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).
Valve spring settings, friction tests on a Silver Ghost, and spring leaf modifications.
| Identifier | ExFiles\Box 43\2\ Scan145 | |
| Date | 8th May 1926 | |
| Oy1-E-5826 -7- May 8, 1926 VII. (cont'd.{John DeLooze - Company Secretary}) However we found that with the valve springs we have been using we get 450 lbs. maximum pull on the Lovejoy strap. We replaced the valve spring by the lightest type and used pack-ing washers under the plug giving the following effects: Spring load on valve. Load on Strap 20 90 35 - - 157 40 - - 180 Of these we think the 40 lb. setting is comparable with the riding quality obtained with R.H. friction-type set at 50 lbs. It is a matter of further trial whether 35, 40, or 45 lbs. will give the best results. The effect of a change of 5 lbs. is very noticeable. The tests so far have been on a Silver Ghost without front brakes. We are very anxious to obtain a set of the new R.R. hydraulics for the front. We believe there will be a big demand for these from owners of existing cars. VIII. Internal friction of springs. Tests which we made on the original springs of 12-MG did not show excessive friction. The testing machine generally shows about 100 lbs. difference between up and down readings on front springs when newly made and greased. This may increase to 150 lbs. after service. We have recently called for a slight easing-off of the end of the spring leaves leaving a gap of .035 between the end of each leaf and the next leaf. This was because we found that sharp ends on the leaves caused them to dig in after a time particularly where there was much negative camber. Yours very truly, MO/E | ||