Can Not Get Vacuum Brakes To Hold Boost!!!!!

[TurboBuRick]

AFR's

Out of all these responses, The one thing I did not see anyone take into consideration AFR's. You may say ,what does AFR's have to do with vacuum brakes? Well it has alot to do with it.
Running too rich will rob your vacuum preassure

 

[chris2316]

Vac Brakes

Vacuum Brakes Work Good!!!!!!!!!!!!!! You Have A Problem With Your Set-up ! I Have A Big Cam And Have No Problem At All Holding Boost !

 

[Frank718]

By the way, I forgot to ask you what brake booster do you use?

Ihade installed the billet vacuum and I can hold to about 5 lb, but when I hold the brake with out giving it throttle, the rpms start to drop and the car wants to stall.

 

[GN owner]

TTA Vacuum Block

I am having the same problem as 2Qwik4u when I converted to vacuum brakes. I am tapping the vacuum off of the PCV line. Looks like from the responses that this might be my problem. Where can I buy the TTA block from?

TIA

 

[Dreamcar86]

I am having the same problem as 2Qwik4u when I converted to vacuum brakes. I am tapping the vacuum off of the PCV line. Looks like from the responses that this might be my problem. Where can I buy the TTA block from?

TIA

I purchased mine from Kirban Performance.

https://secure.mysuperpageshosting.com/kirbanperformance.com/index1.htm

 

[Dreamcar86]

Buy a new, not remanufactured, master cylinder from NAPA for a 1986 Olds Cutlass RWD with 307 engine. You may receive a cast iron one with the plastic reservior. That is fine; this is what I have also. A junkyard booster that actually holds vacuum is also needed. Take a MityVac with you with a large adapter cone and pull vacuum at the yard. It should hold indefinitely. You might even find one that when you pull the check valve out purges on the spot. Mine was like that so I knew it was a good one. Once you use these two critical and proper parts, you should have a solid pedal and be able to hold 10+ psi, maybe more. Also read this article:

Follow a Diagnostic Process When Curing a Low Brake Pedal, Bill Williams, Brake & Front End, June 2001

It is not literally applicable but halfway through step 5, pay attention to the quick take-up valve operation. That is the important information and completely applicable. Front brakes are important also.

You mentioned to purchase a new one from NAPA Auto Parts and I looked them up on the website, they are $75.00 so I decided to look up Auto Zone as well and they are $50.00 for new ones. Is there a reason you chose NAPA over other part stores? Is NAPA carry a better brand?

 

[jamier]

didn't see mention of..

no mention of changing the torque converter. It should help you spool a bit more on the line before the wheels engage I know you have a 44 and the stock torque should be fine but just something to look into . maby switch to a 3000 stall. to help at the line. anyone else??? also what are the condition of your brake lines I had an 87 original line give out on me this past season, wasn't a nice scene with no pedal lol good luck

 

[POWERBRAKEBOB]

Hydroboost Vs Vacuum Vs Powermaster

I Still Ask The Question; Why Did Buick, Who Installed Millions Of Delco Vacuum Boosters On Standard Regals (at About $12.00 Per Unit Cost) Chose Not To Install The Same Vacuum Booster On Their Pride And Joy Grand Nationals? Vacuum Boosters Are Cheaper, But Not Better. Vacum Booster Need Vacuum To Work, And They Are All Rated To Produce Their Needed Output At 20" Of Vacuum. All Vacuum Boosters. The Vacuum Booster Is Connected To The Manifold Hose. The Object Of The Turbo Charging Is To Produce Manifold ***pressure***. This Is The Opposite Of Vacuum! Pressurizing A Vacuum Booster Is Not A Good Idea, And Buick Knew That. Assuming The Vacuum Hose, Under Pressure Does Not Blow Off, (which Has Happened Here) Then The Check Valve Itself Could Blow Apart, Or Blow The Valve Into The Vacuum Booster. The Volume Of Square Inches Of Area Inside The Vacuum Booster Is More Than Enough To Blow It Apart At The Crimps. Any Of These Will Lead To Catastropic Brake Failure! Buick Knew This. They Built The 83-85 T Types With The Bendix Hydroboost. No One On This Forum That Owns One Of Those Cars Complains About The Brakes! Buick Decided To Try The Much More Expensive Delco "powermaster" Unit, 12v Operated, Still No Vacuum On Their Turbocharged Cars. They Knew Better, And They Look At Everthing From A Liability Standpoint. How Will They Be Sued? This Car Was Meant To Perform, And It Is Also Very Heavy For A Race Car. (grand National Events) A Vacuum Booster Under Manifold Pressure Can Not Work. The Hydroboost Is Now Produced By Bosch, And It Just Works. As The Rpm's Come Up, So Does The P/s Pump Speed. It Holds The Hydroboost Even Harder. Guys Are Reporting 22lbs Of Manifold Pressure With Their Foot On The Brake! 22 Lbs Of Pressure Into A Vacuum Chamber Will Blow It Apart. Kind Of Like Sticking A Shop Air Blow Gun Into Your Vacuum Booster, Try It. Oh, By The Way, Checking A Vacuum Booster In The Released Position Means Nothing. The Diaphargms And Center Seals Can Still Be Bad, And Usually Are, And Will Only Leak In The Applied Position, When You Need It. It's Your Car, And Your Life, (maybe Others) Use The Best Products You Can Buy.

 

[10SECONDVSIX]

I tried the Vacuum Set up for one summer. For Drag racing!!!! Stay with the Power Master. I took the Vac right off the car and went back to the PM. That is NEVER comong off. John D...you want to spike up your selling on the VAC set ups that's fine. But for those who have gone and seen.
NOTHING Beats the PM PERIOD...
Hell I even had a Vac Canister...
So for those that are having problems, that's nothing New. Like Bob says, the Vac set up was not intended for Turbo Cars. GM Engineers don't bolt on parts on cars because they have over stock.


Joe

 

[GNocide]

what the two above me just said-power master

-almost every car today has some kind of power assisted brakes not vaccuum

church tabernackle-preach

 

[D's 6 Turbo]

Converted to vacuum myself about 15 years ago....tried everything but the car could never powerbrake(vendor I bought/installed it from even told me "cars are not designed to powerbraked"when I told him about my problem)...switched back to powermaster. A little bit more money but A lot happier now and zero issues powerbraking.

 

[SNOWBIRD]

How Much Boost Can You Hold On The Line With The 86 Caprice Master Cylinder....vacume Brakes,,,3 Inch Rear Cylinders

 

[POWERBRAKEBOB]

Hydroboost Vs Vacuum Vs Powermaster

The 86 Caprice Master Cyl Is 1.125" Piston Size, And The Regal Vacuum Booster/master Is 24mm Or 15/16" The Caprice Would Work For 4 Disc, But The 24mm Has Higher Pressure On A Vacuum Unit. The Caprice Booster Is Similiar To The Regal Vacuum Unit. Guys Have Reported The Car Creeping At 0" Manifold Pressure With The Powermaster. The Vacuum Booster/24mm Combo Would Probably Creep At 5" Of Manifold Vacuum, The Big Caprice Master Would Let Go At 8-10" Of Man. Vacuum. The Hydroboost System Runs Off Of The Power Steering Pump. When The Pump Spins Faster, It Holds The H/b Even Harder. Guys Report (on This Forum) Of Building 15-22lbs Of Manifold Pressure With Their Foot On The Brake With The Hydroboost.

 

[GN owner]

Still having issues with mine ever since it was installed!

"Buy a new, not remanufactured, master cylinder from NAPA for a 1986 Olds Cutlass RWD with 307 engine. You may receive a cast iron one with the plastic reservior. That is fine; this is what I have also. A junkyard booster that actually holds vacuum is also needed. Take a MityVac with you with a large adapter cone and pull vacuum at the yard. It should hold indefinitely. You might even find one that when you pull the check valve out purges on the spot. Mine was like that so I knew it was a good one. Once you use these two critical and proper parts, you should have a solid pedal and be able to hold 10+ psi, maybe more."

My car has not been driven ever since I've converted to vacuum in the latter part of 2006. The brakes are hard initially and I cannot stop quickly if I have to. Like John Larkin mentioned above I have to find a vacuum booster that will hold the vacuum. The ones that I got (two) with my kit did not hold vacuum. Ever since then I have just side lined the car! Just recently I have had time to work on the car so I will buy a booster and make sure that it will hold the vacuum with a Mity-Vac.

 

[gnbooster87]

i tried searching the previous ebay auction that was posted for the proportioning valve but no luck, will this valve work on our cars??
i have a bone stock brake setup(on my vacume brake wagon of course):redface: and will upgrade to S10 cylinders soon...they also offer these in aluminum as well
GM Disc/Drum Combination Proportioning Valve Street Rod:eBay Motors (item 250198100953 end time Oct-04-09 20:48:22 PDT)

 

[gnbooster87]

as stated they also offer and aluminum style, but will it fit
GM Disc/Drum Combination Proportioning Valve ALUMINUM:eBay Motors (item 140320143732 end time Oct-08-09 09:24:16 PDT)

 

[TurboBuRick]

I would use the brass one.

 

[POWERBRAKEBOB]

Prop valve and hydroboosts

We used to be the Delco distributor for those, but they closed up. The only valves out now are made in China. We do have them in brass, both 2 disc and 4 disc types. they will bolt in. I was the guy who started using the 7/8" wheel cyls back in 1987, This is something I do on many trucks that have extra weight on the rear axle. It takes the heat off of th eorotors by increasing the rear brake power. One of the first cars I did was for Bulgari, the jewelry guy. He loves Buicks. We installed 4 wheel B car brakes, and a Hydroboost on that car in 1987, when it had 14 miles on it. It then went to Guldstrand and Duttweiler for their specialties. We still have new and rebuilt Hydroboosts for the G.N.s