Attn. Gearing Guru's

[62 C60]

Let me start by saying, I dont exactly know how to word this so that its not as confusing as a Japaneses matrix.

But, I figure your 4x4 guys would know a little something about this even if its for a 2wd vehicle. Anyway, I was thinking today that if someone were to take 2 4spd transmissions and mount one of them backwards would this essentially transform them from an under drive (anything under direct is a under drive IMO) to an over drive? Then leave the backwards trans in 4th (now in the 1st position) which is a direct 1:1 then once you get the forward facing trans into 4th shift the other into 3rd (now in the 2nd position) giving you a .57% OD (SM465) I know you would have to either A. have some LOOOOW gears, or redline the motor before shifting. Then if you really wanted to haul some tail, pull into 2nd(3rd position) and maybe even 1st (4th position)(5.55% OD HOLY FREAKING SH!T!! that would take balls of steel and then some.)

I know this wouldn't be piratical on a DD with something like, 3.73's and 33's BUT This idea came to me when thinking about a cheep way to have OD in the C60 I'm building that currently has a 261 6cyl and a 2spd axle with something like 5.56, and 8.xx gears in it and 39" tires. Those 5.56's arnt enough.

then for reverse, you could put the front trans in any gear (assuming its the normal one) and the other in reverse if you need LOW gears, or just put them both in reverse and double the reverse ratio, or just leave the front one in direct 1:1 4th gear (assuming its the normal one again)

I have seen people take the range box from a NP203 and run it backwards as an OD and it worked fine. Thats what inspired this madness.

So, essentially you would have 2 transmissions and the shift pattern would be something like this.




Yeah I know, stop being cheep and just buy an OD unit, but hey, its my money not yours, so why do you care?

Your thoughts on this?

[FormerMember]

You'd blow the crap out of the rear trans.

We did it years ago with a 465 in the front and a Clark in the rear. By the time you're done multiplying torque through the first trans, the input shaft is toast on the second trans.

This was 10 spline out, to 10 spline in, both trans front to back (for gear multiplication).

Now, I do know people that have done this with a reversed transfer case... 2:1 with a NP205 backwards, as you said above

[62 C60]

I'm not sure I follow what your saying, when you put the clark behind the 465, did you do it normal for extremely low gears, or, did you do it backwards for OD like I'm saying?

I read something on pirate where someone put a 465 behind a TH400 and whenever he would put everything in low gear it would tear EVERYTHING apart. Then he ended up putting in 2 465's and I think everything worked great even on the street. he just left one trans in direct and shifted the other one.

Im probably missing something here, but if I leave the rear trans in direct until I needed OD, everything else would see no more torque than the input on a transfer case. and with this being a 2 ton truck everything on it is pretty strong.

[FormerMember]

Originally Posted by 62 C60

I'm not sure I follow what your saying, when you put the clark behind the 465, did you do it normal for extremely low gears, or, did you do it backwards for OD like I'm saying?

I read something on pirate where someone put a 465 behind a TH400 and whenever he would put everything in low gear it would tear EVERYTHING apart. Then he ended up putting in 2 465's and I think everything worked great even on the street. he just left one trans in direct and shifted the other one.

Im probably missing something here, but if I leave the rear trans in direct until I needed OD, everything else would see no more torque than the input on a transfer case. and with this being a 2 ton truck everything on it is pretty strong.

That guy on Pirate was a friend of mine. I am an Admin (grendel there, too) there. That was the project I was talking about.He blew the hell out of ANY trans input he put behind it. First 10 spline, then 32 spline 465s, etc, then the Clark. The shock load was just too much to use as a splitter with a stockish transmission. Brownie boxes are common in wrecking yards. I'd go there, first.

T-cases are designed to handle the torque multiplication. They don't shift gears on the fly like you would with that second transmission inline ( think frequency).

[62 C60]

So, my under standing of what you said was, that the shifting from the front trans would tear up the rear one? I guess I would be better off looking for a brownie then with my driving style.

[FormerMember]

Originally Posted by 62 C60

So, my under standing of what you said was, that the shifting from the front trans would tear up the rear one? I guess I would be better off looking for a brownie then with my driving style.

Right, the shock load of doubled and tripled torque will kill the second trans.

Unless you left the first one in gear and shifted only the second one while in motion. Just doesn't seem to be what you're looking for.

[62 C60]

ok, so what if the front one was mounted backwards? Would the engine just tear it up or what?

[FormerMember]

Originally Posted by 62 C60

ok, so what if the front one was mounted backwards? Would the engine just tear it up or what?

Unknown... again, seems like allot of fab work to get a bell housing on the tail of a trans, when your C60 should be running a big trans that could be swapped for any OD trans, pretty easily.

[62 C60]

Originally Posted by grendel

your C60 should be running a big trans that could be swapped for any OD trans, pretty easily.

right now it has a Clark 5spd in it w/o OD and a big trans costs too much. I've looked into it.

[FormerMember]

Originally Posted by 62 C60

right now it has a Clark 5spd in it w/o OD and a big trans costs too much. I've looked into it.

Heh, take a drive, I have a Clarke OD 5 Speed. 100.00 plus the ride. Too fawking big for anything I am doing.


Can buy complete later model trucks around here for 100-1000 with all the parts you'd need.

[62 C60]

Shipping to 47433?

(probably more than you want for the trans. )

[FormerMember]

Originally Posted by 62 C60

Shipping to 47433?

(probably more than you want for the trans. )

I can guarantee that. It weighs like 350lbs!