Transmission Decision Help
 

Hi Folks.
I have finally made some progress on the swap for my '46 IH Metro.
We have the old straight-6 out and are prepping for the 617 to go in.
The plan is to use the 617 as the power for a 4wd scout-based chassis.

https://fbcdn-sphotos-e-a.akamaihd.n...90250189_n.jpg

my biggest question is on transmission ... and i need some help.
the easiest plan would be to just keep the existing MB transmission ('81 300SD that shift and functions just fine) and use the output with the transfer case.

the second option would be to use a 700R4 with adapter plate.
this would need some sort of adapter for the TV cable as well...

so which one is 'better' for my application
GVW is about the same between the Benz and the Metro
the difference is really in the first gear between the two transmissions.
If I take the 700r4 numbers I have:3.06
1.63
1.01
0.70


Right?


And if I 'normalize' the Benz tranny with the 4th gear to match the 0.7, I get this:


2.58
1.68
1.00
0.70


Right?


So the real difference is first gear.
Because you can set cruising speed and rpm with the final drive.
So it is really the difference of 3.06 v 2.58


Is that jump worth all the effort of a new tranny and tv cables and adapter plates?


Thanks again.

geoff

How heavy is the truck compared with a W126?

I'd be inclined to keep the engine and transmission all Mercedes and just adapt the differential.

total GVW will be about 5000 pounds
maybe a bit less
not tooooo different than the 300SD

thanks for the advice ...
that was my inclination as well ...

just want to be sure the transmission can handle the load
which i think it can

cheers
geoff

The 722.3 is known to be a pretty tough transmission - many people use them with loads and loads of horse power. This guy started with a manual transmission but ended up with an automatic because the manual couldn't hack it =>

http://www.peachparts.com/shopforum/performance-paddock/174080-300e-12v-turbo-project.html

Actually, the 300SD weighs 3800 lbs, so the difference between it and the IH is substantial. I would definitely go with the 700R4 or give up hopes of a real OD gear -- you're going to need that low-end grunt.

Do you know the gear ratios of the original gearbox and the power of the original engine?

i will look up the original 3-speed ratios
but that Metro was not really designed to cruise at modern speeds
that said ... i really don't expect to drive faster than 60 ...
really
it will be a big slow rig ... and my hope is to just amble along and soak in life

more tomorrow when i look up the old ratios...

thx

Is it something like this one?

http://1.bp.blogspot.com/-0-Mgg4wikF...n.%2B-%2B1.jpg

Sounds like a really cool project :thumbsup:. Keep us updated on it!

Here is my rig...
the one in your pict is a '50s or '60 Metro ... and a Dually

Mine is a '46 ... the first year after WWII
Partly pre-war (front panel/grill)
Partly post-war (rear wheel wells)

the final image is the desired 'after' photo
some day!!!





https://lh5.googleusercontent.com/-l...9-no/photo.jpg



https://lh5.googleusercontent.com/-H...Final_body.JPG

Wow it has CLK wheels with hub caps on it!

https://lh5.googleusercontent.com/-H...Final_body.JPG

So here are the specs as I know them
notice the GVW is 4600 for the Metro ...but when set up as a camper ... I'm guessing closer to 5000

and the plate on the 300SD says 4785 ... so that i whey I assumed the 617 would be the perfect engine ...

as for the original transmission ... the spec is also below
3.05
1.48
1.00

but remember the Green Diamond 214 only had 73 rear-wheel horse power!


many thanks for all the input!!
Geoff





https://lh3.googleusercontent.com/-N...o/DSCN0144.JPG

https://lh6.googleusercontent.com/-A...no/photo+1.JPG


https://lh5.googleusercontent.com/-l...no/photo+2.JPG


https://lh3.googleusercontent.com/-O...no/photo+3.JPG

GVWR is the max weight of the car fully loaded. A 126 does not weigh 4750lbs.

Gross vehicle weight rating - Wikipedia, the free encyclopedia

sorry ...
i jumped through a million assumptions ... here are the major two
1: GVW is about the same
2: transmission will be 'rated' for about the same

curb weight of the MB is about 3600
curb weight of a shell Metro is about 2700
plus ~1000 worth of shelving/cabinets/camping gear

hope that makes my delusions a bit more clear

cheers
geoff