Drivetrain
All full-size Chevrolets, as far as I know, came equipped with 12-bolt
rears in 1965 (the later models mostly had wimpy 10-bolt units).
The rear in my car has a 3:31 gear, which was the most common ratio used
on Powerglide-equipped cars. I thought, since there's so much weight
over the rear axle, that I'd be able to get away with using the stock open
"one-legger" differential with the 406 engine, but I was very, very wrong.
With the 406 installed, the car spun the right tire at anything past half-throttle
in first gear (even with fat 275 rear tires), then got about 50 feet of
rubber going into second. It was a miracle that it managed to get
into the 14s at the dragstrip with this setup. I looked around
for a swap meet posi unit, but there's no way in hell you're ever going
to set up a 12-bolt posi for less than $500. Too many Camaros and
Chevelles out there. I ended up shelling out $300 for a Powertrax
locking differential. The locker was pretty easy to install (though
I had to hand-sand .010" off the side gear thrust washers to make
the unit fit my carrier (don't ask how many hours that took) and it works
well. I get 100% lockup off the line, with hardly any wheelspin.
On the minus side, the thing clicks like crazy going around corners and
it's a handful in the rain if I get at all heavy on the gas pedal.
The sight of a 4-door Impala going completely sideways usually gets everyone's
attention, if you know what I mean. Anyway, the fact that it manages to run 13s makes up for everything. Also visible in this photo is
the Addco rear swaybar (check out how it attaches to the lower control
arm using a thick steel plate- primitive, but it works).
The cheap rebuilt TH350 transmission I put in the car back in 1991 always
worked, but there was something wrong with the 2nd/3rd shift. It
wouldn't go into 3rd gear at full throttle; I had to back off on the gas
and coax it to shift. This was no big deal during normal driving,
but it was a definite drawback at the dragstrip. Replacing the modulator
didn't help, and several self-proclaimed tranny experts gave me wildly
differing opinions about what was wrong; I don't understand enough about
the mysteries of automatic transmissions to be willing to take one apart.
I thought about putting a 4-speed 700R4 automatic in the car (I even got
one at the junkyard, but I ended up selling it when I figured out I'd have
to get a custom driveshaft made to make it fit), but eventually just went
with the cheap and simple solution of getting another TH350. There
are more TH350s in a typical self-service junkyard than there are handguns
in a Texas bar, so I crawled under lots of 70s Chevys until I found a '77
Chevelle 6-cylinder with wsat loked like a fresh rebuild installed.
The transmission was spotlessly clean, with no crap inde the pan.
It seemed like a wise investment for $40, so I got it, installed a B&M
shift kit, and put it in the car (by the way, it's much more difficult
to install a transmission in a full-size Chevy than it is with a GM A-body
car; the crossmember on the big Chevy looks like something out of a T-34
tank- it weighs about 50 pounds and must be pushed up and out of a pair
of saddles on the frame rails, which is a real trick if the floorpan has
been pushed down by the weight of Ford Escort bucket seats bolted directly
through the sheet metal of the pans). It works perfectly, giving
me vertebrae-straining shifts in all gears.
