THESE CARS. IT IS A DANGEROUS SITUATION. They were built with the same brakes as an S10 PICKUP! The GN weighs 1000lbs more,and is MUCH FASTER. .

I really don't care if anyone wants to spend $550 on a brake system. I don't care if any of you never buy a vacuum brake set up from me. I never said anything negative about the hydroboost. I never had one, so I can't comment on their effectiveness. If you want one, I'm sure you can get what you need local to you for a lot less than $550.

What I did say a couple times, was that PowerBrake Bob doesn't know what he's talking about, meaning, he puts out a lot of incorrect information about our cars and when I pointed that out, being the inarticulate buffoon he is, he now claims I ran down the hydroboost system, which I never did. Right here today, he says the vacuum is the same as on a 1000 lb lighter S-10. Now, that might be true, but the same vacuum brake system is on every G-body car, 2 and 4 door from 1981 thru 1987. I think an NA Regal, Grand Prix, or Cutlass weighs the same as a TR. Right? He says, "the brakes are failing on these cars". Yes, powermasters are 20 years old and they break. That doesn't mean there's a problem with vacuum brakes failing, though he implies there is. His reference to difficulty changing the pedal, I guess, refers to his mechanical ability. It's no problem. And as far as his customers having a hard pedal, I guess that refers to his mechanical ability too. But then, he does know Buick engineers. It just goes to show ya, any moron can be a success in business no matter how much they don't know. Again, I never ran down the hydroboost, just the blowhard. Search it out.

As far as vacuum, some claim to be able to hold up to 15lbs of boost while others have trouble. Personally, I run street tires and don't need to hold boost. I don't care and I have nothing to prove.

 

[bruce]

As far as vacuum, some claim to be able to hold up to 15lbs of boost while others have trouble. Personally, I run street tires and don't need to hold boost. I don't care and I have nothing to prove.

I just finished going to manuals.
Yep, a slight increase in pedal pressure, I can still stage, enter launch mode, and *fry* a set of 285/40x17s. With assist the brakes were almost too easy to lock up, now, with the increase in effort, the *over application* possibility is gone.

In this particular launch mode, the timing can be retarded up to 30d, RPM are held to 2,900, and pedal to the metal.

I now have a system, that doesn't have any possibility of a PM failing, HB failing, or vacuum booster failing. Other then a lose of fluid, or mechanical failure, which is common to the other set-ups, when I hit the brakes, the car will stop.

 

[Red Regal T]

By the way, if you're car don't stop, don't sue me........sue GM. They got the deep pockets. I'm only in it for the gas money. :frown:

 

[QUIP'6']

i converted to vaccum since i went through 3 powermasters in one month thanks to advanced auto so now with vaccum i can hold 14# of boost with street tires and they dont spin while holding and i dont have to worry about stopping they will lock up when i want them to

 

[8AV8]

chose vacuum

OK guys , I chose to go with vacuum. Cost was the main reason. I haven't been to the track so I'm not sure about #'s of boost yet but an annoying thing happened. My brake light came on inside. Do I jump some wires to turn it off or what. I hate looking at lights on my dash.

 

[bruce]

OK guys , I chose to go with vacuum. Cost was the main reason. I haven't been to the track so I'm not sure about #'s of boost yet but an annoying thing happened. My brake light came on inside. Do I jump some wires to turn it off or what. I hate looking at lights on my dash.

Sounds like you might have tripped the pressure differential switch in the combination (proportioning valve).

Try one at a time releasing one of the front bleeders when under pressure, and see if the light goes out. If not, then loosen a rear one when under pressure, and see if the light goes out. You may have to play at this, to get the valve to recenter.

 

[yullose]

This may sound a little silly, but after reading this thread, I got to thinking...

If a Vac booster needs vacuum to be effective, that means there is a diaphragm being pulled by the vacuum... Right ?
What would happen if opposite side of that diaphragm was plumbed in a way that it saw boost pressure when the vac went to zero...

Maybe I'm way off base here, as I've never actually opened up a Vac booster... But I can't help but wonder ???

Basically...

Plumb a "Vacuum" line to the front of the booster, and a "Boost" line to the back of the booster... When the motor stops pulling the diaphragm with vacuum, it will start pushing it with boost instead...
The more boost you make, the better the brakes will work on the line...

Just a dumb idea, but maybe has some potential...

Maybe it will lock them altogether and not release them too....

Who knows... Just an idea.

 

[bruce]

Basically...
Plumb a "Vacuum" line to the front of the booster, and a "Boost" line to the back of the booster... When the motor stops pulling the diaphragm with vacuum, it will start pushing it with boost instead...
The more boost you make, the better the brakes will work on the line...

For alot less work, and better reliability:

http://www.t6p.com/forums/showthread.php?t=9516

 

[SVORay]

Ford used vacuum on all the 84-86 Mustang SVO's, 83-86 Thunderbird Turbo Coupes, Merkur XR4ti, turbo Escorts.

I ran the stock 15psi and never had issues stopping or building boost in my SVO Anyhow, this was very informative reading. I'm going to see about checking out my friends TTA and see up close how well the VB system works on it. I may end up going that route instead of HB. As for the rest of the vehicles with HB, I think my wife's 04 Z71 Tahoe came with HB but my Supercharged Harley came with vaccum I blieve..I have to doube check it. The truck stops on a dollar...what do you expect out of a 5600lb truck.. I've already wraped the front rotors. Damn, now you peoipl e complaining about 500.00 - 1000.00 brake upgrades, the cheapest upgrade on my Harley is 2k I'm thinking of just using a 'chute lol

 

[POWERBRAKEBOB]

Hydroboost Vs Vacuum Vs Powermaster

Hmmmm. O.k. The Guys With The 83-85's Report They Still Work Fine 23 Years Later. Normal Hydroboosts In Truck Use Are Maxed Out On Pressure At Each Stop Because Of The 10,000lbs To 14,000lbs Of Weight They Stop For 20 Years, This Heats The Fluid. The Only Failing Of The High Mileage Hydroboost Is That They Could Leak. This Is Caused By Overheated Fluid, And The Metalic Sediment Worn Off Of The Steering Gears. It's Abrasive. My Point Of The 200,000 Mile Hydroboost (a Lot) Reflects The Need For Clean Fluid. A Filter And Cooler Would Extend That. On Off Road Vehicles, Coolers And Filters Are Popular. How Many Powermasters Lived For 150,000 Miles, Trouble Free? As Far As The Spool Valve Is "not Connected" To The Pedal, This Is A Misconception. The Pedal Linkage Is Directly Connected To The Spool Valve. The Brake Pedal Essentially Moves The Spool Valve To Direct Pump Pressure Against The Power Piston, Which Pushes Directly Against The Master. There Is A Direct Push From The Pedal Against The Master Piston In Any Possible Event. With Or Without Pump Pressure. Those Guys Who Did Not Change The Pedal To A Vacuum Pedal With Their Vacuum Booster Are Over Leveraging The Booster Rod, And Run The Risk Of Breaking The Valve Body Or Tipping The Poppet Valve Over Inside The Booster. If The Vacuum Booster Feels Like It Is Spongy, The Pedal Is Wrong. If It Sounds Like There Is A Vacuum Leak, It's Broken. The Hydroboost Uses The Same Pedal As The Powermaster.