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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 memorandum discussing vehicle handling, including understeer, oversteer, steering geometry, and caster.

Identifier  ExFiles\Box 170\3\  img105
Date  31th October 1936 guessed
  
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(2) Continued:

have a quite pronounced understeer and will stand for quite a bit of the contrary effect.

* This might be done a little more exactly by making a roll-rate test on the car on platform scales as described in my SAE paper on Independent Suspension (Journal March 1934) and adjusting front springs and rear stabilizer till the roll-rates (i.e. rotary stiffnesses) at the two ends were equal.

(3) If the steering has an approximation to Ackermann geometry it means that the inside front wheel which is lightly loaded has the greater slip angle. It might prove better in this case to arrange the steering for parallel geometry, so as to put more of the cornering work on the outer front wheel.

This again is in the direction of oversteer and must not go too far, because of danger in handling.

(4) Personally, I should wash out all caster in the front wheels. It is quite unnecessary in independents since plenty of self-centering effect comes from the natural aligning-torque of the tires. And it merely makes the car more sensitive in handling to variations in the lateral force, and much more liable to wheel-fight.

At this distance I think this is all the contribution I can make.

It would be interesting to know whether any of it is useful.

Sincerely,
Maurice Olley
Maurice Olley

* re Doctor Poehler's IAE Paper of Oct '36 of which we have a print. he suggests another reason why front drive cars understeer namely that either traction or braking reduces the cornering power of tires & therefore calls for an increased slip angle.
'In summary' - while a front drive car is a necessity for ordinary road & track racing it is not the best thing in the world for a timed speed trial.
  
  


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