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Reversed SM465 as overdrive

So i have been researching this old idea, backing a 465 with a second one, run backwards. That 1.70:1 gear would make a 0.59:1
Mating the tails of a pair of 2wd 465s is simple. The challenge is getting the input of the rear one to run a driveshaft.
But Spicer makes a yoke that fits on the $89 MD-465 1.5" input, and takes a 1410 u-joint. And it's only $45. The Spicer part number is 3-4-6561-1.
If. I ever do it, I'll post pics somewhere on the net, depending on where i don't get ridiculed for it. Pirate4x4 already failed.
 
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thenag

thenag

Registered User
Location
Kearns
Tonkaman said:
I've not familiar with this idea. What is the goal?
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What is the goal? for old 4 speeds to get a OD this is a slick way to do it, (about $1600 More than your idea...)
http://www.advanceadapters.com/prod...tter-overdrive-27-with-a-5125-retainer-index/
This mounts between the bellhousing and transmission, so the transmission would move back a few inches.

I have never been in a sm465, but I have been in a np435. 1st and R are straight cut gears, 2,3,4 are helical(?), not sure if that has any thing to do with running at high speed or backwards...

Nathan
 
B

B2-Bomber

Guest
Location
SL, UT
To what end?
Having it constantly in the second 465's 2nd gear? Thus overall raising your final drive ratio? Just re-gear the axle

If not that ^^^ you plan to shift it between the 2nd 465's 3rd (1:1) gear, and then into its 2nd gear once you need OD?
So a 2nd shifter coming up from nearly the back seat since the 465 isn't a linkage trans?
Going to compression shift it without a clutch? With the synchros going backwards? Synchronizers are designed to work with the shaft spinning forwards, and the input (now output) shaft being disconnected via clutch to match the main shaft, and counter shaft speeds.

To save money?
By the time you buy a second trans, the various yokes/joints, mounts, and then modify both driveshafts for the length. I'd imagine you're just barely shy of buying a legit, and superior OD trans like an NV, or OD box. . .all to have a janky, cobbled together system. That is needlessly long and messing with pinion angle. And if you intend to use this on a 2wd vehicle, one less driveshaft. But that also opens up the available OD transmissions considerably.

Or is it just for the "weird" factor? Or the "want to see if i can do it" factor? - i actually respect that.

There really is a reason this isn't already a "thing"
 
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S

SWpike

Did what you were thinking about in 1974, had a 57 GMC that I made into a car hauler for imported cars and small race cars, had a repair shop and needed something to haul customer cars and race cars, didn't want to tow a trailer around town, extended the wheel base and put a single wheel 1 ton rear end under it, put a 390 427 with a turbo 400, couldn't find a rear end with the right gears, so tried a commercial overdrive that ran way to hot, got a sm420 and mounted it backwards, used a short drive shaft with the 400 slip yoke to the ujoint on the sm420, cut the center out of a clutch disk and mounted it in a slip joint that rode in a pillow block to keep it centered and allow for movement, ran it in third gear, but could shift it into 4th if needed a lower gear, tried it in second, but 1200 rpm was like 70 or so. Never hooked up the speedometer, drove by the tach. Always planed on putting a sm420 in place of the turbo 400, but never got around to it. Made a two car trailer to tow behind it, so could haul 3 cars at once. Could run 80 loaded with 3 cars. Drove it all over the east coast and then moved to Az. with it loaded, saw it a couple years ago near Phx. still had the 427 and sm420 in it, wished I still had it.
Have a 1ton 1979 Chevy tow truck with a sm465 and a 454 in it, have a brownie 3 speed back of the sm465 which gives 12 speeds, one under, 1to1 and one over, much better then the modern over drives.
Building a 1959 Chevy 1/2 ton 4X4 with 454 and a NV4500 behind it out of a 1998 GMC 3/4 4X4.
Hope this answers your idea.
 
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