2.62 gear ratio

The truck you are looking at has a direct drive 10 speed it will be like driving a truck with your current ratio and an overdrive transmission with a .74 or .73 ratio. The idea behind the truck you are looking at is that a direct drive transmission has less power loss through the transmission for better mpg. Mega fleets have speced trucks like this for years. Wamart etc.

 

The above is true but to get you have to give. Another words you will loose some bottom end or load starting ability. Mid range will be effected to how much depends on how the rest of truck is specked and how heavy u will be

 

Will suck on hills that rear is for fuel economy. Sounds like an old s national truck

 

If you are light most of the times then it shouldn't be a problem in the hills - correct ?? Also , with a 2.62 vs the 3.58 - would the rpm's be lower while cruising at 65 mph in the 2.62 ??

 

Not at all

a 10 speed direct compensates for the gear difference. a 2.62 or 2.64 geared truck with a 10 speed direct compared to a 3.55 or 3.58 geared truck with a 10 speed overdrive will have near identical (less than 1%) difference in every gear. 99% of drivers wouldn't even notice a difference.

 

On the ratio chart the direct models start with a lower ratio than the OD models. By the numbers on paper it's right. I have swapped trans and rear set ups for customers in search of fuel economy. A few went the extra mile and pulled the power divider and put an air up air down pusher axle. One had us move rear drive axle to forward position and put a tag so he could have a shorter drive line. All these guys were sick after spending thousands for 1 mpg gain on average all of them say it hurt down low. I drove them before and after and I agree. On a 4 percent grade you will loose a gear by ratio not position. If you go to a 15 deep to get your low end back the extra rotating mass takes up more than your gain.

 

If the final ratio is the same the bottom end will be exactly the same. For example 3.55 to 2.64. But if you went 3.70 to 2.64 there would be a difference the same as if you went to 3.42 or 3.36. That is unless you try an overdrive tranny, that won't work well unless you have an 18 speed.

 

It must be a paper thing

 

I dont get why guys dont get this.

Lets do some math.


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with a direct drive trans, top gear is 1.00
2.62*1.00= a final drive of 2.62

Now, with a over speed trans the final drive is .73. The norm rear ratios is 3.58
3.58*.73= 2.6134

So the top end is essentially THE SAME

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1st gear in a direct 10 speed trans is 14.84
2.62*14.8=38.776

For the first gear...a 10 speed with a final of .73 (0ver drive) has a 1st gear of 12.8
3.58*12.8=45.824

So yes, you do loose a tiny bit in your first gear do the final ratio being 38 vs 45. So your first gear isnt as low. But really how long do you stay in first?

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Going into second
2.62*10.98=28.76 (jump of 10)
3.58*9.25=33.11 (jump of 12.71)

Clearly since the direct trans has a higher first gear, the final drive jumps between gears is actually LESS. In other words, once you get out of first this trans will do better on hills since the gear spacing is a little tighter.
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3rd gear
2.62*8.13=21.30 (jump of 7.4)
3.58*6.76=24.20 (jump of 8.9)

Clearly the overdrive trans with the 3.58 has bigger gaps between gears which is worse on hills. The ONLY disadvantage of the direct trans is a higher first gear. But if you can get the truck rolling, shifting in to second will be easier and it will do better on hills. Depending on how much power is needed, you my need to be in one gear lower with the direct set up to obtain the same ratio. As you get in the higher gears, the overdrive trans catches up and there is almost no difference in gearing. Remember, all we care about it the ratio that makes it to the tires. 1.5*2 is the same as1*3. it doesn't matter what math we use to get there as long as the result is the same. A lower rear end can be compensated by a higher trans. As for pulling hills, closer gearing will help on hills and the direct has closer gearing. Off the line the OD has an advantage having a lower first gear, butt hats not a fault of the ratio, its a fault of Easton designing it differently. That higher first will give you benefit on the hills though since you don't spend much time in first.

The driect trans will run a but more efficiently on top gear saving you fuel. IMO overdrive trans are stupid. Why would you make the trans spin faster then the engine just to have a bigger reduction on the rear end.

Now that being said....make sure this truck is speced with a direct trans and not an Od trans with that ratio.