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Thread: Front brake rotors hot to the touch......

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    Luke Skywalker
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    Front brake rotors hot to the touch......

    I installed new wheel bearings and new brake pads. Would the new brake pads be just wearing in causing the rotors to heat up. If the car has not be excessively braked then parked should the rotors be that hot. Car seems to accelerate and coast OK but my concern is I may not have got the wheel bearing end play right. After my first test run I jacked up the front wheels and pulled on the the drivers side tire/wheel and found a fair bit of play there. I tightened the hub nut a bit and that took out the play in the wheel. I've read all the posts regarding the correct way to set the end play and I believe I set it up as stated. Can the end play be reset correctly with the calipers installed?? Can a dial gauge be used effectively to set end play with the calipers still on?
    I had a severe front bearing failure last year at speed that really got my adrenaline pumping and I would not like to go thru that again. Any advice most appreciated.

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    Great Pumpkin NutmegCT's Avatar
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    Re: Front brake rotors hot to the touch......

    Just my two cents here, but - the pads are always in contact with the rotors. So heat will build up even if you don't use the brakes at all. Very different from drum and shoe brakes.

    Is it only the pad/rotor that warms up? or also the brake and hub system?

    Also, can you give us an idea of " ... should the rotors be that hot". You mean too hot to touch?

    Tom M.
    Mac & Phyllis Take a Trip: http://nutmegflyer.com/trip-details-daily-updates/
    History: 1976 MGB, 1959 Triumph TR3A, 1960 Mercedes-Benz 190b, 1958 Rambler American.
    Current: 1953 MG TD27318.

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    Re: Front brake rotors hot to the touch......

    Brakes work by dissipating kinetic energy in the form of heat, so any braking will heat the discs up. In racing they glow red but a few hundred degrees is normal, even for a quick run around the block. I don't know of any reason why you can't adjust the end play with the calipers installed.

  4. #4
    Great Pumpkin TR3driver's Avatar
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    Re: Front brake rotors hot to the touch......

    Make sure the pads are pushed back a bit, so they don't screw up the measurement. Having the dust seal in place also makes it more difficult to measure accurately.
    Note that it may be necessary to sand down the washer just a bit, to get the specified clearance with new components. .003" to .005" (workshop manual has wrong numbers)
    https://imgur.com/a/Uh6OA

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    Jedi Trainee Joe Schlosser's Avatar
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    Re: Front brake rotors hot to the touch......

    No the pads are not incontact with rotors when the brakes are not applied. The square caliper seal pulls the pad back just enough so that they are not touching.
    If they are touching/dragging then something is wrong
    Joe Schlosser
    SCCA National License, Retired
    60 Bugeye, since 1966
    SCCA FP, sold but not forgotten

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    Great Pumpkin TR3driver's Avatar
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    Re: Front brake rotors hot to the touch......

    On a TR3, there is actually a residual pressure valve that holds the pads in (light) contact, for at least some time after each application of the brakes. It does slowly leak down, but they will drag enough to notice (when turning the wheel by hand) when the valve is working properly. I actually remove the RPV on my cars, because I don't like that dragging feeling (even though in reality it does no harm to speak of).

    More modern cars are indeed designed to pull the pads back; but for that to work, there must be some connection between the pads and pistons. TR3 disc brakes have no such connection. Even if the pistons somehow retracted all the way, the pads would still be out against the rotor, held there by the "damping" spring.
    Randall
    56 TR3 TS13571L once and future daily driver
    71 Stag LE1473L waiting engine rebuild
    71-72-73 Stag LE2013LBW waiting OD gearbox rebuild

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    Yoda CJD's Avatar
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    Re: Front brake rotors hot to the touch......

    Yes...what Randall said! Warm to hot discs after driving is normal, since the valve does keep the pads in light contact with the rotors.
    John

    1955 TR2

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