Dual Transmissions, Any comments

[BlazerBud]

My Father in law told me that back in the 70's it was poplular for people to who towed alot to put a second tranny after their main one. Like such: A heavy duty pick-up truck with a big V-8 engline, this would have an automatic tranny with torq converter as usual, but after the main tranny, they would mount a salvage 3 or 4 speed manual tranny to the main one. It would require some moderate brackets and adapters to be made, as well as new drive shaft, but the end result is that they could run the manual tranny in top gear and have a 1:1 gear ratio as normal, or any of the lower gears to get more low end torq when starting out towing.

This all seems logical to me and possible. But I have never seen a build or even heard anyone else talking about this. Does anyone else know of such a set up? I think they did this on two wheel drive trucks mainly.

I was wondering why not do this on a 4 x 4 and mount the transfer case after the second tranny. It seems like that could work also kinda like the doubler transfer case set up using dual tranfer cases, but this could provide super-crawl gearing.

 

[dhcomp]

you can buy over/under gear drives from gearvendors, but what he is saying doesnt' work too well in practice.

Ppl on here have tried it with STRONG manual trannies, and the input on the second can't take the torque multiplication of the first. Either that input shaft breaks, or the linkage between teh 2 breaks.

 

[BlazerBud]

you can buy over/under gear drives from gearvendors, but what he is saying doesnt' work too well in practice.

Ppl on here have tried it with STRONG manual trannies, and the input on the second can't take the torque multiplication of the first. Either that input shaft breaks, or the linkage between teh 2 breaks.

I get what you are saying, it's better to just rebuild a tranny with super low gear ratios if you want to crawl. But, I thought it would be cool to have two trannies and be able to brag about having like 25 mathematically possible gear ratios or something like that.

 

[thatK30guy]

I remember mj doing this or trying to make it work. He used to frequent here but his opinions were regarded as "hi-pinion-ish" and so now he's always over on the PBB instead.

I can't remember exactly if he accomplished this setup but I do remember reading someone did it and broke shafts due to too much torque.

 

[tRustyK5]

There is a local guy here with a pretty wild Ford Ranger. 460, two NP435's and a C6. I have seen pic's, and have heard about the truck from a few other guys but I don't know much about how it's all run. Everything I've heard about this truck is that he rarely breaks stuff, so either he has some real finesse driving, or doesn't get into the deeper combinations much or it's well built. I'm guessing it's a combination of the three.

Rene

 

[dhcomp]

i know the c6 is an auto, what is the 435? transfer case? If so, then its just an auto with a doubler unless im missing something?

 

[sandawgk5]

i know the c6 is an auto, what is the 435? transfer case? If so, then its just an auto with a doubler unless im missing something?

435s are like the little brother to the 465 4 speed manual

Ira

 

[tRustyK5]

435 vs 465 is pretty much same/same. Can't recall which T-case he runs...

Rene

 

[resurrected_jimmy]

Way back when.... a lot of medium duty trucks used to run something like that. My grandfather had an old ford with a 3/4 speed set up he bought from a mining company to use on his farm. With both trannies locked into reverse you could easily walk faster than it would move.

 

[jekbrown]

yeah, search for this kind of crapola on pirate... several peeps have tried it there. I know some yota guys have.

j

 

[Mudstud]

My bud here in town is just a couple weeks away from having his build done. He's running a Toy with dual auto trannys. It's long. I mentioned to him some concern about the second case handling the tork instead of the t-case. We'll see how it holds up once he gets it going. He drives hard so it should be a good test of durability. Has lots of pics showing everything.

http://bb.tennesseeoffroad.com/ubb/ultimatebb.php?ubb=get_topic;f=5;t=000391

 

[Speedo]

I know of a few people who run TH-400s into a SM465s with a married 205 on the 465. One of them is running some 60+ tall rice and cane tires on 2.5 ton Rockwells and a couple are running them on with 1 tons and 16.1 ag tires. The only problem any of them have had is using too low a gear in in the manual tranny and snapping axles. It is a long combination and mounting should take that in to consideration.

435 is a 4 speed manufactured by New Process known as an NP 435, 465 is a Muncie also known as an SM 465 both are granny low trannys.

Gus

 

[muddermilitia]

search on pirate in the chevy section, theres a guy building a s-10 truggy and hes running dual sm465s and has had good luck so far.

 

[BlazerBud]

Thanks for all the input, I thought it may work, just as I think about it in my head. I think it could be done with a mild engine, otherwise I agree, the torq multiplication would be too insane

 

[big83chevy4x4]

i remember mj's setup, he had a custom adapter built and also had a new input shaft built that would take the torque it was recieving. don't ever remember him saying he had a problem, but he was kinda that way.

the other one you guys remember was burbboy, he took a 10 spline yoke off a np205 put it on the stock input of the 465 and used the h yoke from a double cardian joint to joint the 2 trannys. he ended up breaking the stock input shaft.

i think with some research and some custom parts it would hold up just fine.

 

[M-1028]

A friend of mine #4 goin out for top truck in four wheeler magazine (white chevy crew cab) has been runnin a 4L80e/sm465/205 combo for over 2 years now and all he's broke is a 205 front output and a couple stock 60 shafts.