C4 --
Corvette Overview --
1986 DIY Repairs --
THE 1986 CORVETTE DIY GUIDE - BRAKING
Braking
BRAKES

NOTICE: While Corvsport.com has made every effort to ensure that the instruction provided on this site is both complete and accurate, it is presented here for REFERENCE ONLY.  All vehicle maintenance and repairs should only be performed by a qualified technician or mechanic and should not be attempted without the proper tools and/or experience.  Improperly performed vehicle repair can result in damage, injury, and even death.   User discretion is advised.

CAUTION: When servicing wheel brake parts, do not create dust by grinding or sanding brake linings or by cleaning wheel brake parts with a dry brush or with compressed air.  (A water dampened cloth should be used.)  Many wheel brake parts contain asbestos fibers which can become airborne if dust is created during servicing.  Breathing dust containing asbestos fibers may cause serious bodily harm.

The following diagnosis chart provides probable causes for most mechanical issues involving the braking system.
PEDAL TRAVEL
At reasonably frequent intervals, the brakes should be inspected for pedal travel, which is the distance the pedal moves toward the floor from a fully released position.  Inspection should be made with the brake pedal firmly depressed approximately 70lbs while brakes are cold.

Pump the pedal a minimum of 3 times with the engine off before making pedal travel checks.  This exhausts the vacuum assist from the power booster.  Pedal travel should not exceed 2.75" (70mm).


BRAKE PEDAL
Removal


STOP LIGHT SWITCH
Adjustment
The design of the switch and valve mounting provides for automatic adjustment when the brake pedal is manually returned to its mechanical stop as follows:
BRAKE HOSES
Inspection
The flexible hydraulic brake hose which transmit hydraulic pressure from the steel brake pipe on the frame to the calipers should be inspected every 12 months or 7,500 miles (12,000km).  The brake hose assembly should be checked for road hazard damage, for cracks and chafing of outer cover, and for leaks and blisters.  A light and mirror may be needed for an adequate inspection.  If any of the above conditions are observed on the brake hose, it will be necessary to replace it.

BLEEDING AND FLUSHING BRAKE SYSTEM
A bleeding operation is necessary to remove air whenever it is introduced into the hydraulic brake system.

It may be necessary to bleed the hydraulic system at all four wheels if air has been introduced through low fluid level or by disconnecting brake pipes at the master cylinder.  If the brake piping is disconnected at any wheel, then only that wheel will need to be bled.  If pipes are disconnected at any fitting located between the master cylinder  and wheel, then all wheels served by the disconnected pipe must be bled.

When bleeding the rear brake system, the front of the car should be raised higher than the rear.  This will position the bleeder valve near the 12 o'clock position and prevent air from being trapped in the caliper.

Manual Bleeding
Deplete the vacuum reserve by applying the brake several times.





















FLUSHING BRAKE HYDRAULIC SYSTEM
It is recommended that the entire hydraulic system be thoroughly flushed with clean brake fluid whenever new parts are installed in the hydraulic system.  Flushing is also recommended if there is any doubt as to the grade of fluid in the system.  If fluid has been used which contains the slightest trace of mineral oil, all rubber parts that have been exposed to the contaminated fluid should be replaced.

Bleed the brakes in the following sequence: left rear, right rear, left front and right front.
PARKING BRAKE ADJUSTMENT


ROTOR SERVICING AND CHECKING PROCEDURE
Front
Raise vehicle on hoist or other methods that do not involve lifting the vehicle by the wheels.  Remove wheel assembly and replace two lug nuts to ensure proper disc alignment.  Clamp a dial indicator to the caliper so that its button contacts the disc at a point about 1/2 inch from the outer edge.  When the disc is turned, the indicator reading should not exceed .006".  If runout exceeds this amount, the hub and disc assembly should be repaired (turned) or replaced.

Rear
Dial indicate the disc face.  If lateral runout of the disc exceeds the bearing end play by .006" (.15mm), the disc should be repaired (turned) or replaced.

DISC MACHINING
The condition of the disc is a vital factor in the efficient functioning of the brake.

The disc should run true between the pads.  The maximum run-out permissible is .006" (0.15mm) and if this tolerance is exceeded, it may cause pedal flutter or increased pedal travel.  It is also essential that parallelism is maintained at less than .0005" (0.013mm).  The surface of the disc should be smooth.  The scratches and light scoring which appear after normal use are not detrimental to operation, but a heavily scored disc will impair efficiency and increase pad wear.

If the disc run-out exceeds .006" (0.15mm) or is heavily scored, it is permissible to machine the disc but the thickness of the disc must not, under any circumstances, be reduced below the minimum recommended figure of 18.4mm (0.724").  the minimum disc thickness must be obtained by removing equal amounts from both disc faces.  Under no circumstances should the maximum machining allowance be taken from only one face.  In cases where the disc does not clean up within these tolerances, a new disc must be fitted.

ROTOR THICKNESS


MASTER CYLINDER ASSEMBLY
The master cylinder assembly is an aluminum-plastic composite, featuring an integral proportioning valve/warning switch.  The cylinder has dual pressure chambers with a primary piston to supply hydraulic pressure to the rear brakes and a secondary piston to pressurize the front brakes.  The cylinder is designed for a conventional front/rear split brake system with one outlet for both front brakes and one outlet for both rear brakes.  The master cylinder has one reservoir mounted over, and supplying fluid directly to, the primary pressure chamber.  However, the reservoir is also connected to an adapter elbow to supply fluid to the secondary pressure chamber.





























REMOVE AND INSTALL MASTER CYLINDER ASSEMBLY
Remove

Install


TOPICS (Select One)
Symptoms & Causes
Pedal Travel
Brake Pedal Removal
Stoplight Switch
Hydraulic Components
Parking Brake Adjustment

Rotor Servicing
Master Cylinder
Brake Pads
REMOVE AND INSTALL BRAKE PADS
Remove
Install
PARKING BRAKE ASSEMBLY
General Description
The parking brake assembly operates on the Duo Servo principle, where the primary shoe is forced against the drum by application of the parking brake handle.  Force from the primary shoe is then transferred to the secondary shoe and multiplied by a wrapping action caused by drum rotation.  Stainless steel wear strips are attached to the aluminum housing to prevent premature or excessive wear.  All springs are stainless steel and other attaching components are plated.

CAUTION: When servicing wheel brake parts, do not create dust by grinding or sanding brake linings or be cleaning wheel brake parts with compressed air.  (A water dampened cloth should be used.)  Some wheel brake parts contain asbestos fibers which can become airborne if dust is created during servicing.  Breathing dust containing asbestos fibers may cause serious bodily harm.






























REMOVE AND INSTALL PARKING BRAKE COMPONENTS
NOTICE: Be careful not to damage wear shims.  If damaged, it will be necessary to replace the entire mounting plate assembly.
Remove
Install
DISCLAIMER: While Corvsport.com makes every effort to ensure that this information is complete and accurate, you should always consult the manufacturer of your vehicle if you have a specific issue or question.
Parking Brake Replacement
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