brake booster

[76bonanza]

My brake booster is leaking can these be rebuilt? Or do I need a new one. Also mine looks like it is 11 inchs is this the standard size for our trucks? If so can I order any gm 11 inch booster? Thanks for your help.

[krue]

Boosters can't be rebuilt, just replaced.

[76bonanza]

Krue I changed my grommet and check valve and hose. After I shut down the engine I can open hood and hear hissing from rear of booster and if I leave it sit for about an hour I can pull the check valve and seems it has no pressure in it is this normal? Works great brakes good and all. Or do the bleed out the pressure after vaccum is removed?

[krue]

http://67-72chevytrucks.com/vboard/s...d.php?t=182131

Here's how to test your booster.

[Canadian72GMC]

To test your booster....... pump pedal to deplete all vacuum. Pedal should get hard. Hold pressure on brake pedal, and start the engine. Brake pedal should drop slightly toward the floor. The booster should also hold enough vacuum for 2 brake applications indefinitely. And yes, they absolutely can be rebuilt. There are several companies that can do this.

[76bonanza]

Ok I am pretty sure My booster is leaking one hour after I park it I press the pedal and it is stone hard no assit. Also with engine running in park idles around 900 hold brake in slow creeps up to about 1000 and stays untill I release brake then goes back to 900. Seems to brake ok tho.

Next question do I just go to autozone and replace it they are like 90.00 bucks. And if I get one for a 1968 will it be the same as I have now? Not sure if mine is stock or not.

Last question is it just a take off and bolt on deal? I dont have to drain fluid or bleed anything right? Just have someone hold the MC for me.

Thanks for all your guys help.

[76bonanza]

one more thing rubbed off paint and it is a delco 11" so I am guessing it is from a 71-72 I think they are the only ones that came with the delco What is the diff from the bendix and the delco?

Thanks agian

[krue]

They pretty much all interchange in that era. If I'm not mistaken I ran the parts numbers and all the gm boosters (cars and trucks) had the same part number (Oreilly's, and autozone). No bleeding necessary. Unbolt the m/c and tie it out of the way, unhook the linkage at the firewall, unbolt and reverse to install the new one. No difference in usage, just the way it looks.

[rwgregory]

Boosters can be rebuilt. I have copies of the GM factory overhaul manual for
power brake boosters. Send me a PM if interested.

[Bob B.]

Bendix booster were used from 1967 to 1970, Delco-Moraine in 1971-72. 1/2 tons usually had 11" single diaphragm, the 3/4 tons usually had a smaller diameter dual diaphragm booster.

[76bonanza]

Would you say the rebuilds from napa or autozone would be ok? Or is there some were else to get better ones?

[truckdude239]

http://www.partsamerica.com/ProductD...pe=250&ptset=A 89.88 (with new mc) 20 buxs core returnable to any advance auto lifetime free replacement. or http://www.partsamerica.com/ProductD...pe=250&ptset=A
77.97 (without mc) 15 dollar core but for an 12 buxs difference i'd get the one with new mc plus they both hasd lifetime free replacement you and return them to any Advance Auto, Checker, Schuck's, or Kragen store near you

[Swbman]

Brake Boosters can be rebuilt, I recently had the one on my 3/4 suburban done after an engine fire, could of have just gotten a used one but decided to play it safe since I use the burb to pull a car trailer,it cost $70.00.I think Oreilys wanted 199.00 for a rebuilt one .

[76bonanza]

no advance auto, checker or kragne in this neck of the woods but the ones from napa and autozone are about same price with lifetime warrenty.

[truckdude239]

heck for 70 buxs i'd get add an extra 7 buxs in and get the one without the mc that i listed above that way i know its done right and has an warrenty just my $.02

[76bonanza]

Just looked truckdude the one autozone and napa sell is the exact same one that advance has cardone same part number. I will get the one w/o MC my M/C is brand new and dont really want to bleed anything as the brakes work great just leaking vaccum thru the booster

[truckdude239]

thats cool i didn't see your post above mine that last time i posted didn't want to seem like an azzhole but that sounds good to me everything i buy has lifetime free replacement so when it goes bad i don't have to pay for an new one lol

[dwaite72lnghrn]

I always thought they were not interchangeable without the MC because the piston length was different between the two units. Mix them up and brakes would not apply all of the pressure it could or would never drop the pressure all of the way?? Just what I heard. Someone enlighten me please.

[krue]

As far as I know you can mix and match, the rod between the two is adjustable. I've never paid attention to what brand I used and haven't had a problem.

[76bonanza]

How do you go about adjusting it? Or do I just adjust it to match the old one?

Thanks

[krue]

I adjust mine in so that when I push the m/c on the booster there's not a lot of resistance (not engaging the brakes). I try to leave a little bit of slack (1/16th of an inch or so). It's hard to explain, but fairly easy to do.

[76bonanza]

I think I understand when you put them together the rod should not push in on the MC valve.