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).
Modifications to the Phantom IIa rear wheelarch and subframe for larger tyres and improved clearances.
| Identifier | ExFiles\Box 14\8\ Scan192 | |
| Date | 21th December 1929 | |
| TO BY.{R.W. Bailey - Chief Engineer} FROM EV.{Ivan Evernden - coachwork} HS.{Lord Ernest Hives - Chair} x7380 EVI/21.12.29. COPY TO SG.{Arthur F. Sidgreaves - MD}HS.{Lord Ernest Hives - Chair}EP.{G. Eric Platford - Chief Quality Engineer} HO.JIB. REAR WHEELARCH CLEARANCES. PHANTOM IIa With further reference to our EV{Ivan Evernden - coachwork}6/EBN20.12.29. re the above we have now translated our road tests on the drawing board. To obtain the fouling on the roll which we experienced we discover that point of pivotting of of the unbumped wheel must be at the centre of the top plate of the spring. In our tests this occupied a position produced by the car being loaded so that the springs were in a condition of being 1.000. short of fully loaded. We have taken this as the condition to be catered for. It will be seen that, in the case of a lighter loaded car the pivot point is lower and the "tucking in" of the bumped wheel is increased. We send herewith N.Sch.3003. shewing the revised wheel-arch clearances which we wish you to add to the subframe print, and which are based on our tests and investigations. The subframe is cut away the amount suggested by the Expl. Dept. but in not quite the same way. The heelboard is cut away also, and its fixing to the wheelarch is dispensed with. It will be necessary to cut away the subframe support bracket packing and rubber to suit the bottom flange of the subframe. With reference to the clearances for the tyre itself, in accordance with our agreement with "C". we have shewn clearances for the Dunlop Buttress Tread Tyre. Fort Type. 33x6.750. also known as the 7.000. section on a 21ins. rim. This is also equivalent to the India Tyre which is fitted. We wish in future all cars to be made to suit these larger tyres whether the car is delivered with them or not, as we fear that subsequently the owner will fit them either by choice or through necessity. We suggest that the following action should be taken. A set of revised prints should be sent to HD.{Mr Hayward/Mr Huddy} for him to distribute to all coachbuilders concerned on Monday Dec 30th. A letter should accompany the prints conveying the following:- "From experience we find that it would be advantageous to allow a little more clearance for the rear brake drums, and to cater for the Fort Dunlop Tyres being used. We only wish the modification to be effected in those cases where it can be done without delay or expense being involved. Where possible cars under construction should be modified by the coachbuilder. Derby will arrange with Sales to send our men to modify all frames lying at coachbuilders ready for use and those which will be delivered unmodified". Prints and a similar letter should be sent to Paris at the same time if possible but to make certain that they shall have the information as early as possible we sending them a note and sketches warning them of what is to happen. In order to cater for the larger tyres we wish you to increase the height of the front wing clearance circle from 16.000 to 16.500ins. The full-size drawing mentioned in our previous memo has not been made as we believe that this modified Subframe Print will shew the coachbuilder enough to enable him to modify the frames which he has already built partlt into bodies. | ||