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Loose cinchbolt?

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  • Loose cinchbolt?

    I replaced the bellcrank in my '66 Crusier last year, but a couple months after it was done my steering got really squirrely and the car would feel a little out of control when I hit bumps. When I took it back to the shop, they found the cinch bolt for the steering arm hadn't been tightened properly, so they fixed it. Now, about 800 miles later it seems like I'm feeling the same thing happening.

    My question is, is there a way to get that bolt to stay tight once and for all, if it is loose again? Has anyone encountered this?

  • #2
    If indeed this bolt has come loose again, and there is no contributing factors (shimmy or wobble that could shake it loose), the bolt may be failing (stretching or threads stripped). Replace the bolt.

    Another possibility is something else has come loose. If the original mechanic didn't tighten the bell crank properly, maybe he left other things loose too. Have it all checked.
    Mike Sal

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    • #3
      The torque spec on that bolt is much higher then you might expect. If they just used a rachet wrench to tighten it, it will come loose again.


      Arnold Md.
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      64 Daytona HT
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      JDP Maryland

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      • #4
        JDP, where are the torque specs? In the shop manual it only says to "tighten securely."
        "Madness...is the exception in individuals, but the rule in groups" - Nietzsche.

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        • #5
          52-54 Lbs. Ft. and the nut is a special one that is slightly out of shape so it stays put but if you remove it a few times it won't hold that 3 cornered hat shape and will be just like any other nut.

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          • #6
            Thanks Alan. How'd you find the torque spec? Only 52 lbs? That's not much.
            "Madness...is the exception in individuals, but the rule in groups" - Nietzsche.

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            • #7
              my '56 FSM says 60-65 ft-lbs. and that is significantly more than normal for a 3/8" UNF bolt. The factory bolt is Grade 8 (hence the higher torque spec) so if it needs to be replaced or is missing it should be replaced with a Grade 8 fastener.

              nate

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              • #8
                In the chassis parts manual they don't show the bolt, but they reference a couple washers and describe them as "sh'prf". What's that mean? If they are missing could that also allow the nut to loosen up?

                Also, it indicates the bolt and nut are 7/16". Maybe earlier cars were 3/8".

                I'm still not positive it's the cinchbolt, but that's where I'll check first, since I had a problem there before.
                "Madness...is the exception in individuals, but the rule in groups" - Nietzsche.

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                • #9
                  I was giving you the specs on my 53 and it is 3/8" bolt and special nut. No washers.

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                  • #10
                    Where do you find the torque specs??
                    "Madness...is the exception in individuals, but the rule in groups" - Nietzsche.

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                    • #11
                      "sh'prf" is shorthand for "shakeproof" i.e. a star washer.

                      I just looked at my late shop manual and it is indeed a 7/16" UNF bolt on those models, spec. is still 60-65 ft. lb. I seem to recall that the nut on these is a special nut, not a self locking one, but thicker than an ordinary nut.

                      Torque specs are in the shop manual, in the '56 manual it is in the back; in the late manual it is in the front, toward the end of section I.

                      nate

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                      • #12
                        Scott, I dug out 3 more bellcrank pinch bolts and checked them 2 were off 53K's and 1 was off an Avanti. All were 3/8" X 24 X 2 3/4". The nut is 7/16" thick and has a machined raised spot on one end, the other end the last 2 or 3 threads are tweeked out of shape so the nut goes on easy up to the last few threads then you can feel some tightness. All 3 had split lock washers. The specs were from Motors Auto Repair Manual 1957. All of their torque specs are for 30 wt. motor oil. If you use no oil at all, dry threads, you would have to go higher on the torque. Now if you used ARP assembly lube you would have to go down to 35 lbs. So the best thing to do would be to mike the length of the bolt and after you torque it down make shure you have .006" or so bolt streatch.

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                        • #13
                          This is all great information! I did take it to the shop this evening. The mechanic hoisted it up and took the weight off the front tires and moved everything around quite thoroughly while I watched. He checked that cinch bolt and it was tight. It looks like the play is in and around the steering box. I don't think the innards are necessarily out of adjustment, but it did look like the movement was at leat partly due to a worn bushing where the little sideways steering output shaft comes out. Now I'm not sure if I should have the whole steering box replaced by a good used one or just get a new bushing and have them take out the unit and put in the new bushing. That might not even solve the problem. Yuck...this could be expensive.
                          "Madness...is the exception in individuals, but the rule in groups" - Nietzsche.

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                          • #14
                            Did you replace the bellcrank forging itself or the pivot pin kit, or just the bearings?

                            If a bellcrank has been run for years and miles with the pinch/cinch bolt less than tight, it may have worn in an hourglass shape and no amount of torquing that little bolt will keep it tight. Doesn't take much wear to make a difference with all the leverage of the long arms. Power steering cars, oversize tires, or offset wheels all can put stress on that weak link.

                            thnx, jv.

                            PackardV8
                            PackardV8

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                            • #15
                              Did you replace the bellcrank forging itself or the pivot pin kit, or just the bearings?

                              If a bellcrank has been run for years and miles with the pinch/cinch bolt less than tight, it may have worn in an hourglass shape and no amount of torquing that little bolt will keep it tight. Doesn't take much wear to make a difference with all the leverage of the long arms. Power steering cars, oversize tires, or offset wheels all can put stress on that weak link.

                              thnx, jv.

                              PackardV8
                              PackardV8

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