Monday, January 23, 2012

Problems in Motorcycle Braking Systems – Possible Causes and Remedies

We all know that brakes are very vital components of any bike. The properties, characteristics and behavior of brakes do not always remain the same. These are influenced by temperature, operating habits, operating durations and effects of interconnected parts.
Just like clutch (you can read my article on clutch awareness here), we mostly get agree to replace our brake liners on just one note of vehicle inspector at service station. Many of the problems related to brakes can be resolved by adjustment or repairing of one or other component. Let us have some idea about common problem arise in brake system, their possible causes and remedies.

Brake Fade

Incidents in which the brakes fail to hold on the wheels on prolonged application is known as brake fade. The friction behaviour of the brake changes due to temperature and deteriorates with an increase in temperature caused on account of prolonged use.
Possible Causes and Remedies
Brake fade is caused due to repeated severe application of brakes which causes expansions of brake drum, or loss of frictional ability of brake lining, or both. If so, reduce speed/ load and use lower gears. The brake fade vanishes and the brake effectiveness is restored as soon as the brake lining cools down. Brake fluid may have deteriorated in this case. The same could be flushed out and fresh fluid of correct specifications required to be filled in. Poor contact between brake lining and the drum can also cause brake fade.  In this case, the shoes may be ground to correct radius and/or adjusted. Many of us are in the habit of riding the brake pedal, which causes the brakes to drag and thus became excessively hot, leading to brake fade. The driver should not keep his foot on the brake pedal or should not hold the brake lever pressed unless specifically required.

Brake Binding

This is a condition in which the brake gets a tendency of binding the liner to the brake drum and remains in applied state without pressing the brake lever. It is also known as brake dragging.
Possible Causes and Remedies
One of the key reasons of brake binding is defective springs. The brake shoe retracting springs or the pedal return spring may be weak or broken, which should be replaced immediately. Another reason includes jammed brake shoes over the anchor pins. Brake binding can be eliminated by lubricating this anchor pin. In the case of disc brake, the fluid level in the reservoir might be kept excessive which should be rectified to remove brake binding.
Brake Overheating
The overheating of the brakes is most likely due to the same reasons as for brakes binding. Overheating tends to decrease the friction properties and increases binding.
Possible Causes and Remedies
Apart from above said reasons, they may occur also after prolonged use of brakes while descending a slope. In case of disc brakes apart from the above, the piston in the calliper may be seized. As remedy of this, the calliper has to be rebored and the piston should be replaced.

Brake Judder

It is an experience in which a ringing noise radiates from the brakes.
Possible Causes and Remedies
Brake judder may be either due to wrong brake adjustment, which may be corrected, or due to the brake lining rivets being loose, in which case the lining has to be attached again with new rivets. In most cases, the lining also needs to be replaced.

Grabbing Brakes

It is a state in which the brakes are either seized or have a propensity towards seize.
Possible Causes and Remedies
In the case of drum brakes, very usual reason for grabbing is greasy linings. Sometimes worker forgets to clean the liners before assembling which leads to grabbing after some use. Brake grabbing could be reason of wrong adjustment of shoesScoured brake drum also causes grabbing of brakes. The same can be eliminated by grounding the drum within limits. It is also possible that dirt or dust may have entered the brake shoe assembly. It should be cleaned to remove the brake grabbing. A very unusual reason of grabbing is interchanged shoes. Primary and secondary shoes may have been reversed by mistake. Grabbing disappears if shoes are reinstalled correctly.

Excessive Loss of Brake Fluid

As name suggests, it is related with oil leakage form disc brake system. This leakage could be possible from joints, benzo bolts, calliper side, plunger assembly, or reservoir. Brake oil leakage reduces braking effectiveness and includes high maintenance cost if remains uncontrolled.
Possible Causes and Remedies
Major leakages happen at reservoir and calliper, which can be inspected and repaired or replaced as necessary. Another frequent reason of brake fluid loss is loose connections at various joints. Connecting pipe or hose damage should be checked, which has to be replaced soon to avoid further fluid loss.

Presence of Air in the Brake Line

This defect arise particular in disc brake assembly because disc brake works with incompressible brake oil. This incompressible oil acts as a linkage between brake lever and calliper piston. It is a way by which brake lever force gets magnified and applied to the calliper piston. For this purpose, brake oil should have high viscosity. This whole system fails even if a small amount of air enters into the brake line because air is a compressible fluid. Air remains in the form of bubble and compresses itself at the time of braking, resulting in reduced braking effect.
Possible Causes and Remedies
Only leakage can produce air bubble in brake line. Reservoir or calliper may have some defects causing the leak of air inside the system. This leakage should be repaired or replaced if required. Any loose connection can be tightened properly to avoid any air bubble to form. The very safe remedy for air bubble is bleeding of brakes. It is advisable to perform this maintenance process at genuine service station.
I hope you all have enjoyed reading this article and will be helpful to you in future. Leave your valuable experiences and comments.

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