From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Brake squeaks and inefficiency, detailing specific vehicle cases and material investigations.
| Identifier | ExFiles\Box 47\2\ Scan400 | |
| Date | 21th November 1930 | |
| Hs{Lord Ernest Hives - Chair}/GWHL/AD21.11.30 contd. -2- cars. These dampers were fitted to their respective Brake Squeaks. GN-148 Front brakes GN-142 " " XJ-193 " " GN-132 " " } These are recurrent squeaks. In the case of GN-142 the owner, Mr.Lenard, was very bitter in his remarks re the brake squeaks and inefficiency. He is a very fast driver and after using the brakes several times, the efficiency has dropped so much that to pull the car up he has to literally stand on the brake pedal. We cannot, at the present time, do very much for this complaint. The reason for the inefficiency is that with the present brake drums the heat is not got rid of quickly enough and the brake linings lose their coefficiency of friction. We changed the lining of the rear brakes in production to bonded ferodo because of this feature, but we cannot use this material on the front brakes because of its squeaking. It is, however, possible to use it with the anti-squeaking device, and is being used. We still, however, are not free from the inefficiency of brakes when hot even with bonded ferodo, and at the present moment we are trying out a new material for overcoming this inefficiency when hot. The attention of W.W. has definitely been drawn to this inefficiency during the visits to W.W. but it has not been pressed in view of the trouble we had with lost movement of the brake pedal which has been considerably improved. It will be again taken up with them in view of the above complaint. There is another feature in regard to the brakes which I came across (but was not a complaint), which has a bearing on the above, that is the sponginess of the rear brake drums. We have been aware of this but have not realised the effect it would have in case the drum had to be machined out when badly scored. In the case I saw and investigated at Cricklewood, the drums, after they had been ground out approx. .060" were so spongy that the brakes, which had been relined, were not at all efficient and the hand-brake was almost useless. | ||