When I see posts to the list where I know the obvious and simple answer,
I often don't respond and await other people to have a chance to see
their own postings. It is always satisfying to be able to share your
technical knowledge to the less informed.
Unfortuantely, in this instance, all the posters have missed the mark by
a wide margin. It is amazing how some of these myths get repeated often
enough to actually become accepted as fact.
Specifically, this is the cause and effect where MGs in the Americas are
prone to having more squat on the left side suspension.
Please, disregard previous posts that stated the factories have always
used the different sized tires and the air pressure was different at all
corners. The actual explanation is somewhat technical so it is not
surprising that all of you have missed it.
It is common for the left side springs, especially on left-hand drive
cars, to develop a squat over time. You must remember that the engine in
our LBCs rotate in a clockwise direction. This is easy to rememeber:
This rotation is continued all the way to the rear axle where it
contacts the front of the differential gear. As that gear is on the left
side of the axle, clockwise rotation results in forward motion.
What occurs is that the high-performance engine in our MGs, with their
prodigious torque output, cause a twisting action to the frame which
exerts tremendous pressure onto the left side springs while unloading
the right side springs. Not surprisingly, it is always much easier to
spin the right side tire than it is the left side.
This has been known since the beginning of the automotive revoultion. In
England, with their cobblestone streets, the engineers decided that they
would need maximum traction on this right wheel. Thus they have
right-hand drive cars so that the weight of the driver would help
traction on this obvious drive wheel. That the fuel pump is on the right
side was only a secondary issue (added weight) but mainly so that the
gas doesn't have to be pumped uphill as much when postioned on the
right. Obviously, the fuel filler is also on the right side to assure
that the car is always fueled from the "uphill" side. The exhaust is
placed on the left side, naturally, to expell the gases as close as
possible to the ground thus easing air-borne pollutants.
Americans choose left-hand drive by design, also. At the turn of the
century, most of our roads were dirt and quite rough. Thus, extra weight
would be determinental on the suspension. If the right wheel was heavily
loaded on the right side, it would provide a much stiffer ride thus not
allowing the drive wheel to follow the contours of the bumpy road quite
as well. Thus having the driver on the left allows for a comparitively
lightly sprung right drive wheel that allows the spinning tire to follow
the contour of the road better and, thus provides better traction.
Also, at that earlier time, the auto manufacturers knew the roads would
eventually be paved. If the driver was on the left, the right wheel tire
would spin easier. This would result in a squeal that would imply a high
horsepower engine. Horsepower, real or implied, was thought to enhance
sales. Thus marketing would have the opportunity to sell more perceived
horsepower than real horespower.
This sales benefit was the reason that limited-slip differentials took
so long to catch on. The auto manufacters banned their use (along with
high-MPG carbs and self-charging batteries) for as long as they could so
they could market horsepower without producing horsepower.
Once they lost that battle and limited-slip axles became more prevalent,
they contracted with the tire manufacturers to produce tires that would
hold extremly high pressures. Even though 24 to 28 pounds of air
pressure is sufficent to keep the rims off the pavement, selling tires
that could keep 32 to 40 pounds or more would make for a stiffer tire,
thus a smaller contact patch, and, of course, the tire would spin easier
thus making up for the loss of percieved horespower with the limited
slip axle.
There is a simple soultion to the left-rear squat, however. Always park
your car pointing inwards so that you must use reverse whenever you wish
to go somewhere. Then, when backing up, always use the maximum amount of
power. This provides the inverse action of applying maximum weight
transfer to the right side springs which, over time, will have the
springs set more evenly. This, naturally, is why it is more common for
Americans to have long driveways than our English firends, who often
just park on the street.
Please excuse this rather long post but I couldn't sit back and watch
all this mis-information being spread on this beloved list. It is
refreshing to be able to provide technical knowledge, however, instead
of the usual jocularity and silliness.
Bob Allen, Kansas City, '69CGT, '75TR6
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