The Stovebolt Site Forums The Shop Area Engine Shop Crazy drivetrain overdrive idea

Well here goes... I'm sure there has to be something wrong with this, but here it is anyway. Most of us want/need overdrive in our trucks. I was thinking of bolting 2 trannies together, tailshaft to tailshaft. The first tranny bolts up to the engine like normal and is shifted as normal. The 2nd tranny is installed backwards via some kind of engineering wonderment. The driveshaft would be somehow attached to the input shaft of the 2nd tranny (again via some kind of engineering wonderment). The second tranny would be run in 2nd gear. When the tranny is in 2nd gear the input shaft has to turn faster than the output shaft, giving you overdrive. The only problem is that this tranny will be running backwards from what it's used to. The bearings won't care, and neither should the synchros. The only problem I can see is with the cut of the helical gears... I don't know how big an issue it would be though... So am I completely nuts?

You might want to have your drinking water tested. :confused:

You would have to have a really powerful stereo to drown out the howl that set-up would produce,LOL,
Scott

Heh heh--

I guess this is for ur 49. The other thing u might consider is just buying a muncie or saginaw tranny with electric overdrive which bolts right up and wud actually work.

Yep, you're juuuust abooouuut therrrrrrrre aaaaaaaand....
Done!
You've gone completely nuts.
But hey, they said that about the people who said we'll land on the moon.
Just don't listen to the little voices in yer head!
Who's gonna be doing the engineering wonderment?

LOL... I was kind of expecting this response.. I'm soon to be an engineering graduate (in 2 weeks) Can you tell? I'm always thinking of strange stuff like this.. This is coming from the guy that put a small block Chevy V8 in a '55 Jeep in 6 hours.
I still think it would work though. I'm pretty decent at fabrication and have access to a milling machine and lathe. Then just give me my welder and get out of my way

Well, if you run a few numbers, using 2 SM 420's, 3.73 gears and 31" tires, and you had the first tranny in 4th, and the other in 1st, you could theoretically do around 120 mph AT IDLE. I think you would be going through clutch very, very, very quickly.

Hahaha...I like the SM420 idea.. It would give you roughly a top speed of about 392mph I was basing my idea around 2 3speeds. It would give .6 : 1 overdrive with the rear tranny in 2nd gear

Quote:
I guess this is for ur 49. The other thing u might consider is just buying a muncie or saginaw tranny with electric overdrive which bolts right up and wud actually work.
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That's been thought of. Check this out: www.gearvendors.com

Another thing you could do maybe is set up a Powerglide 2 speed in front of a Muncie, and have the Muncie rigged like a divorced transfer case, with a short driveshaft connecting them. I wouldn't want to try to figure out the clutch arrangement or the balancing of the engine!!!
Just buy a Gear Vendors overdrive and your Muncie will become an 8 speed manual!

Something like this was done in the past, and it was a good idea. It was a two-speed rear end. This was sold as a kit that could be added to a car, but is no longer available. I do not remember what they called it.

I read where some of the street rod guys were using two turbo 400's just the way want to use to 3 speeds. The second unit was for underdrive. They could gear them down with 2.56 or 2.41's then shifting both transmissions they could have a real low first gear.

A simple slip joint between the two should work! You also shouldn't need a clutch on the second unit, Just shift it into overdrive before getting going. You could use 3 gear as 1 to 1 and 2nd gear for overdrive. Tractor guys do it all the time for crawling speed when fabricating drivetrains! Joe

Then again, I've been jonesing for a Brownie (Spicer 5831 C) auxillary transmission to hook up to my SM 420 on my 1 ton. This was not an uncommon deal on big C50 and up dump trucks, etc.

Anyone know of a set up I could mooch at a reasonable price?

http://www.6066gmctrucks.org/spicer-5831-b.htm

The idea would work, and might get de-bugged in a decade or so. My brother, (also an engineer) had a buddy at Tennessee Tech who was determined to grind his own camshaft for a Ford 302 we built in the high school shop where I teach. After a couple of hours of "Camshafts 101" from yours truly, he decided maybe it wasn't such a bad idea to let Comp Cams do the honors!.

An engineer and a line mechanic had a footrace. The rules were very simple. There was a bikini-clad lingerie' model at one end of a long hallway, and our two competitior were at the other. Race rules: Run as fast as you want, but each time you run, you may only travel half the remaining distance. Halfway, then half of that, half again, etc. The engineer grabbed his pocket calculator, set up his laptop, and started figuring. The tech eyeballed the distance and took off. Results: The engineer never got there. The tech got "close enough for all practical purposes!"

Jerry

There are two kinds of engineers. Those who can tell you why it won't work and those who don't know why it won't work.

I prefer the ones willing to take the challenge.

We tell that joke as a contest between mathematicians and engineers. You'd be better off spending the time and money adapting a better transmission (NV4500 or NV5600) and/or a higher speed rear end.

ive also thought about the powerglide.i like to use one as an underdrive.take it,get rid of all the unnessasary parts[torque converter,valve body},make an adapter to hook it to the back of my turbo 400,and use a cable/electric solenoid to shift it.then go find 2.50 rearend gears.in other words a cheep gearvenders unit.

Pull the cork on the Jim Beam!

This has possibilities!

Spicer should have a U-joint for the coupling.

Get the right spline yoke to fit the input shaft of the rear box and weld her up!

With the right gear we could be turning 800 RPM engine speed at 148 MPH!

May have to go Diesel power to twist the gear!

Headin' out to the back 40 to see what's in stock!

Southtowns27

It can be done and has already been done. I live in Brasil, and I saw similar set ups here, always in pick up trucks for the sake of not having enough space to assemble all the hardware required under a car. Your ideas are correct, just a few words on it:
leave the drivetrain exactely as it is, them grab a second tranny, You should look for the smallest one, and try to locate a close ratio 3 speed. If You get a tranny with a 1.66 2nd, a common number, the resulting overdrive won't be sooo tall in a way to make it useless. You just drive it everywhere with the second tranny in 3rd, when on the road and willing to drop the revs, put it in 2nd. You're thru. Don't know what car is in to get the mods, but making it this way it should work. When choosing the 2nd tranny make sure it's in sharp shape and has a good slanted gears to reduce noise. Anyway there will be some thou. Feel free to e-mail me if You need more infos.
Good luck!

Q: What's the difference in cowboy boots and engineer boots?

A: Cowboy boots have the BS on the outside!


Jerry

Sounds like that NY engineering school has a few too many blue state profs with weird ideas that are causing your brain to go into a "what if" do loop.

Down here in Texas our engineers learn to address real everyday problems such as how to clone a cow (well you get the male cow and female cow together see...) or how to genetically engineer new corn strains (sounds yummy).

Good luck with your idea. Never know if it will implode unless you try it.

I'll donate a Muncie 3 spd to the project

Well, let me rephrase.. I'm an industrial engineer, also known as an operating engineer. I've also been a heavy equipment technician and operator since 1997. Personally, I think it's fun to TRY to do strange things that most people say "That'll never work" about. You'd all probably like the drivetrain I have in my Willys Jeep, 16 forward gears, 4 reverse. It's powered by a 283 and the 4x4 is all still fully functional. Lots of people told me I couldn't do it..Still running like a clock 25,000 miles later. It's a daily driver, gets 18MPG, runs a 9 second 1/8 mile, and will climb a tree
I can't see why my overdrive idea wouldn't work...yet anyway.
Truckedup, if you're serious, send it over...

South,you're an hour or so west of me? drive on over,pick it up,good tranny.Get a pizza, go for old truck rides.

Where abouts are you located? I'm about 45 minutes SE of Buffalo

I'm in Webster,near Lake Ontario,about 12 miles east of Rochester.You might be more like 2 hours away.If you want it,give me a call 585-216-9887,if I don't answer,leave a message,I'll call back, Tony

This summer I took a picture of a mid-engine Olds station wagon. That's right. Ugly as sin, would never get a fraction of what he put into it, but I had a lot of respect for the ballsy engineering. He supercharged his motor and stuck it on a Toronado transaxle to drive the rear wheels.

These bizarre ideas sometimes work. I have heard of people grafting two trannies together. Gear Vendors is doing nothing more than that, using a planetary gear transmission for their overdrive. Similar to an electronically shifted Lenco.

So here's an interesting question, what if you stuck a Lenco in line with the tranny of your choice? Aren't they a clutchless manual?
Shift on the fly at full power, no problem. I still think there's a clutch action going into first gear only though.

Let's see if any backyard engineers can come up with something.

When I was building my fish hatchery I had this engineer friend help. I didn't go for all his ideas but some of his stuff is working to this day. In fact, we made some innovations that are now becoming standard in the industry. A real engineer lives in a sort of selfimposed prison and looks at everything in life wanting to improve them mechanically.