by brian_bp » Sun Aug 05, 2007 9:55 pm
Gerdo... about the Toronado and drag racer examples:
The important thing is the location of the centre of the tire relative to the bearings; where the hub face happens to be is irrelevant, since the bolted-together parts act like one big part for this purpose.
The Toronado (and everthing front-wheel-drive since) have lots of wheel offset and lots of hub offset, putting the tires in line with the bearings - the force (not really "pressure") is not way out from the bearings. The offset is particularly noticeable in the Toronado wheels because it was unusual for the time, and because the wheels were so narrow (compared to today).
The dually front wheel (turned inward for large offset) plus spacer (whether there really is a spacer or it's built into the hub) adds up to required net offset.
The Toronado and dually front are essentially the same configuration, with the wheel offset providing clearance for hub components, whether for drive components (the FWD Toronado) or just a spacer. The GMC motorhomes based on Toronado drivetrains actually use dually wheels, in single configuration both front and rear, because back then (the 1970's) those were the only wheels sized for truck tires which had enough offset. The rear suspensions, not driven or steered, are functionally the same as a trailer suspension, as with the rear of any front-drive vehicle.
Drag cars with obviously wild offsets of the tire centre from the bearings have solid axles. Unless they're full-floaters, the axle shaft is part of the hub, carried by the outer bearings (at the ends of the axle housings) and the inner bearings (in the final drive or centre section). This huge span between bearings means that the leverage of the offset tires isn't fatal to the bearings, which have the halfshaft for leverage. Trailer axles are like front suspensions, not like driven solid axles - inner and outer bearings are close together.