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SHU-ES1
13-10-2009, 05:00 PM
hello all,

just a question, why is it when i brake hard from say above 100km/hr the steering wobbles like my front wheels are wobbling? is this the ABS working and normal? or is there an underlying problem to this? any help would be appreciated.

cheers.
riruiz_88
13-10-2009, 05:34 PM
top of the list would be, warped rotors. check the thickness at 8 (at least) different sides of each rotor, if they are out alot then they may need machining.
aaronng
13-10-2009, 06:59 PM
Warped rotors. Not ABS.
SHU-ES1
13-10-2009, 07:04 PM
the rotors look like oem, i thought they were a lot more durable than this. what could've caused them to warp? thanks for the info guys.
riruiz_88
13-10-2009, 07:08 PM
constant high temperatures, type of pads, many things man. just give them a check man, could be something else. but this is most likely cause, use a vernier caliper and check at least 8 sides of each rotor for thickness. i think minimum thickness is ~19mm
mocchi
13-10-2009, 07:10 PM
top of the list would be, warped rotors. check the thickness at 8 (at least) different sides of each rotor, if they are out alot then they may need machining.

umm, what does thickness and warped rotor has anything to do with each other?

checking warped rotor with a dial runout?
riruiz_88
13-10-2009, 07:17 PM
the rotor will have a different thicknesses at each different point of the rotor face. this is how you get the "wobbling" effect, the rotor is not balanced properly. i only said vernier caliper as it is an easier measuring tool to get and cheaper.
aaronng
13-10-2009, 07:21 PM
With a vernier caliper alone, you might not detect a warped rotor. If you find different thicknesses, then you know that something is wrong. But all the thickness measurements are the same (both faces warped in the same direction), you still need to use a runout dial to check if the face itself is warped.
riruiz_88
13-10-2009, 07:25 PM
fair enough about that, but i am on the right track about unbalanced rotor causing "wobbling" feeling.
mocchi
13-10-2009, 07:40 PM
the rotor will have a different thicknesses at each different point of the rotor face. this is how you get the "wobbling" effect, the rotor is not balanced properly. i only said vernier caliper as it is an easier measuring tool to get and cheaper.

umm, how can the rotor have different thickness? can someone please explain with factual evidence?

thanks.
aaronng
13-10-2009, 07:49 PM
fair enough about that, but i am on the right track about unbalanced rotor causing "wobbling" feeling.

You can check the weight balance of the rotor and can find that it is equal on all sides even if it wobbles. It is not the weight that causes wobbling. It is the uneven surface pushing back against the brake pad and rotor, causing vibration which you feel through the steering rack/suspension and into the steering wheel/cabin.
SHU-ES1
14-10-2009, 10:42 AM
thanks guys. ill go get them checked out, it'll give me an excuse to get slotted rotors :) this has never happened to me before, i always thought oem gear was quite durable. cheers again!
aaronng
14-10-2009, 01:44 PM
thanks guys. ill go get them checked out, it'll give me an excuse to get slotted rotors :) this has never happened to me before, i always thought oem gear was quite durable. cheers again!

The OEM rotors are durable. But if you overheat your brakes from braking from highway speeds and then keep the brakes held down at the lights, then the heat will be transferred through the pad into the brake caliper, causing uneven heating at that spot compared to the other areas on the rotor.