Threadlocker to Flexplate Bolts

Engine, Trans & Driveline

  1. 66 Sat

    66 Sat Well-Known Member

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    Hi, we recently re-installed the engine/transmission in my car and I've noticed my father-in-law used Permatex Low-Strength threadlocker (Purple) on the torque convertor to flexplate bolts, rather than the Medium (Blue) or High (Red). The bolts were all torqued to spec.
    My question is has anyone had bolts come loose after using the low strength stuff? He would have also used it on the flexplate to engine bolts which is lot harder to fix than the torque convertor bolts. I realise now we should have used the blue (hence my question), but what does everyone reckon?
     
  2. Cranky

    Cranky Banned Staff Member FBBO Gold Member

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    I've had bolts come loose using red!
     
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    • vintage chromoly

      vintage chromoly Well-Known Member

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      I use red for just about everything.
       
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      • 66 Sat

        66 Sat Well-Known Member

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        This isn't a race car, only a cruiser with the odd quarter mile pass. What about the flexplate to engine bolts? They are the ones I'm most concerned about as it's a major pita to fix. I actually have the red and blue in my garage, but he brought some over with him and I didn't notice what he'd used until after the engine was in.
         
      • Bee1971

        Bee1971 Well-Known Member

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        On my 1971 Superbee , when I rebuilt the #s matching motor back in the mid 90s

        I didn't use any locktite on the cam bolt , flexplate to crank and flexplate to converter

        Was nice pulling everything apart

        Street use only

        How do I remember this - Well it just got rebuilt again into a Stroker Kit , and the #s Transmission just got rebuilt also this past fall

        Zero issues with those bolts mentioned after 25 years with no locktite

        However I did replace all the bolts with ARP Hardware this time around
         
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        • PurpleBeeper

          PurpleBeeper Well-Known Member

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          In my opinion, I wouldn't worry about it, but just be aware that if you have a "rod knock" someday, it might be the torque converter coming loose. On the other hand.....you can get to those bolts easily through the access cover. Your choice.
           
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          • Cranky

            Cranky Banned Staff Member FBBO Gold Member

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            Never had crank to flex plate bolts come loose even without Loc-tite.
             
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            • 66 Sat

              66 Sat Well-Known Member

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              Thanks fellas, I think I'll re-do the torque convertor bolts for peace of mind.
              Cheers
               
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              • PRND21

                PRND21 FBBO Gold Member FBBO Gold Member

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                If the bolts move when you retorque them, you’re breaking the glue (Loctite), so to speak. If you go to the trouble of retorqueing them, I think I would take them out, clean them and use the red Loctite and retorque. I don’t think I’d worry about the crank bolts. Just my opinion.
                 
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                • BeeKool

                  BeeKool Well-Known Member

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                  I've had flexplate bolts come loose w/o loctite. Ive used the blue ever since
                   
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                  • wyrmrider

                    wyrmrider Well-Known Member

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                    locktite
                    4 Cyl
                    6 cyl
                    Harleys
                    so why not V8
                    I do not use single bolt cams after several disasters and lost races
                     
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                    • 66Satellite47

                      66Satellite47 FBBO Gold Member FBBO Gold Member

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                      I now use red on flex to converter bolts(7x16"). Back in the day used Green, ("replaces welding and brazing") after blue came loose & ground up the cam bearing boss. Use red on the flex to crank bolts for insurance.
                       
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                      • wyrmrider

                        wyrmrider Well-Known Member

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                        There is a reason Mopar goes to more bolts on the racier engines
                        locktite helps for us without the special cranks
                        before locktie we used safety wire
                         
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                        • Brainemaster

                          Brainemaster New Member

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                          • Brainemaster

                            Brainemaster New Member

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                            The color means little. There is Red Locktight that is Medium and Blue Permatex that is medium. I suggest you use Medium regardless of the brand, torque to specification in across pattern and then rotate the final torque after.
                             
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                            • 66 Sat

                              66 Sat Well-Known Member

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                              Well they've been in for 3 years now with regular trips to 5,800 rpm and they haven't come loose yet, so I think they'll be fine...
                               
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                              • gtx6970

                                gtx6970 Well-Known Member

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                                same here
                                 
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                                • Hubbarocks

                                  Hubbarocks Well-Known Member

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                                  i have large bottle of blue, i put that S#!T on everything
                                   
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