TNTUBA

iTrader: (1)

They all went to Rossler Built 3 speed TH400s
All of them shift over 8,000 and one is over 9,000.

They aren't cheap.

But if your goal is 1/8th mile drag racing....I don't think you will ever get enough torque out of a 4 cyl to pull a glide's first gear and be fast.

Car's with big block torque and capable of running in the mid 4's found speed going away from the glide.

I think your best bet, if you wanted to go Auto would be the TH400....It's not going to be street friendly with the 1:1 3rd gear and a loose converter....but it will work great at the drag strip.




If you wanted to be bolt action. I'd tell you to get the G-Force GSR Gearbox. It fits quite well in a Miata trans tunnel.

patsmx5

iTrader: (16)

Thank you for that information. I have heard good things about Rosler. Good to know their TH400s can rev that high, very good to know.

On the glides 1st gear I think you're right. The only way it would be kinda-fast is with a race-car stall and even then, not as fast as a 3 speed could be.

On the TH400, it's my understanding that a 4L80E is almost identical to a TH400, but with an overdrive stuck on it and it's electrically shifted vs hydraulically shifted. I think the 4L80 is a bit bigger to fit, and heavier of course.

If the 4L80 would fit, I wonder if it's a better option? As you said, loose stall and no overdrive won't be street friendly, and a 4L80 fixes both of those.

Th400 would be cheaper though which is a plus.

Stealth97

iTrader: (5)

My dad ran a turbo 400 on his big Block 500 horse 427 vette at 7000 RPM with a 100 shot on top... Ran great. Manual shift. A built Th400 will take anything you'll be able to throw at it. Bell housing is super wide though.. The same trans is behind his 502 now with no issues.

miata2fast

iTrader: (2)

Dude, seriously. You are way over thinking this. You will be so much more successful if you keep it simple. I have tried about every traditional American auto except for Dodge variants at the track, and know how awful it is if your transmission is not set up properly for your motor combo, and how glorious it is when it works in harmony with your setup.

For what you are doing, I highly recommend a manually shifted valve body, reverse if you can get it in your existing transmission, and a good converter. For a turbo motor, I can't even imagine not having a brake.

I mean really, what is the big deal of having to shift an auto manually? Weren't you manually shifting a clutch transmission?

Leafy

iTrader: (1)

The good thing with the 4l80e is that you can add a red neck trans brake for 2 bucks. Just jumper the 3rd gear shift solenoid with a monetary switch.

patsmx5

iTrader: (16)

I'm not sure what I was supposed to gain from this post. What transmission are you recommending? All the other stuff you mentioned is going to happen, the question at this point is which trans to build and install.

fivehundredton

Still blown away by this build.

miata2fast

iTrader: (2)

My point is stick with what works with small displacement motors. I would stick with a Jatco transmission personally, or look for other transmissions that are used in 4 cylinder drag setups. TH400 and 4L80E transmission is way too much. They will only slow you down. You balked earlier when I mentioned manually shifting with tranny brake.

miata2fast

iTrader: (2)

Check out Import Transmissions

Turbo 350 might be an economical choice that will hold up.

patsmx5

iTrader: (16)

I will call them tomorrow. Thank you for the link, I had not seen them before. They even do bellhousing work to make those bolt up to rotaries, so there's a chance I could get them to make one that would bolt up to a BP.

patsmx5

iTrader: (16)

And after searching about that company, found another (Performance Automatics) and will be calling them tomorrow as well. The sell a C4 auto rated for 1,000HP with a LIFETIME WARRANTY. But to make it better, this trans is very small, and if you get the "case fill" version, it has a removable bellhousing that bolts where to pump goes from the factory, and has what looks like a 5" or so centering circle right on the front. This would make putting the mazda bellhousing on it 10x easier as I have a machined concentric circle already on the front, designed to center a bellhousing.

So this trans:
Easy to put a bellhousing on, in fact easiest I've found yet.
Tiny enough that it will fit in the car no prob. Smaller than the miata auto it looks like!
Very small on the front, where almost every other trans has a bulge for the bellhousing this one does not.
Weighs 110lbs or less, so very light almost as light as a powerglide.
3 speeds, not 2.
Rated for 1,000HP
Lifetime warranty.
Manual valve body
Trans brake
~2,850 for the transmission

Downside is no OD, no lockup converter. Everything else is pretty sweet though, and pricing isn't too bad either for what you get. It has upgraded everything internally, some folks are putting 1,400HP through them without breaking them.

farpolemiddle

Without the OD and lockup with a high stall it is going to suck as a DD. I have been there with a TH350. Never again. If you haven't spent time in a 3 speed with a high stall ask someone at the track that has that set up to take you out on the highway for a bit. But it will go fast and it will be cool.

patsmx5

iTrader: (16)

I have not driven a car like that.

How bad would it be for city driving? I've seen videos of folks with V8's driving around stop light stop light with like 5,500 converters and they are ok for just easing around town, surprisingly. Most could pull away with traffic and keep revs under 2,500 even with a 5,000 stall.

I know highway is going to be bad.

It seems there is no auto that does everything. It's like cheap, light, small, has overdrive, has lockup, has removable bellhousing, can hold lots of power all in one does not exist. If you give up small and light you can have the rest, or give up reliable and holds power and then have the small/light/overdrive/lockup.

farpolemiddle

It is pretty bad. The best recommendation I have is if you do this is to have a custom converter made to your specs. There are "tight" and "loose" high stalls. TQ Converters are like anything else when it comes to drivability and building for speed. If you buy a run of the mill TQ converter from Summit or wherever you will hate it. A good shop will factor in the weight of your car, HP/TQ, how the car will be driven, ect. I don't know if it is a factor for you but expect your gas mileage with one of these to probably cut by a third.

fivehundredton

Pat, are there no transmissions in production cars that would fit the bill? Lexus, Audi, Dodge pickups have 8sps now etc?

sixshooter

iTrader: (12)

^This. The actual stall of a converter is related to engine power and vehicle weight.

patsmx5

iTrader: (16)

I ordered a custom converter today, and will order the trans tonight. Going with a C4 auto, reverse manual valve body, trans brake, built for 1K hp with lifetime warranty, and a custom 8" converter made to my car, with one free restall if it's not right the first time. They are even going to do custom mounting tabs and pilot bearing to make it work with my flexplate and crank. They're sending me a dummy converter first so I can check the mounting depth of it to set the pads the correct distance from the flex plate.



Still gotta find and order a dipstick for the trans, and a trans mount, and maybe some material to make an adapter to bolt my bellhousing to the new trans.

patsmx5

iTrader: (16)

Nope. I needed something that can take 8,500 RPMs and not break doing it, and take a lot of pwoer, and that will fit in my car without making a new transmission tunnel. Only things that will fit are 3 speeds and maybe a couple of small 4 speeds. The 6 or 8 speeds are huge, not a chance they would fit.

C4:http://www.onlymustangfords.com/imag...p-21495118.jpg

6 speed ford: https://www.google.com/imgres?imgurl...act=mrc&uact=8

This is what the trans I'm ordering looks like: http://www.performanceautomatic.com/...e_image-18.jpg

farpolemiddle

Like a boss.

Monk

iTrader: (3)

I was thinking c4, but I have broken them behind my mildly powered 302.
Of course, yours looks like it will be quite a bit stouter than my shoddy 15 year old benchtop build.
It's probably the best route for what you are hoping to achieve.