Brake success story.. technolcgy wins..
Discussion
My S4s has has brake vibrations for a while now.. I have tried to understand the problem and figure out what is causing it. Some internet research had me believing that that warped rotors are a myth. Of course rotors do get a little warped in some cases, but some newish studies say that this does not cause shaking. Cars either have floating rotors, floating calipers, or pistons on both sides of the disc (or a combination of these). Any warp should be transparent to these systems. The pads should follow any warp in the rotor and not shake the car.
What they say is that the discs get a sticky or slippery spot on them from either rust, or oil, or embedded pad material (from holding pedal firm on hot hot hot rotors.)
Anyway armed with that and being a believer and an engineer.. I still took the rotors off and took them to a place with a brake lathe and wanted them to skim them. The solution for warp or sticky spotted rotors is the same anyway - turn them down a bit.
Well the crusty old fart at the shop refused to skim my discs.. blaa blaa blaa 30 years of experience "rotors these days are throw away"... *(12 year old car - sheesh)* not enough thickness to machine
I try to get him to set it up and at least measure the runout.. he says "no way if I see even 4 "thou" runout, I know that will never be OK" Buy new discs..
I get irritated and tell him that it has taken scientists hundreds of hours of testing to undo the damage done by 30 years of mechanics like him... and that by not following the technical advice of engineers, that they are needlessly and falsely diagnosing problems.... I also remind him that Metric has been the Canadian system of measurement for at least 30 years and that is ridiculous to measure in inches.. and maybe his damn 30 year old micrometer is out of calibration also.
Anyway, I had to put the discs back in my backpack and walk home shamefully.. I reinstalled everything and cleaned and lubed everyting nicely so they are like new. I used a wire brush and cleaned and never-seized the hub mounting surfaces too.
I half-hoped the cleaning etc.. would help the shake. But at the first stop, the shake was as always.
So, I went to a quiet farm road on the outskirts of town, and did endless 0-120km/h-0; until the brakes were so hot they went up in smoke. The pedal got a little yukky too. This was the recommended way to get rid of the sticky spots on the discs.
Next, I drove for 10 or so minutes in the cool air without ever touching the brakes, to let them cool.
GUESS WHAT>>>>???????????? MY shakes are gone.. it is like a new car..
Bruce
What they say is that the discs get a sticky or slippery spot on them from either rust, or oil, or embedded pad material (from holding pedal firm on hot hot hot rotors.)
Anyway armed with that and being a believer and an engineer.. I still took the rotors off and took them to a place with a brake lathe and wanted them to skim them. The solution for warp or sticky spotted rotors is the same anyway - turn them down a bit.
Well the crusty old fart at the shop refused to skim my discs.. blaa blaa blaa 30 years of experience "rotors these days are throw away"... *(12 year old car - sheesh)* not enough thickness to machine
I try to get him to set it up and at least measure the runout.. he says "no way if I see even 4 "thou" runout, I know that will never be OK" Buy new discs..
I get irritated and tell him that it has taken scientists hundreds of hours of testing to undo the damage done by 30 years of mechanics like him... and that by not following the technical advice of engineers, that they are needlessly and falsely diagnosing problems.... I also remind him that Metric has been the Canadian system of measurement for at least 30 years and that is ridiculous to measure in inches.. and maybe his damn 30 year old micrometer is out of calibration also.
Anyway, I had to put the discs back in my backpack and walk home shamefully.. I reinstalled everything and cleaned and lubed everyting nicely so they are like new. I used a wire brush and cleaned and never-seized the hub mounting surfaces too.
I half-hoped the cleaning etc.. would help the shake. But at the first stop, the shake was as always.
So, I went to a quiet farm road on the outskirts of town, and did endless 0-120km/h-0; until the brakes were so hot they went up in smoke. The pedal got a little yukky too. This was the recommended way to get rid of the sticky spots on the discs.
Next, I drove for 10 or so minutes in the cool air without ever touching the brakes, to let them cool.
GUESS WHAT>>>>???????????? MY shakes are gone.. it is like a new car..
Bruce
Edited by bojangles on Saturday 14th October 03:44
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