Research from TRW suggests that only 2 per cent (4.2 million) of the European car parc changes parts such as handbrake cables on an annual basis. It is suggested that this figure should be much higher and workshop mechanics, fitters and technicians are strongly encouraged to check cables more regularly.
Types of Cable
There are two main types of cable, these are as follows:
1. Braided wires building a rope – Braided ropes building together the cable: give high flexibility
2. Braided wires building the cable: give high strength
3. Grease (MoS2) between the ropes and wires: giving low friction
OE dictates which design to use depending on flexibility requirements.
Why cables need to be changed
It starts with a little crack: The image above shows that the polyamide cover has been destroyed. Water and dirt have caused corrosion and the outer diameter is expanding. This means that the cable cannot slide freely anymore.
Most common failure:
The parking brake cannot be fully released which can lead to:
Grinding noise (high wear and tear)
And in the worst case the car won’t move
Less common failure:
The hand brake lever cannot be moved by driver
No hand/parking brake available
How to test handbrake and clutch cables
1. Test on a rolling road test bench
No significant dragging should occur
If a lot of dragging occurs the handbrake cable could be one of the reasons
2. Remove the drums
Actuate the hand brake lever and check whether the hand brake mechanism is working properly
Release the hand brake lever – the shoes have to go completely back to their rest position
If in doubt disconnect the cables and check the cables only
Always complete these tests before mounting new parts. TRW Handbrake and Clutch cables are tailor-made for each car and the specific needs of each braking system.