400i Transmission Question......

my understanding as a former GM car collector is that they were special castings for the Ferrari engines. i could be wrong though, as i have not seen a 400i / auto in person. i have about 8 BOP pattern 400 transmitions her eif you need any pics!

(BOP)= buick / olds/ pontiac

 

The TH400 for the 400 series is a standard GM trans. I have forgotten the letter code. There is a flat cast aluminum adapter that links the trans to the block.

 

and a special tail piece to mount to the torque tube going to the diff.
Ken

 

good to know, thanks. sorry for my mis-information.

 

+1 on the above replies.
Adapter plate and a tail piece and you're all set.

 

My son just told me that Chevy in recent years made a 4-speed TH400. The 4th gear is actually an overdrive gear. These trannys are more modern with some electronic controls, but the guys with older Vettes have figured out how to adapt them to 'manual mode'. This will cut down on RPM on long high speed trips (good or bad is personal choice).

Has anyone made this conversion?
Ken

 

Is he talking about the 700r4?

 

Has anyone carried out this conversion?

Is it possible?
How does it affect driving conditions? Revs, MPG etc???

Love to hear your comments
Niall

 

i have a New conversion kit made and sold by Ferrari to convert five speed to auto. $5000.00 has radiator, front and rear adpters, transmission, all shift components

 

Who did you buy this kit from and do you have a part number for it?

 

I can understand converting the 3 speed auto to the newer TH400 4 speed auto, but surely you're not thinking of converting a 5 speed manual to an auto are you?

 

This question really interests me. What Im wondering is since the adapter for the bellhousing bolts to the bell housing im assuming that means you could bolt that adapter to a new gm 6 speed manual in theory. Get a flywheel made up by fidanza and then you have the ability to run gm clutches and have the 6 speed. Can anyone help me out here am I way out in left field with this or does it seem remotely reasonable?

Thanks a bunch by the way this is my first post and this community seems great been reading here for a while now.

Matt.

 

kit was aquired from shop in cincinnati ohio, came from estate. i put it away. one of those just in case buys. not planning on removing a 5 speed. i have four autos, never know.

 

You've got to me kidding me! There's plenty of auto's out there.....just can't believe it.

+1 on that John

I'd say you're in center field on that one Matt, a new adapter plate & tailpiece if needed & you're good to go.

 

What I mean is.....that would be the "antitheses of all things the Maranello manufacturer stood for" relived.
(as quoted by QV500)

 

You think a new adapter plate would have to be made up? I believe the bell housings on the autos to manuals are the same pattern so I think the adapter off the auto would bolt right onto the manual. Then yes something would have to be made up for the rear. Seems like a good way to get a durable clutch set up out of the deal. Upgraded clutches for gms are very common and can hold a huge amount of power with no drama. Seems like a pretty exciting project to me.

 

That part I don't know, my suggestion would be worse case scenario. But if you could fab. a fly. w/little difficulty, a plate would be a snap.
I'd be very curious if this could be done!

+1!

 

I would not be making the flywheel myself I would have to get a custom one made. Fidanza has done plenty of one off and custom flywheels in the past for stranger cars and purposes than these so I see no reason they wouldnt do it for this, you think there would be any sort of demand on here for them. If we could get a few people together to agree to buying a flywheel they discount the price pretty significantly. This is all just talk right now as I dont even has a 400 yet but am working on moving some assets around (IE some of the dozen or so cars I have) and making room in my wallet and garage for one.

 

I am also surprised no one has done this. If you went with a 700r4 and put a set of 4.30 gears from a manual transmission car the over all top gear ratios is almost the same. The th400 top gear is 1:1 x 3.0=over all 3.0 to 1. The 700r4 top gear is .7 so, .7x4.30= 3.01. On initial analysis you might think why would I do that? Welll here is why. Lets do a first gear comparison. Th400 first gear is 2.48x3.0=7.44 this is completely BS first gear and is why the automatic cars absolutely suck off the line. The 700r4 first gear is 3.06x4.30=13.158. That ratio is just a little more than half of the stock set set up. Now imagine the sluggish off the line performance of the automatic with a first gear with such a lower ratio. Also you would keep the same over all top end performance. The difficult part of the swap is the 700r4 is about 2.5" longer, also there are probably not a lot of 4.30 gear sets laying around. This sounds like it would be a win/win swap. It would really wake up an automatic cars off the line performance.

The ratios would be as such, this assumes 3.0 for the th400 car and 4.30 for the 700r4 car.

th400 700r4
First: 7.44 13.158
Second: 4.44 6.96
Third: 3.00 4.30
Fourth: N/A 3.01

Not only would first gear be dramatically better but the rpm drop between the gears would be much less, this would allow the engine to remain in the "heart" of its power band.

It is also interesting compairing the 400r4 vs the Ferrari 5sp manual. This once again assumes 4.30 final drive for both cars.

700r4 5sp
First: 13.158 11.137
Second: 6.96 7.33 Note the 5spds second gear is about the same as the th400 first
Third: 4.30 5.39
Fourth: 3.01 4.30
Fifth: N/A 3.50

In looking at the numbers the automatic would actually (especially if it had a 2500-3000 rpm stall torque converter) be faster than the 5spd off the line. In the mid range acceleration the 5spd would catch back up due to the closer spacing of the ratios. At cruise on the highway the automatic would have an advantage because the engine would be turning over at a slightly slower rpm.

Now you automatic guys need to get busy and do this! Brett, are you listening? You could be the pioneer in doing these swaps!

 

Jim,

What's a 700r4 specifically?
Matt was suggesting the swap of a 6sp man. in place of an auto..
iirc, adapter plates are used for auto tranny's, 5 sp. bolt right up to the block. I have no idea of bolt patterns of the variety of trannies out there, man. or auto..

Bruce

 

A 700r4 is the 4spd version of the th400. It adds an overdriven fourth gear. Third gear is the same 1:1 ratio in each transmission. A lot of the original GM muscle cars had the th400 in them and the owners have switched to the 700r4 to gain the over drive gear for better drivebility. Imagine driving a Chevelle with a 454 big block turning over 4000 rpms at 70 mph. Now switch to the 700r4 and your closer to 3000 rpms. The Ferrari 400 really dosen't need to lower its highway rpm but needs to improve the off the line acceleration. By having an over drive transmission you can lower the rear end ratio and use the overdrive to make up for the difference on the highway while gaining hugh advantages in acceleration in the lower gears.

I had a 96 Impala SS I sold since I was getting the Ferrari. There are a group of guys that converted their cars from autos to the 6spd. It is a lot of work to do the swap, but a lot of guys had done it so the reasearch was done. The difference is the Impala was never available with a manual. I would guess that 60 of the swaps have been done to the Impala (GM B body) platform.

I would think you would have two possible routes in doing the swap to the 400s. One, find a donor car and swap the pedal assebly, shifter, transmission mounts etc or fab up the parts using non Ferrari parts. There were never very many 5spd 400s so the second route is probably the way to go. Since it sounds like there is a pattern to adapt the Ferrari block to the GM transmission you could in theory use any transmission that GM has used.

My original thoughts on the 700r4 is you would gain most of the performance of the manual transmission with out nearly as much work.

 

The 700R4 is a GM transmission used in a lot of cars and trucks since the 80's. 4 speeds (4th gear is overdrive) and the torque converter is "lock-up" style.

This tranny is popular with the streetrod guys and probably would work fine in a 400i once you had it bolted up (with an adapter plate) and a driveshaft made to fit.

It looks like the biggest challenge might be the driveshaft. The 400i uses a "torque tube" that connects the transmission rigidly to the differential housing. The 700R4 typically uses a conventional telescoping driveshaft. It's not a big deal but some parts might have to be "engineered".

 

We were considering that swap one time years ago. The price of a 5 speed ring and pinion or a complete rear end stopped the project. At the time the price was about the same as for a run down 308. There were no donor cars available at the time.

 

For all of you waiting for a auto to manual transmission conversion Don at International Dreamcars has been working on one and it should be ready for testing soon. He is putting a 5 speed Tremec into a 400a and would like to be able to make it into a kit.