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PTFE Front crank seal

Discussion in 'Technical Q&A' started by viphoto, Jan 17, 2011.

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  1. viphoto

    viphoto Formula Junior

    Sep 11, 2010
    264
    Carlsbad, CA
    Full Name:
    Mark
    #1 viphoto, Jan 17, 2011
    Has anyone installed/used one of the newer design PTFE Seals for the front crank (in my case 308GTB) No spring? and they say no oil or grease when putting it on and let it sit at least 4 hours to set? Comes with a plastic insert to keep it at the shaft size til install. I am assuming a rolled piece of shim stock to help guide it on would be in order? Any tips or comments appreciated.

    Thanks as always for the input.
     
  2. Rifledriver

    Rifledriver Three Time F1 World Champ

    Apr 29, 2004
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    Brian Crall
    #2 Rifledriver, Jan 17, 2011
    I would be curious as to what needs improving in that area. The standard seal was not known to be a problem.
     
  3. viphoto

    viphoto Formula Junior

    Sep 11, 2010
    264
    Carlsbad, CA
    Full Name:
    Mark
    #3 viphoto, Jan 17, 2011
    Not sure anything needed improvement..especially given my lack of experience with an F car. From what I understand the factory boys at BMW, Audi and VW have opted to go with them which I assume was for a good reason. Turns out that the late 90s E36 BMWs use the same size seal 44x60x10 and the one at the local dealer was the new style....so I thought Hmmmm maybe worth a shot. Parts is Parts....although given the boys in Italy, maybe not...
     
  4. Rifledriver

    Rifledriver Three Time F1 World Champ

    Apr 29, 2004
    36,806
    Cowboy Capitol of the World
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    Brian Crall
    #4 Rifledriver, Jan 17, 2011
    The standard seal has never been a problem. It's cheap, readily available and easy to install. Never felt the need to reinvent that particular wheel.
     
  5. JoshECS

    JoshECS Formula Junior
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    May 3, 2010
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    Josh Hill
    #5 JoshECS, Jan 17, 2011
    From what I've seen working on both groups of cars the PTFE seals don't seem to "scar" the crank/cam surfaces like the older seals with springs.

    I haven't done any real testing to confirm if the grooving is related to the hardness of the metal or the seal style and tension...but that's my $.02
     
  6. Rifledriver

    Rifledriver Three Time F1 World Champ

    Apr 29, 2004
    36,806
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    Brian Crall
    #6 Rifledriver, Jan 17, 2011
    So every other engine overhaul we install a new speedi sleeve?




    Better to concentrate our efforts to fixing what is broken in my opinion.
     

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  7. JoshECS

    JoshECS Formula Junior
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    May 3, 2010
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    #7 JoshECS, Jan 17, 2011
    That certainly is not the end of the world, is it.
     
  8. viphoto

    viphoto Formula Junior

    Sep 11, 2010
    264
    Carlsbad, CA
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    Mark
    #8 viphoto, Jan 17, 2011
    Last edited: Jan 17, 2011
    Thanks Brian, your probably right....I wish I had known there were cheaper suppliers before carelessly buggering up my $60 one over the weekend...I can barely get one of the older ones on why would I want to tackle one the sensitive PTFE ones... I can see maybe during a rebuild on a a fresh crank surface...but doing an in car change ...Keep It Simple! (which is the biggest lesson I am having to learn with my first F car)

    I also came across this at BearingTrends.com in their FAQ section...which makes the whole PTFE thing even less simple
    1. What are the shaft requirements for Teflon seals?

    PTFE (“Teflon”) lip seals are usually more aggressive and abrasive to the shaft than standard elastomeric lip seals; therefore, they require a hardened sealing surface. For best results, Chicago Rawhide generally recommends a shaft hardness of 55 to 65 Rockwell C scale, and a surface finish of 8 to16 µin (micro-inch) with a machine lead angle less than 0±0.05 degrees. The final surface finish should be achieved by using the plunge ground finishing method.

    2. How are they installed?

    PTFE lip seals do not have the elastic properties that rubber lip seals possess; therefore, installation and handling are crucial elements in successful operation and function. Shaft keyways and splines, as well as drill holes, ports, and shaft steps (sharp-edges), have the potential to tear PTFE lip seals. If the hardware permits, these obstructions can be covered and accounted for by using thin walled, nylon installation tools. Installation is more difficult when the shaft is installed from the oil side of the seal, and we recommend using a cone or bullet.
     

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