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308 Differential/axle seals

Discussion in 'Technical Q&A' started by Doug, May 28, 2005.

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  1. Doug

    Doug Formula 3

    Nov 13, 2003
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    Louisville KY
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    Doug
    #1 Doug, May 28, 2005
    I am finally getting around to replacing my leaking seals where the axle goes into the diff. I got the new seals from T.Rutlands. I pulled the axle and the old seal on the pass side and it is larger than the new seal that I got from T.Rutlands in both thickness and diameter. The car is a '76 308GT4. There are also other differences in the seals appearance. Also, the new seal pops in easily with plenty of "play". Will it expand when the flange is put back on? Is there a new updated seal or could they have sent me the wrong ones? I was hoping to get this done this weekend, and I won't be able to contact them until after the holiday.
    The old seal is a Gaco MIM4562
    The new seal is a Gaco 52556
     
  2. Verell

    Verell F1 Veteran
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    #2 Verell, May 28, 2005
    The seals should be a press fit into the housing, and gently snug around the drive shaft.

    Sorry, but you've got the wrong seals fer sure.
    I recently received new differential seals for my '82 308 QV, they're just marked with the standard dimensional markings:
    45-62-10

    (45 - shaft diameter in mm, 62- housing diameter in mm, 10 - seal width in mm.) Maybe you can compare these meas'ts to see if they match your car, or the new seals.
    Good luck!!!
     
  3. Doug

    Doug Formula 3

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    #3 Doug, May 29, 2005
    Thanks Verell. Just what I didn't want to hear in the middle of this project.

    Another question.
    The bolt that holds the flange to the diff had a thick coating of some red rubber gasket type material. It was on the bolt and some on the splines of the flange as well. Would it be some form of locktite or gasket. On re-installation should I just put in the new seal(when I get correct ones), followed by the flange and then just use an impact to tighten the bolt? Then reinstall the axles(which I will rebuild with new grease).?
     
  4. Gary48

    Gary48 Guest

    Dec 30, 2003
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    #4 Gary48, May 29, 2005
    Doug, the material is probably red silicone sealer, a very good practice would be to clean off the old and re-apply upon reassembly. Apply sparingly so silicone won't squeese out into the diff. when tightening.
    Just a note of caution! When I had my 246 diff. apart the left bearing was toast. What I had discovered was that the bolt on flange has a hole about 1/2 in. in diameter that has to be installed straight up to receive lube, this flange was installed incorrectly by someone and starved the bearing, taking it out. I am making the assumtion that the 308 has the same design. Hope this helps.

    Gary
     
  5. Verell

    Verell F1 Veteran
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    #5 Verell, May 29, 2005
    The red material is indeed a form of RTV sealant. It ensures that the flange bolt & washer seal in oil coming thru the splines.

    Gary348 is right, the left differential flange has half of an oil passageway in it that must be lined up with the matching passageway in the differential casting.

    Don't use an impact to tighten the bolt, far too easy to severely overtighten. Like every other bolt in a Ferrari, it has a torque spec, look it up & use it.

    I recommend using Loctite/Permatex 515 or 518 to seal the differential flange back to the differential. It's made for sealing metal to metal joints like these. It doesn't skim over like RTV, only sets up when air can't get to it. Gives you plenty of working time. I also use a thin smear of 515 or 518 around the outer edge of the seal housing before installing the seal. Very thin, just enough so you can see the sealant's color.

    Easy to cleanup by wiping any excess off. Use sparingly, only takes about a 3/32" diameter bead.

    I'm sure you already know to not get any kind of sealant onto the seal's sealing lip as it will never seal properly.
     
  6. Doug

    Doug Formula 3

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    #6 Doug, May 30, 2005
    Both of my flanges are identical and they have no hole in them? Am I missing something?
     
  7. Verell

    Verell F1 Veteran
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    #7 Verell, May 30, 2005
    Umm, Sorry about the confusing terminology,
    We're talking about 2 different things. I'm talking about the large Al ring(aka flange) that holds the seal, not the flanges for the CV joints. The ring is mounted to the drivers side of the differential with studs. If you're just doing seals, you probably haven't pulled it so don't need to worry.
     
  8. Gary48

    Gary48 Guest

    Dec 30, 2003
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    #8 Gary48, May 30, 2005
    Doug, ya I guess I was a little to far into the job as well.

    Gary
     
  9. Doug

    Doug Formula 3

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    #9 Doug, Jun 4, 2005
    Got the correct seals and put the drivers side back in. I can't remember during removal if the seal is flush with the housing or is it pressed in. The fit is tight and I don't want to force it in anymore if it is not supposed to be. Right now it is flush with the diff. housing.
     
  10. Doug

    Doug Formula 3

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    #10 Doug, Jun 5, 2005
    Ooops, never finished the question.
    Is the seal supposed to be flush with the diff housing or is it pressed in furthur?
     
  11. Verell

    Verell F1 Veteran
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    #11 Verell, Jun 5, 2005
    Flush is fine, the sealing lip is recessed from the face of the seal, so is further inwards.

    BTW, Seals depend on the mating surface holding a film of oil. Over time the old seal will have polished the mating surface so smooth that it won't hold oil. Scuff the sealing surface of the flanges with 600 grit sandpaper or green scotchbrite.
     

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