Why are some PreWarCars chain driven?

I suppose the main reason for the separate chain drive is the dimensioning of the differential and its wheelsets. Because the chain drive has a strong reduction ratio, the differential can work with a higher speed and therefore with considerably lower forces. For the same reasons, the planetary wheel sets that had long been commonplace were used in the front axles of all-wheel-drive heavy trucks.

Frazer Nash used chain drive with separate gear wheels and dog clutches. This removed the need for a gearbox and differential. Therefore they did not go round corners, they just changed direction.

Perhaps our correspondent means cars like GN and Frazer-Nash that used a chain transmission, as opposed to merely chain final drive? I'll leave it to someone from the "Chain Gang" to explain that one!!

If two drive chains with rear wheels loose on a dead axle I would think the right angle drive to the chain sprockets would have included a differential of some sort, either multi pinion or bevels.

Tony.

Mack trucks kept chain drive up into the 1930s.

For once I can perhaps participate with something: Chain drive is a simple solution to connecting a flexibly mounted rear axle to the bolted on engine and gear box, and I assume the likewise bolted on differential and distributor shaft. Chain drive is susceptible to wear and tear but with the limited mileage accumulated at that time and the extensive maintenance which would anyway be necessary that was acceptable. But of course it disappeared once solutions were found to connect the rear axle directly to the drivetrain.