BUILDING A
HIGH-MILE ENGINE
The other day a guy brought in
an ’01 GT with 180,000 miles, wanting me to put a set of ported heads
on it. I told him I wouldn’t work on
the car. You can’t accept the liability
of cracking something open that
has that many miles on it.
(Above) Steeper rear gears and a better shifter will make a big difference in
performance feel.
(Below) Major engine work will produce major power, but it can be expensive, and you can
get a lot of improvement with smaller, less costly mods.
photo: Jim Smart
Being that the cars are older
now and getting up there in mileage, you may have to budget for a
rearend rebuild, consisting of at
least putting clutches in the
Traction-Lok, and possibly installing new bearings and maybe fresh
axles. Changing the rearend gear
alone will do more to improve the
feel of how the car accelerates
than doing anything to the motor,
for the same amount of money.
Fuel mileage is obviously impacted
by changing the rear gear ratio, but
not as much as some people
make it out to be. In fact, a gear
such as a 3.73 will give you better
fuel mileage around town and only
knock off 1 or 2 mpg on the highway — a fair trade-off for the additional kick in the pants it provides
over stock.
The rearend is commonly an
ignored part of normal maintenance. If the fluid was changed,
and the correct fluids and friction modifier were used on
schedule, they’d last a lot longer.
But the Traction-Lok clutches are
a known wear item, and if you
drive hard or run sticky tires,
you’ll wear the clutches out in a
shorter period of time.
Aftermarket companies like
Eaton and Auburn have come
out with replacement differentials that out-perform the factory
Traction-Lok.
Issue 1 FOX Mustang Magazine 35