2 speed vs th400

[csr57c]

We are working on a new roadster and was wanting some advice on what transmission we should use thanks

[ronnieroadster]

To help guide you along by any number of knowledgeable members on this site a lot more information is needed. Things like which roadster class, engine type, induction, rear axle all those details and more would help greatly towards getting some suggestions.
 Ronnieroadster

[Beef Stew]

Reid https://reidracing.biz/ makes both PG and Turbo 400 cases. Gearvendors make overdrives for both.

[kiwi belly tank]

We are working on a new roadster and was wanting some advice on what transmission we should use thanks

It's a simple question you can answer, do you have enough engine to work with the rpm drop from 1st to high in a glide?
Also there is no lock-up converters for a glide or 400 without running a direct drive.
The 4L80e gives you 3 speeds (forget about the O/D) plus a lockup converter & you can run it without an ecu.
  Sid.

[Stan Back]

What's so terrible about a 4-speed?  The first three are there just to get you to 4th.  And you're done with them in the first mile.  And then it's a lock-up (straight-thru).  No fancy conversions to something they weren't designed to do.  If something goes wrong, it's probably your fault and the fix is simply mechanical.

What'd I miss?

Seven El Mirage and Bonneville roadster records with one.  Ran outta horsepower before I ran outta gears.

[gnomenator]

Hey Sid, I think you meant a 4L60 trans. The 4L80 is bullet-proof but is a huge tranny for a roadster. If you build the 60 correctly ,it can survive well and the lock-up eliminates slip. I built mine to run behind a 496ci bbc and it has several seasons on it and still works perfect,but I tear it down and inspect it about every other season! I lock it after 1st gear and that works great, just have to remember to unlock as you slow down Again, it depends on a LOT of factors that we haven't heard from crs57c !

[Beef Stew]

What's so terrible about a 4-speed?  The first three are there just to get you to 4th. 

Seven El Mirage and Bonneville roadster records with one.  Ran outta horsepower before I ran outta gears.

I agree. A new M22 can be had for less than $2,700. That's what I'd use if I was building a roadster today. I got my first rock-crusher in the 1960s, and stopped breaking transmissions.

[jimmy six]

You can purchase 4-speeds from Tex Racing and choose hundreds of gear combinations. Yes many of the cases and gears are used but NASCAR transmissions from the era are in perfect condition. Magnesium or Aluminum cases are available with or without cooling pumps and Long or Hurst shifters. I run one in my roadster and it had a 80% nitro GMC 12 port 6 cylinder in front of it and its got aa .96 overdrive for its last gear. I paid $2500 for mine.
A RAM triple disc clutch is fairly inexpensive and you can have no linkage with a hydraulic TO bearing.  We've had the same TO bearing for 7 years without a leak in our 1/2 mile dirt car.
There are 5 speed air shift Libertys also in cars currently running. Good Luck

[kiwi belly tank]

Hey Sid, I think you meant a 4L60 trans. The 4L80 is bullet-proof but is a huge tranny for a roadster. If you build the 60 correctly ,it can survive well and the lock-up eliminates slip. I built mine to run behind a 496ci bbc and it has several seasons on it and still works perfect,but I tear it down and inspect it about every other season! I lock it after 1st gear and that works great, just have to remember to unlock as you slow down Again, it depends on a LOT of factors that we haven't heard from crs57c !

He's talking Glide or 400 & a 4L80 is the same dimensions as a 400, only 4" longer than a short one & just about bullet-proof right out of the junkyard for about 150 bucks! We put a used one on a twin turbo Duramax in a drag truck & figured we'd run it until it blew up. That was six years ago & it's still there, now with a billet converter to get it to launch harder. A short TH400 rear housing bolts up to a 4WD 4L80, now it's 2WD 32 spline.
A stout 4speed manual is $$, a clutch & flywheel is more $$$ & now you have to fit a clutch pedal in that tiny foot well you've ended up with.
  Sid.

[gnomenator]

Hi Sid , what I was talking about with the difference between the two is the girth and weight of the 80 over the 400. The 80 fits in a pu nicely but might be too big for a small car like a roadster no? And the 80 weight is about twice the 400 if weight is an issue...

[salt27]

Turbo 400-130lbs, 4L80e-187lbs.

57lbs less pounds of lead to buy but it may or may not be where you want it.   

[JR529]

We run a TH400 from Kilgore in the #369 Roadster. It used to have a Muncie 4 speed. We have talked about this within the team since we switched and all agree it was the best move and we would never go back to a manual again.

We run a turbo car and the auto lets us stay at WOT over shifts keeping the boost up. We also never miss a shift.

[Stan Back]

". . . just about bullet-proof right out of the junkyard for about 150 bucks!"

We had a lot of time and some money invested in our program.  I wouldn't want to head out once a year with a "just-about bullet-proof" transmission.

And from what (little) I know, they're not easily fixed in the field.

[Beef Stew]

We had a lot of time and some money invested in our program.  I wouldn't want to head out once a year with a "just-about bullet-proof" transmission.

Just about bullet proof doesn't cut it. I didn't spend all that time building an engine. Then destroy it because I used junkyard parts.

As someone once said: "Speed is expensive, how fast do you want to go?"

[csr57c]

Thank everyone for your input. We are newbies. I was wanting to stay with an automatic because my daughter is going to be the driver and I want to give her something she can just get down the track with the first year. We are building a fuel roadster with a d class engine. I have some experience with direct drive power glide but was not sure if the gear split would be an issue.  Thanks again.