Re: 304/290/200R4

[Peter Marano <carmine@xxxxxxxxxxxxx>]

 Frank said:
"I ran a 3.08 with mine and it got worse mileage than it does with the 
3.55 gears"

And:
"My car didn't like the 3.08 gears even on the highway -- highway 
mileage was hurt the worst since the engine had to work a bit pulling 
hills in OD (it was only running around 1400 rpm at 70, now runs around 
2000). Takeoff was fine."

So I did the math:  3.55*.75=2.66.  This leads me to believe that 2.66:1 
final drive ratio is in the range that will deliver excellent if not the 
best possible fuel economy.  Rear axle gears have been available in this 
range for years.  Since these ratios keep the pinion, pinion bearings, 
yokes and driveshaft spinning slower it would appear that it might help 
the overall fuel efficiency.  Now if it is possible to eliminate a 
planetary gear set another increase in efficiency should be realized.

That’s what led me to suggest:
"My two cents worth:

Don't use an overdrive, more parts spinning around will use more fuel.
Use the Warner Gear aluminum transmission, if you must the 998 allows
the lockup converter and a lower first gear.  AMC 7&9/16 axles can be
had with 2.35:1 and 2.37:1 ratios.  There is no point in using extra
gears to spin the drive shaft and pinion faster so that it will turn the
ring gear the proper speed.

By way of comparison my 1971 Javelin with 304 and 2.87:1 gear ratio got
20mpg.  I don't think the large axle is required if you use a ratio with
a large pinion."

Then Andrew offered:
"that's fine once you're moving, but a lower overall first will help
mileage in stop-and-go, not to mention starting on hills.  if you do
a lot of that the tradeoff is worth it."

And Frank simillarly responded:
"If first gear isn't low enough mileage in town will suffer with rear 
axle ratios like 2.35 / 2.37. That's why the OD trans -- you can have a 
low enough axle for good take-off/towing capacity and still get good 
highway mileage. To high a gear will hurt mileage more than help. A 
lock-up torque converter is a must. The best bet is a manual overdrive, 
of course!"

And now I must reply thusly:
The combination up for discussion is a 290/304 V8 in an American or a 
Rebel not a 2 litre 4 cylinder in a Gremlin.  A high torque 290 will 
probably be traction challenged with 2.35:1 gears in an American.

A lower first overall first will make the combination more fun, but 
probably uses more fuel unless the engine makes less torque at RPM than 
is required to accelerate the vehicle.  However I did offer the 998 
which can be had with 2.75:1 first gear set and lockup converter.

No towing. This combination is for V8 looks and sound with economy, ship 
by truck?

The best bet is actually the SR4 transmission 3.5:1 first and 1:1 top 
gear.  Doesn't Armand just post that he had a 304 with SR4?

Peter Marano	
Kenosha WI