No vacuum brake assist while under boost

[tlap]

I have the vacuum brake conversion on my '86 GN. It does have a check valve in the vacuum line.
When the engine is producing boost I noticed that the brake pedal is very stiff, but when vacuum is available to the booster the brakes work great.
Is there any check valve that might work better than others for blown cars?

 

[lrayzer]

My buddy did the conversion and installed a pump to cure his issues, I went Hydro.

 

[Paulo]

Rebuild your powermaster!

 

[Phoneguy]

I believe there is a vacuum canister that you can add

Bryan

 

[hiboom]

I have a vacuum canister added to mine helped a little but not much I'm leaning to just go hydro and be done.

 

[dragrazor]

Why would you have the brake on if you are under boost? Are you talking about building boost at the line with the brake on? Why not get a line lock then? I guess it would be dangerous if you suddenly had to stop. How long would it take for the engine to create enough boost to stop after getting off the gas pedal?


Posted from the TurboBuick.Com mobile app

 

[tlap]

Paulo, I don't have a powermaster to rebuild, I bought the car this way!
Dragrazor, when I am going up a long grade the turbo is producing boost, and sometimes you have to brake for traffic. It only takes a few seconds to regain the power brakes again, but it is the emergency stops I am concerned with.
I just connected my hand vacuum pump to the line going to the booster. It wont develop enough vacuum to even register on the gauge.
If a booster is working correctly, are they capable/expected of holding a vacuum once they have been drawn down? or is it typical to see them lose vacuum fairly quickly?

 

[dragrazor]

Tlap, i missed that part,lol. I live in florida where its flat. You have an issue with the check valve or booster it seems. The booster should be able to hold vacuum.


Posted from the TurboBuick.Com mobile app

 

[Nick Micale]

When a vacuum booster is installed correctly and is working properly, it will have enough vacuum reserve for one or 2 pedal applications.

The check valve on the booster will keep a vacuum in the canister unless there is a leak in the internal diaphram.

If you cannot pull a vacuum when your vac pump is hooked up to the booster hose, you have an internal leak, and the booster needs to be replaced or rebuilt?

Having done over 100 of these conversions, all of them perform better than the PM, and are much more reliable.

The GN's which been converted to vacuum and have trouble building boost on the brakes means the installation was not done properly, or the car has other issues?

 

[Paulo]

Paulo, I don't have a powermaster to rebuild, I bought the car this way!

Eh, that sucks. I was anti powermaster for a while after I bought my car because I heard people's rants about how unsafe they are, etc., but to be honest I have learned that most people don't know what the hell they are talking about, especially on the internet! If you maintain it, rebuild it (there is a company that sells a rebuild kit) then there should be no issues.

Just my 2 cents, thanks for listening ;-) Good luck to you either way!

 

[87GNSteve]

Eh, that sucks. I was anti powermaster for a while after I bought my car because I heard people's rants about how unsafe they are, etc., but to be honest I have learned that most people don't know what the hell they are talking about, especially on the internet! If you maintain it, rebuild it (there is a company that sells a rebuild kit) then there should be no issues.

You realize the above statement was made on the internet and can mean you don't know what the hell you are talking about?

 

[Paulo]

You realize the above statement was made on the internet and can mean you don't know what the hell you are talking about?

If an attempt is being made to get a rise out of me you will not succeed. Does having 2,215 posts mean you know what the hell you are talking about??

 

[87GNSteve]

If an attempt is being made to get a rise out of me you will not succeed. Does having 2,215 posts mean you know what the hell you are talking about??

Well according to you probably not. But the nature of these forums is for people to share their knowledge most times from experience; so if one takes the position that most don't know what they are talking about, what is the sense of sharing your opinion?

 

[Paulo]

Well according to you probably not. But the nature of these forums is for people to share their knowledge most times from experience; so if one takes the position that most don't know what they are talking about, what is the sense of sharing your opinion?

Well you attempted to make a connection between me saying "internet" and you implying "turbobuick.com" when all I said was internet. I was just trying to advise someone to beware. So I will just leave it at that.

God bless and have a good night!

Paulo

 

[87GNSteve]

"Turbobuick.com" is on the "internet" so the connection is natural.
And Yes, May the Lord richly Bless you also.

 

[pacecarta]

I have the vacuum brake conversion on my '86 GN. It does have a check valve in the vacuum line.
When the engine is producing boost I noticed that the brake pedal is very stiff, but when vacuum is available to the booster the brakes work great.
Is there any check valve that might work better than others for blown cars?

Paulo, I don't have a powermaster to rebuild, I bought the car this way!
Dragrazor, when I am going up a long grade the turbo is producing boost, and sometimes you have to brake for traffic. It only takes a few seconds to regain the power brakes again, but it is the emergency stops I am concerned with.
I just connected my hand vacuum pump to the line going to the booster. It wont develop enough vacuum to even register on the gauge.
If a booster is working correctly, are they capable/expected of holding a vacuum once they have been drawn down? or is it typical to see them lose vacuum fairly quickly?

they should hold vacuum practically forever , they should not leak down
you cant expect to pull a vacuum with a small hand operated vacuum pump as the vaccum booster has a large reserve area . a simpler test is to run the engine , then turn it off , wait a while and then pull the check valve on booster and listen for the vacuum
if the booster holds vacuum the check is good and so is the diaphragm inside the booster , if no vacuum either the check is leaking (or grommet) or the booster has a leaking diaphragm (it happens especially if the booster gets moisture inside and gets rusty) . with boosted cars its a good idea to run a second inline check valve , i use a steel one from imports. you should only use hose designed for vac brakes (wont collapse) and use clamps on the hose to prevent blow off

Why would you have the brake on if you are under boost? Are you talking about building boost at the line with the brake on? Why not get a line lock then? I guess it would be dangerous if you suddenly had to stop. How long would it take for the engine to create enough boost to stop after getting off the gas pedal?

the purpose of a line lock is to hold the front brakes locked while allowing the rears to be unlocked so that you can perform a burnout to heat the rear tires up before a pass ..it is not for holding boost at the line

Eh, that sucks. I was anti powermaster for a while after I bought my car because I heard people's rants about how unsafe they are, etc., but to be honest I have learned that most people don't know what the hell they are talking about, especially on the internet! If you maintain it, rebuild it (there is a company that sells a rebuild kit) then there should be no issues.

Just my 2 cents, thanks for listening ;-) Good luck to you either way!

your 2 cents are worthless .....not just because I read your post on the internet but ... for one .. because the 25 yr old PM is an accident waiting to happen and ...two.... because no such rebuild parts exist and replacement pumps also no longer exist and even rebuilts are done using old parts and their life is much shorter than the originals


fyi the above is not my opinion based on internet hype but from real but world experience with these cars on a daily basis
and my post count is built on years of posting detailed advice not BS posting

 

[Paulo]

your 2 cents are worthless .....not just because I read your post on the internet but ... for one .. because the 25 yr old PM is an accident waiting to happen and ...two.... because no such rebuild parts exist and replacement pumps also no longer exist and even rebuilts are done using old parts and their life is much shorter than the originals

Why don't you go back to school, get an education, pretend like you actually graduated high school, because for you that is probably a stretch, GED is more in line I assume. People like you tend to thing that because you just keep bombarding the internet with your useless and unsubstantiated claims you have some sort of credibility. Oh my you have so many posts on TB.com let me bow down to you and assume that you actually know what you are talking about. Say what you may and pretend to know what you think you know. I know a person much wiser than you and trust me I know that because I know the person, he has been running the PM for over 1o years and has never had a problem. I plan on doing the same so keep trying to reinvent the wheel and pretend you have some sort of brains, when in reality ....mush mush, typical "internet worthlessness". And I will leave it at that because you don't know what you speak of.....

 

[charlief1]

Fights and BS will not be tolerated Paulo. Paul has been working on these cars for a long time and has at least 20 years on you so I'd keep this in mind. While everyone may have an opinion and can freely express it that doesn't mean that either of you can call names or create a situation. The one thing I will point out is that GM no longer offers the powermaster in any vehicle and there has to be a reason for that.

 

[Paulo]

Fights and BS will not be tolerated Paulo. Paul has been working on these cars for a long time and has at least 20 years on you so I'd keep this in mind. While everyone may have an opinion and can freely express it that doesn't mean that either of you can call names or create a situation. The one thing I will point out is that GM no longer offers the powermaster in any vehicle and there has to be a reason for that.

Talk to your TB buddies about fights and BS or even creating a situation....Because it as always, it goes both ways.....

I am not here to debate experience, because if someone thinks they have experience doesn't deem them an expert. What someone thinks is experience is worthless to me. I will "within my 1st amendment right" call you out as you are calling me out. So if I run PM and I have no problems I will state that. And I will say it again, a lot of people on the internet claim to know what is "right" just like I am, take it with a grain of salt, just keep an open mind. It comes down to a difference of opinion and I will stick to my point that if you maintain a PM and care for it, you will have no problems.

 

[pacecarta]

to maintain all you can do is change the fluid annually
you can buy an accummulator ball when that leaks (180.00) and you can replace the pressure switch (100.00)
short of buying a rebuilt PM unit from cardone thats it !
please post links to those rebuild kits for the PM
will these kits fix a PM motor thats popping the fuse or leaking from the pump , or running constant and not building enough pressure to reach the switch pressure ???
hank terry who owned the tooling for the PM motors used to sell them but that's a thing of the past as he sold the tooling to cardone

i dont "think" i have experience , I do. i deal with these cars every day so what i post is not just an opinion based on one sunday driver car.

and for the record i did GED.... at 15, junior year to enter college. i was one of those who screwed the bell curve for the rest