IHADAV8.com - Turbo Buick Tech, and Nonsense
Tech Area => General Buick Tech => Topic started by: drew87gn on June 06 2012, 01:14:59 PM
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Looking for some good info. Long story short after 12 years of having my GN off the road I finally got my car running. Took my car to work, ran great. On my way home while on the highway I step on the brake and the pedal won't budge, :wtf: then I see the break light go on..Almost smash my car. Took my time on the back roads and got my car home safe. I spoke with Highway Stars and it was suggested that I switch my GN to a vacuum brake conversion kit because it's the best way to guarantee safety. Is there a vacuum brake conversion kit out there that can be recommended?? Thanks, Andy
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Some vendors sell complete kits but you can get it all yourself & save $100+ but the pedal itself will be the hardest part to find.
Brian has the kits www.gbodyparts.com (http://www.gbodyparts.com/)
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Last I saw Kirban is the only source for PM remans.
Rockauto were sending yours out for rebuild to Carcone, don't know if that's still the case.
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Thanks for the info. I quickly went on both Kirban's and Gbodyparts website and saw they both offer remanufactured PM's. Any reviews on the remanufactured?? I'd like to keep the GN original but if there's issues with the rebuilds then originality isn't worth it over safety.
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My opinion is that the rebuilts are a pretty iffy proposition. I doubt they do much other than fix whatever is obviously wrong so you may end up with one that will need a new pump motor, etc. in a few months. Depending on the warranty and your patience, you can give it a go and hope for the best. A powermaster that works as designed is a good system. One that does not can give you a rock hard pedal that may make you wish David Banner was riding shotgun with you :)
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The saving grace is the lifetime warranty.
Looks like a new switch and accum on the one I have.
Not installed yet but the high pressure side has been holding +400lbs for a few months on the bench. (fingers crossed)
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My opinion is that the rebuilts are a pretty iffy proposition. I doubt they do much other than fix whatever is obviously wrong so you may end up with one that will need a new pump motor, etc. in a few months. Depending on the warranty and your patience, you can give it a go and hope for the best. A powermaster that works as designed is a good system. One that does not can give you a rock hard pedal that may make you wish David Banner was riding shotgun with you :)
HULK SMASH PEDAL!!!
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Yikes,
My brakes seem to work fine but the brake light always flashes a bit when I first back her out of the garage. Was planning on just leaving it alone but after reading this I have concerns. When we take the cars to a carshow, the wife drives the GN with our 3 year in the back. The wife is small and I'm concerned about this " hard pedal" issue.
It would be work but could I go to a junk yard and get the brake assembly ( pedal, master cylinder, booster, etc) out of a 87 Regal, Monte Carlo, Grand prix and install that??
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yeah
here is a write up http://www.gnttype.org/techarea/brakes/Powermaster_to_vacuum.html (http://www.gnttype.org/techarea/brakes/Powermaster_to_vacuum.html)
I have done it in less than two hours from start to end....once I spent a lot more time because the pedal bolts had a couple of tinnerman nuts as lock nuts and I was too stubborn to get out of the floor and get some side cutters to snip them off.
I like to replace the vacuum block on the plenum with one that has a vacuum port aimed at the brakes. Others have tee'd into the pcv line. Many think it is better to install a new master cylinder...it might be, but some of this new stuff ain't worth a damn so I guess it is a personal choice.
You don't need to brake lines from the mc downward...you can just bend the originals a little so they line up with the new mc location
It used to cost less than $100 if you go to the wrecking yard for the pedal.
Some use the original pedal and drill a new mounting hole in it...should be a template somewhere online that shows where.
It takes King Kong to stand on the pedal if the system fails....that is for sure. I went up a curb one day to keep from hitting a school bus....
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Thanks Steve :atbeer: , I will definately be making this conversion. To much to risk by hoping they never fail.
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Found an old 87 buick a guy is turning into a stock car, puts in his own complete braking system. $50 for pedal assembly, booster and MC if I remove it. Is there a way to determine if parts are good or bad? no motor in car now. A rebuilt MC is $38, booster is $198, dont know if you can buy a pedal assembly anywhere. Plan was to get old stuff, and new MC and clean it all up and do the conversion so only questionable part would be booster.
?
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boosters seldom go...master cylinder is probably good..that is what I would do...cost you more than $50 to find a pedal from a vendor type, I suspect
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Found an old 87 buick a guy is turning into a stock car, puts in his own complete braking system. $50 for pedal assembly, booster and MC if I remove it. Is there a way to determine if parts are good or bad? no motor in car now. A rebuilt MC is $38, booster is $198, dont know if you can buy a pedal assembly anywhere. Plan was to get old stuff, and new MC and clean it all up and do the conversion so only questionable part would be booster.
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That's a good buy, for two reasons.
1. Good price
2. you get to learn how to remove the assembly/learn the mechanicals on someone else's car.
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take the wrenches suggested in that link I gave you....plus a pair of side cutters just in case you run into tinnerman nuts used as lock nuts
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What is the difference on the brake pedal/arm? Cant look at car as its in the body shop. I'm assuming the vacuum brake booster actuator arm wont just hook up to powermaster brake pedal/arm??
Would save some gymnastics under the dash if it would!
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everything hooks up with no problem. The hole in the pedal is in the wrong place to provide the correct leverage and throw on the pushrod.
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What is the difference on the brake pedal/arm? Cant look at car as its in the body shop. I'm assuming the vacuum brake booster actuator arm wont just hook up to powermaster brake pedal/arm??
Would save some gymnastics under the dash if it would!
Dammit - I can't remember why - but they are NOT interchangeabl e. I know the brake arm / shaft attaches at a different spot, causing a different angle.
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yeah
here is a write up http://www.gnttype.org/techarea/brakes/Powermaster_to_vacuum.html (http://www.gnttype.org/techarea/brakes/Powermaster_to_vacuum.html)
I have done it in less than two hours from start to end....once I spent a lot more time because the pedal bolts had a couple of tinnerman nuts as lock nuts and I was too stubborn to get out of the floor and get some side cutters to snip them off.
I like to replace the vacuum block on the plenum with one that has a vacuum port aimed at the brakes. Others have tee'd into the pcv line. Many think it is better to install a new master cylinder...it might be, but some of this new stuff ain't worth a damn so I guess it is a personal choice.
You don't need to brake lines from the mc downward...you can just bend the originals a little so they line up with the new mc location
It used to cost less than $100 if you go to the wrecking yard for the pedal.
Some use the original pedal and drill a new mounting hole in it...should be a template somewhere online that shows where.
It takes King Kong to stand on the pedal if the system fails....that is for sure. I went up a curb one day to keep from hitting a school bus....
If you install the new booster, get under the dash, see where the pushrod lines up with the pedal, mark the location on the old brake pedal, take the old brake pedal off and drill a hole at the right place, then you can remount it and use it. Just be sure the push rod is not being depressed at all when the brake pedal is not being touched in order to prevent the brakes from partially locking after the pedal has been released following a stop
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Thanks guys, I have the pedal that came with the vacuum set-up, was just looking to be lazy. I hate under dash work, back cant take it anymore :icon_smile: . Got all old stuff out of a stripped car that didnt have a dash so removal was easy access. I hope old booster is good, dont know how to test it? Going to get a new MC, $35 with core swap, so cheap that its easier than cleaning up and painting old one.
Thanks!!
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don't throw the old m/c away.
You can apply a vacuum to the booster and see if it will hold it
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Stupid question time, how can I do this?
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well, you could use a Mitey Mite or you could hook a vacuum line from your engine to the booster's check valve for a few seconds, then disconnect it. After a couple of minutes, pull the check valve out of the booster and see if you hear the air hiss as it fills the booster.
I have seen very few that failed. If they do, it is usually just the check valve.
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stupid question #2, I'm assuming the check valve the round plastic thing coming out of the metal booster body that the hose connects to. This just pulls out?? The directions you sent me mention replacing a check valve, this is it?
Thanks again!!
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yes
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finished swapping the pedal/parts yesterday. Got a new master cylinder but used the old booster ( mistake :013: ) changing the frickin pedal is the worst part. One item that should be added to the tools needed list is patience, which I have little, cause anyone over 6 feet and 200 lbs will need lots and lots for that portion of the job. Also good call on the side cutters, had to fight with one of those nuts also. Anyway got it all done and bled and fired it up and the booster is bad :icon_oak: , why didnt I test that dam thing!!! Ordered a new one and its back under the frickin dash tommorrow to replace that.
Of all the things I've done so far on the GN, this one is by far the biggest PIA!
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You sure that booster is bad? I know it is possible, but, I have never seen one fail
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I am a bit over 200 lbs and 6 ft tall...when I started getting older, I always pull the seat out to make it more comfortable... otherwise it takes 15 minutes to find a way to wiggle out
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I agree with Steve, you may have gotten a bad one but highly unlikely. Make sure you have enough vacuum tested AT the supply side of the check valve, 18 inches. The booster should store enough vacuum for 4-5 pumps. Start the car, let it run couple minutes, shut it off. Pump the brakes 4-5 times, start the car, should feel the pedal drop a little. I also started to put the OEM style filters in the feed line to protect further as the cars get older. 6 bucks, cheap insurance. Back under my rock.
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Taking the seat out was contemplated, hindsight says that would have been a much better option. The booster is bad for sure, I pulled straight vacuum right from the port to it and when you start the car you can hear it hiss under the dash. Its sucks but changing it wasnt the worst part, you can kneel outside the car and lean in and get to those nuts, and there should be enough play to just unbolt the MC and move it out of the way to replace the booster. New one is supposed to be in Friday morning
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Everyone keeps telling me what a terrible idea it is to tee off the brake vacuum line? The PCV valve port is where I'm pulling vacuum. The conversion write up tee's into that line, can i pull vacuum to the PCV valve from a different line and run straight from old PCV port to booster?
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Didn't you get a new vacuum block with an extra port for the brake booster. I get mine from Caspers if you didn't.
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finished!!! :rock: Ran straight vacuum from old PCV port to booster. Ran a different line from PCV and tee'd into line going to charcol canister. Works and looks good, pedal seems maybe a little soft at first, might have to bleed them again.
Thanks for all the help!!! :atbeer:
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Make sure the proportioning valve is brass and not iron
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Didnt check that, its whatever GM put in. I'll look tonight. That link with "how to" didnt mention changing it out so I never looked at it.
Thanks
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Cars originally came with iron. GM came out and advised a change to brass because the iron tended to corrode and not work properly. I found an improvement when I changed them out.
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Finally found sometime this weekend to do the brake conversion. Overall the project in my opinion wasn't that bad. The brakes work but I feel that the pedal's is soft. I need to press the pedal approx. 1/2 way down before the brakes start to grab. With that said I took the car out and overall the brakes work well.......Sho uld I be concerned with a soft pedal or is this a characteristic of the conversion. I bled the brakes well, also notice that when I step on the pedal that the brake fluid bleeds back into the master cylinder. Is this OK??
Thanks
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Here is another couple of sites for the vacuum brake conversion:
http://www.tomsttype.com/html/vacuum_brake_install.html (http://www.tomsttype.com/html/vacuum_brake_install.html)
http://www.montecarloss.com/community/ubbthreads.php?ubb=showflat&Number=757283#Post757283 (http://www.montecarloss.com/community/ubbthreads.php?ubb=showflat&Number=757283#Post757283)
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I am probably long ago used to the pedal...I think it has more movement but should firm up pretty well.
Altho I normally use either a vacuum pump or the injector type bleeder depending on which I find first, I often drive the car for a few days and then do a gravity bleed by opening all four bleeders and let them drip for awhile (thru a hose to a glass or jar). Just be sure to watch the reservoir to not let it run low during the process
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Sometimes air gets trapped in the front of the master cylinder sits it's tilted so much. You may have to tap it with a rubber mallet while you're bleeding it. When I did mine, it seemed the pedal was more solid with normal travel.
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getting the master well bled is 75% of the battle...I have pulled off the old and put the new master/booster on after a good bleeding and had good brakes even before bleeding at the wheels
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I agree, Steve. But the other 25% possibility of air getting into the system after a successful bench bleed is: the last line connections at the master cylinder, accidental air getting in during normal bleeding, and prior air from before the conversion (and I'm sure numerous other reasons). If any of these happen, the air could find it's way to the high spot of the master cylinder.
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That is the reason that the injector should work well...persona lly, I have not seen much difference...a nd, I was not disagreeing with what you said :)
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I wasn't figuring you were disagreeing, just adding another perspective. Not everybody has an injector. Even an injector has a difficult time getting the air trapped in an inclined master, rare as it is.
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There's aftermarket hydro boost electric motor brakes on the Web, I can't recall the place right now,but if didn't want vacume,an didn't want factoy failer again. there that last option
Enjoy!