O/D T-case for the bobbers

[wehring]

FYI All,

The t-case in the M939 trucks has a .732:1 high range ratio instead of 1:1.

This is a difference of 15 mph at the same rpm.

Justin Wehring
979 997 3112

 

[Chevytruck]

Isn't the 939 series transfer-case prone to cracking when backing in low range?

 

[wehring]

Yes but...

It is but you need to understand why. The low range reverse ratio is 11:1 and inexperienced drivers transition from drive to reverse in haste and shock the case. The cases I know of were also tied in with a heavy load. I have used reverse in low range with no problem.

The possibility of this happening in a bobbed deuce (much lighter and no tandem axles) is reduced.

Justin Wehring
979 997 3112

 

[gimpyrobb]

So a 939 Tcase is a direct replacement for a deuce Tcase? I am only asking cause I know nothing of the 939 trucks.

 

[wehring]

no

No. It will be a moderate conversion. New shafts and mounts will be necessary.

Justin Wehring
979 997 3112

 

[jesusgatos]

But if you were putting 5-ton axles in there at the same time...

 

[BFR]

I see the point of sourcing a trans with a deeper O/D (or tom's gearset), but I can't see the advantage of this. I don't mind shifting the transfer to get a heavy load moving, but it would annoy me to have to do it all the time.

 

[clinto]

Isn't there a rotational issue here.............. like the driveshafts spin a different direction than the deuce... or am I thinking of the GMC 135/211 transfer/axle issue?

 

[wehring]

ideas

Excellent questions, all. I am stuck in AZ for another week before I can get home and make this more than an academic idea.

Justin Wehring
979 997 3112