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365 Transaxle

Discussion in 'Technical Q&A' started by Colin Angell, Feb 10, 2013.

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  1. Colin Angell

    Colin Angell Karting

    Jun 17, 2004
    118
    #1 Colin Angell, Feb 10, 2013
    I have just replaced the tapered roller bearings supporting the differential cage in the transaxle of my 365 GTC. Whilste the transaxle is out of the car I decided it would be a sensible time to change the universal joint which connects the gear change rod to the gearbox, as mine shows quite a bit of wear and is very sloppy. I have bought a new universal joint and started to machine it to suit the existing set up.

    Connection to the gear shift is via a 5mm diameter pin which is a sliding fit and is held in place by circlips at each end. Connection to the gearbox rod is again by a cross pin, but their are no circlips and the ends appear to be peened over. I filed off one end and tried to drift the pin out, without success. I then tried drilling out the head to about 7.5mm diameter but was still unable to drift out the pin.

    The parts book and workshop manual seem of little help and I am hoping that someone is able to offer some clear advice. Perhaps these were fitted with taper pins, or other mechanical fixings? I am just at the point of removing the side cover from the gearbox in order to be able to machine off the existing joint and any help would be appreciated. Oh incidentally, I think the transaxle is more or less identical to 330 GTC and Daytona.

    Many thanks

    Colin
     
  2. 335s

    335s Formula Junior

    Jan 17, 2007
    870
    SF Bay Area
    Full Name:
    T. Monma
    #2 335s, Feb 11, 2013
    these pins are soft-RC 10-20(?)
    they are, effectively, a "size to size" interference fit...since they are driven in, and are rather soft, frequently they distort as they gall upon insertion.

    You would be well advised to remove shiofter cover(replace shaft o-ring seal at this juncture as well, and remove on the bench.
    DISASTER can occur if the hammer swings become toooo enthiusiastic....it will come apart much easier on the bed of the Bridgeport!
     
  3. Rifledriver

    Rifledriver Three Time F1 World Champ

    Apr 29, 2004
    37,288
    Cowboy Capitol of the World
    Full Name:
    Brian Crall
    #3 Rifledriver, Feb 11, 2013
    All true.

    Well said.


    A GTC transaxle almost falls out anyway and properly drilling the pin is the way to go.
     
  4. Colin Angell

    Colin Angell Karting

    Jun 17, 2004
    118
    #4 Colin Angell, Feb 11, 2013
    Thank you for your prompt replies. I can hear wise words and had really come to the same conclusion. I think it quite likely that the pins distort in their holes with many years of use and are probably not straight anymore anyway, so they will try to resist being pushed out. I will do as you suggest and remove the cover and shaft, before carefully setting up for accurate drilling. I will probably refit using a roll pin, any objections?

    Many thanks
    Colin
     
  5. Rifledriver

    Rifledriver Three Time F1 World Champ

    Apr 29, 2004
    37,288
    Cowboy Capitol of the World
    Full Name:
    Brian Crall
    #5 Rifledriver, Feb 11, 2013
    A roll pin would probably work but my first choice would probably be a bolt with an unthreaded shank or a straight hard pin. If you drill to a known size that can always be done later because a roll pin is easy to remove.
     
  6. Peter

    Peter F1 Veteran
    Owner

    Dec 21, 2000
    6,441
    B.C., Canada
    #6 Peter, Feb 12, 2013
    Last edited by a moderator: Sep 7, 2017
  7. 335s

    335s Formula Junior

    Jan 17, 2007
    870
    SF Bay Area
    Full Name:
    T. Monma
    #7 335s, Feb 12, 2013
    the appropriate pins with the appropriate RC is available from Grainger in bags of 20 for 10-15 dollars, they are "soft" enogh such that a slight tap with a ball headed drift and a dead shot brass faced hammer will provide adequate "distortion" of a "size to size" interference fit such that bench extraxction is required in the fiture-which was Ferrari's original intent-imo...
    use an eyepiece and examine surface of the end of the original pin, you ought to observe a delicate counter bore/dishing of the surface, meant to distort upon peening at intstallation
    fwiw...
    these were not meant to be removed with ANY regularity....
     
  8. Colin Angell

    Colin Angell Karting

    Jun 17, 2004
    118
    #8 Colin Angell, Feb 14, 2013
    Job done. Thanks for all the help. I filed through the outer casing of the existing joint, which then fell apart. I mounted the shaft on exact centre on my lathe in a four jaw chuck and turned off the remaining body, to expose the original shoulder and 12mm diameter reduced shaft end. I don't have a milling machine/Bridgeport, but I made a simple jig to mount the shaft on the cross slide of my lathe and was able to accurately drill out the offending pin. I drilled to 4.9mm and then put a 5mm reamer through and was very pleased with the result. The new joint needed some minor machining to mate properly with the existing shafts and I then assembled the gearbox end with some Locktite and a force fit pin. The new joint has a smaller outside diameter, so I have also made a new, shorter removable pin for the forward connection, which should be fitted with 5mm external circlips. I have always had some problem fitting those, because the circlips are so tiny, so I have cross drilled the new pin and will fit with safety wire to put my mind at ease for the future. Hopefully this will see me through the next 40 years!

    Many thanks again

    Colin
     

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