GH400 Replacemnt | FerrariChat

GH400 Replacemnt

Discussion in '365 GT4 2+2/400/412' started by Choptop400, Oct 24, 2014.

This site may earn a commission from merchant affiliate links, including eBay, Amazon, Skimlinks, and others.

  1. Choptop400

    Choptop400 Karting

    Oct 10, 2014
    138
    Huntington, NY
    Full Name:
    Frank L Caponi
    I am new to the form Ferrari Chat (great) but a long time tifosi of Ferrari. I have been reading the threads with great interest. However, I have not seen any threads that have completely answer the age old question. Can you convert or transplant the GH400 3 speed with a later model GM unit with 4 or 5 speeds? There is much discussion but no evidence that it is possible without going bankrupt or cutting the Ferrari to pieces. Thoughts, comments.
     
  2. aidanparte

    aidanparte Formula 3

    Jul 18, 2004
    1,222
    I'd be interested to know if anyone has done this 'economically', too. It does come up from time to time. BTW, it is the GM TH400 transmission.

    Aidan
     
  3. bobzdar

    bobzdar F1 Veteran

    Sep 22, 2008
    6,367
    Richmond
    Full Name:
    Pete
    Shouldn't be too difficult,you'd need a bellhousing adapter, modify driveshaft depending on the trans used and possibly move the crossmember. Best candidate due to similar size and rating to the th400 is a700r4.
     
  4. It's Ross

    It's Ross Formula 3

    Jul 30, 2007
    2,028
    Barrington, Ill. USA
    Full Name:
    Ross
    While about any Chevrolet pattern bell housing trans. will bolt to the Ferrari adapter the rub is the output. Ferrari uses an enclosed drive shaft, torque tube, that doesn't lend itself well to modifications. If the transmission tunnel needed work to accommodate a longer "gearbox" this would only make matters worse.
    I don't know of it having been done. Given the complexity of modifying the torque tube and the driveshaft, desirability of an automatic gearbox at all and the value of the finished product I'm not surprised.
     
  5. Ak Jim

    Ak Jim F1 Veteran
    Owner Rossa Subscribed

    Dec 23, 2007
    8,451
    North Pole AK
    There have supposedly been some transmission swaps but no one has ever posted any pictures. Call me a doubting Thomas but until I see pictures or an actual car with a swap I doubt a swap has been made.
     
  6. It's Ross

    It's Ross Formula 3

    Jul 30, 2007
    2,028
    Barrington, Ill. USA
    Full Name:
    Ross
    EDIT: I stand corrected, member Jagbuff's twin turbocharged car is reported to have a 4 spd auto box. Perhaps he will provide the details.
     
  7. Arvid

    Arvid Formula Junior
    Silver Subscribed

    May 28, 2012
    668
    Norway
    Full Name:
    Arvid Andersson
    Should be perfectly doable i think. The most difficult thing in my book would be if the output shaft on gearbox have different diameter.
    The steel tube should be easy enough to modify as long as it needs shortening. It is nothing else than a steel tube that can be measured,cut and welded. The driveshaft could also be shortened and new splines cut into it. Probably best to leave shaft to a spesialist :)
     
  8. godabitibi

    godabitibi F1 Veteran
    Silver Subscribed

    Jan 11, 2012
    6,252
    Papineauville, Quebec
    Full Name:
    Claude Laforest
    You also have to think about the shifter. The old Corvette guys are doing it all the time and they have a shifter kit for the console.
     
  9. Rifledriver

    Rifledriver Three Time F1 World Champ

    Apr 29, 2004
    33,736
    Austin TX
    Full Name:
    Brian Crall
    I was involved with someone who did a rather complete plan on converting a TH400 car to a 700R4. This was 15 or more years ago.
    We considered the differential ratio of the automatic car unsuitable for the overdrive transmission, and besides the entire idea was to give the car better performance so we wanted a set of the 5 speed cars gears for the project. At that time Maranello Concessionaires was the only place that we could find them. The price was astronomical and drove the overall price of the conversion too high. I see them listed with prices far more tolerable now but don't know if they are actually available. The other choice would be to find a 5 speed donor car and those aren't growing on trees.
     
  10. Rifledriver

    Rifledriver Three Time F1 World Champ

    Apr 29, 2004
    33,736
    Austin TX
    Full Name:
    Brian Crall
    The shaft and torque tube are easy. Done all the time in the custom car world.
    The tail housing from the 700R4 gets cut off and the rear housing from the 400 gets grafted on. Not a stumbling block.
     
  11. Rifledriver

    Rifledriver Three Time F1 World Champ

    Apr 29, 2004
    33,736
    Austin TX
    Full Name:
    Brian Crall
    I know of several times good plans were made by capable people but when all the costs were tallied it was not considered worthwhile.

    To take a car that the market is not strong on, spend a bunch of money on it and have it worth less when done? Not too many who think the finished product justifies that.
     

Share This Page