T86aa First Gear Help!

Hi there!
I am building my first cj5 and have come across the issue of trying to find a first gear for a T86AA. I’ve gotten some mixed information when It comes to differences between a T86AA first gear and a T86E-12u gear. I’m hoping someone can help me with this issue and let me know if this gear would work for a T86AA transmission from a v6 dauntless!

 

First post. Welcome from Boston.

Can't help you with your gear question, but maybe I can give you some background. If I had a T-86 with a broken gear, I would replace all the gears with T-90 gears. The internal dimensions of the T-90 and T-86 are the same, but the gear design is critically different. The T-86 has spiral splines on the main shaft; the T-90 splines are straight. The T-86 sliding gears are helical; the T-90s are straight. The straight gears are stronger but make more noise.

If you rebuild your T-86 with T-90 gears, it will be functionally identical to a T-86 with a bit more whine in 1st and reverse. You can even buy a turnkey T-86 built with all-new T-90 gears, if that interests you. 3 Speed Transmissions | Herm The Overdrive Guy

The T-86 was also used in the early/mid-60s Jeep trucks and Wagoneer, 2WD apparently. I have no idea which parts, if any, from those transmissions will work in a CJ T-86. Possible there were other non-Jeep applications too.

You could also swap to the later and more modern T-14, which replaced the T-86 in 1968(?) and is synchomesh in all forward gears.

 

Thanks for the tip! We have already decided to go the route of rebuilding the 86 as it was. I have pretty much everything I need except a first gear and I was hoping I could either get help finding one or some info about using the t86e-12u first gear instead.

 

Supposedly gears for the T-86 are unobtainable today. All the NOS is gone, no one is making replacements. Good luck with finding the parts you need. Jeeps are oddballs in the car world, and aftermarket support is quite limited. Suspect this gear is available because it won't work for your application. You could try asking Herm (see above) - I hear he responds well to phone calls, not so readily to email.

 

The BW 1st /Rev sliding gear diameter or tooth count has to mate with the small rear gear on the cluster.
If the 1st or reverse gear ratios match up between the two T86 transmission versions then know that the gears are interchangeable.
I can look up specifications for the Jeep T86AA but frankly I have no idea if the T86 E that you mention is from a Studebaker, Ford or GMC.
Bottom line... if outside diameter matches with the Jeep part then it almost certainly will interchange. Unless by chance the tooth angle was changed....

If gear ratios were different between AA and E then you may possibly be able to make it work by also using the E cluster gear so long as it fits your main drive (input).

 

to bad your so far away, I'd sell ya a whole t-86 for $125.00

 

May be worthwhile regardless. I suspect the only way to get a good CJ T-86 1st gear today is to buy a complete working transmission.

 

The gear shows it’s for a ford but it also says that will fit other vehicles including Jeep!

 

If I wanted to convert this T86AA to a T90 gear set how should I go about it and what input shaft would I need for a 225 v6?

 

To have the correct main drive gear for Dauntless You essentially need all the guts from a Jeep T90J transmission.
The T90 J was used on all 1954-1965 Jeep PU and SW models that had a 6 cylinder engine.
“J”essentially identifies the T 90 as one with a long main drive gear.
Only basic rebuild parts will be fully interchangeable like all bearings, the countershaft, gaskets blocking rings etc. No gears can be mix and matched T90 to T86 except as complete gear sets.
Edit:
T90C main drive gear is not long enough for the Dauntless.

 

Could I use a t90 complete rebuild kit and swap out the input shaft for a t90j shaft?

 

A rebuild kit does not include gears. These are typically purchased individually, and you cannot mix gears between the T-86 and T-90. Does your T-86 1st gear have broken teeth, or are the edges of the teeth worn?

You can use the gears from a donor T-90A transmission, and substitute the input shaft for a T-90J. A T-90C will not work as a donor, as Ken mentioned.

Also, you cannot substitute the complete T-90J for the T-86. The T-86 case is different on the outside from the T-90J, and matches your trnsmission-to-bellhousing adapter. You could use the T-90J complete if you also obtain an adapter that matches the T-90 case.

 

Ethan, I'm in Syracuse NY and have a t-86 I will give you if you can find it a ride. It was behind a 225 and has been replaced by a t-18. It was in good shape with low miles and according to the PO had been rebuilt. The bad is that when it was removed from the jeep the transfer case was separated without using a main shaft support so the internals will all need to be relocated. It will have the parts you need or you can reassemble and run it.

 

The Jeep part number is 944771.
Let me check; I may have one.

 

The teeth are broken on my first gear. I meant to say the overhaul kit that kaiser and summit racing sell. They have all the new gears and internals but I would need to order a t90 j input shaft to make it compatible with the v6.

 

Is the first gear and cluster gear in good order? Also is it used to the point where matching it with other used internals would cause incorrect mating?

 

It was working just fine and would still be in there however I found a JEEP T-18 from a CJ5 with the 6:33 first. I can't answer your second question.

 

Well, this was a generous offer to give this transmission for free if you could find it a ride to you. Seems impertinent to ask for more ... kinda think it's up to you to decide if you want it and figure out how to get it to you.

 

Conversation started.

 

So long as the donor parts remain serviceable you should encounter no problems mixing and matching parts from various transmissions so long as they are from the same model and have same gear ratios.
Jeep only used the AA version so all Jeep T86 parts can be mix matched without concern.

I’m not a fan of the t86aa myself, but very glad to see them being salvaged for standard Jeep builds.