Performance imporvemnet

Torque converter and a valve change. To cheap and easy things

 

The one thing that you can do cheaply to a 400 auto is sort out the gearbox.

Good old GM, you've got to love 'em !!

 

Put a 700R4 auto trans in it. Much better first gear and a TH400 is a power hog. Even just putting a TH350 in it would net higher RWHP numbers.

 

I'm still waiting for someone to post some pictures of one of these cars with a transmission swap. Call me a doubting Thomas but until I see pictures or an actual car with a different transmission I won't believe it. Even cars that have had an engine swap to an American V8 still use the same transmission.

As far as your car, get a hold of one of the hundreds of shops that build these transmissions and tell them the specifications of your car, IE engine HP and torque, rear end gear ratio, and weight of the car, and what kind of performance characteristics you are looking for. In all reality just a few changes to the valve body and new torque converter will make a huge improvement. The internals of the th400 won't have to be modified to handle the relatively low horse power levels of these engines.

 

Remember the bearing inside the propeller shaft. Mine was almost completely frozen and clogged with old grease. It was forcing the tranny to overwork,and was tearing its guts out (literally and actually) trying to move the car. The total tranny rebuild excluding removal and re-install to the car was only about a thousand dollars US. Thank you. Jq.

 

"I'm still waiting for someone to post some pictures of one of these cars with a transmission swap. Call me a doubting Thomas but until I see pictures or an actual car with a different transmission I won't believe it. Even cars that have had an engine swap to an American V8 still use the same transmission."

Jim is right. There is a reason this transmission swap is, shall we say, unattractive.
First the 400 came in 3 different lenghts from 28 3/8" to 37 7/8" with all variations based upon the same 24 5/16 face of bell housing to tail shaft housing mount. The 700R4 case is 23 3/8 with an over all length of 30 3/4.

If we assume Ferrari used the 24 5/16 parts, that still leaves an inch difference to be accounted for in propeller shaft length. This is pretty straight forward in open, Cardan style dirve shaft modification. With a Torque Tube shaft like the Ferrari has (and the C-5 and up Corvettes) it becomes an expensive nightmare.

Not only do you have to shorten the solid propeller shaft, and maybe re-cut the front spline if possible, but you also have to shorten the Torque Tube housing. This last requires jigs and volume to make it worth the time to any machine shop.

I'd be surprised if the TH-400s in our cars do not already have a shift kit in them. My '84 Ferrari sure shifts differently than the TH-400 in the '84 Southwind motorhome we had for 20 years. Also be aware the RV converter does lock up. And it stays that way until you touch the brake pedal. I pitched a lot of fan belts off the MH and from my Lincoln hot rod before I learned that one.

Finally while the 700R4 was originally vacuum operated most surviving examples require a stand alone computer to run them. These little boxes run in the $1K and up price range.

For what it is worth,

Greg

 

I bought a pile of old parts and catalogs last week, and going through the transmission parts catalogs, there is a listing for a "400-3" shift kit for the turbo 400 transmission to go to a manual shift. Aside from that, I have been able to find no information.
The 400-1 kit is stock, 400-2 is a performance automatic and the 400-3 is a manual (clutchless) shift. Anyone ever heard of one? I know there are the ratchet shift kits you can put in now to get a manual shifting automatic, based on drag racing practice, but this looks like it might not have required messing with the shift mechanism.

 

On a lark, I did a search on 400-3 transmission kit and found a Trans-go kit on eBay for $140. It is said to be a reversible modification. Anyone ever tried one? I have a question submitted to the seller regarding mods to the shifter if any, and reversibility.

 

Found a bunch for much less than $140...

 

You can convert automatic transmissions to a full manual valve body. I had a Torqueflite 727 that was modified in this way in a hot '68 Charger R/T 440 I owned. It had a very loose converted, with a high stall speed, the RPM's that the engine starts to engage the transmission.

I would not recommend this, it is a full on drag racing set up and the shift under full throttle were brutal bangs! Also the high stall converter generates more heat in the Auto trans so additional cooling is recommended. checking the torque tube bearings would be step one IMHO, then, there are meany respected auto trans specialists, B&M, Transdapt etc that can provide what is commonly referred to as a "shift kit" to firm up the shifts-go mild one step up from stock or you will have a hard shifting trans not in character with your vehicle. Looking at a more modern torque converter will help too-lots of stuff available for these transmissions.

Contact some of the vendors and do some searches on upgrading the Turbo 400 you will find tons of info and possibilities.

 

Some chats where people have installed this particular kit talk about the effect of various hole sizes on the shift intensity. Smaller holes give less of a harsh shift. It will also act like a normal (higher shift points) AT in Drive. I was thinking if someone wished for a manual in their car, but only had an AT, a compromise might be a kit that is kind of like a clutch-less manual (like you get with paddle shifters). There is no modification required to the shifter; the ratchet shifters and slam shifts for drag racing are not appropriate in this car; agreed.
I had actually been doing searches and had not seen this kit. Stumbled onto it in the old parts store catalog for Turbo 400 rebuilds, and searched from there.
There is also a 400-2 kit that raises the shift points. Right now, mine shifts so quickly and smoothly that I don't really get to enjoy the engine sounds. I will likely go to this kit.

 

I shift mine manually with the quadrant when I feel like winding it out.
If it howled like that all the time it would get really old after a few hours on the road.
Greg

 

Yes, it is reversible. Shift kits are just basically some flat plates with holes in them to redirect tranny fluid flow within the internal channels of the throttle body. I have one in my 1980 400i, and it works wonders for the performance. B&M and TCI have made them for many (30+) years, now. There is really no need to re-invent the wheel, here. They really are the "go-to" guys. AND...be sure to get the "street" kit model, as the others, as the previous poster stated are really not suited for our use. This is definately a"while your in there" mod-upgrade thing to do. You'll be so glad that you did it. The additional control over in-town driving is profound if coupled with the proper torque converter, which is also a "must". Also, I converted to synthetic ATF, and what a difference in smoothness. In my case I use Amzoil for everything in my cars. And yes,...there is no leaky seals. I hope that this is of some value to someone. Thank you very much. Jq.

 

Thats not correct, they have a torque converter lockup connector on the side that gets ignored. You might be thinking 4L80E which does require a pcm. Ive put a lot of 700R4s in cars, had a lot of GMs over the years. Its a fuel economy thing that isnt needed in this application. Whats more is it has an actual throttle valve not a kick down switch like a 400 so you can alter your shift points with a popsicle stick on the side of the road.

The tail stock is one piece that needs to be made as well as the coupler with bearing support and seal. Didnt say it was easy but converting to a stick would be hard on the wallet instead. This winter Im digging deeper into this. Plopping a 575 engine in my 400 has occurred to me as well and a 700R4 behind it.

 

my view. if you want more buy a car with more. don't butcher these old cars. and that reminds me(butcher) Brett put the mains in backwards

 

Cars can be modified without butchering them so they can easily be undone. I'm also of the belief that I bought it to enjoy it not save it for the next person to enjoy. I like the look of the 400 vs the other 4 seater options so a 612 for example would give me the power but would be a trade off.

 

That would be awesome along with a brake upgrade!

 

Yep, I fully support the idea of a modern v12 into the 400.

 

The 700r4 with the differential gears from a manual car would be really nice but infact a very difficult swap.