It may be a slighty warped disc, this can make a clicking noise which will be regular and speed up or slow down.
This is a note which we have from EBC, have a read.
[FONT=Verdana, Arial, Helvetica, sans-serif]5. Intermittent noises from rotors or rotor vibration[/FONT][FONT=Verdana, Arial, Helvetica, sans-serif]
If sport rotors are not checked for runout, driving without even applying brakes will exhibit a clicking noise on a “Once-per-rev” of the wheel basis. If you encounter this, especially early after having rotors installed return them to the service shop and have them checked for runout. Recommendations for maximum permissible runout vary from 0.001 to 0.002 inches on most European cars to 0.003 to 0.006 on larger USA Trucks and SUV’s. Figures above these are not only unacceptable but they will cause brake vibration after a period of 3000 to 4000 miles. (Read below in Blue please) which is not grounds for warranty. Mounting rotors on dirt or rust and scale covered hubs or excessive use of mounting greases and most often incorrect tightening of rotors from first install are the common reasons for excess runout. If your installer knows his job he will hand tighten the rotor studs in a diagonal fashion with gradually increasing torques by hand and final tighten with a TORQUE wrench and ideally you wont even see or hear an air gun being used. Guns (including air guns) are for cowboys and are often used by them.
Why do rotors suffer vibration after 3000-4000 miles and how can EBC be so precise in this mileage estimate, surely it cannot be the same for every car???????? … this is a common question.
The reason the mileage is more or less the same for every car where vibration occurs is that the problem develops OFF BRAKE or when you are driving without applying the brake. The more freeway driving you do the more easily this can occur. The excess runout mentioned above caused in 90% of the cases by bad fitting and not checking for runout (and the other 10% due to a hub not running true such a car that has impacted a curb at some time) … causes the pad to “Kiss” the rotor gently each revolution of the wheel as you drive. After the above mileage period the pads wear a microscopic thin spot on the rotor and a condition known as DTV occurs. This DTV (Disc Thickness Variation) causes the brake to pulse. A small amount of runout itself does NOT cause vibration but the tiniest amount of DTV does cause vibration. That is why when a rotor is not running true the car does not exhibit vibration in the first few miles and this explains how it shows up later (3000-4000 miles).
How can I cure this vibration problem ??????
Rotors will need to be turned at a machine shop or brake fitting center or replaced. EBC sport grooved rotors can be turned with good results on standard AAMCO brake lathes. If too badly scored or worn some rotors will have to be replaced. New pads will ALWAYS be needed.
Before taking your car to the shop, check if the vibration is coming from the front or the rear to save costs in unnecessary brake work. Generally vibration under braking that can be felt through the bodywork or seating of the car is a problem on the REAR brake and vibration felt on the steering wheel is related to FRONT brake problems.
What are the best pads to prevent or limit brake vibration????
Any good quality pad with a high thermal conductivity will reduce the chances of vibration both due to DTV as described above or vibration at speeds due to what we call thermal shock. Thermal shock is common on European cars and all pads in the EBC range are especially good at reducing vibration. Our online catalog recommends the minimum grades for your car and shows options.
Read this (June 06) comment from an EBC Brake user …[/FONT]
