[A/S] Axle Ratio Again

["Harvey Barlow" <harveybarlow@xxxxxxxxxxxxx>]

Gary,

You can probably live with the truck as it is if your towing will be limited
to only 1500 miles each year .

But if you really want an answer, please give us more detail.  Is your tow
vehicle a standard 1/2 ton p/u or Suburban and how is it normally loaded
camper shell, tools, luggage, passengers, etc.?  What engine does your tow
vehicle have (Vortech 350)?  What is the current gear ratio (3.42)?  Is it a
2wd (one differential gear set) or 4wd (with 2 gear sets to buy)?  What size
trailer and loaded weight?  What type of terrain do you tow over?   How do
you evaluate your rig's current performance?  Are you willing to trade
increased performance for lost fuel economy?

You can get away with using a 4.10 differential set because with the 30%
overdrive provided by your 4L60/TH700R4 transmission you will still have an
economical final drive ratio of 2.87:1 while driving solo.  While towing
with overdrive locked out as your '93 Chevy owner's manual prescribes, you
will be towing with a final drive ratio of 4.10:1.  Your truck will be only
slightly less economical while running light in overdrive but will have
considerably more torque when towing, probably at little cost in fuel
economy if you are towing a rather large and heavy trailer because your
truck is likely to be lugging with a frequently wide throttle opening (long
fuel pulses from port fuel injection) while towing with the usual 3.42:1
gear set which provides a final drive ratio of 2.39:1, a ratio inadequate
for towing with a 350 ci engine which doesn't produce maximum torque much
below 3700 rpm.

If you really have your heart set on a 3.73 gear set you can order that ring
and pinion set from Chevrolet or from a number of aftermarket suppliers at a
cost of probably around $200.

I'm not a federal emissions cop of course but changing differential gear
sets in a late model vehicle heavily loaded with federal law mandated and
factory equipped emissions control devices probably violates some federal
emissions law.

Harvey Barlow
Lubbock, TX
WBCCI # 1171, WDCU, VAC