pulley bolts

Discussion in 'Manton Push Rods Top Alcohol Tech Questions' started by overkill69, Sep 23, 2015.

  1. Mike Canter

    Mike Canter Top Dragster

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    Back when in the Navy we used a lot of safety wire on bolts in the aircraft. When done correctly the bolt is not going to back off. It can't, thus the reason for safety wire.
     
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  2. Blownalky

    Blownalky Top Sportsman

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    So how would you get the safety wire tight in a flat back pulley? I have a hard enough time for ring gear bolts in a vise, LOL.
     
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  3. overkill69

    overkill69 Member

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    The only way its possible to tension it correctly is because the 11mm pulley diameter is so big there is room to work. Also we do it at the shop on a lift. lol.
    Several on our crew are experimental flight mechanics and nobody has ever seen a fastener actually stretching wire trying to back out. The blower drive on a screw hemi has at least a dozen engineering issues that would never make it to an aircraft.
    We have safety cable guns at work that go to a preset tension automatically before they cut the wire. Even with cable, the fastener will lose some torque as it stretches the cable.
    After one lap this weekend the wire was tighter than a human could twist it. We made two more full passes and it seemed to stay the same.
    We have another race next week and are crunched for time. I may drill the bolts for .041 wire or use the cable gun.
    Over the winter I plan on drilling everything to 7/16.

    one thing surprising about this mess is it shows no sign of movement between the parts...it doesn't even damage the anodizing on the pulley. Obviously, it has good clamping force if we can just maintain it for a weekend.
     
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  4. Mark Leigh

    Mark Leigh Member

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    From all I have read here so far it sounds like it's progressed to where the pulleys need to have dogs on the back like the wheels in Top Fuel --- the bolts are being asked to do 2 things instead of 1------- clamp and resist rotation --- they would probably do well at clamping alone -- if the pulley had a dog or key on the surface of the crank hub ? If you guys run the same bottom all the time -- what about a dowel pin ?
     
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  5. Joad Donnelly

    Joad Donnelly Member

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    You're right, I did it was stretched when I should have said it was pulled tight by the bolts backing out.
     
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  6. wld4x4

    wld4x4 Member

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    studs

    RBS sells a stud that also works well with the ring along with grade 8 lock nuts. I run a 47 tooth 14mm with no problems.
     
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  7. Joad Donnelly

    Joad Donnelly Member

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    I have never been taught that the purpose of safeties of any type is to maintain torque, it is there to keep the fastener from falling out. The purpose of safety wire is the same as a cotter key.

    Here is a statement from an aircraft engineering document I found:

    The word safetying is a term universally used in the aircraft industry. Briefly, safetying is defined as: “Securing by various means any nut, bolt, turnbuckle etc., on the aircraft so that vibration will not cause it to loosen during operation.” These practices are not a means of obtaining or maintaining torque, rather a safety device to prevent the disengagement of screws, nuts, bolts, snap rings, oil caps, drain cocks, valves, and parts.
     
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    Last edited: Oct 1, 2015
  8. Mike Canter

    Mike Canter Top Dragster

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    Exactly what I was taught in the Navy.
     
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  9. Joad Donnelly

    Joad Donnelly Member

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    For sure Mike C. So in our case the safety wire is serving its intended purpose since it is never intended to maintain a specific torque value....it's simply keeping the bolts from falling out even though the bolts have lost some torque by backing out slightly due to the vibration.

    Joad
     
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  10. turbo69camaro

    turbo69camaro Member

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    If i had a blown auto screw car with the wagon wheel sized lower pulley and trying to rip it off the hub on the 2 step.I would make a special hub with a larger hub diameter to better support the large pulley and drill it and the pulley for a larger 8 bolt pattern. I see lots of cracked pulleys egged out bolt holes and sheared off bolts on these type of cars.
     
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  11. overkill69

    overkill69 Member

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    I thought the same. The elaborate RCD degree wheel profile and spline setup is beyond my machining skills. I think Reehl can make the pulley blank if requested.
     
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  12. Will Hanna

    Will Hanna We put the 'inside' in Top Alcohol
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    conical flange adaptor

    Have you tried the conical flange adaptor like PSI used to make? Wizard sells them now. Basically it is a cone that shares the load of the crank bolt down to the pulley bolts.
     
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  13. Blownalky

    Blownalky Top Sportsman

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    Like this? Listed at $175.00.

    [​IMG]
     
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  14. Joad Donnelly

    Joad Donnelly Member

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    That cone set-up doesn't look like it will fit over the end of our splined crank.
     
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  15. jody stroud

    jody stroud ZOMBIE Top Dragster

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    You are using bolts that have shoulder that engages the pulley and threaded only where is screws into the crank hub? If the threads are seeing shear load that could be your problem.
     
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  16. Blown5402

    Blown5402 Member

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    Conical Cone

    I have been running the conical cone on my pulley for 3 years now on a screw and no movement or bolts loosening, but check them every round just to make sure too! THANKS! Jim
     
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  17. REEHL EQUIPMENT

    REEHL EQUIPMENT Active Member

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    That part above doesn't look like it will work with the RCD spline non-bearing support hub.

    Should work with the PSI spline non-support hub.
     
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  18. Joad Donnelly

    Joad Donnelly Member

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    We are using bolts with a shoulder on them. We were using the NAS bolts that RCD sells (we drilled them for safety wire) but we are going to give some grade 9 bolts a try this weekend.
     
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  19. Joad Donnelly

    Joad Donnelly Member

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    We are using the RCD splined non-bearing support hub. Any other ideas of getting some support on this big pulley without going to a crank support set-up? We may end up making some changes over this winter but just looking for possible things we could try for this last race.

    Joad
     
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