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Iron Butt
Posts: 825
, WI | rdbudd - 2012-12-18 12:40 AM bigdogtx - 2012-12-17 10:58 PM Rollin' - 2012-12-17 10:12 PM The gear ratio for 5th gear is listed as .685. That's overdrive. RPM's at 80 was around 3300 and the vision was running about 2900 if I remember correctly Since this discussion has turned so technical, 80 MPH on the Goldwing is 3429 RPM and on the Vision it is 3028 RPM, which is a 401 RPM overdrive advantage for the Vision. The Goldwing, with its "overdrive 5th gear" is turning 401 more RPM than the Vision at 80 MPH. Ronnie If you put a larger rear sprocket on a Vision the RPM will be also be higher at 80 mph but it still has an overdrive transmission. |
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Visionary
Posts: 1632
Jasper, MO | Rollin' - 2012-12-18 1:08 AM
rdbudd - 2012-12-18 12:40 AM bigdogtx - 2012-12-17 10:58 PM Rollin' - 2012-12-17 10:12 PM The gear ratio for 5th gear is listed as .685. That's overdrive. RPM's at 80 was around 3300 and the vision was running about 2900 if I remember correctly Since this discussion has turned so technical, 80 MPH on the Goldwing is 3429 RPM and on the Vision it is 3028 RPM, which is a 401 RPM overdrive advantage for the Vision. The Goldwing, with its "overdrive 5th gear" is turning 401 more RPM than the Vision at 80 MPH. Ronnie If you put a larger rear sprocket on a Vision the RPM will be also be higher at 80 mph but it still has an overdrive transmission.
Exactly, and you would have defeated the reason for having the overdrive gearset, just as Honda did. It would be just like changing the rear end gears in my car example. The transmission ratio is an overdrive ratio, but the overall combined gearing is not. Honda used an overdrive 5th gear ratio just so they could make the claim they have overdrive. In practice, they do not have overdrive.
Honda could even make the claim that they have a bigger overdrive in their top gear than the Vision does, .685 for Honda and .84 for the Victory. If you only look one transmission ratio, you could be misled into thinking the Honda has a better overdrive ratio. They could even legally get away with that claim.
Honda uses a primary ratio of 1.591 and a final drive ratio of 2.75. Multiply those with the .685 5th gear and you get a gearing ratio of 3.00 (2.9970 to be exact). The engine turns three times for each time the wheel rotates.
Victory uses a primary ratio of 1.5 and a final drive ratio of 2.12. Multiply those with the .84 6th gear ratio and you get a gearing ratio of 2.67 (2.6712 to be exact). The Vision's engine turns over 2 and 2/3rds times for each revolution of the rear wheel.
Honda can call it whatever they want, but the COMPLETE transmission package is not overdrive and their motor is spinning 13% faster going down the road than the Victory's is. If you have to insist on the point that a single ratio in the complete driveline is an overdrive ratio, then I would have to agree, but it takes three ratios plus the tire height to determine whether you've accomplished an overdrive function or not. Functionally, the Honda does not have overdrive. They defeated it with their choices of primary and (mostly) secondary gearing.
Overdriven (and underdriven) gears also have a lot more frictional losses than direct driven gears. The bigger the ratio, the more friction. This causes power losses between the engine and the rear wheel. The Goldwing has a .685 ratio and starts out with 118 HP at the crank and delivers 96 to the wheel, losing 22 HP in the process. The 2008 Vision has a .84 ratio (and a belt drive) and starts out with 92 HP at the crank and delivers about 83 HP to the wheel, losing 9 HP in the process. More importantly, the Honda starts out with 128 FT/LBS of torque but only delivers 104 FT/LBS to the wheel. Victory starts out with only 109 FT/LBS at the crank but gets 101 FT/LBS to the wheel. Honda is shooting itself in the foot with their choice of gear ratios. They probably did it to get the favorable 1st and 2nd gear ratios that make the Goldwing feel so powerful at low speeds.
Ronnie
Edited by rdbudd 2012-12-18 10:45 AM
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Iron Butt
Posts: 825
, WI | Ovedrive - an automotive transmission gear that transmits to the drive shaft a speed greater than engine speed.
If your biggest concern is the number of gears and low engine RPM you could trade the Vision for a dump truck. |
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Visionary
Posts: 1632
Jasper, MO | Rollin' - 2012-12-18 10:42 AM
Ovedrive - an automotive transmission gear that transmits to the drive shaft a speed greater than engine speed.
That's true. So what? That's only one part of the drive train. You left out the rest of the story. The drive shaft only applies power to the final drive and the combination of the transmission and final drive ratios determine whether you end up with a true overdrive or not. The Goldwing has a combined gear ratio of 3.00-1 while the Vision has a combined gear ratio of 2.67-1 with both machines being operated in their overdrive gears. The internal gearset ratios are not the end of the story and, by themselves ,do not determine whether you have an effective overdrive or not. One gearset does not, by itself, make an overdrive combination. That would be an oversimplification to say that it does. Is Honda's .685 transmission gearset more of an overdrive ratio than Victory's .84 transmission gearset. Sure it is. If you wanted to, you could make the claim that the Honda has more overdrive than the Victory if you limit your view to just those two ratios. Is the Honda's combined 3.00-1 ratio more or less than the Victory's 2.67-1 ratio? Is the Honda's 3000 RPM @ 70 MPH more engine speed or less than the Victory's 2650 RPM @ 70 MPH? Which one really has overdrive when the complete driveline is looked at?
The whole purpose of overdrive is to lower engine RPM at a given road speed for the purpose of increasing fuel economy or to increase the speed achievable for a given final drive ratio. It also affects the riding experience, giving you a relaxed engine or a busy engine. The Vision runs 2650 RPM at 70 MPH vs the Goldwing running 3000 RPM @ 70 MPH with both machines being operated in their transmissions' overdrive gears. In my experience, the Vision always beats the Goldwing on fuel economy when they are ridden together. In some conditions, I've beat the Goldwings by 5 MPG while running 80+ MPH. In my opinion, the Vision is also much more relaxing to ride than the Goldwing, and the engine speed has a lot to do with that.
Dump trucks? Where did that come from? Very few dump trucks have overdrive, even within the transmission ratios. They use a large number of gears to multiply the engine torque to move heavy loads. They use a lot of UNDERdrive gears to get the load moving and up to road speed. Redline in 1st gear will only get you up to about 5-7 MPH. It takes 9 or more gears to even achieve a reasonable road speed. I've driven 15 speed trucks that couldn't go over 85 MPH and that was wound out at 2200 rpm in 15th gear (redline). Apples and Oranges.
You are using the term "overdrive" as it relates to ONE particular gearset out of the total package of primary gears, transmission gears, and final gears. I'm using the term "overdrive" as it relates to the whole driveline and how it relates to the RPM/MPH equation, which is the only thing that matters in practice. True overdrive reduces the engine speed, usually increases fuel economy, and can enhance the driving/riding experience.
I know you're a smart guy. I think you're just funnin' me  Winter blahs setting in?
Ronnie
Edited by rdbudd 2012-12-18 12:18 PM
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ON THE FENCE AGAIN
