Recommended Vac. brake booster

ThikStik

My sleep apnea is winning
Hi. i got rid of powermaster awhile back. I got a junkyard cutlass vac booster and it went bad pretty fast and now hisses with pedal on and has little assist.. I replaced the check valve which was already ok. Last time i went down track the brake lights came on while at WOT..i guess boost was getting behind the diaphragm? I see that the parts stores have the booster for $$$ over the regular g-bodys but i guess thats a power master but cant verify. Thanks for any ideas. Rick
 

pmesfun

Active Member
I got a regal v8 booster from the parts store. It was around 140 with the master cylinder.

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whitehot1

Well-Known Member
I bought my vac. brake booster from AutoZone back in 2002 with the master cylinder and a lifetime warranty. The application was for an 1987 Monte V8. I've never had a problem with it ever.
 

ThikStik

My sleep apnea is winning
Now I see that there is a single and a dual diaphragm listed at Rockauto for the 1987 Monte.
 

fast86gn

Texas Moderator
Staff member
Wow... sorry about the booster going bad, those things seem to last forever most of the time. I got my Vac booster from a Junkyard Gutlass over 15 years ago and still going strong today.
 

ThikStik

My sleep apnea is winning
Regarding the B-body booster: The thread mentioned a possible mismatch of line fittings to MC. Im thinking that the MC must be paired to the B Body booster. Just not sure what to do now.
 

ThikStik

My sleep apnea is winning
Wow... sorry about the booster going bad, those things seem to last forever most of the time. I got my Vac booster from a Junkyard Gutlass over 15 years ago and still going strong today.
Thanks, I know Right! I got a v-8 cutlass one from the bone yard and it lasted about a week. i still dont get why the brakes apply slightly under boost...just my luck lol.
 

whitehot1

Well-Known Member
Now I see that there is a single and a dual diaphragm listed at Rockauto for the 1987 Monte.

Which ever the application you decide to buy the booster for get the dual diaphragm one. You may get a little better price on Rockauto but you won't get the warranty that Autozone offers. Chances are you will never have a problem with it but if you do it's good to know you won't have to pay out of pocket to replace it,ever.

This is something i use instead of the cheap plastic vac. check valve that the hose connects to on the booster. I did this after one of the cheap plastic ones failed and it reminded me of when the powermaster went out and i couldn't push the brake pedal down to stop.

http://rjcracing.com/product/rjc-pcv/

One more item that i use is this vac. block with the extra vac. port for the brake booster hose. My brakes never worked very good after the conversion until i added this.

http://www.kirbanperformance.com/pr...A+VACUUM+FITTING+FOR+VACUUM+BRAKES+#6797.html
 
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whitehot1

Well-Known Member
I believe the TTA style vacuum block is a must if your changing over to vacuum brakes.

You are right it should be a must to use.

But when i did my first vac. brake conversion a long time ago. I followed the conversion procedure in the techarea on gnttype.org. This is the step in that procedure that was recommended for hooking up the vac. hose to the booster.

12. Connect up the vacuum source. I used a plastic 5/16 "T" to connect the vacuum between the vacuum port on the throttle body and the pvc valve. I ran the hose between the back of the throttle body plenum and the coil pack straight to the port on the booster. If The hose were the same 'age' as the rest of the underhood stuff, it would not be visible. Everything looks very 'normal' and un-obtrusive. It has been suggested that you use small hose clamps (#4 I think) to prevent engine boost from blowing off the lines. I recommend you change the PVC valve while you are at it.
 

ThikStik

My sleep apnea is winning
Thanks all..yes I got the vac block that sits on plenum. I learned that the large tap for the brakes actually can un-screw itself as well!! I like the idea of the "tee". That RJC PCV vlve is also great advice. Ive been out of the loop and didnt know that problem was finally solved. I always get a rear main leak after beating on it.
 

Boxcars

Banned
Just my opinion but I prefer to "T" into the PCV line and run a 3/8" vacuum hose to the check valve on the booster. I didn't like this big hose off the TTA vacuum block running across my engine, plus at times I had problems with that vacuum nipple on the block.
 
I fought my vacuum brakes for years and finally fixed them once and for all. The brakes were so bad the previous owner even spent money on 4 piston ssbc front calipers, which did not help. I ended up drilling and tapping the lower intake manifold and running a dedicated 3/8" line directly to the booster. In my opinion the TTA style vacuum block does not provide sufficient vacuum to evacuate the booster. I also installed an inline check valve made for air brake systems on heavy trucks(which constantly exceeds120psi). I used Parker brand push lock hose and fittings. My brakes perform perfectly now.
 

fast86gn

Texas Moderator
Staff member
In my opinion the TTA style vacuum block does not provide sufficient vacuum to evacuate the booster.

I guess every car is different, I use the TTA block with no issues. I do have a few other brake upgrades but I can hold 10-15 lbs of boost at the line with no problems.

I will say this without naming anyone. This was back almost 20 years ago I was told by a respected Buick TR guru that if I go to vacuum brakes I would need a separate vacuum canister or there would not be enough vacuum under boost to hold the car still. Needless to say that is not the case.
 
It might have been a few bad factory check valves in a row. So I did what I always do and eliminate every possibility, weather it was lack of orifice size or inability to fight off boost. I fixed my cars issue.
 
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