Caliper Question

auto_pilot
auto_pilot Posts: 256
edited October 2007 in The Clubhouse
Installing brake calipers on a car requires certain torque ratings for the bolts...Why does the bolt back out when it is not torqued properly? And can over torquing the bolt cause it to back out as well?
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  • edbert
    edbert Posts: 1,041
    edited October 2007
    Not torqued enough it can back out. Torqued too much can either strip the bolt, cause it to break, or make it near impossible to remove the next time you have to do an service on the brakes. Good luck and let us know if you have any other questions. Brake jobs are a beast.
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  • jcaut
    jcaut Posts: 1,849
    edited October 2007
    I see Edbert beat me to this but since I already had it typed, I'm gonna post it anway. He wasn't as witty as I am. ;)

    Hmm..

    I haven't partied with Nelson Pass or Emilio Bombassei, and I didn't sleep at a Holiday Inn Express last night, but I WILL take a stab at your question.

    The brakes are obviously a critical system on the car: A caliper coming loose could a disaster. The engineers who design these things, take into account the forces that will be acting on the brake components, the materials of construction, etc., and come up with torque specifications for the fasteners.

    A couple (of many) things that might make the bolts want to back out if they weren't properly torqued are vibration and thermal cycling.

    I don't think that over-torquing the bolts would cause them to back out-- It would more likely cause some sort of component damage (stripped threads, stretched bolts, etc.). Torque wrenches are easy to use, and probably aren't used enough by most "mechanics". An impact wrench is NOT a torque wrench.

    Jason
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