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Crazy Doubler idea, opinions wanted!

gonecheenin

gonecheenin

1/2 ton status
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Aug 8, 2004
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Vandergrift, PA
Dual Transmissions

Thats my idea, 2 SM465's feeding a NP205 out to my 4:11 geared rears in my 74' K20 longbed (soon to become a shortbed, or close to it anyway)

352:1 low crawl in 1st/1st/lowrange

I'm thinking that a 10 spline drive sleeve should also fit the 10 spline input on the input shaft of the tranny, and if i play around with the factory t-case adapters i can hopefully find one that will allow me the right distances for the input shaft so i can use a simple flat peice of 1" or so thick steel as a connector between the t-case bolt pattern from the first tranny to the bellhousing pattern of the second tranny. plus the factory t-case adaptor will give me a way of adding the second tranny mount into the combo. The worst thing i can see happening is bending/breaking the input shaft of the second tranny from missalignment/torque and SM465 input shafts are easy to change and very available

beauty of the idea is that this would probally be a unuasable (in most case's) crawl ratio, BUT i also have 2nd and 3rd gear to use I don't know the actual ratios but i'm figuring about 3:1 in second and 1.5:1 in 3rd, so that would make my crawl in 2nd/1st/low range be 161.5:1
and
3rd/1st/low range will be 80.8:1
or
2nd/2nd/low range will be 74:1

Etc.......

Now the reason i'm listing the ratios with the second tranny in the lower gear is i'm figuring a major drawback of this setup would be the strength of the SM465 input shaft. I know people have run 600 horse big blocks in front of them with no problems, but still 6.55 time's the anount of torque it's used to feeding into that input shaft could be disasterous, so i'm fguring smart driving should solve that problem


What do you all think, feasable/ worth it?

I do gotta admit, part of what is driving me to do this, is too see what a 352:1 crawl ratio would be like /forums/images/graemlins/grin.gif

The curiousity is KILLING me /forums/images/graemlins/woot.gif
 
If I remember correctly MJ is still working on it trying to get a custom input shaft made. Another guy on here did it and snapped the input off of the 2nd tranny the first trip out, it's not made to handle the torque multiplication from the first tranny.
 
Burb Boy tried it in his, but I think what he ended up breaking was the CV joint that he used between the two 465's.
 
I figured that the input wouldn't handle the multiplication from the first tranny, thats why i figure that when driving i would go as low as possible in the second tranny before i even take the first tranny out of 4th, therefore keeping the torque off of the second input shaft

I don't know, i'm gonna see if i can even get it to work right on my garage floor then i'll see what i break in real life /forums/images/graemlins/thumb.gif
 
just got to think, whatever the torque of your motor is, at 2:1 on the first trans that torque is about doubled. So say you are making like 300 ft lbs of torque, 600 some on the second ones input. If you put the first trans in creeper (6.55:1) well thats a lot of torque /forums/images/graemlins/wink.gif. I know you understand that I just felt like saying it all over again.
 
That was actually my intention, i'm thinking that even driving down the road i'll use the second tranny like normal and only touch the first tranny when i'm all out of slower gears in the t-case and second tranny

I figure that if i start at the rear and work my way up i should be good

Yep, sled dog, i thought of that in fact i did the math and came up with using 300 ft lb of torque from my 350ci that the axles with this kinda gear reduction would be seeing 105,798 ft lb's of torque /forums/images/graemlins/yikes.gif
wow, even my stock pickup throws 16,153 ft lb of torque through the axles
Kinda gives you alot of respect for what you think is a "Weak" axle, don't it /forums/images/graemlins/bow.gif
 
So are you going to shift from the back seat or what? Be kind of hard to shift while going down the road when the shifter is a foot behind you...
 
actually the shifter would be located between the front seats. Replace the bends with a straight shifter and it would be right there. The output of my 241 tcase isn't even past the front seats of the K5.
 
[ QUOTE ]
actually the shifter would be located between the front seats. Replace the bends with a straight shifter and it would be right there. The output of my 241 tcase isn't even past the front seats of the K5.

[/ QUOTE ]

I would think it's about the same distance my 205 is behind my 465 /forums/images/graemlins/thinking.gif It's still in front of the factory console and if it was straight (as Alan said) I would be able to shift a second tranny there. The t-case lever however would be a little farther back than that. /forums/images/graemlins/doah.gif
 
the t-case lever would be between the front seats (i have buckets in my truck) or i could always go linkage setup kinda like the aluminum t-cases have
and the second shifter i'm pretty sure could just be installed 180 degrees from normal so that the bend goes forward instead of back

Kinda look like a old floor shifted 3spd manual chevy g10 van, that is if any of you guys ever saw one of those freaks /forums/images/graemlins/rotfl.gif Worked pretty good in the van though for as weird as it sounds
 
I think feeding the rear output of a normal, married 205 into the input of a divorced 205 is a much better idea.
 
i was thinking about asking this very question. i saw it in a 2 1/2 ton 4x4 truck in petersons. he has two 5 ton trans, my ony thought was one hell of a out/inputshaft.
 
I think there were at least 2 guys on PBB that have successfully run the stacked 465s for some period of time.
 
Burb Boy ran/runs it and he broke it. He sheared off the input of the second transmission if I remember correctly. I asked some questions about this awhile back. You might be able to find them searching threw my user name and Burb Boy's user name.

Harley
 
[ QUOTE ]
I think feeding the rear output of a normal, married 205 into the input of a divorced 205 is a much better idea.

[/ QUOTE ] heck if someone were to go this route I would run an NP241 to a divorced 205. If you have the room why not? Lot lower than a normal doubler or a 205-205. ANd seeing as the weakest parts of a 241 are the case and the chain, chain wouldn't even be neccessary.
 
Using the 241 also gives you better lowrange options with the 2.72 and a 2:1 lowrange. Plus a deeper double low range.

It would be like a Klune V and a 205 with some extra length in it. The chain in a 241 shouldn't really be an issue. It is pretty beefy, you just need to protect the case.

Harley
 
If I can find a divorced 205 locally that's exactly what I'm going to do. I don't have to worry about driveshafts, I'm covered. /forums/images/graemlins/whistling.gif
 
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