2.62 gear ratio

You may loose a gear, but did you loose speed? If the ratios is different, you should be able to maintain the same speed in a different gear

 

[TABLE="width: 720"]
[TR]
[TD]OD Trans[/TD]
[TD]gear ratio[/TD]
[TD]rear end[/TD]
[TD]final ratio[/TD]
[TD]Gap[/TD]
[TD][/TD]
[TD]Direct Trans[/TD]
[TD]gear ratio[/TD]
[TD]rear end[/TD]
[TD]final ratio[/TD]
[TD]gap[/TD]
[/TR]
[TR]
[TD]Tenth[/TD]
[TD]0.73[/TD]
[TD]3.58[/TD]
[TD="align: right"]2.6134[/TD]
[TD="align: right"]0.9666[/TD]
[TD][/TD]
[TD]Tenth[/TD]
[TD]1[/TD]
[TD]2.62[/TD]
[TD="align: right"]2.62[/TD]
[TD="align: right"]0.917[/TD]
[/TR]
[TR]
[TD]Ninth [/TD]
[TD]1[/TD]
[TD]3.58[/TD]
[TD="align: right"]3.58[/TD]
[TD="align: right"]1.3604[/TD]
[TD][/TD]
[TD]Ninth [/TD]
[TD]1.35[/TD]
[TD]2.62[/TD]
[TD="align: right"]3.537[/TD]
[TD="align: right"]1.2576[/TD]
[/TR]
[TR]
[TD]Eighth [/TD]
[TD]1.38[/TD]
[TD]3.58[/TD]
[TD="align: right"]4.9404[/TD]
[TD="align: right"]1.8258[/TD]
[TD][/TD]
[TD]Eighth [/TD]
[TD]1.83[/TD]
[TD]2.62[/TD]
[TD="align: right"]4.7946[/TD]
[TD="align: right"]1.6768[/TD]
[/TR]
[TR]
[TD]Seventh[/TD]
[TD]1.89[/TD]
[TD]3.58[/TD]
[TD="align: right"]6.7662[/TD]
[TD="align: right"]2.5776[/TD]
[TD][/TD]
[TD]Seventh[/TD]
[TD]2.47[/TD]
[TD]2.62[/TD]
[TD="align: right"]6.4714[/TD]
[TD="align: right"]2.1746[/TD]
[/TR]
[TR]
[TD]Sixth[/TD]
[TD]2.61[/TD]
[TD]3.58[/TD]
[TD="align: right"]9.3438[/TD]
[TD="align: right"]3.4726[/TD]
[TD][/TD]
[TD]Sixth[/TD]
[TD]3.3[/TD]
[TD]2.62[/TD]
[TD="align: right"]8.646[/TD]
[TD="align: right"]3.0392[/TD]
[/TR]
[TR]
[TD]Fifth[/TD]
[TD]3.58[/TD]
[TD]3.58[/TD]
[TD="align: right"]12.8164[/TD]
[TD="align: right"]4.7256[/TD]
[TD][/TD]
[TD]Fifth[/TD]
[TD]4.46[/TD]
[TD]2.62[/TD]
[TD="align: right"]11.6852[/TD]
[TD="align: right"]4.0872[/TD]
[/TR]
[TR]
[TD]Fourth[/TD]
[TD]4.9[/TD]
[TD]3.58[/TD]
[TD="align: right"]17.542[/TD]
[TD="align: right"]6.6588[/TD]
[TD][/TD]
[TD]Fourth[/TD]
[TD]6.02[/TD]
[TD]2.62[/TD]
[TD="align: right"]15.7724[/TD]
[TD="align: right"]5.5282[/TD]
[/TR]
[TR]
[TD]Third[/TD]
[TD]6.76[/TD]
[TD]3.58[/TD]
[TD="align: right"]24.2008[/TD]
[TD="align: right"]8.9142[/TD]
[TD][/TD]
[TD]Third[/TD]
[TD]8.13[/TD]
[TD]2.62[/TD]
[TD="align: right"]21.3006[/TD]
[TD="align: right"]7.467
[/TD]
[/TR]
[TR]
[TD]Second[/TD]
[TD]9.25[/TD]
[TD]3.58[/TD]
[TD="align: right"]33.115[/TD]
[TD="align: right"]12.709[/TD]
[TD][/TD]
[TD]Second[/TD]
[TD]10.98[/TD]
[TD]2.62[/TD]
[TD="align: right"]28.7676[/TD]
[TD="align: right"]10.1132[/TD]
[/TR]
[TR]
[TD]First[/TD]
[TD]12.8[/TD]
[TD]3.58[/TD]
[TD="align: right"]45.824[/TD]
[TD] [/TD]
[TD][/TD]
[TD]First[/TD]
[TD]14.84[/TD]
[TD]2.62[/TD]
[TD="align: right"]38.8808[/TD]
[TD] [/TD]
[/TR]
[/TABLE]


As you can see, the gap between gears is lower on the direct trans but it has a slightly higher 1st gear. Hills are not about what gear you can maintain, its about how fast you can go. With smaller gaps, a downshift isn't as severe.

 

Read my post I said lose a ratio not a gear or position. I realize on paper this works I have done it and on the ground it doesn't. I have spent 18 years working on trucks and equipment. I own and established a very successful independent repair facility that specializes in transmissions, differentials, and yellow iron. I also have a reputation for building engines that will hold and run like a raped ape. When we look at one we find the problem and fix it not pour money in it and hope. I have rigged trucks for all types of O/O told most you dpon't want to do that. I think I know a little dab about ratios, forgot mpre than most. Take a look at my profile page ofn this ol pete and another I have done shows before and after photos. I am trucking cause its been what I have always wanted to do, took a lot for me to let others work unsupervised in my shop under me. I have good employees luckily. They don't want us advertising on the forum so I don't. Hopefully this isn't. I am Cooter of Cooters Diesel Service, referred to in my signature by the way.

 

I'm gonna bow out of this and unsubscribe. How many of these little ratio charts would you like I have books of them. Most are in my memory I have studied them so much. You have no idea what it takes to rig a truck. Because the paper says it don't make it so and cause its says it won't doesn't mean it will. But you all ready know it all Psshh what could a dumb ### hillbilly really teach you? Nothing yesterday you wasn't sure if your alternator was failing and today you are gonna school me on ratios and be condescending while doing it. Priceless

 

So because I lack experience in one area, i cant contribute in another. If you pair the wrong trans with that ratio, you might not get what you want. You can spec a truck on math or gut instinct. Personaly i would rather spec it based on math. Math doesn't lie. But with a direct trans you may be in a different gear for the same speed. The math suggest that drivers find the truck has less power because the speeds for a given gear are not what they are used to. That is just drivers needing to get used to a different config, not any thing wrong with the truck.

If your so sure the truck looses power on hills with a direct trans, explain why. And saying you have to drop a gear doesn't mean you loose power or speed. (compared to od) It simply means the truck is speced different.'

For the guy who said they respeced all their trucks, did they change out the trans AND the rear ends, or just the rear end?

 

Is there a difference in reverse gear between the direct ten and super ten?

 

It's ok my transmission/gear mechanic is hard headed as well. Just because he knows the part number of every bearing in every transmission, people think he's an expert in " real world" application. I have at least three buddies who came to him and me as well for advise on what to swap their 9 and 10 speeds with. In all three instances they all ended up with single overdrive 15 or 13 , following gear guy recommedations and all of said they wish they would have listened to me, the O/O trucker with "real world" application experience!

 

The info I have doesn't have reverse listed. I would think they are different but don't have data to back that up. Although i don't think anyone mentioned a supper 10 yet. Thats a different set up. The trans I was talking about are a direct 10 or an Overdrive 10.

 

I'd believe you if you could show any math of why your correct. Real world has way to many varibles to accurately measure performance. If you are in fact right, there is some mathematical reason for it. Untill i see that, I will have to disagree.

The only thing I can think of...is that in 9th on an OD trans you will be in dirrect and thus a few% less power required to get up the hill. On a direct trans if you drop out of direct you rin a gear that has slightly more resistance since 10 is direct. But that would only effect power in 9th and it would sacrifice a tiny bit in 10th. And really i dont think its enough to notice a difference, just enough to get a little better mpg in 10th.

 

One example we pulled front drive axle housing and all, removed rear drive housing and all. Pulled 3.58 ratio out installed 2.62. Reinstalled rear drive in front drive position, had drive shaft cut and balanced. Install air up air down tag in rear drive position. Trans swapped at this time to compensate gear change. As you know removing front diff helped here you are turning less gears and mass. We still can not pull the same hill with empty truck and trailer. Before swap he could pull said hill in od now he can't pull it in 1.0. I can tell you why. It's called final ratio for a reason it takes more torque multiplication the higher your final ratio is. All this was done for fuel millage. He gained 1.0 mpg not worth the 14 grand he spent getting there.