I am contemplating using a 400 turbo trans behind a 350 HP SBC motor in a new 32 project. Am I a dinosaur for using this trans?
Dinosaurs are kool. A 400 is a little heavier, has (I think) better ratios overall, and it will NEVER break for your purpose. Ever. Take it a step further, it's like an automatic version of an M22. Yes? Yes? Run it bud, ya got my vote.
Mmm, yeah, sorta ! I'd say fine, use the T-400 IF...you have in excess of about 600hp. Otherwise, with, as you state, a 350hp engine, to me...a well built T-200-R4 would be a much better choice. Done correctly, they can be built to withstand easily, 750hp for the 4 speed, and over 1000hp with the 3 speed version (T-200). A very nice first gear for pulling away from a stop, AND the overdrive for lower rpm freeway driving. I've got a car that I'm working on that has about a 550hp engine, and it has a T-200-R4 trans. in it. This trans. also has an internal brake in it for better starting line (racing) reaction. It's got 3.70 rear end gear, so the around town, or "stop light" performance, will be..."nice" ! Plus the T-200-4R is smaller and lighter of all of the cheaper GM transmissions. Easier packaging under the car, and the engine isn't lugging around the extra weight of the T-400. A note, some seem to like the T-700-R4 trans. While it can also be built to withstand an easy 500hp, the gear ratios were NOT very well designed/planned. I had one in a car years back. With even a moderate amount of power, first gear is useless ! I used just, 2nd-3rd-4th 95% of the time. This is in fact why the T-200-4R came to be, to correct the T-700's short comings, it's lousy gear ratios. That's a short dimes worth from me. Mike
If you don't need OD it will do everything you need . So will a good turbo 350. Have had one (400) in my 57 vette for years . Ran in the 10's before it became a street car again same trans just changed the converter . 90,000 miles on the street lots if 1/4 mile runs. That said I'd love a OD and lower gears .
Nothing wrong with a turbo 400. Aren't we all here to celebrate the old ways. I would be concerned more about packaging than what trans for a small block. On the opposite side of the spectrum I ran a turbo 350 behind a 427, for less parasitic loss, and then a Saginaw 4 speed simply because I had a shifter.
Great trans. Shifts a little early into 2nd in stock form. Stout. Possibly even overkill on a light weight car
Look at all of the heavy duty one ton trucks and motor homes with 400 Turbos. Fantastic transmission, I used one in my 11 second bracket car with a Small Block.
My model A has a 468 bbc with a th 350 and I don't have any negative issues ...except maybe my wifes lack of appreciation....for turbo 350s ...or 9 inch rearends or something or other.
I seem to recall that one of the benefits of the TH400 was the relative simplicity of its operation. Each upshift only involved the application of another clutch pack, 1st to 2nd and 2nd to 3rd. There were no "timing" issues with simultaneously releasing a band and applying a clutch (or visa versa) for the upshifts. No opportunity for a "flare-up" in RPM between gears, or any momentary overlap of having a band and a clutch applied at the same time.
My son had a 88 C10 with a 4.3 and a Turbo 400. Never would have thought GM would put that combo together, but they did.
yup, it's a good design...two overrunning clutches, unlike the Ford and Mopar transmissions that rely on band adjustment being just right to shift smoothly.
You'll be overkill with a T400, which means great reliability. Easy to hook up and run, the electric kickdown is nice because you can hide it inside the car on throttle pedal and no external carb cable required. Just a vacuum modulator hookup from the engine. Also a little more parasitic loss vs a T350 as previously said. But for a street car that slight hp loss is insignificant. Biggest drawback is the lack of OD and it is fairly large size. In a light car, run a 3.0-3.25 rear gear and you will still have good street performance; along with good highway driving. Your 350 hp engine could do fine with a T350 as well. I am not really a fan of T350 with a higher hp engine. They can/will break if you put too much power in front with too much traction out back. I broke T350 twice in my old OT drag Camaro with a BBC. These were modified to be stronger than stock, obviously not enough! Finally wised up and put a PG (with a transbrake). Easier to drive and no weak links like the T350.
A little longer, a little heavier, and yep as said, a little more parasitic drag but, built right they are practically bullet proof. I'm a dinosaur and proud of it.
Must have it built right. They can be broken. First time was told that the factory was using plastic where they used to use metal. My trans guy fixed it up right, plus did a shift kit. However, couldn't believe that I did it again. Before all that, I ran with a TH350 no prob other than a broke modulator spring.
I've got one in my Model A behind a Nailhead. The 400 is a great transmission. A bit complex, but smooth shifting and very strong. On light throttle acceleration I can barely feel mine shift. I remember when the first of the 200 series transmissions came out. I went to a GM class and was amazed that the people who built the 400 could build such a cheaply built transmissions. Based on what I read, they must have really done a lot of development on it.
If you are a dinosaur, then so am I. I'm putting one in the 35 Ford that I am currently building. I have also have had one in my 31 Ford since 1979 and it is still going strong. I've even raced the 31 at nostalgia drags a number of times.
About 15 years ago, Hit a pothole one night coming home from a cruise night, my knee came up and hit the shifter into park while doing about 35, locked the wheels up and stalled the engine. Restarted it, put it back in gear and it’s been fine since. Turbo 400 are pretty tough.
Yep, ran a turbo 400 in a 3200 lb, 11 second street car for years and never tore it up. They are pretty tough transmissions.
Looking it up on a transmission site a Turbo 350 with converter weights right at 120 while a Turbo 400 with converter weighs 135. A whole 15 lbs difference. Seems like a lot more when you pick one up and stick it in the back of a pickup by yourself though. I had a 400 in the 48 behind a 350 in my avatar photo in 1982. The only one I ever had trouble with was one in a 76 Seville my wife drove that my daughter beat the hell out of when she was a teenager. I'm still hearing stories about her antics with that car 25 years later.
While the 400 is a bit larger and heavier than others, it is a rugged and well designed unit. There are various length output shafts and extension housings available to tailor the length you need.
So @krylon32 are there any actual concerns about it? If it's a reasonable mileage clean trans any worries can be erased off the to-do list.
I’m a manual trans guy but if I were in your shoes I’d opt for the T-200-R4. Smaller and lighter than the TH-400 and you’d love the 4 gears.
If ya got it, run it. A simple shift kit is all you need. Can always splurge for a converter if ya want. Bullet proof.
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