vacuum brake conversion

[Bugsy]

As I understand it , Gm made the Powermaster system for turbo Buicks because the vacuum systems didn't work the best for street use .So , why do the vacuum conversion kits work now - - or are they just a compromise and have drawbacks as well ?

 

[TurboBuRick]

IMO vacuum brakes

are a compromise.
If you want to put some good brakes on the car go with a hydroboost.

 

[Nick Micale]

As I understand it , Gm made the Powermaster system for turbo Buicks because the vacuum systems didn't work the best for street use .So , why do the vacuum conversion kits work now - - or are they just a compromise and have drawbacks as well ?

They work now because the "information" you received is bogus. GM and others used vacuum brakes on many turbo production cars.

The most notable GM turbo car is the 1989 Turbo Trans Am that has a Buick turbo V-6.:biggrin:

In all the vac conversions I have done, all the owners have said it does work as good as the PM, and most like it much better.

I would not rely on your "source" for info and advice on your GN.

There is NO compromise or drawbacks.

 

[v62go]

They work now because the "information" you received is bogus. GM and others used vacuum brakes on many turbo production cars.

The most notable GM turbo car is the 1989 Turbo Trans Am that has a Buick turbo V-6.:biggrin:

In all the vac conversions I have done, all the owners have said it does work as good as the PM, and most like it much better.

I would not rely on your "source" for info and advice on your GN.

There is NO compromise or drawbacks.

does the vacum brakes hold boost on the line as good as the powermaster?for example 10lbs or better...

 

[Nick Micale]

does the vacum brakes hold boost on the line as good as the powermaster?for example 10lbs or better...

Once the pedal is depressed, the method of assist be it vac or hydraulic, has little or no bearing on how the brakes hold the car from moving.

It now is a function of the type and condition of the friction surfaces, and clamping force of the cylinders to keep the wheel from turning.

If enough torque is applied to overcome the clamping force, then the friction between the tire and road [or track] surface, which varies, will also help keep the car from moving.

With a 12 sec. and some high 11 sec. GN's, we have been able to achieve 10 psi launch boost.

To keep the rear wheels from turning at this level, the rear drums and shoes must be "matched" for full surface contact. When OSHA came into the repair shops years ago, they shut down the machines used to arc the shoes to match the drum.

When a drum is turned or worn, the contact diameter gets larger. To compensate, thee shoes need to be ground to the radius of the drum for full contact and GOOD holding power.

I know this is a long answer, but as you can see, most owners do not understand the importance of all that goes into the "simple" item of launching a turbo car with LOTS of low end torque.:biggrin:

 

[v62go]

what i was getting at,my pm acummalator ball must be going bad or something associated with the pm and its not holding back boost no more.everything was working fine until that(holding boost 10 lbs plus)just wondering if i could expect the same with the vacum set up...thanks for all the info nick....

 

[jdpolzin]

My car has had all three brake systems on it in the past three years. Started with the Power Clunker, didnt want to die when they fail so I took it off. Then i got a new vacuum kit for a Monte SS and didnt like the way he brakes felt. Couldnt hold boost at the line unless I revved the engine, let off the brake, and hit the brake again while the engine was revving all in one motion. Didnt like them at all. They did work fine on the stree for normal driving. Now I have the hydroboost. Practcally the same cost as the vacuum, just as easy to install, and the holding force of the brakes is completely out of the park compared to the other two.

 

[2badgn]

Look into the Hydroboost. It's better than vacuum and the PM. Hydroboost came on 84 and early 85 GNs. It is also on alot of heavy duty trucks and high performance cars. it connects to ur power steering pump.

Hydroboost is more expensive than vacuum but it will hold better than the vacuum brakes.

 

[Bugsy]

To those of you who have done it and been happy , where's the best place to get a quality hydoboost kit [ complete to convert 87 GN ] ?

 

[2badgn]

It depends how much money u want to spend. Alot of guys have sourced out rebuilt Hydroboost units plus a master cylinder from 84-85 GNs from various autoparts stores for around $200 or so. U also have to find the correct power steering lines from 84-5 GN and a tee fitting. Some guys have used the HB from late model Chevy Astro vans but I think this requires some modification. Some have reported that it is difficut to find even rebuilt HBs from 84-85 GN.

The other alternative- which costs big money-but it will give u the best brakes ever - is to buy a new aftermarket Hydroboost unit designed specifically for GN and other G body GMs. If u go to dealerlist u can find various dealers that sell the Hydretech Hydroboost braking system. It has a one year warranty. The HB, MC and line set should run around $785. Some might think that this crazy when u can buy vacuum brakes for $200 but the choice is yours. U could be saving the front end of ur car! The prices of parts on the Powermaster are not cheap- $100 for brake switch, $150 for accumulator ball, $300 for PM motor.

Check out the following vendors from that dealer list: musclerodzs. com and Classicperformance.com.

Also search Hydroboost in this thread and u can see pics of some units installed in GNs.

Good luck
Frank

 

[jdpolzin]

Everything is available at the parts store including the hydroboost unit, the master cylinder, the two high pressure lines, and of course a 3/8 hydraulic hose for the return as well as a 3/8 brass tee and hose clamps. Use your powerjunker pedal, it's the same. Best money you will ever spend on your car. Very simple to swap.

 

[Rafs-T-Type]

since vacuum brakes work on vacuum doesn't that mean when you go from vacuum to boost the brakes would no longer hold?

 

[Bugsy]

So at the auto parts store I'd ask for these items for any 84 Regal or just the turbo model ?

 

[jdpolzin]

Just ask for an 84 GN.

 

[v62go]

anyone have any pictures of their hydroboost setup?

 

[turbo nasty]

Take what Nick said for fact the tTA had it from the factory
I changed over to teh vac setup and I can hold just as much on the line as with the PM.
It pushes through the brakes the same as the PM around 7 ish psi.
Now convertor brake type shoe contact, heat etc etc all pasy into this, Im NOT a pro rear s10 wheel cylinder guy..... wet road and a panic stop sideways into another car due to rear wheel locking isnt fun
Dont like the fact that the HB when turning the wheel and braking at the same time as you hit the brakes you feel the brake apply slow the steering and vise versa. i.e.-Pulsing in the steering with braking and vise versa
This is just my experience with the several HB vehicles I have driven and drive frequently.

 

[Bugsy]

Nick - From experience you like the vacuum conversions .Which of the vacuum conversions have you found the best

 

[Nick Micale]

Nick - From experience you like the vacuum conversions .Which of the vacuum conversions have you found the best

I use e reman booster and master cylinder from a 1987 Regal non-turbo V-6 which both come with a lifetime warranty.

In all the years in doing these, one booster and 2 MC's have been replaced free to the owners.

In answer to the second comment, the vac booster has a check valve which with give 2 or 3 assist stops without engine vacuum. So during the boost phase, vacuum is stored in the unit, and should also be stored in the factory vac resevoir.

 

[TurboBuRick]

anyone have any pictures of their hydroboost setup?

Here you go!

 

[2badgn]

Here you go!

Where did u buy ur hydroboost and how do u like it? What do u like the best? What dont u like?

How much did it cost?

any problems?

Thanks

In the market to convert to HB very soon.

Thanks
Frank