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bad bearing in cam drive case

Discussion in 'Technical Q&A' started by bpcurtis, Jan 6, 2004.

  1. bpcurtis

    bpcurtis Rookie

    Nov 5, 2003
    19
    Dickinson, TX
    Full Name:
    Burnell Curtis
    I rebuilt my 75 308 GT4 several years ago and now a bearing on the shaft of the cam drive is bad. Can this case be removed without removing the engine and dropping the transmission? I am going to try and remove the bottom studs and try and pull the case forward but it may be too tight to do this. Anyone done this?
     
  2. james patterson

    james patterson Formula Junior
    Professional Ferrari Technician

    Dec 8, 2003
    417
    Dallas Texas
    Full Name:
    James Patterson
    Yes this can be done with the motor in the car. You will have to drop the oil pan and remove the oil pick-up tube and the studs that mount the tube to the front cover, this is the most difficult part of the job. Then just as you thought, pull all the lower studs that go through the trans case and then gently pry the cover off. You can then rebuild the cover on the bench and replace the support bearings in the block. It is not a fun job but beats the heck out of pulling the motor.
     
  3. yelcab

    yelcab F1 Veteran
    Consultant

    Nov 29, 2001
    9,068
    San Carlos, CA
    Full Name:
    Mitchell Le
    Yes it can be done (i have not done this in the car). But according to some other folks on this board that have gone through this process, the aggrevation and the difficulty in doing this job with the engine in the car is very high, to the point of being almost worth it pulling the engine.
     
  4. 4re gt4

    4re gt4 Formula 3

    Apr 23, 2002
    2,279
    Roseburg, OR
    Full Name:
    Hans E. Hansen
    Rob Garven did this. I don't think his disassembly process was as extensive as that mentioned above.

    Note that there are two entirely different bearing/seal setups. Early cars (probably yours, and certainly Rob's) have an outside seal with two inner bearings. Newer cars have an external bearing, with the seal in between. Apparently the exact bearing specification is critical - just an equivalent sized one may not do. Contact Rob.
     
  5. robertgarven

    robertgarven F1 Rookie
    Rossa Subscribed Owner

    Feb 24, 2002
    4,968
    Ventura, California
    Full Name:
    Robert Garven
    yes I have done this twice (dont ask) anyway it is not really that hard. The only part being the oil pick-up tube but all I needed was a 10mm craftsman swivel socket. My car had the four bearings with the seal outside. If you are going to do this you should replace all 4. I had an outside bearing fail and caught it before it did any damage. I found bits of the bearing cage in the sump. You will need a slide hammer with a inside grip to remove the inner bearing. I got one at harbor freight to remove the inside bearing. I can post some pictures later if anyone wants. There is a technique to remove the outer bearings with out doing the inner ones but you need a special tool that goes inside the races of the outer bearing and pulls them out, them you hammer in the new ones. I could never get the Wurth puller even though I had the part#. I have heard that the outer bearings fail after several belt changes due to the tension of the new belts stressing out the bearing.
    Not a hard job but time consuming, and you need to mark everything as the gears are not straight cut and the last part when you put the case cover back on you need to have the cam drive gears set up perfectly as when you tighten the bolts it presses the gear shaft into the inner bearings. If you do it wrong it all has to come apart again. I did a pretty good job and I am not that smart or talented, just take your time and get a good digital camera!!!!

    Rob
    call me if you need some advice.
     
  6. Verell

    Verell F1 Veteran
    Owner Consultant

    May 5, 2001
    6,951
    Groton, MA
    Full Name:
    Verell Boaen
    I replaced my timing drive bearings & seals w/the engine in the car.

    I started it a few weeks after RobertGarven started his project. This thread in the old tech Q&A archives has pretty much a blow-by blow running description of what I ran into.

    < http://www.ferrarichat.com/discus/messages/256120/21198.html >

    Robert & I had several threads going at about the same time as we got into different complications. It's worth looking at all of them.
    Go to: FerrariChat.com » Technical Q&A Archives
    < http://www.ferrarichat.com/discus/messages/256120/256120.html >

    and search for 'timing drive' 'cam drive' & 'belt drive'. The threads I'm talking about were posted during the spring & early summer of 2002.
    There's a lot of detail, including more than a few things we did wrong along the way & had to redo.

    GET SNAP-ON SOCKET:
    About the only thing I'd do differently is spring for the Snap-On 12 point short flex socket. Both for it's smaller diameter, & you really need a 12 point because it's very hard get enough rotation to move the pickup tube nuts to a 6-point. I probably spent a couple of extra hours because I was using the Craftsman flex socket, not counting the time to grind it shorter & to reduce it's OD.

    REPLACE INNER & OUTER BEARINGS AT SAME TIME:
    If an outer bearing has failed, then the drive gear will have cocked the inner bearing's inner race & damaged the bearing. If you don't replace the inner bearing, there's a strong probability that it will fail within a few thousand miles & you'll get to replace both inner & outer again...


    BTW, when Jonathan & I picked up his car at Boston Sports Car, they were finishing up a timing drive replacement. They said that they prefer to do it with the engine in the car as it is definitely less time now that they've got it all figured out. In retrospect, I tend to agree.
     
  7. tbakowsky

    tbakowsky F1 World Champ
    Professional Ferrari Technician Consultant

    Sep 18, 2002
    14,414
    The Cold North
    Full Name:
    Tom
    I just did this to my car yesterday. But I have the engine out of the car. You can do the job with the engine in but it's a serious pain. The bearings are very cheap to buy even from the dealer.
     
  8. bpcurtis

    bpcurtis Rookie

    Nov 5, 2003
    19
    Dickinson, TX
    Full Name:
    Burnell Curtis
    Thanks everyone for the advice. I have taken off th muffler, timing belts, harmonic balancer, all nuts, double nutted the bottom studs and removed them, and taken the pan nuts off. Problem is, the pan will not drop down. I have forced it about 4 inches down and it is clear of the studs, but will not drop down. It seems to be stuck on the oil baffels. Any advice?

    Burnell



     
  9. Steve Magnusson

    Steve Magnusson F1 World Champ
    Lifetime Rossa

    Jan 11, 2001
    18,161
    Texas
    Full Name:
    Steve Magnusson
    Reread James Patterson's post: "...remove the oil pick-up tube..." (a separate portion of it extends down into the sump -- you need to remove the external tube and then fish out the internal tube below it).
    You might also need to remove the oil temp thermistor that pentrates the front wall of the sump (but can't I recall if that's absolutely necessary or not).
     
  10. yelcab

    yelcab F1 Veteran
    Consultant

    Nov 29, 2001
    9,068
    San Carlos, CA
    Full Name:
    Mitchell Le
    Both the oil pick up tube and the Oil Temp sensor do have to come off before the oil pan will drop out, well, maneuvered out is more like it.
     
  11. bpcurtis

    bpcurtis Rookie

    Nov 5, 2003
    19
    Dickinson, TX
    Full Name:
    Burnell Curtis
    thanks, I am just not reading the past threads enough. I have now reread all of it. The oil temp sensor and dip stick are out and the pan is off. The oil pump tube is off (PITA). Now the nuts on the gear drives will not come off. Impact wrench and long bar will not do it. Will try again tomorrow andas a last resort, will cut them off.


     
  12. yelcab

    yelcab F1 Veteran
    Consultant

    Nov 29, 2001
    9,068
    San Carlos, CA
    Full Name:
    Mitchell Le
    When I did mine, the engine was out of the car, and the nuts did not come off. They were ... rusted on real tight. So I had to dremmel tool cut it out. It is a very good idea to use new nuts anyway, just don't get too shocked when you find out it is $30 for each nut. Not to mention $75 for the socket. And, you may end up nicking the drive gear shaft with your dremmel, if that is the case you may want to buy new gears.

    This job is getting more ... expensive everyday, isn't it?
     

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