400 auto box problem | FerrariChat

400 auto box problem

Discussion in '365 GT4 2+2/400/412' started by simonc, Aug 6, 2006.

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  1. simonc

    simonc Formula Junior

    Nov 1, 2003
    882
    Herfordshire, UK
    Full Name:
    Simon Campbell
    #1 simonc, Aug 6, 2006
    I have rebuilt the GM400 gerabox in my 400 and was very careful to follow the workshop manual to the letter. New seals, bearings, clutches and band were fitted. I have refitted the box to the car and have a major problem. When I put the car in reverse it does not move properly, it just creeps very slowly backwards plus it pumps gearbox oil out of the small overflow pipe on the top of the box. I have drained the oil out and it seems a little blacki-sh and smells of burnt out clutch. The clutches and band were new and teh box was filled with new ATF oil. Obviously it has done zero mileage since the rebuild.

    I obviously have managed to get something wrong. Does anyone have any idea what this might be?

    Simon in London
     
  2. SpannerMan

    SpannerMan Karting

    Nov 7, 2005
    116
    San Diego
    Full Name:
    Erik Rathmann
    #2 SpannerMan, Aug 7, 2006
    Sounds like line pressure is low, since you did not state whether or not the forward gears are working, I will assume they are, which makes my diagnosis untrue. The "turbo" 350 uses a pressure regulator that rides in a hole drilled into the aluminum valve body. The steel piston wears out the aluminum and causes low pressure to first and reverse. Don't know if this applies to the 400 though.
    If your workshop manual has info on pressure tap locations, you could measure the line pressure in various circuts.
    Also, did you put in a new pump? Did you fill the tourque converter before installation?
    Are you sure all the check balls are in the proper locations?

    Since fluid is pumping out the vent tube there may be a trans cooler line blockage. Or a crack in the case/valve body.

    Just throwing out general suggestions, I don't have any specific info on your tran....yet

    Good luck.
    E
     
  3. simonc

    simonc Formula Junior

    Nov 1, 2003
    882
    Herfordshire, UK
    Full Name:
    Simon Campbell
    #3 simonc, Aug 7, 2006
    The forward gears seem to be working OK and feel as normal driving in the garage, although I have not taken it for a drive.

    I must be honest and say I did not fill the torque converter as I assumed this would fill automatically from the gearbox when the engine started.

    From your earlier post I assume that forward gears mean that if I have forward gears then the line pressure should be OK. Is that correct?
     
  4. dstacy

    dstacy F1 World Champ
    Owner Rossa Subscribed

    Jan 23, 2006
    11,784
    GMT -5 & GMT +1
    Full Name:
    Dave
    #4 dstacy, Aug 7, 2006
    Simon, sorry to tell you this but if the fluid is black and smells burned you're going to have to pull it back out.
     
  5. SpannerMan

    SpannerMan Karting

    Nov 7, 2005
    116
    San Diego
    Full Name:
    Erik Rathmann
    #5 SpannerMan, Aug 9, 2006
    I agree, if you did not fill the torque converter, most likely some part of the trans ran dry long enough to cause harm. Even though there may be pressure in the system now.
    E
     

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