400i Transmission Question......

Yes, there's a guy (Timp) on this forum who is having it done to his sea-foam green 400A. I think there is a thread devoted to it, and it gets resurrected from time to time.

Aidan

 

Well that puts a damper on the party! So the 400, 365 gt42+2, and 365 gtc4 are the only cars to use this ring and pinion? It seems like a ratio change is almost mandatory for a transmission swap. An overdrive gear of .7 with the 3.00 gives an overall ratio of 2.10 which is probably unuseable.

BTW what would it cost to have a set of gears made? In the last forza magazine there was a 612 that had a custom gear set made. They did not mention any dollar amount, but it must be staggering!

 

How much would it cost to get a set of rear end gears made up? If a batch of 10 were ordered I would guess that the price would be reasonable.

How much would a manual pedal box cost and are they still availible from Ferrari?

Regards,

Art S.

PS. There is an outfit called John's Cars ( I think that is the name) that does B-W to GM TH 400 or 700r4 for Jaguars. He may have the experience to support any conversions.

 

Good info guys for the auto owners who might consider converting.....
btw, 2'3's of 400s were auto, 1/3 5sp.

 

Sorry for digging this old thread abain.

Is it known whether the conversion to a Tremec 5-speed transmission was carried out? Are details known about this?

 

No reported success on a 400. There is however in this forum a reference to a Ferrari replica based on the 400i chassis/engine that uses a tremec. There have been lots of discussions regarding gearbox upgrades for these cars, and at the end of the day you do not have so many upgrade possibilities:

1) the torque tube arrangement requires a beefy gearbox case, so a 400R4 conversion is not such a good idea: 400R4 is also known as 4L60, so that's an "..L60" case much weaker than the TH400 a.k.a 3L80 ( so ..L80 case). Note that the issue is not the transmission power-train, but the case itself. When I wanted my own tranny to be overhauled, the case did not resist the pressure test given the stress it had previously sustained. If I could fail a 3L80, no doubt the 4L60 would not last long. A 4L80 could sustain the torsion of the torque tube but it is way too wide (more on that next).

2) The transmission tunnel is narrow, so any transmission that is thicker than the 3L80 will just require to make some cut-out in the leather of the central console, next to the passenger seat. 10 years ago, there was a turbo converted 400i on ebay with a 400R4 and one could see the cut-out on the interior trim.

3) for manual transmission, the pedal box of the 400 is a work of art and quite visible from the engine bay, butchering it would be plain ugly, so at the very least you would need a 400i manual pedal box (something that was obviously not needed for the above mentioned replica).

Be it a manual tremec or any non original auto, you would have to solve these technical issues: custom rear axle gear ratios, custom torque tube, custom spin-line shaft, new cross-member on the chassis, quite a bit of work on the fiberglass of the transmission tunel,re-routing of the rear air conditioning, and finally properly fix the upholstery.

At the end of the day, if you want a manual upgrade, best bet is to buy original ferrari parts from a 400i manual donor which ends up more expensive than buying a 400i manual in the first place, and comes with a lower market value (the 7th digit of the VIN will still say this chassis left Maranello with an auto gearbox).

A well sorted out TH400 is really a nice match for this car, before considering any major surgery I would first consider an overhaul of the stock gearbox.

 

Thank you very much for your actual replay.

 

Differential is also different.

 

Whoever does such a conversion it would be a labour of love with no intention of selling with a ROI.

Ive debated it several times on my own car but I think more HP is the answer - for me anyway. Add 150HP and the 3 gear slush box wont matter much but it'll take the abuse. The TH400 can live behind a 454 in a pickup truck with a camper complete with a fridge and stove. With a 150HP bump in output It'll eat any manual 400 that ever rolled off the assembly line.

 

These engines seem pretty high HP per liter. Not sure you could that big of a power boost without force induction.

 

More displacement, better cams, head work and higher compression. Not an inexpensive solution but it would look stock so there's a certain value in that. We recently went through this on the 67 mustang. Went from 289 to 347 cubic inches and added 175HP over stock in the process - naturally aspirated. The 3 speed auto really doesn't matter anymore, the car just gets up and goes. We debated putting in an AOD to get one extra gear but I think tunnel clearance is a problem and a manual conversion means cutting the floor as well. Same problem we face on the 400, the engine was the answer.

The boxer engines are 5L and the injected versions are 340HP. My ex 82 boxer got a substantial boost in power when I rebuilt the engine. I wish I put it on the dyno but I can say it pulls hard right to 7500 RPM. No porting was done but I bumped the compression to 10.5:1 and had cams made with a profile everyone says wont work on CIS, can't be done in the porsche world or Ferrari's etc etc.

 

An advantage (one of a few actually) the 400 has over the boxer is the exhaust manifolds and this is important. The boxers are severely restricted on number 6 and 7 primary pipes to clear the axles and would require custom manifolds to overcome that, I see a 20HP gain in that mod. The 400's are great in that department and nice long primaries too which helps torque. The intake plenums on 400's are injected boxer parts mounted upside down on the cam covers so the throttle body and plenum volume are the same and I know they can support more HP. The sensor plates are the same but a more direct route than the boxer has to take to get air into the engine, another advantage. The question is really how much the intake ports flow, the boxers fall down in that department and could use a larger intake valve as well as some porting. Ferrari ran the inboard intake port on a lot of race engines so there might be a nice surprise waiting there.

 

Sounds like you like to do some good old fashioned hot rodding, I like it! Just curious ever thought about switching to a modern fuel injection system either replacing the original system or even replacing Weber carbs?

 

You could indeed use a bigger intake valve as the seat is huge: on my car when the welder refurbished the head we decided to go for thinner seats (same valve diameter smaller seat outer diameter), so has o beef up the head, but you could well do the opposite, i.e thinner seal for with bigger inner diameter, or you could just grind the seat and reclaim approx 1.5mm.

Also a proper distribution chain, allows to reclaim quite a few hp lost due to improper timing (as the chains gets longer the timing is not any-more consistent).

That's a fragile head though so not sure about high compression pistons. My brother has a 365 with very aggressive domes. Two valves were bent. He was lucky the exhaust one did not broke. I wasn't so fortunate (the sodium left a ugly track on the piston sleeve, and the piston itself broke into zillion pieces: the biggest left-over was the size of a button cell...).

As far as the TH400 is concerned, if you start playing with the gearbox stick at high rpm the friction band will not last long on this engine.

 

Stock is never good enough! Ive converted other CIS cars to EFI and managed to squeak out 375 HP on a 308 QV - stroked to 3.4L however. Ive thought about offset grinding cranks in boxers and my goal between bore and stroke changes is 6L. This is challenging in a horizontally opposed engine where the opposing rod wants to hit the companion cylinder. Im sure I could get 5.7 out of a 400 engine easily though. I know the CIS can support 400+ HP. It supports 390 on a Testarossa, same injectors, pumps etc. So unless its an all out effort to make maximum HP I would keep the CIS so it looks stock but maybe puts out 425, even 400 would be fine. A 400 with 400HP, the name plate on the back will take on a whole new meaning

As for the compression ratio and the cylinder head its a non-issue, even the head gasket wont complain. The advertised ratio is higher than actual on any ferrari engine Ive measured of this vintage. 10:1 is a nice number I like to go with on a rebuild. Its not too high and it ups torque - compression has no effect on HP, Smokey Yunick proved that probably before I was born. That and the above mentioned mods and I think the engine would honk. I would put a better torque converter in it as well.