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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).
Analysis of the advantages and disadvantages of using a detachable sub-frame on chassis-less cars.

Identifier  ExFiles\Box 144\4\  scan0064
Date  12th April 1940
  
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Separate sub-frames. Eight replies have been received. One of these contained only a proposal form. Of the remainder none charged more for a Morris than the other two. Two charged more for a Vauxhall than for either of the other cars. These were W.Howe, Slater & Co. & Bell (H.O. Brierly Broker).

Two required a higher premium on the Ford than the other cars.

It appears that the lack of a detachable sub-frame does not involve the payment of increased insurance premium. It is reasonable to suppose from this that the lack of a detachable sub-frame does not increase the cost of repairing collision damage.

Other factors to be taken into consideration in deciding for or against a removable sub-frame are :-

(1) Effect on overall stiffness. (2) Silence & (3) Ease of Assembly.

(1) Overall stiffness. The Vauxhall & Morris tens have the same torsional rate, axle to axle. Good stiffness can be obtained with either type of assembly.

(2) Silence. A bolted sub-frame is unlikely to reduce noise unless rubber is interposed between the body and the sub-frame. The use of rubber here has been accompanied by a serious reduction in stiffness.

Dash to floor details and axle and engine mountings all affect noise more than permissible variations in the sub-frame fixing.

(3) Ease of Assembly. For economical assembly of chassis-less cars the main units have to be resting on the track in pre-determined positions by the time they meet the body. although a separate sub-frame affects the arrangement of the components it is doubtful if it simplified the operation.

A removable sub-frame does concentrate loads at the attaching bolts and both the body and the sub-frame require local strengthening.

TO sum up, there are no outstanding advantages to be gained by the use of a detachable frame extension,
Cont'd.{John DeLooze - Company Secretary}
  
  


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