Chris ,Jay Dick S. , Chuck N. , Jarrid and others;
Several posts are seen with owners asking a bit more about
clarifications on proper SAFE OD operation.
If you all will please carefully read the mail which has been offered
by myself, Jarrid and others, you can easily get the clear picture on
this subject
Rootes did send over series III cars with 3.89:1 gears but as
reported....they regretted this and went back to 4.22:1 with OD cars
when the series IV (and V) were made. The comment was made that
Rootes must know what they were doing...etc. No they didn't know
what they were doing and the guy who made that decision probably was
demoted (I hope). They may have been getting reports from mid and
western states where cars could fly at really high speeds.
Mercedes almost went bankrupt when their 300S sedans and lovely
coupes burned up hundreds of engines sustaining 90mph for hours in
our western heat. The cure was a taller rear axle ratio to get the
rpm down about 1000 lower. These heavy tanks for being asked to
sustain like 5000rpm all day long and couldn't take it back then.
Yes you guys have read the message correctly ! It says that 3.89 WITH
OD engaged is too much load on the engine if you allow the revs to
get too low. If you do the intelligent thing and shift OUT of OD
when mph drops too much you will have no problems. Use the thing
properly and reliability will be OK.
The city and mid range accel. of the 4.22 ratio will cream the guy
using 3.89 in outright drags and slalom events.
With the 3.89 installed I would never have OD engaged below say 3200
rpm. Yes I know the car feels and sound OK in this ratio and at
lower rpm...but just don't do it to much.
Re. the Solex carb on Series III, No this carb had nothing to do with
the gear choice because when it was new it did work nicely and
produce rated HP. Later of course we came to curse this device.
Jarrid has posted some useful rpm/mph data which should be copied in
case this subject comes up in the future.
Keep in mind guys....original skinny 13" tires are not likely on your
cars these days as most are running the superior radial play tires
and these may have a different rolling radius. Your odometer and
speedometer may be off somewhat. When on the interstate, check out
both against the mile posts. 60mph is one mile per minute!
Dick T.
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