2.64 gear ratio?

2.64, from what I have heard is great for direct. If it is a direct 10 speed, then there should be little difference between that and an overdrive 10, with, say 3.55.

 

Will you be running California?

 

Mine has a 2.64 direct 10 speed. Does just fine. Haul reefer out of AR to UT, TX, FL, Northeast region, and Chicago area. Gear ratios matter somewhat but the bigger question is where your rpms will be at the cruising speed you desire. A 2.64 direct puts me at 1350 at 60 mph; right where I want to be. If you want a 70 mph truck that setup wouldn't suit you. Determine how fast you want to cruise and find a truck with specs that will give you that speed at the proper rpm for that motor.

 

I'd have to look up specs, but EPA07 is DPF and EGR (on most makes) and EPA10 is SCR (most makes).

I would love a pre-emissions truck, but if I had to buy an emission rig it would be SCR. They seem to have a better rep....

 

It'll never pull like an od trans and taller rears. Numerically the ratios are the same...but they don't pull like the taller rears do

 

If you have two trucks going down the road at 65 mph and both turning 1350 rpms; one having and OD with a conventional rear and one running direct with a faster rear there is no difference in how they will pull. These components are spec'd as a system; the engine, transmission type (OD or direct), and rear end ratio, when viewed as a whole, determine a trucks cruising speed, rpm, and gradeability. If you spec one wrong it will yield a weak truck. You can't look at them in isolation and assume a faster rear is worse than a 3.42 or 3.55 in terms of gradeability; it depends on the other components as well as your desired cruising speed and the rpm the engine will be at that desired speed.

 

What you are in term describing is the same ratio ASSUMING you're on lp22.5s as a 3.36 axle ratio now then anytime you would care to test your theory on your truck will pull like one with the taller ratio you're more than welcome to although once again as with all these scenarios you find ways to make an excuse weather it be bad fuel wrong gear to start the grade winter fuel what have you.

I've run trucks geared fast in the back end with direct drive transmissions they DO NOT pull like the od trans and the taller gears in the back. Not only have I run trucks that way it was the big deal back when fuel was $4.00+/gallon. I won't be naming names but a company I'm close with went through and bought about 20 brand new units with fast rears and direct 10s ran the same lanes as before they've since all gone down the road. Why? No pulling power it might work for somebody who runs flatland with the occasional mountains. It doesn't work in the lineup of running 90k+ down highways climbing hills. Just because it comes out the same on a calculator doesn't make them equal in the real world. Why everybody says this I don't know you have gained nothing with fast rears and a direct drive trans than you would have with an od trans and taller rears aside from putting more strain on the drive lines because you're working everything a lot harder.

 

The direct drives are popular for the fuel savings. It is claimed to yield 3% greater fuel economy. If you spec a direct drive and fast rear and run the engine above or under the recommended rpm range it will be a weak truck. that is what I'm trying to say. These components are designed to work together and not as separate pieces. It is true that the fast rear and direct drives cause greater drive train wear but this is taken into account now by truck manufacturers through beefier driveshafts and such when customers spec this way. Any setup can tear up a drivetrain when operated by a poor driver, regardless of how it is spec'd.

 

We ran dd15 455 10 direct and 505 linked to the dt12 direct. Some had 2.47 and the newer ones had 2.64 limited to 62 I was about 1350 ish with lo-pro and about 1275 with 2.47. We ran 80k plus and both did ok for the northeast hills with a de-tuned ryder spec. Its a shame the little 350 mack my dad has would of eaten that big 15L. Get rid of the ryder tune and its a new beast.