Landracing Forum
Tech Information => Steering - Suspension - Rear End => Topic started by: ronnieroadster on December 06, 2016, 04:18:21 PM
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Would anyone have an idea about how much horse power it takes to turn a quick change rear axle? My rear axle choice has been a good old Halibrand six spline quick change its small size works well in my application. At speed week I ran a 28 inch tall rear tire and a 270 final drive ratio. I've heard the quick change gives up some MPH the added advantage of the easy gear change seems to blend that out at least for me. But I would like to get an idea on what it take's to make it work not looking for exact numbers just some general knowledge from you fellows in the know.
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According to these sources a Hypoid (most popular third members) gear set is 92 to 96 percent efficient at power transmission. A spiral bevel (V-8 quick change) gear set and a single spur gear set are both 99 percent efficient. That makes a V-8 quick change 98.01 percent efficient . Tell me again why I should dump my quick change.
http://www.zakgear.com/Hypoid_worm.html
http://www.roymech.co.uk/Useful_Tables/Drive/Gear_Efficiency.html
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According to these sources a Hypoid (most popular third members) gear set is 92 to 96 percent efficient at power transmission. A spiral bevel (V-8 quick change) gear set and a single spur gear set are both 99 percent efficient. That makes a V-8 quick change 98.01 percent efficient . Tell me again why I should dump my quick change.
http://www.zakgear.com/Hypoid_worm.html
http://www.roymech.co.uk/Useful_Tables/Drive/Gear_Efficiency.html
Very interesting I knew hypoid pinion location in the 9 inch Ford was not as efficient as the Chevy 12 bolt due to the pinion location my thought has been the Chevy was closer to the centerline. I always wondered if the centered pinion location of the quick change spiral bevel would be a better choice.
I'm thinking its a pretty good choice.
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I have run my setup on an engine dyno & a chassis dyno. We have a Winters Extreamliner quick change and my calculations show a 25% loss through the drive line.
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Ron, your 2.70 ratio is a calculated number I presume & you have arrived at that with an over driven set of spur gears with a 4.11 ring & pinion, that's a whole different animal & a lot more junk to go through than actually having a 2.70 ring & pinion.
How about one of the numerical whizzbangers on the forum show us some real numbers on what the difference is here because it defies logic to suggest a quick change could be more efficient in this situation?
Sid.
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Ron, your 2.70 ratio is a calculated number I presume & you have arrived at that with an over driven set of spur gears with a 4.11 ring & pinion, that's a whole different animal & a lot more junk to go through than actually having a 2.70 ring & pinion.
How about one of the numerical whizzbangers on the forum show us some real numbers on what the difference is here because it defies logic to suggest a quick change could be more efficient in this situation?
Sid.
Sid the 270 is the change gear final drive the ring and pinion ratio is 378. I would expect more HP loss from turning the lower shaft to the spur gears and then turning the pinion certainly more stuff to move and more bearings to turn compared to just a ring and pinion.
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Were there ever any bevel-gear ring-and-pinion QC's made (not spiral-bevel)? If so, that would be the most efficient QC design.
Efficiency of any gearset can be significantly improved by a well-designed lube system. Dragging gear teeth through a bath of viscous gearlube is NOT efficient.
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I suspect that no matter how efficient the gear sets are..The power loss comes from gear multiplication through the change gears. I have a Benson q/c in my 3 window and rotating the input by hand is a challenge with the change gears swapped around for long trips. In their "normal" position I have a 4:86 final drive and the input spins easily. JB
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Exactly, you get torque multiplication through a reduction drive & the opposite through an overdrive. Unless you have enough HP on tap to overcome that you're at a loss when overdriving to a lower axle ratio.
Can somebody come up with some real numbers here??
Sid.
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Real numbers will come from real testing. Whole lot of variables to consider. But gear reduction is always your friend.
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Ron couldn't you adapt a v belt pulley to the input shaft and belt up an electric motor. Then by reading the motor amperage you would know the horsepower. By changing motor pulleys you could see the change in HP for different pinion speeds. You also could see the effect of cold and warm rearend lubricant.
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Ron couldn't you adapt a v belt pulley to the input shaft and belt up an electric motor. Then by reading the motor amperage you would know the horsepower. By changing motor pulleys you could see the change in HP for different pinion speeds. You also could see the effect of cold and warm rearend lubricant.
That would give an idea of fluid friction loss but not include loaded gear mesh loss, which is probably considerably larger and proportional to the input/output operating torque.
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Ron couldn't you adapt a v belt pulley to the input shaft and belt up an electric motor. Then by reading the motor amperage you would know the horsepower. By changing motor pulleys you could see the change in HP for different pinion speeds. You also could see the effect of cold and warm rearend lubricant.
Having the rear end under load would take a lot more HP to turn and thats the unknown I was hoping to sort of get a number on. Dynorooms numbers are real world and his example is an eye opener on the percentage of loss.
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I have run my setup on an engine dyno & a chassis dyno. We have a Winters Extreamliner quick change and my calculations show a 25% loss through the drive line.
Your numbers show what I was looking for. One question what transmiion did you use?
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I have run my setup on an engine dyno & a chassis dyno. We have a Winters Extreamliner quick change and my calculations show a 25% loss through the drive line.
Your numbers show what I was looking for. One question what transmiion did you use?
Jerico 5 speed
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It's easy to calculate the efficiency of a rear by how hot it gets and converting the heat into hp . If a rear is 70# steel , 15# alum. and 4# oil and it gains 35 deg. during a 1.2 minute run that's 393 btu / minute that converts to 9.27 hp . For 600 input hp that says the rear is 98.5% efficient .
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How much air flow did it have on the run?
Was the cover finned aluminum?
Did you use a pump and cooler?
. . . and whatever.
Feed those into the sliderule, too.
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This hypothetical car is a lakester . No air cooling .
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No way it is 98% efficient.... chain drive isn't even that good.
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Rears would be over 200 deg. after a run if the losses were 5% .
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No way it is 98% efficient.... chain drive isn't even that good.
Ditto on that one!
Sid.
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Do the math . It takes .12 btu to heat one # of steel one deg F . Alum. is .22 btu . Oil is .45 . 42.4 btu / minute is one hp .
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And nothing radiates the heat between measurements?
I'll race with a Dream Wheel, but a computer is beyond me.
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Amazing how many people ask "what's a Dream wheel?". I tell most of them, it's a slide rule for cars. :-D :-D
Ron
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Stan;
At relatively low temperatures very little heat is lost by radiation. At the temperatures John is talking about the radiant heat loss is nil.
Regards, Neil Tucson, AZ
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While the temperature measurement method is sort of an elegant way to estimate power loss, it is, like many things, fraught with generally unmeasured variables. And recall that the example in the beginning was just based on arbitrary quantities of the weights, time, power etc.
In addition, varying convective cooling, some radiant loss, non-constant application of input power, uneven temperature distribution within the gearbox, and so on. It can be done but a lot of stuff needs to be carefully measured to generate a valid result.
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Do the math . It takes .12 btu to heat one # of steel one deg F . Alum. is .22 btu . Oil is .45 . 42.4 btu / minute is one hp .
The math seems good, but where does the 35 F degrees come from? I would stick with the 4-6% cited in one of the tech articles.
It is an interesting method to calculate losses though!
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Interesting stuff heat transfer air flow over the housing way to many variables the way I see it. Looks like a simple percentage is not an easy figure to determine. SO
Taking into consideration something Stan said. Using the wonder wheel I have from Mark Williams the calculated speed based off tire diameter, gear ratio and RPM came out perfectly to my top speed recorded.
Go figure. :dhorse:
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The question was never about gearing & speed, it was about power loss through a QC & I think Dynoroom's numbers are realistic. I know your engine is at the ragged edge & you're interested in getting more of it to the wheels so I would suggest you build a 7.5 10 bolt & give it a shot, even make it a bolt in so you can switch them to see the difference. S-10 housing is probably about the right width. I think I have a 2.56 & I know I have two sets of 2.41's & I think you could use a bigger gear.
Sid.
https://www.youtube.com/watch?v=hMy8nGYOOrk&t=248s
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My comment was really about feeding in the data. My old cardboard's answer is within a MPH at 200-speeds at Bonneville. I'm thinking that all the factors fed into a computer that comes up with an unbelievable number is missing something.
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Frank06 said "No way it is 98% efficient.... chain drive isn't even that good." Actually roller chain is really only 90 to 92% efficient the best drive "chain style" drive are the HVO belt drives which are over 98% efficient. Sorry for the hi-jack now back to quick change question.
Rex
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The latest issue of Hot Rod Mag has an interesting article about the Ford 9 inch its not anything helpful for my question but still good reading.
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They quoted an efficiency number in that article.
Regards, Neil Tucson, AZ
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AMC products from 1982-87 used a 2.21 gear set. Maybe somewhere out in industrial gear-land there is a bevel gear set of 1.5-1 that a clever person with a mill and lathe (No, I am not volunteering) Could machine a case that would mount change gears to get you down to the ratio you want...Double gear reduction working in your favor.
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Maybe somewhere out in industrial gear-land there is a bevel gear set of 1.5-1 that a clever person with a mill and lathe (No, I am not volunteering) Could machine a case that would mount change gears to get you down to the ratio you want.
Has already been done by one person I know of, his name was George Parker (RIP), he made a quickchange back in the early 1990's and you could get it with a 1.5-1 or 1-1 ring and pinion.
Mel Swain (Swain Bros-Helash-Hoover) used the unit in his Blown Fuel Modified Roadster, in 1994 with a 1-1 ring and pinion. They still hold the top 3 engine class records at El Mirage in BFMR some 20 plus years later.
Tom G.
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See...Every now and then I have a lucid thought...............
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IIRC John MacKichan used a 1.5-1 bevel gear in a V8 QC center section in his and Tim's liner. He machined everything but the center housing (side bells,etc.) to make it work. I think with the right spur gears they could get .63-1 final drive ratio. Huge hours involved to get it done.
Ron
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When Mickey Thompson first considered "challenging" (pun intended) Cobb's record in late '58, the first item he envisioned was single-spur-gear sets (1:2) at each wheel, to obviate the need for pinion shafts/bearing to spin about 13,000 RPM. These four gearsets were actually the very first pieces fabricated. Admittedly, this approach could possibly require reverse-rotation engine(s)- but it served very well in the Challenger 'liner (since 2 of the 4 engines needed reverse-rotation anyway). Just something to keep in mind...