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Drive flange end float 308

Discussion in 'Technical Q&A' started by Difaz, Jul 29, 2010.

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  1. Difaz

    Difaz Karting

    Mar 30, 2005
    116
    Sydney Australia
    Full Name:
    Phill
    #1 Difaz, Jul 29, 2010
    I changed the diff seals for the driveshaft flange on my 308 GTB today and noticed some end float on the driver side flange (RHD car). The passenger side flange did not seem to have any end float only the driver side, about 2-3mm. At first I thought the centre bolt was loose but when i got there it was tight.

    Seals are number 65 on table 22
    Flange is number 5 on table 27

    Is this normal to have some end float?

    Thanks in advance for any help.
     
  2. sowest

    sowest Formula Junior

    Aug 18, 2006
    899
    #2 sowest, Jul 29, 2010
    The drive flange bolts to the differential side gear. The side gear is limited in its motion towards the center of the differential by the spider gear assembly. The side gear is limited in its motion away from the center of the differential by the limited slip clutch pack. Some motion in the side gear and flange is not unusual, but it seems to me that 2-3 MM is bit excessive.

    What to do. I don't think I would tear the thing apart at this point if the gear oil isn't showing a lot of metal in it. The limited slip plates are probably worn. If everything works and sounds normal, I think that I would use the car and keep an eye and ear out for any unusual signs and perhaps dump the oil again in a few thousand miles just to see what it looks like.
     
  3. sowest

    sowest Formula Junior

    Aug 18, 2006
    899
    #3 sowest, Jul 29, 2010
    The motion of the drive flange may be the cause or at least contributing to the seal leak. The question is: was the seal bad or is there so much motion in the flange that even a good seal cannot cope?

    Still, I think that I would replace the seals and keep an eye on everything before I took the differential apart. I am assuming that the car gets normal street use and that you are not entered in a 12 hour enduro race this weekend....;>)
     
  4. Difaz

    Difaz Karting

    Mar 30, 2005
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    Sydney Australia
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    Phill
    #4 Difaz, Jul 29, 2010
    Hi Sowest

    Thanks for your input.
    The seals on both sides were equally bad. Hard as nails and starting to crack. 32 yeras old I imagine.

    There doesn't appear to be any problem with the function of the diff, no chatter just a very slight groan on full lock when performing U turn quickly (hard to hear).

    Measured the static preload on the diff plates (lock one wheel & turn the other) and it came in at 41lbs which is about right from what I have read. No noise at all when measuring this, nice and smooth.

    I did change the oil last week (neo 75/90 NS) and it appeared normal. No unusual metal particals just a small amount of fine pickup on the magnet.

    Funny you should mention 12 hour enduro. I was going to track the car today but decided not to until I got some answers.

    Had I not replaced the seals I would never have noticed. Guess I'll just drive and pay attention for anything unusual.

    Thanks

    DIFAZ
     
  5. sowest

    sowest Formula Junior

    Aug 18, 2006
    899
    #5 sowest, Jul 30, 2010
    I think that you are OK. My only second thoughts were about the possibility that the leak was a result of the flange moving around more than the seal could handle. If you found the seals to be hard and brittle, then I would feel confident in using the car. They are pretty tough and durable machines. No need to imagine demons. Sooner or later, real demons will show up......;>)
     
  6. duck.co.za

    duck.co.za Formula 3

    Jan 9, 2007
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    Cape Town South Afri
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    Dave
    #6 duck.co.za, Jul 30, 2010
    Either we both have the same problem or everything is OK !! I am busy rebuilding my motor and have done all the seals in the gearbox as well . I also noticed this end float , I have it on both sides . Ask my local Ferrari agent and he didn't seem think it was a big issue .
    Please keep us posted
     
  7. darthenzo

    darthenzo Formula Junior

    Dec 8, 2007
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    Glendale, Arizona
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    James
    #7 darthenzo, Jul 31, 2010
    I was hoping your username indicated an Arizona address, but Sydney is too far for me to offer a helping hand in person... not that I wouldn't love to explore your beautiful country. Oh well.
     
  8. Difaz

    Difaz Karting

    Mar 30, 2005
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    #8 Difaz, Jul 31, 2010
    Took the 308 out today for a good drive after replacing the seals. Gave it loads of stick with plenty of sideways action and happy to report there wasn't any noise or anything unusaul and no leaks at all.

    I'm curious about the link between my name and Arizona?
     
  9. luckydynes

    luckydynes F1 Rookie

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    #9 luckydynes, Aug 1, 2010
  10. Difaz

    Difaz Karting

    Mar 30, 2005
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    Phill
    #10 Difaz, Aug 2, 2010
    thanks great link with the answers I was looking for. I'll monitor things and note the rate of deterioration.

    Cheers
     
  11. BigTex

    BigTex Seven Time F1 World Champ
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    Dec 6, 2002
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    #11 BigTex, Aug 2, 2010
    Arizona USA is abbreviated "az" on postal items......so the last part of your LogIn name...
     
  12. Difaz

    Difaz Karting

    Mar 30, 2005
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    #12 Difaz, Aug 2, 2010
    Just curious, what side of the diff is the preload bellvel washer on. Driver side (LHD car) or passanger side?
     
  13. sowest

    sowest Formula Junior

    Aug 18, 2006
    899
    #13 sowest, Aug 3, 2010
    Are you talking about the washer that sets the differential carrier bearing preload? That is on the left side, the side with the bolt on plate/seal holder. If you mean the washer that is part of the limited slip clutch pack, I thought that there was one on each side. I don't have anything to look at for reference here. I seem to remember one on each side, closest to the carrier housing.

     
  14. Difaz

    Difaz Karting

    Mar 30, 2005
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    Phill
    #14 Difaz, Aug 3, 2010
    The washer that is part of the clutch pack is what I meant. It makes sense that there are two.

    Thanks
     
  15. sowest

    sowest Formula Junior

    Aug 18, 2006
    899
    #15 sowest, Aug 4, 2010
    Last edited by a moderator: Sep 7, 2017
    I have been thinking about the question of end float raised in this thread. I was also a little uncomfortable about statements that I made in my first post. I am thinking that there should really be no end float on the side gear/CV joint flange beyond what is normal operating and oil clearance. The heads of the side gears run against the interlocking pieces that provide the axles for the spider gears. This sets the limit of the side gear motion towards the center of the differential. The limit of the side gear motion away from the center of the differential is set by the thrust washer that is keyed to the main carrier housing. ("B" in the attached diagram) The two side gears and the two spider gear axles can only move from side to side within the limits of the two thrust washers. Any end float would have to be a result of the thrust washers being worn. I think that I also remember doing a 308 or two where the locating tab of the thrust washer had sheared away and started turning with the side gear. This wore away the main carrier.

    At first, I thought that limited slip clutch wear could be the cause, but the only clutch plate connection to the side gears would be the clutch plates that have the internal splines that resist turning motion of the side gear but are free to slide from side to side. The diaphragm or belleville washers provide compression on the clutch plates. This compression is passed from one side of the main carrier housing to the other by the pieces marked "A" in the attached diagram. The compression or pre-load on the clutch plates should not affect the lateral motion of the side gears.

    I wish that I had a differential to look at, rather than just pictures....;>)
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