I have a T18 with the really low Granny Gear now...But I also have a decked out TH400 w/a B&M stick Shifter and stall converter sitting in my garage...Should I stick with the manuel T18 or should I buy the adapter and go Turbo400? I can't make up my mind..Please Help!! :confused:

For your info I'm currently running the T18 with a Dana 300 and Chevy 350 5.7 TBI

TH400. I ran a T18 for about 4 years, and it's a good tranny. But after swapping in a TH400 a couple years ago, I'd never go back to anything with a clutch. Only real downside is that the TH400 sucks up a fair amount of horsepower.

It all comes down to preference as T-18's and TH400 are darn good transmissions. I *prefer* T-18's.

ok my opinion

you have the t18 in and working and you will need a new front and rear driveshaft and the adapter for the tcase to go auto
if this is going into a cj5 with the stock wheelbase the rear drive shaft will be very short with the 400

i am running a th400 and i love the auto

i would run what i had unless i decided to extend the wheel base

this is all based on you having a stock wheelbase cj5

apple vs orange.

I've had T18s and I've had solid autos (727s and their variants mostly). Like the T18 but I'll take a solid auto over a stick anyday for my wheeling...

either will do well.

if you've never wheeled an auto rig, borrow one for a few hours. then pick if you like the auto or stick more.

But if I go auto should i beef up the engine?I hear you will lose a lot of uumph...That Granny Low is nice...

if this is going into a cj5 with the stock wheelbase the rear drive shaft will be very short with the 400

let me repeat that because it's very important.

can't jump start an auto, no good for me when the starter is full of mud.. depends the type of terrain you wheel on, and if you have the right gear setup for what you want to do.. I like a clutch for what I do here in east NB, lotsa mud, very deep..

But if I go auto should i beef up the engine?I hear you will lose a lot of uumph...That Granny Low is nice...

only like 15hp difference at the wheels. Trust me, when you get to know what they can do, torque converters are nice :D

The only two drawbacks to the auto IMO are:

- if you get low on fluid you're fawked
- if your starter goes you're fawked.

Carry a starter, some hi-temp RVT and 6 quarts of auto fluid and you're not fawked :flipoff2:

only like 15hp difference at the wheels. Trust me, when you get to know what they can do, torque converters are nice :D

The only two drawbacks to the auto IMO are:

- if you get low on fluid you're fawked
- if your starter goes you're fawked.

Carry a starter, some hi-temp RVT and 6 quarts of auto fluid and you're not fawked :flipoff2:


A TH400 is notorious for eating not 15hp but 20-25% of your power at the rear wheels through parasitic drag, it is one of the worst for power consumption. Ive played around with the T400 trying to get better (lower parasitic drag) numbers out of it on the dyno and have not been able to get decent numbers without hampering my off roadability. I will agree though that there are benefits to an automatic when wheeling but in this case a CJ5 is a tight drivetrain and there is no room for the T400 without serious driveline issues.

Personally i think his money is better spent on a gear set swap, like 4:1's for his dana 300 that alone will make a world of difference. basically the closer you can get to 100:1 with your manual tranny the better you are. I think that the agonny of the swap that the giant benefits you are looking for are not entirely there.

Iw ill say that at 110:1 with my old manual tranny NP435/D300 4:1 & 4.10 axles combo it functioned relatively close enough to the 727/D300 4:1 that i swapped in later that i felt like the swap really wasnt worth it plus i ended up with heating issues with the auto cooler in front of my ratiator.

overall there are benefits it could go either way personally since you already have a good setup in there id keep it and improve upon it but its also personal preference

Thanks guys for your opinions.....now anyone want to buy a TH400?