Brake problems are among the most common issues encountered by owners of Holden HK, HT and HG models. These vehicles were produced with both drum and disc brake systems depending on model specification. Early HK models were commonly fitted with drum brakes on all four wheels, while front disc brakes were standard on luxury and V8 models and available as an option on Belmont, Kingswood and utility models. Like any hydraulic braking system, components can wear, deteriorate or become contaminated over time, eventually affecting braking performance.. When braking performance changes it usually produces clear symptoms that help identify the underlying fault. The following troubleshooting guide is based on factory workshop manual information and outlines common brake symptoms along with the most likely causes and remedies.
Excessive Pedal Travel (Low Brake Pedal)
When the brake pedal travels further than normal before the brakes begin to apply, the system may have a hydraulic or mechanical issue.
Possible causes include:
• Master cylinder fluid level low
• Poor quality brake fluid with a low boiling point
• Air trapped in the hydraulic system
• Brake hoses soft or expanding under pressure
• Excessive disc brake runout
• Wheel bearings or steering components loose or worn
• Brake shoe knock-back after hard cornering
Typical remedies include refilling the master cylinder with approved brake fluid, bleeding the hydraulic system to remove trapped air, replacing weak hoses and inspecting discs, wheel bearings and steering components for excessive movement.
Spongy Brake Pedal
A spongy or springy feeling brake pedal generally indicates a loss of hydraulic firmness somewhere in the system.
Common causes include:
• Low brake fluid level in the master cylinder
• Poor quality brake fluid in the system
• Air in the hydraulic system
• Brake hoses expanding under pressure
• Caliper seals soft or swollen
Repairs normally involve bleeding the hydraulic system and replacing contaminated brake fluid. In some cases hoses or caliper seals may require replacement.
Hard Brake Pedal
If the brake pedal requires unusually high pressure to stop the vehicle, the problem is often related to the power brake system or a restriction in the hydraulic circuit.
Likely causes include:
• Power brake booster malfunction
• Brake linings contaminated with brake fluid, oil or grease
• Brake lines, hoses or connections dented, kinked or blocked
• Master cylinder cups swollen
• Master cylinder bore corroded or rough
• Caliper pistons frozen or seized
• Caliper cylinder bores corroded or rough
• Brake pedal push rod or linkage binding
Correction generally involves checking the brake booster unit, replacing contaminated linings and inspecting the hydraulic components for corrosion, restriction or seizure.
Grabbing or Pulling During Braking
If the vehicle pulls to one side or the brakes grab suddenly when applied, the braking force is uneven between the wheels.
Possible causes include:
• Brake linings contaminated with brake fluid, oil or grease
• Loose brake caliper mounting
• Brake lines, hoses or connections dented, kinked or blocked
• Master cylinder bore corroded or rough
• Caliper pistons frozen or seized
• Caliper cylinder seals soft or swollen
• Caliper cylinder bores corroded or rough
• Pedal linkage binding and suddenly releasing
Repairs normally involve cleaning or replacing contaminated linings, tightening or repairing caliper mountings and inspecting the hydraulic components for damage or corrosion.
Brake Fade (Pedal Falling Away Under Pressure)
Brake fade occurs when the brake pedal gradually falls away while steady pressure is applied, or when braking performance decreases during repeated braking.
Common causes include:
• Poor quality brake fluid with a low boiling point
• Hydraulic connections loose or leaking
• Master cylinder primary cup worn or damaged
• Master cylinder bore corroded, worn or scored
• Caliper cylinder seals worn or damaged
• Caliper cylinder bores corroded or scored
• Bleed screw left open
The usual remedy is to repair any hydraulic leaks, replace worn hydraulic components and refill the system with approved brake fluid before bleeding the system thoroughly.
Brake Noise, Chatter or Squeal
Noise during braking may indicate worn components, incorrect adjustment or contamination within the braking system.
Possible causes include:
• Bent or worn brake backing plate
• Brake shoes slipping or rubbing against the backing plate
• Brake shoes scraping due to incorrect clearance
• Incorrect brake shoe lining
• Foreign material embedded in the lining
• Brake drum distortion or poor condition
• Brake shoes not seated properly against the backing plate
Typical corrections involve machining brake drums, installing correct linings, lubricating contact surfaces and adjusting brake shoe clearance. A small amount of high-pitched squeal can sometimes be considered normal with disc brake systems.
Dragging Brakes
Dragging brakes occur when the brakes fail to release completely, causing the vehicle to feel sluggish or as if it is being held back while driving.
Possible causes include:
• Brake lines, hoses or connections dented, kinked or blocked
• Master cylinder compensating port restricted by a swollen primary cup
• Residual pressure check valve fault
• Caliper pistons frozen or seized
• Caliper cylinder seals swollen
• Caliper cylinder bores corroded or rough
• Hydraulic push rod at the power brake unit out of adjustment or binding
Correction generally requires inspection of the hydraulic system, freeing seized components and ensuring that the pedal linkage and push rod operate freely.
Brake Service Tools
Factory workshop manuals for the HK, HT and HG models also list special service tools used for brake maintenance. These include a brake shoe adjusting tool designed to engage the adjusting wheel through the backing plate and a handbrake rear cable remover tool used to compress the retaining spring cap during removal of the cable from the backing plate. While many modern mechanics use alternative tools today, the factory tools ensured correct adjustment and safe servicing of the brake components.
Understanding Brake Symptoms
While this troubleshooting guide helps identify the likely causes of brake problems on Holden HK, HT and HG models, the complete repair procedures, adjustment specifications, diagrams and step-by-step servicing instructions are contained in the official factory workshop manuals.
While this guide helps identify common Brake problems, the Holden workshop manuals available from Car Manuals Direct include the original specifications, adjustment settings and repair procedures used by Holden mechanics when these vehicles were new.