T90A vs T90C, What a difference!

Just for curiosity I have a T90F transmission that I think came out of a 2 wheel drive Scout,no transfer just a yoke,are the gear ratios different ?parts useable in a T90A?

 

IH used various T90’s between 1961 and 1973.
Most if not all used a 16 tooth main drive gear (input).
So they are most likely to be suitable with a T90C not the T90A.
Re-using the IH main drive depends on its length and the IH main shaft will have limited applications.

 

well there we go I opened up the transmission. What am I working with here? I didn’t spot anything obviously broken.

 

T90 guts in a T86 case. Count the teeth on the main drive gear (nearest bellhousing). I expect there to be 18 teeth.
-Donny

 

That looks real clean inside.
Please get rid of the silly putty and put a real gasket on it.

 

Thanks oldtime,when I get time Ill pull cover off and compare just for giggles

 

Yeah Jim we’d love to see the inside of your IH T 90.
Have not found one yet that will convert to a Dauntless bell with T90 C gears.
Count the input teeth and measure the stickpout.

 

Not piling on!

Brian, T-90J guts, no doubt. Straight teeth on sliding 1st & R gears, straight splines on the main shaft. The T-86 gear teeth are helical, and the T-86 splines slightly spiral around the shaft.

It's a good repair for the T-86. You should be happy.

 

Well I’m glad thats all good. Ill grab a gasket and button it back up. Now i still have the issue of what’s making that rattling noise.

 

The oil in the bottom of the transmission looks milky to me (contaminated with water). If that's all the further it will drain, I'd do my best to suck the rest out. You could add a little mineral spirits or kerosene to the bottom of the case and make the remaining oil easier to remove - just be sure to remove it all, and don't bathe the gears in it.

 

Also, the transmission and transfer case share oil, so you should drain both.

I'd guess it's a Dana 18, but I cant be sure from that angle. If the rear driveshaft is offset to the passenger side, it's an 18.

 

I bet one of your floor pan bolts is contacting the drivetrain and making that noise. I had that issue with mine, and they can make a loud thunk, especially when the drivetrain shifts from torque. Take a close look at the ends of the bolts to see if they are marked up from making contact, especially the two just above the bellhousing.

 

I believe so.

OH ****. So after just reading this, I didn’t drain this at all. The photos above was the level it was at as I opened it.

 

See I thought so too. But the video I have while driving it, I have the floor out with all the bolts out. Still making the noise.

but now I’m thinking I could have that sound cause there was not enough oil in the transmission

 

I would love to swap in a T90C with the 5.38s on my M38a1. that combo would have a CRAZY low range crawl speed.