I am just bouncing around ideas but has anybody heard of connecting
two gearboxes together and then add the transfer case. This should
result not only in low crawling gear ratios but also an extra
overdrive ratio which would be just what I am looking for. In effect a
ten speed gearbox based on two five speed gearboxes.
Could be lots of problems though, extra length, cost, etc etc but just
wondered has anyone tried it.

Thanks

Smokeyone

Smokeyone wrote:
>
> I am just bouncing around ideas but has anybody heard of connecting
> two gearboxes together and then add the transfer case. This should
> result not only in low crawling gear ratios but also an extra
> overdrive ratio which would be just what I am looking for. In effect a
> ten speed gearbox based on two five speed gearboxes.
> Could be lots of problems though, extra length, cost, etc etc but just
> wondered has anyone tried it.

You'll have a few more than 10 speeds, more like 25, as you would have 5 speeds in the front box with 5 speeds for each in the
rear box, 5*5=25. You would likely have trouble with torque multiplication if running the front box in say 1st gear, as you
would be getting ~4X the engine torque into the rear box.

On Toyota pickups, running dual transfer cases with stock or lower than stock gearing is common, I have 2.28:1 in the front
case, 4.70:1 in the rear case, however both cases are 1:1 in high range (no overdrive). Perhaps you could use a setup like this
coupled with a low numeric axle ping&pinion ratio. I have overall gear ratios from 4.1:1 up to 206.8:1 with 20 forward speeds:
http://4crawler.cruiserpages.com/4x4/4R_TechInfo.shtml#Transmission

--
Roger

Roger Brown <r.c.brown@ieee.org> wrote in message news:<3F776747.2A2F4EE4@ieee.org>...
> Smokeyone wrote:
> >
> > I am just bouncing around ideas but has anybody heard of connecting
> > two gearboxes together and then add the transfer case. This should
> > result not only in low crawling gear ratios but also an extra
> > overdrive ratio which would be just what I am looking for. In effect a
> > ten speed gearbox based on two five speed gearboxes.
> > Could be lots of problems though, extra length, cost, etc etc but just
> > wondered has anyone tried it.
>
> You'll have a few more than 10 speeds, more like 25, as you would have 5 speeds in the front box with 5 speeds for each in the
> rear box, 5*5=25. You would likely have trouble with torque multiplication if running the front box in say 1st gear, as you
> would be getting ~4X the engine torque into the rear box.
>
> On Toyota pickups, running dual transfer cases with stock or lower than stock gearing is common, I have 2.28:1 in the front
> case, 4.70:1 in the rear case, however both cases are 1:1 in high range (no overdrive). Perhaps you could use a setup like this
> coupled with a low numeric axle ping&pinion ratio. I have overall gear ratios from 4.1:1 up to 206.8:1 with 20 forward speeds:
> http://4crawler.cruiserpages.com/4x4/4R_TechInfo.shtml#Transmission

Hello and thanks for the reply............
Whoops, 25 speeds to play with -
Would I really have a problem with the first box in first gear and
torque multiplication - you see I am trying to figure out a way to
come up with an extra overdrive gear so the second box idea would
solve all that.

Thanks

Smokeyone

"Smokeyone" <Cuttysark@btopenworld.com> wrote in message
news:6c138c77.0309282147.7a69844b@posting.google.com...
> Roger Brown <r.c.brown@ieee.org> wrote in message
news:<3F776747.2A2F4EE4@ieee.org>...
> > Smokeyone wrote:
> > >
> > > I am just bouncing around ideas but has anybody heard of connecting
> > > two gearboxes together and then add the transfer case. This should
> > > result not only in low crawling gear ratios but also an extra
> > > overdrive ratio which would be just what I am looking for. In effect a
> > > ten speed gearbox based on two five speed gearboxes.
> > > Could be lots of problems though, extra length, cost, etc etc but just
> > > wondered has anyone tried it.
> >
> > You'll have a few more than 10 speeds, more like 25, as you would have 5
speeds in the front box with 5 speeds for each in the
> > rear box, 5*5=25. You would likely have trouble with torque
multiplication if running the front box in say 1st gear, as you
> > would be getting ~4X the engine torque into the rear box.
> >
> > On Toyota pickups, running dual transfer cases with stock or lower than
stock gearing is common, I have 2.28:1 in the front
> > case, 4.70:1 in the rear case, however both cases are 1:1 in high range
(no overdrive). Perhaps you could use a setup like this
> > coupled with a low numeric axle ping&pinion ratio. I have overall gear
ratios from 4.1:1 up to 206.8:1 with 20 forward speeds:
> > http://4crawler.cruiserpages.com/4x4/4R_TechInfo.shtml#Transmission
>
> Hello and thanks for the reply............
> Whoops, 25 speeds to play with -
> Would I really have a problem with the first box in first gear and
> torque multiplication - you see I am trying to figure out a way to
> come up with an extra overdrive gear so the second box idea would
> solve all that.

Probably. The input shaft to most transmissions is designed for the max
engine torque, but your rear transmission is going to get multiples of that
when the front transmission is in any lower gear.

Gear vendors overdrive makes a 2 speed overdrive for full size pickup trucks
and a few other vehicles. You might want to see if they make something for
you.

>
> Thanks
>
> Smokeyone


--
S'later, Mike Locke

in theory:

gearbox 1 & 2
1st 3:1
2nd 2:1
3rd 1:1
4th 1.2:1

running 1st and 1st 9:1 great crawl ratio, esp with a 2:1 tcase bringing
it to 18:1, god i hope you are running rockwells and don't mind running
those high revs

4th & 4th only 1.44:1, that's not a whole lot for overdrive compared to
running the highways

i have seen double tcases, which would give you a 4:1 drop total, good
also for crawling i would guess, but i don't know. the math to me with
doubling up a transmission doesn't help you a whole lot if you want
overdrive gears
--
Ben Jerew
ASE Master Technician
New Country Lexus of Latham, NY
Amateur Off-Roader

>in theory:
>
>gearbox 1 & 2
>1st 3:1
>2nd 2:1
>3rd 1:1
>4th 1.2:1
>
>running 1st and 1st 9:1 great crawl ratio, esp with a 2:1 tcase bringing
>it to 18:1, god i hope you are running rockwells and don't mind running
>those high revs
>
>4th & 4th only 1.44:1, that's not a whole lot for overdrive compared to
>running the highways
>
>i have seen double tcases, which would give you a 4:1 drop total, good
>also for crawling i would guess, but i don't know. the math to me with
>doubling up a transmission doesn't help you a whole lot if you want
>overdrive gears
>--
>Ben Jerew
>ASE Master Technician
>New Country Lexus of Latham, NY
>Amateur Off-Roader
>

i would belive they are reffering to double T cases,not double trannys, such as
the ones at http://www.marlincrawler.com/ for toyotas, everything drives the
same except you have dual T cases, for 4wd low and 4wd low low, it looks as if
they also have other applications other than just toyota,





79 T/A WS6 455 ,Hurst 4 spd, Blk w/ t-tops, Heavily Fortified, 4mpg

00 Ram 2500HD QC V-10 4x4,Blk,5 spd,4:10 LSD, 10mpg

98 Intruder 1400, Blk, 5 spd, 25mpg

TOXICTAVRN wrote:

> i would belive they are reffering to double T cases,not double trannys, such as
> the ones at http://www.marlincrawler.com/ for toyotas, everything drives the
> same except you have dual T cases, for 4wd low and 4wd low low, it looks as if
> they also have other applications other than just toyota,
>
>
>
>
>
> 79 T/A WS6 455 ,Hurst 4 spd, Blk w/ t-tops, Heavily Fortified, 4mpg
>
> 00 Ram 2500HD QC V-10 4x4,Blk,5 spd,4:10 LSD, 10mpg
>
> 98 Intruder 1400, Blk, 5 spd, 25mpg

well, i'm certainly hoping they were referring to double transfer case,
which owuld be great for crawling. but they were saying something about
wanting overdrive gears? smells like a pipe dream to me. i think if i
ever go for crawling, i'm gonna get rockwells before i think about
getting a double atlas
--
Ben Jerew
ASE Master Technician
New Country Lexus of Latham, NY
Amateur Off-Roader