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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).
Technical report on brake performance and coachwork issues, including locks and body rattles.

Identifier  ExFiles\Box 108\1\  scan0367
Date  18th February 1936
  
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The Girling rear brakes which we want to standardise on the second half of 'M' Series have not given any trouble since the rod failure. We do not believe that there is the slightest possibility of a failure occurring now that the dimensions of the rods have been increased. The rear brakes have been progressive, well-equalised and entirely free from brake squeaks, in spite of the fact that no tipping shoes have been employed. Undoubtedly a lot of this is due to the increased width gained by incorporating the hand-brake shoes in the foot-brake shoes. If the Girling brakes are standardised on the last half of 'M' Series we should, of course, recommend that a cast iron rear drum is used as on Wraith. In contrast to the rear brakes, the front brakes, which are standard, have given quite a lot of trouble due to the leverage to the front having been too great on more than one occasion. It is quite clear that our brake area on the front of the Bentley is such that it is imperative to limit the amount of front braking whatever type of drum is used. With the cast iron drum it is particularly easy to over-heat them, and when they are over-heated they pull violently. They are also susceptible to judders. Judders occurred during our test of the car, and bent the front toggles. The brakes pulling to one side or the other were, in our opinion, responsible for low speed wobbles. Under conditions of snow, our standard front brake system is very unsatisfactory, because the brakes are likely to freeze on. This occurred previously when we were in America. As a result of this test, we are going to ensure that we have increased front braking area on all future designs. We are also ensuring that for the remainder of the test G.E.17. runs with the standard amount of front braking, and no more.

COACHWORK.

We are not clear as to whether any decision is to be made following the results obtained on the body of this car, but if so, somebody from Park Wards should try the car without delay, as there are various creaks and rattles which were not in evidence on the standard all-steel body.

We are falling out with the silent travel locks as they require constant lubrication if they are not to stick. The safety catch on the standard locks fitted to the Wraith in France does not seem too reliable, on two occasions a door has flown open.

We recently examined a new design of lock which has been developed by the Rover Co. and Messrs. Wilmot Breedon, and it appeared to be far more promising than any
  
  


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