Gn brake problem

[Al Peters]

My 86 gn has vacuum assist brakes and they dont hold boost very well. Can I make them work better or should I give up on the system?

 

[87GNSteve]

If the check valve in the brake booster doesn't work it will hot hold well. Easiest way is to pull it out and see if you can blow though it. Some guys add a check valve in the line between the booster and manifold.

 

[Al Peters]

Thanks Ill check on that check valve.

 

[Clark6]

Also what is your boost psi sat at?
After you do the s-10 brake pads and back wheel cylinder which you should hold a few more.

Check to see what your boost is at maximum.

I have found that with my vacuum brakes the higher i turn up the boost the less they will hold... the more I turn down the boost the more I could hold on the line by foot brake. At 17 psi I can hold 5-8lbs. of boost on the foot brake 20psi. 0 lbs of boost and higher it gets less and less. I have the s-10 set up but a 3000 stall. @ 20 psi I can hold 0boost which is right at 3000rpms right before it creeps forward.

 

["Reaper"]

Did you check to see if your rear brakes are adjusted right they may be to loose?Also you can get these.
1984 1985 1986 1987 Buick Regal Grand National Turbo T T-Type GNX SOFT COMPOUND REAR BRAKE SHOES (4) SET #6722

Shaun

 

["Turbo-T"]

Are you at the track when foot braking boost? If so are you doing a foot brake burnout without a line lock? Heat on the rear shoes will cause them to not hold as well.

BTW welcome from another Missourian.

 

[Al Peters]

Im running 21 lbs of boost. And im doing a line lock burnout but I have stock brakes and wheel cylinders.

 

[84BuickGNYorkPA]

Try after you stage the 1st light, drop the tranny in neutral, give the motor a rev(this will give the brakes more vacuum )and push the brake pedal on hard. Then pull the tranny into drive and bring the throttle up, inching up just a hair to trigger the 2nd stage light, then smash the brake to the floor and stand on the throttle as the lights drop......

Chuck

 

[2QUICK2B6]

Try after you stage the 1st light, drop the tranny in neutral, give the motor a rev(this will give the brakes more vacuum )and push the brake pedal on hard. Then pull the tranny into drive and bring the throttle up, inching up just a hair to trigger the 2nd stage light, then smash the brake to the floor and stand on the throttle as the lights drop......

Chuck

Thats what i do and i have the rear s 10 brake upgrade and soft compund shoes

 

[Roger]

84 / 85 hydroboost doesn't use vacuum or elec, neither does standard (no boost) setup.