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Thread: CV Meltdown

  1. #1
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    CV Meltdown

    I had a unfortunate event two days ago.
    After a very spirited drive on central Oregon rural roads, after coming to a complete stop, I engaged First aggressively and my 72 T kinda blew up.
    It was the pass side half shaft. It left with a considerable amount of destruction. Brake caliber and brake caliber housing fitting (requiring a new trailing arm. It also punctured the WHEEL !
    thankful I was doing zero mph

  2. #2
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    Did the bolts back out or fail? I got a 914 from a fellow where his bolts came loose, and when he took off from a stoplight the CVJ took out the gearshift rod and did other damage.
    Porsche Historian, contact for Kardex
    Addicted since 1975, ESR mbr# 2200 to 2020 03
    Researching Paint codes and Engine Build numbers

  3. #3
    Senior Member
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    I wouldn't call the bolts coming loose a CV meltdown , because that certainly seems what happened .

  4. #4
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    they backed out. I went back to the scene of the crime and picked up all the pieces. One bolt was is sheared off, the remaining are all intact. I am surprised that I had no warning, no clunking no vibration, if it was loose I would have thought it would have given me some indication. In the process the half shaft ripped the caliper off breaking the caliper as well as the housing the caliper bolts to. I guess the question is should one use a thread sealant when installing these components?

  5. #5
    Senior Member bob joyce's Avatar
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    new shore washers?

  6. #6
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    First, everything must be grease free. New Schnorr washers every time! You do have the hardened half moon plates for the Schnorr washers to seat on? A bit of Loctite blue 242 could be used. Torque them to spec in stages as you do wheel nuts. New bolts drilled for safety wire are a great option. After driving for a few hundred miles, check the torque again. Not a bad idea to do it again in a thousand miles. Really, the only reason they come loose is because they were not correctly installed.
    Porsche Historian, contact for Kardex
    Addicted since 1975, ESR mbr# 2200 to 2020 03
    Researching Paint codes and Engine Build numbers

  7. #7
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    Thanks to all who responded Got the car up in the air and checked the intact side(driver) all good and tight. I am ordering new washers, thanks for the advice.

  8. #8
    Senior Member 911quest's Avatar
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    Double check the balls and inner cage. If they have wear they can cause binding which can lead to the axle bolts coming loose.
    Tony Proasi
    www.stuttgartspecialists.com
    52 split window coupe
    67 912

  9. #9
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    Thanks Tony, that is an interesting problem. I stand corrected then, it is not always incorrect assembly.
    Porsche Historian, contact for Kardex
    Addicted since 1975, ESR mbr# 2200 to 2020 03
    Researching Paint codes and Engine Build numbers

  10. #10
    Senior Member kentf14's Avatar
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    +100 to this advice.
    I had a local mobile mechanic torque my CV bolts w an impact wrench. Had the same failure as described above. Fortunately I was about a mile from home and the CV came loose off the output flange so it didn’t beat the underside of the car.
    Ever since this incident I compulsively check the bolts whenever I’m under the car, and keep a supply of fresh schnorr washers on hand. Oh, and I stopped using that mechanic
    Quote Originally Posted by davep View Post
    First, everything must be grease free. New Schnorr washers every time! You do have the hardened half moon plates for the Schnorr washers to seat on? A bit of Loctite blue 242 could be used. Torque them to spec in stages as you do wheel nuts. New bolts drilled for safety wire are a great option. After driving for a few hundred miles, check the torque again. Not a bad idea to do it again in a thousand miles. Really, the only reason they come loose is because they were not correctly installed.
    Last edited by kentf14; 02-01-2021 at 08:31 PM.
    E911SR & RGRUPPE
    '65 911 "The Ol' Gal" (long gone)
    '73 S Coupe #306

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