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 memo discussing brake judder on Spectre models and proposed solutions.
| Identifier | ExFiles\Box 92\4\ scan0077 | |
| Date | 13th June 1935 | |
| X306 To E.{Mr Elliott - Chief Engineer} c. to Wor.{Arthur Wormald - General Works Manager} c. to Da.{Bernard Day - Chassis Design} c. to By.{R.W. Bailey - Chief Engineer} c. to Hdy.{William Hardy} Hs{Lord Ernest Hives - Chair}/Gry.{Shadwell Grylls}6/HW.13.6.35. SpectreCodename for Phantom III Brakes. On both SpectreCodename for Phantom IIIs 2-S-1 and 3-S-1, which have semi-servo brake systems and consequently good brakes, we can produce a violent judder when decelerating from speeds above 65 m.p.h. This judder shakes the whole car and we originally believed was caused by the front brakes. Noticing a similarity between this judder and that on the Girling Bentley car, we ran SpectreCodename for Phantom III 2 with rear brakes only. The judder was still present as on the Bentley, and on this car we almost eliminated the judder by raising the line of pull of the rear brake ropes 1 1/2". On SpectreCodename for Phantom III 3 the judder is worse than on SpectreCodename for Phantom III 2 and the line of pull lower. We consider it essential that on SpectreCodename for Phantom III the line of pull of the rear rope should be raised as far as possible up to the Phantom position, i.e., the centre of the axle. Will Da.{Bernard Day - Chassis Design} let us have a scheme for this. We know that on the Phantom the rear brakes are slightly un-selfservo-ing, and that movement of the axle under braking forces is approximately a rotation round a centre 2" below its centre line. The Phantom amount of negative servo does not produce judders. Similar actuation on SpectreCodename for Phantom III should be a safeguard against this trouble. Hs{Lord Ernest Hives - Chair}/Gry.{Shadwell Grylls} | ||