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Direct Drive Trans?

Trucking Cody

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I know more about trucks then cars, but the idea is the same.

Is elio using a direct drive transmission? Running in direct gear instead of overdrive can significantly reduce the power loose caused by the transmission. The loss in top speed can easily be compensated for by useing a different rear end ratio. (in elios case, front dif ratio) I run my trucks with a lower number rear end in a direct drive set up. I have the same performance as a traditional od truck, but I get much better mpg in the direct gear (top gear on my trans)

So, is the elio using stupid overdrive trans like every other car on the market or have they opted to use a direct drive trans to save fuel at cruise speed? If they are using a od trans, can i swap out the front dif for a lower number and run it in 4th? (im guessing 4th would be direct if it's an od trans?)

Are they using standard diffs or highly custom diffs that i could not easily replace?

Using transmissions with a direct top gear in my trucks saves me about $10,000 each a year in fuel.

I'm really hoping they didnt overlook this mpg saver, but i dont see any info about trans ratios. They also didn't respond to my email asking about it.

In all reality, overdrive is just compensating for a poorly speced differential and is a scam perpetuated by auto manufactures. For those of you that dont understand this concept......
in an od trans vehicle, the output of the trans is faster then the input when in top gear. To compensate for this there is a higher number differential which makes a huge reduction in speed so the axle speed is much lower then the trans output speed.

In a direct drive set up top gear is a 1 to 1 ratio. motor speed on the input of the trans is the same as the output speed. Do the power going strait through the trans and no gears being used, there is less lost power. since the output isnt faster then the input, the reduction in the differential is less. With a properly speced trans and dif, you have the same power in first gear and the same top speed, but, while in top gear you use less power in a direct set up.
 

McBrew

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There are NO gears used in your 1:1 ratio? I'm not familiar with that type of transmission. I'd think there would still have to be two gears meshed together, even if they were the same.
 

wheaters

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There are NO gears used in your 1:1 ratio? I'm not familiar with that type of transmission. I'd think there would still have to be two gears meshed together, even if they were the same.
Not necessarily so. In a RWD drive gearbox the main shaft is locked in "top" gear and becomes a simple "straight through" drive shaft. No gears turn against the lay shaft and the lay shaft isn't driven.

I can understand where TC is coming from with his question. I swapped the diff in my Liege's rear axle from the standard 5.1 to a 4.1 and reduced the engine rpm for any given road speed. The downside is that the car becomes taller geared right across the spectrum so it's not as easy to drive in stop/start traffic and the clutch gets a harder life.
 

CheeseheadEarl

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Apples and oranges, Cody. Big rigs run a fairly constant speed a high percentage of the time. A car spends it's time at much more varied speeds. Ideally, gearing the E to run in direct at say 50-60, will do better in OD above 60 despite the mechanical losses. Gearing to run direct at 60+ means you'll have a dog below that, or be downshifting.

We as car buyers don't have the option to pick axle ratios like we did 30 years ago. Even pickups are limited to one or two choices any more.

Are you a Kevin Rutherford fan by chance? I listen to his show on the way home from work sometimes, despite being a reformed trucker for close to 20 years. His message is good, but I think he may push those backing him for more than they're worth sometimes. I know he follows the Elio as well.

I think Diesel Electric is the future of big rigs, if they can overcome the weight issue.

For those unfamiliar with big trucks, Aerodynamics, electronic engine controls and a bunch of smaller factors have nearly doubled fleet fuel economy since I was driving in the late 80s/early 90s.
 

skygazer6033

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Welcome TC --- I know what you're saying. In a RWD non overdrive transmission high gear is simply a sliding collar that latches the input and output shafts together. Can't get simpler than that. However in a FWD transverse engine transaxle because the gearbox is offset from the engine there's always one set of gears engaged even in high gear. Consequently high can be any ratio you want. No need for 1:1. In my Accord both 5th and 6th gears are overdrive.
 

Jambe

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CrimsonEclipse

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Turbine Hybrid. I have heard of this idea, considering the power curve of a turbine, a hybrid design would be perfect.
Air bearings is an interesting concept. It eliminates oil related maintenance. Reductions in parts count will also reduce maintenance costs, I'm guessing around 50%.

Turbines don't scale to smaller sizes very well. I haven't seen too many aviation based turbine solution for sub 500 SHP simply due to economics.
Sames goes for any small auto solution. I'd see an EV solution for Elio long before a turbine or diesel solution.

Would it work? Sure
Will it fit into an economic profile that a manufacturing company is willing to consider? Not likely.
 

Trucking Cody

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For those of you that think you would have a slow car or additional clutch ware with direct...your wrong if the trans is speced right.

The first gear on a trans with direct as the top gear has a lower 1st gear to compensate for the lower number diff. All the gears are lower. The speed at a certain gear with an a direct trans and lower number diff is the same as a od trans with a higher number diff.

Basically an od trans is most efficient in 4th gear meaning it is most efficent at a lower speed. I dont know about you guys, but i mostly drive in top gear in my car. You want to maximize the efficiency of the gear you use the longest.
 

Trucking Cody

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Welcome TC --- I know what you're saying. In a RWD non overdrive transmission high gear is simply a sliding collar that latches the input and output shafts together. Can't get simpler than that. However in a FWD transverse engine transaxle because the gearbox is offset from the engine there's always one set of gears engaged even in high gear. Consequently high can be any ratio you want. No need for 1:1. In my Accord both 5th and 6th gears are overdrive.

If your correct, this thread is moot point. I'll have to do some research on front wheel drive trans. So on your accord, 4th (assuming it's 1to1) still uses 2 gears? If this is the case, i'm surprised elio didn't consider putting the engine in the back and using a direct drive trans facing forwards. I guess having a drive shaft under the driver would take to much space...also the weight of the motor wouldn't help traction.
 
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