T90 transmissions

DaveNeale · Post by **DaveNeale** » Mon Feb 27, 2017 3:44 am

I have several T90 tranys in the barn, all with the same 2ed gear kick-out problem. I want to rebuild one for my M38-A1. Did the M38 & the M38A1 jeeps use the same T90? If not or if so, what is the case number I should look for on the side of the gearbox?

4x4M38 · Post by **4x4M38** » Mon Feb 27, 2017 7:56 am

Hi Dave,
Not trying to be anal or anything but you have one of each.

Why not pull the covers and see what you have?

Post by **wesk** » Mon Feb 27, 2017 1:27 pm

Yes the M38, M38A1, M170 all used the same tranny.

Note both trannies are the same part number. A larger & easier to read version is here:
http://willysmjeeps.com/v2/modules/gall ... _M38A1.jpg

DaveNeale · Post by **DaveNeale** » Mon Feb 27, 2017 2:12 pm

I think what I have in the MD now is from my m38, I also have one from a 2a, and also a 56 cj5 one, and a second A1 one. They all have the same ailment, And all had some degree of water infiltration. I couldnt remember which was which, and was going to try and fix one. I might as well repair the one that belongs in the jeep. It's an early A1, a 1952, sn 18822, dod 9/52 USMC

pacho · Post by **pacho** » Sat Apr 15, 2017 5:59 pm

Hi, one quenstions about T90. Did the Cj3b and the m38a1 use the same T90?
In fording condition.

Thanks in advance
Regards
Pacho

Post by **wesk** » Sat Apr 15, 2017 6:45 pm

No, but that was mainly because of the difference in the shift lever tower.
The M38, M38A1 & M170 used a 800079 tranny and the CJ3B used a 644315 tranny up thru sn 57348-93446 and a 931790 tranny from sn 57348-53447 & up. with 3B's using a factory replacement tranny 934316 for a replacement for either of the two earlier units.

pacho · Post by **pacho** » Sat Apr 15, 2017 8:11 pm

Thanks Wesk

Regards
Pacho

carioca · Post by **carioca** » Sat Apr 15, 2017 8:41 pm

Dear Wes,

Looking at Novak's info, it shows 3 variations on T90 :

T90A1- used on L and F head four-cylinder engines
top shifter
7" input shaft (protruding part of it) with 15/16" X 10 splines
18 TOOTH IMPUT SHAFT
33 TOOTH DRIVEN GEAR ..resulting in a :
2.79:1 - first gear
1.55:1 - second gear
Third gear has 1:1 ratio ( as all other gear boxes )

T90C - used with F head ( not L head ) four-cylinder engines
top shifter
7" input shaft (protruding part of it) with 15/16"X 10 splines
16 TOOTH IMPUT SHAFT
35 TOOTH DRIVEN GEAR .. resulting in a :
3.34:1 - first gear
1.85:1 - second gear
Third gear has 1:1 ratio ( as all other gear boxes )

T90J - used with SIX-CYLINDER engines
column or floor shifter
9 1/4" input shaft ( protruding part of it) with 1 1/8" X 10 splines
18 TOOTH IMPUT GEAR
33 TOOTH DRIVEN GEAR .. resulting in a :
2.79:1 - first gear
1.66:1 - second gear
Third gear has 1:1 ratio ( as all other gear boxes )

Since the T90C uses a case marked T90A, the best way to differentiate them is
opening the top and count how many teeth are there.

I also have a question : witch gear boxe was used in the M38 ( MC ) ?

tks[/b]

4x4M38 · Post by **4x4M38** » Sat Apr 15, 2017 9:30 pm

The T90A-1.

Post by **wesk** » Sat Apr 15, 2017 9:43 pm

Using Warner Gear model numbers will not help with ID'g differences between each Willys jeep model useage. Best to stay with Willys part number or Warner Gear part number. The model designations shown above often covered several several Willys pn trannies.

The M38 & M38A1 & M170 all three used the same trannie WO# 800079 or Warner Gear # AS3T90C.

carioca · Post by **carioca** » Sat Apr 15, 2017 10:36 pm

Thanks for your help.

T90 transmissions

T90 transmissions

T90s

T90 A1 / T90 C / T90 J