Gear Ratios

[detmatt]

The 2.94 was std in the Imps for at least a couple of generations.

 

[Rick T]

I have a 78 Chrysler New Yorker Brougham with the factory window sticker it states sales code D53 axle ratio 3.2 what actually is a 3.2 thanks

 

[Davea Lux]

I have a 78 Chrysler New Yorker Brougham with the factory window sticker it states sales code D53 axle ratio 3.2 what actually is a 3.2 thanks

D53 is the option code for a 3.23 ratio rear axle. That means the pinion shaft will turn 3.23 times for each full revolution of the ring gear.

Dave

 

[Rick T]

D53 is the option code for a 3.23 ratio rear axle. That means the pinion shaft will turn 3.23 times for each full revolution of the ring gear.

Dave

Thank you that’s what I thought because I was looking up gear ratios. It also came with sure grip

 

[Gerald Morris]

I love my 2:76! Always have preferred tall rear gears for rolling on the highway. I strapped a 1976 Lincoln Versailles rear end to my '68 Mustang w a "baby C6" meant to bolt to the smaller 335 Cleveland block I ran in it which enabled me to run in 2nd gear up to 90 mph without red-lining that motor.

THEN, I got my 1966 Chrysler New Yorker!

I never looked back in regret.

 

[jmustian]

Example: 2.93:1

The driveshaft rotates 2.93 times for each 1 time the rear tire rotates.

Let's simplify and say 2:1. Imagine a teeter totter that has one side 2 times longer than the other. Put a 100 lb kid on the long side and he can lift a 200 lb kid on the short side. The 100 lb kid has to move twice as far as the 200 lb kid moves.

Same thing with the gear ratio... Increasing the ratio allows the engine to push the car easier, but it spins more. It also gets less MPG and wears out faster.

Decreasing the ratio makes it less easy to move the car, but the engine doesn't spin as much. Better MPG and less engine wear.

So.... Real world... Performance street car... 3.23 or 3.55:1 (of the ratios you quoted) Highway car 2:93 or less.

The difference in 2.93 and 2.94 (as quoted) would be impossible to notice a difference. The difference between 3.55 and 2:93:1 is very noticeable with faster acceleration and less gas mileage.

Im glad someone explained that . was wondering why i have a 2.76 in my 300.

 

[CBODY67]

Im glad someone explained that . was wondering why i have a 2.76 in my 300.

For a normal 440/350, the 2.76 was standard, with the 3.23 being optional. IF it was a 440/375, the 3.23 would be standard. This is for the then-used 8.75" rear axle. In later years, the "3.2" was really a "3.21" ratio. 2.93-thereabout ratios were usually for C-bodies with a 318 2bbl TF combination. 3.55 was an 8.75" ratio, but 3.54 was a Dana-axle ratio.

Enjoy!
CBODY67

 

[rkrochen]

Hi Clay where are you in regards to completion of the car. Haven’t heard much from you lately. Send some pics.

 

[Justin Plant]

Please remember, simply changing the rear end may bring problems too. I changed the axle ratio in my El Camino from 2.73 to 3.73. The 700R4 did not like it. I had to mess around with governor weights and throttle cable adjustments to get it to shift normally. Granted, I took a big swing when I changed mine, but a change in ratio throws a lot of engineering out of balance.

 

[Gerald Morris]

Please remember, simply changing the rear end may bring problems too. I changed the axle ratio in my El Camino from 2.73 to 3.73. The 700R4 did not like it. I had to mess around with governor weights and throttle cable adjustments to get it to shift normally. Granted, I took a big swing when I changed mine, but a change in ratio throws a lot of engineering out of balance.

Yes, BIG changes in gear ratio can seriously overload and severely DAMAGE other drive train components. I learned and rued my own foolery when I installed the rear end from a 1978 Lincoln Versailles on my '68 Disgustang, wanting the low ratio and rear disc brakes. The tight arse gear ratio certainly would push that sheetmetal FAST on the highways, until it strained the connecting rods in the 351 Cleveland engine to breaking. Admittedly, my heavy foot had MUCH to do w that, but pushing that C6 to twist those late 1970s highway gears loaded that high revving small block motor heavily. I would have an engine built for the required high torque before trying something like that again.

Conversely, going from 2.76 gears to say, 4.10 will make for easy off the line starts, and easy red-lining your engine. THIS destroys plenty motors.

 

[Dads300]

For something with a stock engine, I like 2.76 gears. Not much difference in performance from a 3.23 once you’re rolling, but it makes modern freeway travel much more enjoyable. I even put 2.76 in my soon to be on the road 70 GTX 440/4speed. I can’t wait to try it out.
Travis..

 

[cbarge]

69-71 Imperials.

View attachment 255130

Also 66 67 B bodies with LA 273 and AC.
The Boab's 2.94 cane from a 67 Sattelite.

 

[Dads300]

My brothers 67 coronet 440 with 383 2 barrel had 2.94 as well
Travis..

 

[marty koirtyohann]

So these were available;
3.55:1; 3.23:1; 2.94:1; and 2.93:1
Can someone explain the difference from one end to the other for us gear illiterate folks?
Do these 4 choices really make that much of a difference?

i would bet a higher gear (2.94/2.93 ) after all 73 was the start of the oil embargo but that would just be a guess u may have a tag on the cover undr one of the bolts it would be stamped ion the ring gear but thsts a mesy job unless its leaking gear lube. but y do u want to know for? the smaller the first # the better the mpg but slower out of the hole(off the line or pulling aaway from a dead stop)

 

[detmatt]

3.55 was the optional gear ratio for 4 Speed and some automatic equipped cars. Usually found with big block engine with a performance nameplate. 440HP, 426 wedge HP, 426 Hemi and some 383HP. This ratio also used on some 340 equipped cars
3.23 was the standard gear ratio for all of the above and was a widely used gear ratio on most standard performance cars up to the early '70's. Also used on many of the large C-Body cars as standard gearing.
2.93 was a standard ratio on many cars thru the mid to late 1970's where more economy was desired while still maintaining some performance potential. I don't think there was a 2.94 ratio in stock factory mopar gears.
A 2.76 ratio was also offered on cars with an economy rating and became more common as fuel economy standards were implemented on larger cars.

As far as the difference, the lower the gear ratio, eg. 3.55 the more turns the drive shaft has to turn to travel a fixed distance. More turns means more torque transmitted to the wheels but lower fuel economy because more turns translates into higher engine RPMs at various speeds.

Dave

2.94 was standard in the Imperials for years.

 

[CBODY67]

Seems like 2.94 was in 8.75 rear axles and the 2.93 was in the smaller ring gear rear axles?

Look at how the rear axles play into the tire sizes. A 2.94 with 9.15x15 tires would effectively not be that far from a 2.76 with 8.55x14 tires on a '66 C-body car. A 2.94 with 7.75x14 tires would be closer to a 3.23 with a larger tire as a 3.23 with the same tire might be closer to a 3.55 . . . or there-abouts, as to highway cruise rpms.

Happy Holidays!
CBODY67

 

[twostick]

2.94 was standard in the Imperials for years.

My 71 has a 3.23 SG. I don't know if the original owner ordered the car or if it was off the lot.

Somebody would have to check those 2 boxes off in the order for sure tho.

Kevin