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By mr.uglyduckling - 15 Years Ago
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hey i recently had the wise ass idea to run dual tranies in my truck just for craps and giggles the second basicaly being an over/underdrive unit ie regear it so second is 1:1 3rd some ratio oof overdrive 4th being even more overdrive and not forgeting 1st as an underdrive. i just need to know what the limitations are pretaining to regearing a tranie. why you ask i just want something different and i think it would be badass! young bucks bring fresh ideas!!!!!
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By yehaabill - 15 Years Ago
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Y-Guy Young Buck: A couple of things, if you're going inside the transmission to actually swap gears lots of $$ will be required. The early 4 wheel drive trucks had "divorced" transfer cases(short driveshaft from trans to the transfer case) That might be a way to do what you're looking for but you would have to find a way to put "yokes" on the units you would be using, plus driveshaft angles, plus total length of all might create problems.. Keep the idea's coming. Bill Pray for our troops,especially today!
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By charliemccraney - 15 Years Ago
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All that 2 3 speeds will get you is underdrive. To simplify things, let's assume that the gear ratios for both transmissions are 3:1 in 1st, 2:1 in 2nd, and 1:1 in 3rd. With the 2nd trans in 3rd, your ratios are 3:1, 2:1, and 1:1. With the 2nd trans in 2nd, your ratios are 6:1, 4:1, and 2:1. With the 2nd trans in 1st, your ratios are 9:1, 6:1, and 3:1. In this scenario, you actually only have 6 ratios as 6:1, 3:1, and 2:1 are possible with a couple combinations of the hypothetical transmissions.
If you were to use this setup with a tall rear ratio, like 3.00:1 or taller, you can achieve the same thing as overdrive, as compared to what you had.
My personal opinion is that it would be neat but for the price/time involved to get it to work as desired, simplify the idea and install a 6 speed.
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By 57FordPU - 15 Years Ago
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How about this for giggles. First if you use two 3-speeds lined up in a row, you would never get to over drive. But if you turned the second one around backwards and made a coupler for the two tail shafts to mate up and shorten and machine the second tranny input shaft to accept a drive shaft yoke, you could have a six speed with the sixth gear being over drive. By only shifting the second tranny from 2nd to 3rd, you would have five gears to get to 1:1 and the sixth gear would be over drive. When you shift the second tranny to 3rd, you would have direct. When you shift to 2nd in the second tranny you would have an over drive effect. (1st direct, 1st over, 2nd direct, 2nd over..........etc. Nothing new here, it would be like having a 2-speed rearend............just using different pieces.
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By charliemccraney - 15 Years Ago
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Turning the second around would work. Using my hypothetical ratios, it will provide 7 unique ratios of 1:1, 2:1, 3:1, 1:2, 3:2, 1:3, 2:3. If you figure in 3:3 and 2:2, it's technically 9 speeds.
It will make for an interesting shift pattern and you'll have to be flying to make use of the 1:2 and 1:3 ratios.
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By aussiebill - 15 Years Ago
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charliemccraney (5/31/2010)
Turning the second around would work. Using my hypothetical ratios, it will provide 7 unique ratios of 1:1, 2:1, 3:1, 1:2, 3:2, 1:3, 2:3. If you figure in 3:3 and 2:2, it's technically 9 speeds.
It will make for an interesting shift pattern and you'll have to be flying to make use of the 1:2 and 1:3 ratios.Charlie, how about fitting a gearbox to each side of the diff, cut the axle tubes, adapt trans input shaft to act as axle from diff center, then adapt trans output shaft to reconnect to wheel end of axle. Then you could sit in the back changing gears and have 3 independent speeds fpr each axle, good for off road??     just kidding!
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By pegleg - 15 Years Ago
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OR, you could put one wheel in reverse and the other in forward and drive in circles!! Like GM does most of the time!!!
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By aussiebill - 15 Years Ago
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pegleg (5/31/2010)
OR, you could put one wheel in reverse and the other in forward and drive in circles!! Like GM does most of the time!!! Frank; OR put both in reverse and drive backwards like GM does all of the time!
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By mr.uglyduckling - 15 Years Ago
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ok im being serious here like above mentioned what are the limitations to regearing a transmision? the second 4spd being regeared so first is underdrive second is 1:1 3rd od 4th another od that was what i was saying i thought i made that clear above! further mor if i was intending on having something someone else has already done id just throw a t56 in it! p.s. even i know that two stock 4speeds coupled together is just basicaly gonna turn my truck into a 1/2 ton tractor!!!!
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By Bob's 55 - 15 Years Ago
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Interesting concept but where would you get the gears for "re-gearing the second four speed"? Not to mention how you would connect the two?? I think someone already mentioned a two speed rear axle. Or maybe looking into a Gear Vendors Under/Overdrive? I have one on my C-4 and with gear splitting gives me six speeds altho I don't usually use it like that. I use it as 1st to 1st OD for close ratio take off shift (just mash the button for second) and 3rd O/D for highway.
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By charliemccraney - 15 Years Ago
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The only limit is your imagination... and the depth of your pockets. To get what you want will require custom gears. Can you make them? Can you afford to pay someone to make them? If you can do either of these, then go for it.
By the way, I think you would be the first to install a T56 in a Y block truck if you were to do it.
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By mr.uglyduckling - 15 Years Ago
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ok does any one know where one could get custom cut gears? and i am still thinking about the t56 depends on how pricy regearing the second tranny is.
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By charliemccraney - 15 Years Ago
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mr.uglyduckling (6/1/2010)
ok does any one know where one could get custom cut gears?
A machine shop that does custom work. Get out the yellow pages and call some local machine shops. Check with some local transmission shops to see if they know of anyone. Maybe call a place like David Kee Toploaders to see if they can point you in the right direction.
Actually, Google "custom gears." A lot of manufacturers come up.
Another thing that comes to mind is that you may have to provide the dimensions for the gears, particularly if it's a less popular gear box you're using. The transmission will have to come apart. Can you do it or will you have to pay someone? Measurements will have to be taken. Can you do it or will you have to pay someone? Drawings will have to be made. Can you do it or will you have to pay someone? The transmission will have to be put back together. Can you do it or will you have to pay someone? When you're calling places, keep this in mind. Maybe you'll find a place to which you can send your gearbox, they'll handle all of the design/ fabrication work, and send back an assembled tranny with your custom gears. Or maybe you'll have to hire individual companies for each step. There is a lot more to it than that which appears at first glance.
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By John Mummert - 15 Years Ago
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I'm surprised John F hasn't jumped in here. He mounted a second transmission backwards, uses 3rd gear straight through and 2nd acts as an overdrive. Jerry Christenson did the same thing behind a 460/C6 in his 57 convertible.
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By Hoosier Hurricane - 15 Years Ago
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John: Were you referring to me, or "the other John F" from Missouri? I have not done this, but my friend Bob Bayles did. He had driveline vibration, and eventually something failed, so he gave up. I suspect he did not support the original input (now output) shaft properly. On an engine the front of that shaft is supported by the pilot bearing. On my car hauler I have separated an overdrive unit from its transmission and mounted it in the driveline. Required making a front half of a case and making the input shaft accept a U joint yoke.
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By mr.uglyduckling - 15 Years Ago
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ok then i now know what i have to do wish me luck i shal be informing you on my results so heres to nothing
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