is aT90 tranny strong enough for a sbc 350?

well is a t-90 --(in my case from a 66 tux park) strong enough to handle a conservative driver with a mild small block chevy 350--on and off road-mud but nothing outlandish. would my axles be the weak link then or would it just toast the transmission and transfer? is there a chevy standard transmission that will work with stock dana 27 up front and stock dana 44 out back?? if so what donor vehicle might i find such a transmission. all of them i have found have the transfer on the wrong side.
i have seen adapters to hook a 350 to everything but is it really a good idea.
opinions please.

 

I had a 350 in speedy with the T90 and worked that Jeep hard. I never had an issue with it. I kept the D27 and it was fine too. There is a myth out there that these parts aren't strong enough. I don't believe it and it's up to you if you do. I sold that Jeep to Duke54. You can ask him about it as well.

 

Yup i like it havent broke anything yet.

 

In the 60s and 70s there were lots of SBC-into-CJ swaps. In those days, people thought they were strong enough. However, the central difference between then and now IME is tire size. Tire technology, and the affordability and variety of (what would have been in the '70s) huge tires has changed greatly.

Also, 265s and 283s were a common swap then, but today's 'small' block is often a souped-up 350 or 383, The 4.3L (262 cid) Chevy V6 is more comparable to the SBCs of the 60s, and fits in the engine compartment better.

Also remember that most of these T-90s are 40 years older than they were when the SBC-T-90 swap was most popular.

Another point - the SBC-T-90 adapter is really a GM-T-90 adapter, and will work with almost any GM bellhousing. The V6s are a much better choice becasue of how much better they fit in the engine compartment, aside from the power concerns.

 

I don’t know ‘bout the T-90, I personally wouldn’t risk it since there’re literally millions of GM transmissions lay’n ‘round bone yards all across the US that can do a better job, but the Dana 27 front and Dana 18 transfer case will probably be OK with street and mild wheel’n use.
You will break parts in that Dana 27 if you abuse it, though. Just don’t hop it, they can’t handle the shock loads.
I’ve read that the Dana 18 is designed to handle only 200 lb/ft of torque, someone please correct me if I’m wrong, but I’ve got a fairly high strung Corvette 327 with cam, carb, intake, headers, yada yada, and the only issue I’ve had with it is that it leaks from the rear output. I’ve also read that is a very common problem with Dana/Spicer 18’s.

 

I am fairly new at this, but it is my understanding that a T-86A is a T-90 beefed up to handle the 225 Dauntless, and is almost identical to the 90 on the outside, so it would be an easy swap, and gain some strength.

 

I don't totally buy it. There's too much variability in drivers to take any one driver's experiences as proof.

For example, the impact load of dropping the hammer and burning rubber from a standing start, compared to breaking the tires loose while rolling would be immense IME. Also, the B-W 3-speeds are not fast-shifitng transmissions - try to shift too fast and you'll miss a shift, with possibly dire consequences.

So, IMO everything depends on the driver, the condition of the transmission, the other drivetrain parts, and some luck. By reducing the power output of the engine, you take the driver and luck out of the equation to some degree. Whether you'll be happy with the 350-T90 combo is something you'll have to judge, based on the reliability you will tolerate and the responses from several people.

 

AFAIK the T-86 is adapted to the V6 but isn't any stronger than the T-90. It's possibly weaker, since 1st and reverse are beveled to make them quieter, but beveled gears are weaker than straight-cut gears.

You can take the T-90 gears and put them in a T-86 case, they are that similar (no mixing gears though).

 

I'd do it and not even think twice about it...
in this day and age of "gotta have a 4 speed" we sometimes forget to just keep it simple.
are there better/stronger choices ? most certainly
but the SBC/T90 is time proven and well tested
on paper, maybe it is small, weak, inferior, etc etc etc
you can pick it apart if you like
you just can't argue with success though

 

Thats a myth, Jeep used several motors from the factory including the v6 that put out more than 200lb/ft of torque.

 

Yup, do it it'll work. I found I was less likely to tear stuff up because I didn't push as hard, didn't have too. If you are that worried about too much power there are several choices smaller than a 350, from 265 to 327 etc. I like the 307 but harder to get now but a lot of 305's out there. I ran a 305 in an cj7 with a T4 for two years backin the early 80's.They say you can't do that.....I didn't know any better then.

 

i have seen a t-90 and stock dana 25 get the poo kicked outta them form a guy with a 231 oddfire. the only thing he ever broke was a rear 41 axle shaft and he was running 33's. he was on the 33's for about 3 years.. he was soo crazy he was the only one with enough balls to try this one wash out section and the guy on 37's decided it wasnt a good obsticle to try lol..

 

Shaggy's had a 283/T90 combo installed since I bought it in 1970. 'course, it hasn't been on the road since 1986. R) But I had no problems with this setup in the 16 years of mild off road driving, mostly elk and blue grouse hunting and fishing trips in the Rockies. The only problem I can recall was in the early 80's, my boy peeled out of a gravel parking lot in 2 WD and hit the paved highway. Split the T90 case. I never thought about it before, but I wonder what effect that stunt had on the rear axles. I guess I'll find out when I pull them to install 11" brakes. FWIW.

tommy b

 

In my experience with t-90's, t-14's ,dana27, yes you might get by with it but what fun is it going off road and being afraid to step on that throttle pedal when you need to.the big tires are the real killer.my current jeep w/225 v-6 /t-14 / D27 /D44 w/powrloc ,31-10.50 tires , is almost 40 years old and i drive it very gentlie.Been There.

mike s.

 

I never was afraid of it

 

Ah, thanks. IIRC, I read that from Hazel at JP magazine but didn’t think it was quite right considering my own experience.

 

I don't know anything...but, I think my first concern would be to have a spare drive shaft/U-joints. It seems like they would go before the T90 or Dana 18 the majority of times.

 

I did a 302 in a 48 2a. The front axle lasted about a week. The t-90 held up for as long as the jeep was together. I had more trouble tearing up turbo 400's behind a mild 401.

 

thank you all for your well reasoned and considerate responses. i think i'm going to just go for it. i assume the advance adapters GM to t-90 is the preferred bell housing.(?) i've been on a wild whirlwind of long range car trips for the past month and half--(not in a jeep and have been without a computer. i am very excited to be back home and near the shop.

i am running smallish (for this site)tires and plan on reinstalling even smaller stock style non directional tires or just mild bfg all terrains --just barely over stock size---sounds like the consensus is is i keep my foot ou of it i shouldn't crunch too much. heck it is all replaceable anyway.