PROBLEM ENCOUNTERED
When ever I braked at high speed the steering would vibrate and the brake pedal pulsate. It just gets worse and worse. Turning/machining or skimming the rotors would only solve the problem for awhile (10,000km) and the problem would come back. So after living with this problem for the life of the vehicle and trying to understand what causes DVT I hope I have solved the problem once and for all. Read on to find out what I did.
DISC VARIATION THICKNESS (DVT)
Common know as warped rotors more because it feels like the rotors are warped rotor rather than it being the truth. DVT is basically the rotor wearing away unevenly. Some parts of the disc has worn away more than other parts causing high and low spots on the rotor.
My case was so severe that even at 10km/h-20km/h with constant brake pressure you can feel when the brake pad bites when it moves across the high section and release when the hits the low section of the rotor. Clear sign that cementite has started to form and the rotors are in a down spiral of self degradation.
A good article can be found here: http://www.stoptech.com/tech_info/wp_warped_brakedisk.shtml
SOLVING THE PROBLEM
So I needed to get rid of as much heat as possible. The standard rims didn't really help in that area as its not you regular 5 spoke with huge holes type rims. I want to keep the standard rim so the only choice left is to remove the inside rotor dust shield to improve air circulation to the rotor.
Next was to get a new set of brake pads. I have used Original Akebono Nissan brake pads and EBC Kevler brake pads. They are really expensive where I live. RM600.00 for Akebono Nissan and EBC Kevlar was about RM450. So I started to search a pad which was kind on rotors and still had good performance. So I decided to try out Bendix General CT. I took a look at the Bendix Metal King and the metal fibers that were on the pad looks really scary and have heard that its not really kind to rotors. So Bendix General CT was the way forward. Price for 1 set was only RM95. Far cry from the arm and a leg that I use to pay of the Akebono and EBC.
So next was new rotors. I went to the spare parts shop and asked if that had rotor for my A32 3.0L. They said yes and its by TRW and its RM145/pc so 2 pcs was RM290. The guy had to order them but that only took a few hours. So when the rotors arrived and I opened it up to check to my surprise this looks very different from my rotors. So I said do you have the 2.0L version he said yes and I asked him if I could compare the two. So he brought them out and to my surprise the 2.0L rotors looks similar to the set on my car. Crap all this while I've been having the wrong set on rotors on my car.
From the factory I started having the problem so I changed to a set of slotted rotors and the 2nd set of slotted rotors were based on what I had originally on my car. I said DAMN here is your problem.
The difference between the 3.0L and 2.0L rotors is that the 3.0L rotors are much thicker and has more "metal" to dissipate more heat caused by the heavier and high powered engine. I measured the new 3.0L discs and they are 26.2mm thick (min. thickness 24mm) vs. 21.2mm on my current slotted rotors (min thickness 20mm). I would guess a new set of the slotted rotors would have been only 22mm-23mm which is still far from 26.2mm!
INSTALLATION OF NEW BRAKE ROTORS AND PADS
So I removed the inside dust shield, cleaned the new rotors of their protective coating and installed the new pads and changed the brake fluid.
TEST DRIVE
First experience of the Bendix General CT brake pads are that the titanium strip really works as advertised. "The pads works straight out of the box." They did really work straight out of the box. The initial bite is good and was surprised by the performance. So I drove the car about 50km on the highway at night to bed the pads in. Did it with increasing speeds and cooling/cruising between each application and did it at night as there were less cars and the air is much cooler then.
AFTER 2000KM
My experience with the Bendix General CT is that its good value for money and the performance is good enough for most applications except for hard street driving and track use. It was never designed for those purposes anyway.
I did notice that the initial bite had dropped off a little and I suspect that the initial titanium strip on the pads has been worn off and it was the strip that gives the good straight out of the box feel. But the pad in general still has good initial bite (but not as much as EBC greens for example). The pads are really progressive smooth and quiet. The only noise you will get is when you ar in "D" and the car has stopped and to just release enough pressure for it to crawl/creep forward, the pad will groan. All the pads I have used does that and thats no big deal. You can "drive" around that problem.
All in all I'm very pleased with the performance of the Bendix General CT and the value it present.
I did notice on a few occasions while driving on the highway, the toll gate was coming up and where the temps were cool (ambient temps about 26-28 celcius) after it had rained. The pads lost some of its initial bite. It felt like an OEM organic pads; smooth and no inital bite and like the pads were cold. But once you get the heat back into then its ok and the bite comes back. This is also not a big deal as its not like there "weren't" any brakes like some full metal pads used for track use where you can have a heart stopping moment of no brakes cause the pads are cold.
As for my DVT problem. Well currently solve and everything is good. The real test is when it reaches the 10,000km mark where the old DVT problem would start to surface.
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