T90 input shaft questions.

So i blew up the input gear (from what i can see its the only one) on my t90 (or so the top shifter cover says).

It seems there are about 7 options on ebay and no one local has anything.

so the question is, WHICH ONE?!

Its a 67 cj5 that i know was rebuilt about 2-3 years before i got it, it runs great until i broke it
Dauntless v6, with some sort of an adapter plate / spacer between the bellhousing and the tranny.
then a d18 behind it. (missing the ebrake)


Now im assuming the shaft should be pretty long with the spacer in there, what is the spacer / adapter even for? is it factory?

if so, anything else bolt to that and the transfercase where i can just replace the whole thing?

If my easier option is to replace. does anyone know which input gear i should buy?!

thanks a MILLION

 

If it's a factory V6 (ie not a swap), the transmission is a T-86 and I expect none of them will work.

The long input shaft and adapter is correct for the factory V6 Jeeps.

A T-86 is the same size as a T-90, but the spur gears are beveled, and the splines in the main shaft are helical. A T-90 will have straight-cut gears and straight splines. The side of the case of the T-86 has"T86" cast into it. https://www.novak-adapt.com/knowledge/t86.htm

 

dammit i had this typed out and it didnt post.

Novak says, "The T90C has a 16 tooth, helically cut input gear. The cluster gear has a 35 tooth driven gear"

sure this is a t86? that might make it easier. here is a pic with the cover removed....

http://s18.postimg.org/4ogj20lop/1948256_627119840756864_6200980835947423584_n.jpg

 

That's a T-90. Straight cut spur gears, straight splines. You either have a V6 swap or someone has replaced the T-86 with a T-90. Or it could be T-90 gears in a T-86 case. That works too.

The only input shaft that works with an adapter is the one for the T-90J.

 

A comment - it seems unlikely that the broken input gear has not affected the cluster gear. It would be hard to see from this POV. Just be aware.

 

My experience with a t-90 behind a v6 was short lived. 5 miles. I wasn't surprised as that transmission was trash. The input shaft would be the t-90j one that is longer. I also had issues with the bearing retainer. To rebuild it with new gears synchros and bearings was over 700 bucks. I just looked on craigslist and bought a sm420 for 75 bucks and then bought the novak adapter for 550 or so. I had a much stronger, good working 4 speed transmission then and was still under the price for the parts to rebuild the t-90. Just my experience. to do again i would go sm465 because they are much more plentiful or the t-18 or whatever the other good one is.

 

A T-90 in good condition will live behind a :v6:
I've had one in my 70 for years.
I agree with Tim that there's probably more damage to the cluster gear.

 

I want to clarify, my particular t-90 was trash. I have used them before and had no issues at all. My particular one was too far gone. I only went SM420 purely for cost effectiveness and in addition the 4 speed low gear option. Lots of guys run the t90 behind v8s.

 

A lot of how a T 90 will stand up depends on the driver, even if it is behind a built SBC.

 

The Jeep PN for the T-90J input is 906203. A search for that finds both Omix-Ada (imported) and NOS parts.

This https://www.willysjeepparts.com/T90_Main_Drive_Gear_And_Bearings.htm plus lots of listings for the import part.

 

As Tim has mentioned, you'll have a lot of collateral damage inside that transmission.
Take it out and take it apart and see what's useable.
Or look for a replacement transmission.
I prefer to rebuild what I already own; or, rebuild a replacement that I might acquire.
That way I know what I have and it's condition.
I would avoid purchasing a "rebuilt" from a private party unless you know the individual you are buying from.
And even then........?????

 

Yep, in proper condition, a T90 can actually take a little abuse in a light Jeep without big tires. I wasn't too nice to the stock T90 tranny in my 3B for 2 years behind a 327 and had zero problems. That transmission is still in the shop. Like other posts, a major failure of any geared component in a transmission usually results in just lbs of scrap as the loose pieces destroy everything else.

The most cost effective replacement is going to depend on whether the transmission is actually a T90 or a T86. If it is the latter, or the latter with T90 gear set, a T14 is significantly stronger and doesn't require a lot of modifications to install. If the former and you don't want to go the 4 speed route, just find another T90A and rebuild with the T90J main drive gear. Around here, a usable T90 can usually be had for less than $100.

 

you guys are awesome. so far i havent found the time to get the tranny out the jeep. ( in the middle of moving and the garage is PACKED )

Looking into options mainly to get it on the road the fastest. but upgrading to a sm465 would be awesome. My only issue is, I would need an adapter to fit the sm465 to the buick bellhousing, then one to fit to the dana 18 to the rear of the 465 as its an offset dana 44 rear.

i do remember reading once that the sm465/420 may bolt to this bellhousiong or stock adapter... or a chevy bellhousing will bolt to the buick block and then its just mating the dana 18?

Im not toooo worried about length as the rear driveshaft needs to be replaced too.


what am i missing here? would the stock shaft from a sm465 fit the dauntless?

 

The T90A and T90J have the same cluster gear. The T90C is different and unfortunately, no long input shaft/main drive gear was ever manufactured for it to my knowledge. Hence the T90A guts rather than the better low gear of the T90C gear set for converting a T86.

 

The GM transmissions like the SM420 and SM465 will bolt up to your bellhousing - you have a GM bellhousing behind your V6. However, you will need a kit to make the SM transmission connect to your transfer case. You can also adapt the Ford transmissions to the GM bellhousing - see here - https://www.novak-adapt.com/catalog/adapters/engine_to_transmission/ford_to_gm.htm

The Jeep T-18s will bolt up to your transfer case, but they are different on the front end. It is possible to merge a Ford and Jeep T-18 (or IHC T-18) and make a transmission that will bolt up at both ends, using only junkyard parts and some minor machining. This has been discussed a lot in the past here.


The OP's transmission is definitely a T-90. This is a T-86 - note the differences in the sliding gear tooth angle and the spline design:

 

Glenn,
I have a book designating the "1962 Jeep Service Standards".
Realize that the Jeep service standards changed over time.
Standards are dependent upon model and vintage.
New service standards were issued each year covering all Jeep models.
The various vintages and models had various types of options.

The long T90 C input shaft was actually used as early as 1947.
That fact is readily discernible via it's early part number.
In fact the T90 C was the only available input shaft on the earliest Pickup Trucks.
The earliest trucks from 1947 to 1950 were standard with L-134 Go Devils, 4.88 final drive ratios and T90 C transmissions.
In 1954 the Super Hurricane became available for the first time for Pick Ups and Wagons.
If Pick Up or SW was equipped with the then optional Super Hurricane 226 engines; a T90 J with it's long maindrive gear was required.
Various differential ratios are fully dependent upon the engine and also the transmission.

Bottom line is one should be aware that the Jeep was and it yet remains in a constant state of change that we commonly call progress.