17-12-2018, 11:16 PM
The thing to remember about the "second spring" is that it's mythical.
The Blue Book says that the throttle return spring must act directly on the the throttle spindle (so that if the throttle control mechanism fails the throttle will shut). This frequently means a second spring on a road car (and a second one is always wise in any case) but the important part is that it acts directly on the throttle spindle.
Blue Book wording:
5.4.2. Be equipped with a positive method of throttle closing by means of external spring/springs so that in the event of failure of any part of the throttle linkage the throttle(s) are sprung closed.
The Blue Book says that the throttle return spring must act directly on the the throttle spindle (so that if the throttle control mechanism fails the throttle will shut). This frequently means a second spring on a road car (and a second one is always wise in any case) but the important part is that it acts directly on the throttle spindle.
Blue Book wording:
5.4.2. Be equipped with a positive method of throttle closing by means of external spring/springs so that in the event of failure of any part of the throttle linkage the throttle(s) are sprung closed.