I understand how gear ratios works, "I'm a mountain bike weekend warrior" I change gears a lot and know that higher the gear easier it is to pedal and the lower the harder it is to pedal, so you use higher gear at low speeds and lower gears at higher speed, its only logical.

What I don't understand is why Exactly manual cars seem to go with very high gear ratios and automatic goes with lower gear ratios?
Is this because the Automatics are stuck with only 3 maybe 4 gears in the tranny to work with and the Manual have 5 to 6 gears?

Another thing, can someone explain the gear options for the Dana 36/Automatics and the options for Dana 44/manuals to me?

What options came from the dealer? and witch gears are available in the after market.


:cheers: :cheers:

Ps: I have an automatic with Dana 36, 2.70 gears, what would be my best option without changing the carrier?

 

I read the best gear option would be 3.07

Can these gears fit inside my stock rear diff carrier?

 

Short answer is that 6sp has a higher top gear (more overdrive), so cruise RPM remains acceptable with high numerical rear end ratios. A 3.73 or 4.10 rear axle ratio still allows a 70 mph cruise RPM under 2500 in 6th gear.
The 4 sp Auto trans doesn't have as high a 4th gear, so to keep cruise RPM acceptably low, you need a lower numerical rear axle. On the other hand, Autos have a torque converter that effectively multiplies torque, so the effective gear ratio is higher at low speeds and high throttle openings.
The Dana 36 and 44 rear ends differ essentially in torque capacity or ruggedness. Either will accept similar gear ratios. With a 6sp, shock loading on the rear end is higher, so a more sturdy rear end is is used from the factory. When you bump up horsepower or quicken shift times in the auto, changing to the Dana 44 adds some reliability.
A lot depends on how you use the car. If you are a racer, cruise RPM is largely irrelevant. From the factory, the Vette is set up to achieve low noise and "good" gas mileage at cruise. When you begin to change things for performance, both noise and gas mileage are traded off to the extent you can live with.
Some newer (non vette) cars now have 6 sp autos to get a broader range of gearing.
From the factory, all 6sp manual came with a 3.45, I believe.
Autos came with a 3.07 standard, with a performance option of 3.25, I believe. Any auto guys correct me if I got it wrong.
In the aftermarket, 3.73 and 4.10 are popular with the 6 sp. 3.45 or 3.73 are most popular with the auto, again driven by cruise RPM considerations.
Hope this helps!

 

3.07s are available for the D36, so you dont have to change your carrier, though with a 383 and a Superram coming soon, it might be in your interest to change to D44 for longevity.

Basically, yes. Manuals give a personal selection of what gear you want to be in, automatics dont unless you shift it manually and even then youre limited to 4 choices. They try to match gearings up for best fuel economy too.

In the D36, I believe only 3 options made it thru all the years: 2.59, 2.73, 3.07. I believe 3.33 was available in 84, not sure. 2.73 was a performance option for the vert, 3.07 for coupes and 3.07 was standard with Z51 in SOME yrs. (it was in 86, i know). Otherwise you get 2.59

D44 was 3.07 until the M6 came out, then they messed around with the gearings in 89 getting it right (maybe in 90 too), and thru the 90s they stuck with 3.45.

 

Logical, yes, but stated exactly backwards. It is clear that you understand the reasons for gears. For clarity, low gears, are the gears you use to get started and climb that steep hill. Higher gears allow you to maintain a high speed without over revving your legs and throwing an ankle bearing. A diff with 4.11 gears is lower than one with 3.07 gears.

Standard and optional gear ratios, in Corvettes, varied from year to year and equipment. In 1984, the standard ratio was 3.07:1, for both autos and sticks. An optional 3.31:1 was offered on Z51 suspension cars, only. Very few '84s came with the 3.31 gears. Later, 2.59:1 was a common auto spec.

The Dana 36 was used in all C4 automatics. My literature shows they were availble in 2.53, 2.59, 2.73, 3.07, and 3.31 ratios. The Dana 44 was used in all standard shift cars except the '84 (it used the 36) and was sold with 2.73, 2.87, 3.07, 3.33, 3.45, and 3.54 gears. Any model 36 will hold any gears made for any 36. Likewise with the 44s. There are additional ratios made by the aftermarket. The internal case that the ring gear bolts to, the diff case, changes within certain series of gears. For these axle models, the change comes when you cross the 3.00:1 line. All the diffs with a ratio starting with a "2", uses one case and all diffs with a ratio starting with a "3" use a different case. To further comlicate matters, some of the aftermaket manufacturers make a special "thick" gear that allows the use of "3 series" gear ratios on "2 series" cases.I don't show a "2.70" ratio availible for a 36. It is probably a 2.73. As you can see from the above, the lowest you can go using Dana (GM) gears is 2.87:1, without changing the diff case. I am quite sure the aftermarket offers a 3.75:1 gear set for the "2 series" case and probably others, too. I hope this is of some help. Good luck, and...

RACE ON!!!

 

Thank you very much for the explanation guys

Thats what I ment... 2.73 :rolleyes:

 

With a 383 stoker in there I wouldn't go over 3:07 in a Dana 36...