JS wrote:
> Matt Whiting wrote:
>
>> Tunez wrote:
>>
>>> Thanks for the suggestion, but been there done that ( torguing the
>>> wheels )
>>> but after a couple 60 MPH brake checks the pulsation went away so I
>>> think
>>> hyundaitech was right, it may been a little rusty on the inside of
>>> the rotor,
>>> Still gonna have dealer check them out cause it seems to me that the
>>> inside/outside
>>> calipers should be hitting the rotors at the same time with the same
>>> pressure..... apparently they are not cause the outside the rotor was
>>> clean
>>> and shiny but the inside was not. What ever it was the pulsation is
>>> gone and
>>
>>
>> It depends on the caliper design. Most calipers only have a moving
>> piston on one side. The pad on the other side is pressed against the
>> disk through movement of the entire caliper in this sliding mount, not
>> by pressure directly from the pistion. Thus the force on that caliper
>> isn't the same as the force on the caliber that is directly actuated
>> by the piston. The force is the force from the piston LESS the
>> friction force in the sliding mount, which can be substantial when it
>> gets a little rusty and full of brake dust and other grit.
>>
>> So, it isn't unusual at all for the pads on piston side of the disk to
>> wear faster, and keep the disk shinier, than the pads on the other side.
>
>
> Well if everything is working right (properly lubricated) the difference
> in pressure should be a couple ounces at the most... the more severe
> the corrosion/dirt/wear/lack of lubrication the more the pressure
> difference is.

Yes, but the proper lubrication seldom lasts from one pad replacement to
the next, at least not in our PA winters. The road salt, water, dirt,
etc., will remove the lube in one winter. The difference in force then
is a lot more then a few ounces. Keep in mind that the caliper is being
forced against the mount with a LOT of force when under hard braking. A
rusty or even dirty slide will have a lot of friction and will take a
lot of force to move when under the force of heavy braking.


> Using the wrong lubricant will gum the slides up badly, be sure to get
> the right stuff.

Or worse yet, melt at high temps and get on the pads or disks.

Matt