atc 70 with a overdrive

[big_daddy124]

I got this idea to put another tranny in my 70 behind the existing engine/tranny. I cut it all apart from the crankcase tonight and i need to get it welded where it holds gear oil then mount it. im going to cut holes in the sides of the body where the 2 shafts will come out. i flipped the axle around and im putting disk brakes on it so i wont have to worry about swapping brake sides also. any one ever tried this?

[Autophysn]

no, but sounds like a mad scientist thing to me. Post some pic's, I want to see what you are talking about. Having a hard time visualizing it.

[big_daddy124]

i will post some pics today

[oscarmayer]

:pics: :pics: :pics: :pics: :pics: :pics: :pics: :pics: :pics: :pics: :pics:
:Bounce

[Blown 331]

I see what you are saying but I think its going to provide more underdrive than anything. If 4th in a stock 70 is an overdrive (higher ratio than 1 to 1) you might get slight OD if both transmission are in 4th but that probably wont gear you up much.

[Billy Golightly]

We do this with swamp buggies down here all the time to get enough gear reduction. Engine/Trans/Trans2/Transfer/Rear. Never seen or heard of it being done in a trike or quad though.

Definitely interested to see how it turns out!

[big_daddy124]

i know what your saying but a stock 70 has 2 gear reductions in the final drive. a 4-1 from clutch to trans then trans to output is a 2-1 so im going from output on trans1 to output on trans2 and final will be the input on trans 2 to rearend so gearing up 2-1 i believe. we had talked about turning it around and getting more underdrive but i dont think a 70 needs any lower



I see what you are saying but I think its going to provide more underdrive than anything. If 4th in a stock 70 is an overdrive (higher ratio than 1 to 1) you might get slight OD if both transmission are in 4th but that probably wont gear you up much.

[Blown 331]

i know what your saying but a stock 70 has 2 gear reductions in the final drive. a 4-1 from clutch to trans then trans to output is a 2-1 so im going from output on trans1 to output on trans2 and final will be the input on trans 2 to rearend so gearing up 2-1 i believe. we had talked about turning it around and getting more underdrive but i dont think a 70 needs any lower

I still think you are going to get more underdrive with it than you will overdrive. But if that is the case you could always gear it way up on the sprockets which would give you a lot more top gearing and still be ok with all the underdrive. If someone looks up all gear ratios in a 70 you'll have your answer. I'm betting 4th is an overdrive so you will gain some but in the case that 4th is a 1 to 1 ratio. When you hook 2 transmissions together that are 1 to 1 in 4th, well it's still gonna be 1 to 1 and you won't gain any OD at all. Just a bunch of underdrive. Example if 1st gear is 4 to 1, putting both transmissions in first will cut that 4 to 1 down by another quarter. If any of that made sense.

[big_daddy124]

yea it makes sense if your running them both the same but say first is 4 to 1 and im using the output of my gearbox as the input it should be 1 to 4 right? since the thing factory is gear reduced i am turning it around and making it gear up. fourth is 2-1 none of it is actually 1-1

[Blown 331]

yea it makes sense if your running them both the same but say first is 4 to 1 and im using the output of my gearbox as the input it should be 1 to 4 right? since the thing factory is gear reduced i am turning it around and making it gear up. fourth is 2-1 none of it is actually 1-1

OH, you are correct then. I mis-understood. Yeah if you put the second trans in backwards then you will have several OD gears. Sounds really interesting if you can pull it off and have the power to pull it. Good luck!

[big_daddy124]

OH, you are correct then. I mis-understood. Yeah if you put the second trans in backwards then you will have several OD gears. Sounds really interesting if you can pull it off and have the power to pull it. Good luck!

lol i am glad it makes sense to someone other than me. i trimmed all the engine away from the gearbox/tranny now i gotta get the sides welded up and fabricate a removable cover so i can repair it if ever need be. i will post pics soon

[KASEY]

WHY ,,, 70's don't have enough power to pull a tall 4th gear anyway,,, with an adult on it,,, going up 2 teeth on the countershaft will achieve the same thing...

[super90]

Its been done on 4x4s before, but the gear box was bolted to the hub which spun the gears inside to another hub on the bottom which geared it lower.

[WIkid500]

Sounds cool. Reminds me of the old 2 stick semi's used to gave. Grab one lever, go grab the next go again, grab another, just don't grab both and screw up lol.