Re: Suzuki Kizashi: Common Steering Vibration Issue when Braking Quote:
Originally Posted by scofield Also in new cars you would see a lot of black residual kind of substance of brake pads on the front wheels due to the friction however as time passes by it reduces .This friction sometimes leads to deforming of the disc surface, which can cause wobbling. |
Actually the black residue is known as 'brake dust' which consists of the brake pad and rotor components that are worn off as the brakes are applied. The amount of brake dust generated is mainly dependent on the pads, as 'softer' pads generate more dust as they disintegrate more completely when contacting with the brake rotor (disc). More aggressive or 'harder' pads will generate less dust, but typically will also wear the rotor more quickly. However, these pads will also provide more braking power in more severe conditions such as racing, or braking from 200km/hr to zero.
Two of the main causes of brake rotor (disc) warping (wobbling) is improper 'bedding in' of the pads, and uneven heat stress. Properly bedding-in new pads to the rotor is critical for optimum braking power as well as longevity of the system. The pad material must be transfered onto the rotor in a gentle fashion before any hard braking takes place. Typical Indian city driving for about 500km without any hard stops should do this just fine. Highway braking with a set of new pads and rotors can almost instantly warp a set of rotors (even really good ones), so avoid any abrupt stops with a new car or after a fresh brake job.
And since pads and rotors become a matched set after the bedding-in process, it is important not to change the pad type when replacing just pads. Ideally, replace both pads and rotors at the same time, keeping them a matched set.
Heat stressing a rotor can happen after a hard stop and then holding the brakes. The hot pad is now sitting on a singular spot on the rotor while the rest of the rotor cools. It is important to continue to move slowly after a hard stop to keep the hot pad from 'resting' on one spot on the rotor. I've made rotors last 100k miles using this technique. I am almost always just replacing pads.
Wobbling and rotor warpage can also be caused by the wheel not being replaced in precisely the same orientation as it was on the car before since it is used to hold the brake rotor to the hub of the car. Furthermore, the lug nuts must be torqued to the proper spec (103.5 ft/lbs in a star pattern for the Kizashi) as specified in the service manual. Placing the wheel back on the car in a different orientation as previously installed or improper lug nut torque can also cause warpage.
And this explnation made me just think of another possible cause to the problem--are the lug nuts on fully and tight? This type of extreme shaking can happen if they are not. There is a jack in the trunk of the car with instructions on how to use it. Use it to lift the car so that the wheel is just off the ground. Place your hands on the top and bottom of the wheel and see if you can move it--if so the lug nuts or wheel studs are a possible cause and the wheel isn't on properly. The car is undrivable in this condition and should be repaired where it is in this case. Quote:
Originally Posted by scofield Once you get the new discs but as the pads are old the friction is much less, I haven't had an issue after that in my car and this happened at around 10K KM. Now I am on third set of brake pads at 66K but haven't changed the discs since then. |
The reason you're feeling less friction is because the pads are no longer 'bedded-in' to the rotors. You have to wait for them to transfer enough material to the rotor before having full braking power. You'll also notice less dust until this happens. Drive carefully during this time period as you have reduced braking capability compared to your older worn-out pads. |