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Quantum drum brake cable problem

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  • Quantum drum brake cable problem

    Hi all,

    I've just been servicing the brakes on my 912 Quantum which is fitted with rear drum-brakes and was concerned to find the inner cable had deteriorated badly where it is clamped to the operating-lever on the back-plate. Several of the strands were broken and the only option was to replace the cable inner. The problem wasn't that obvious until I had removed the large coil-spring which covers the part of the cable affected.

    Investigation has revealed the bolt that clamps the wire strands doesn't pivot, but just clamps the wire tight to the lever. Flexing of the wire at the clamp-point each time the brakes are operated stresses the wire and the strands eventually break. What is really needed is the arrangement as on the carburetor-linkage where the clamp pivots so the cable always pulls in a straight line. It's not rocket science but proves what a cr@p design the drum brake unit is.

    Brake failure could obviously be a major problem in the wrong circumstances, so I think it's worth anyone with the drum-brake setup having a close look at the state of the brake cables on their machine. Other than a 50 hour check of the cable adjustment and an unspecified interval to inspect the brake-shoes, there's nothing in the Inspection and Service Schedule to check this part of the mechanism.