Re: [A/S] Avalanche Question

["Myrna Warren" <uncleneal@xxxxxxxxxx>]

I have an '01 Z-71, 5.3, Auto with 4.11 gears.  I bought it used last
January with about 32,000 miles on it.  My experience is similar to Will and
Bonnie's.  At about 45,000 the overdrive suddenly failed.  (when not towing)
The Chev dealer rebuilt the trans.  The 4th gear clutch plates were worn
slick, the other plates looked like new.  I had always used the Tow-Haul
when pulling my car hauer, and the truck didn't appear to have been used to
tow before I got it (the brake controller harness was still in the glove
box - no wear on the hitch).   Now I tow in 3rd gear with the Tow-Haul
engaged.  Pulling the car hauler I get 14+ mpg, as good as I got in
overdrive before.  My personal opinion is that GM sets the line pressure in
the trans as low as possible so that the trucks will get the best gas
mileage possible when they are tested by the Gov't.  It takes power and fuel
to make pressure: less pressure, less fuel.  But it takes a good bit of
pressure to keep the overdrive clutch from slipping when the torque
converter clutch is locked up and a heavy trailer is being pulled.  I live
in the N. GA mountains, pressure that would be adequate for Florida is not
adequate for pulling mountains, even empty.  And pulling hard up a mountain
empty is like pulling a trailer on flat ground.  I use the Tow-Haul to force
a shift to third then.  One thing I'm going to do is to find a way to
increase the line pressure before I start towing the Airstream this Spring.
Neal