How To Tell of Brakes are Functioning as Designed

Status
Not open for further replies.

ed1948

Royal Smart Person
Aug 6, 2016
1,286
1,613
113
Quinte West, Ontario
I know that sounds like a stupid question. The only other G Body driving time was a few years with my 79 Lemans wagon. My 86SS, stock, does not seem to have confidence inspiring brakes. No, I have not hit anyone/anything yet which means the brakes function. Here are a few details and observation.
-after a short trip front brakes will be too hot to touch while rear drums are barely warm(I realize front brakes do about 75% of the work)
-brake pedal effort seems high when compared to new, all disk cars
-no swerving or change in direction when braking hard
-emergency stop almost has front wheels locking up
-parking brake will hold on an incline, Using parking brake to slow(in neutral) from 10mph takes 100 feet
-new flex lines last year, brake system bled - no bubbles, pedal firm, rear shoes adjusted for just minimal shoe drag, parking brake adjusted to spec, recent tires
-last year I had air bubbles in the rear lines and the shoe to drum gap was loose.

I don't want to throw parts at it. My concern is the huge temperature difference between the front and rear brakes. The previous , previous owner replaced disks and pads, shoes and drums within the last 10K. Visually all parts like near new, no leaks and all is clean.

Wondering, though, about the pad and shoes - possibly they're not matched?? Perhaps the rear shoe friction material is too hard? Maybe this is normal for stock G Body's??
A good start would be to replace friction materials with a good matching set but before I spend $ and get more grief from the financial director, is there anything else?
 

pontiacgp

blank
Mar 31, 2006
29,270
20,391
113
Kitchener, Ontario
Check to see if the wheel cylinders are loose, the retaining clip may be broken. Check the drums and shoes to make sure there is no glaze on their surfaces. Also check the flex line to make sure it isn't ballooning.
 
Last edited:

UNGN

Comic Book Super Hero
Sep 6, 2016
3,048
3,264
113
Southlake, TX
With power brakes, pedal effort is pretty much all the brake booster. Make sure it gets and holds vacuum. If you can lock the fronts, your brakes are working as designed for a daily driver. Locking the back is bad.

Turbo Buicks need to have a lot of rear brake to hold boost and you generally have to run larger tires in the back and remember not to panic stop in the rain to avoid rear lock issues. To achieve this -All long shoes and manual S10 wheel cylinders...but for high pedal effort, look at the vacuum system.
 
  • Agree
Reactions: 1 user

pontiacgp

blank
Mar 31, 2006
29,270
20,391
113
Kitchener, Ontario
When I changed the rear end from the G body rear with the wheel cylinder retaining clip to the A body rear with the bolt in wheel cylinder the increased rear braking was noticeable. The two rear ends use the same drum and the same size of shoes and I had the S10 wheel cylinder in the G body rear.
 

ed1948

Royal Smart Person
Aug 6, 2016
1,286
1,613
113
Quinte West, Ontario
-the rear shoes are adjusted to barely touch drum
-brake cylinders are secure
-shoes and drums were deglazed a few hundred miles ago
-booster holds vacuum
-backing plate is good
-auto adjusters free and lubricated

Just going by the temperature difference between the front and rear it seems the drums are along for the ride.
The parking brake is weak at slowing car down.
 

RegalBegal

G-Body Guru
Jul 10, 2009
705
747
93
Goldsboro, NC
Don't forget these cars had less than stellar brakes even when new. Espically if yours came with a single diaphragm booster. IIRC The Monte's came with those
 
  • Agree
Reactions: 1 user

MC96

Master Mechanic
Dec 7, 2015
458
492
63
Make sure the combo valve hasnt been tripped. Thats a fun lesson to learn

 
  • Informative
  • Like
Reactions: 2 users

Texas82GP

Just-a-worm
Apr 3, 2015
7,981
18,676
113
Spring, Texas
Maybe consider adding the bolt down brackets for the wheel cylinders to hopefully improve rear braking.
 
Status
Not open for further replies.

GBodyForum is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to amazon.com. Amazon, the Amazon logo, AmazonSupply, and the AmazonSupply logo are trademarks of Amazon.com, Inc. or its affiliates.

Please support GBodyForum Sponsors

Classic Truck Consoles Dixie Restoration Depot UMI Performance

Contact [email protected] for info on becoming a sponsor