I have a 996TT. I want to know do you wait for the brake light to come on to change pads, or is it better to change it before the light comes on? Any effect on the rotor if you change later?

My friend has a E46 M3, his brake light didn't come on, and he has to change the rotors and brake pads. The car was shaking when he was braking. So maybe it's better to change earlier? Wonder how come no warning light on his M3.

Thanks.

 

As long as you change them before the steel backing plate touches the rotor you're okay

 

With that said you're best bet in not waiting til the last minute

 

I just picked up a few sets of bhp track/street pads from ebay. They have front sets for $50 to blow them out. They were like $220 last year but they are getting out of making that type of pad. My friend used them last year and they worked very well at the track.

 

So is there a brake light warning light when the pad is low? I wonder if the sensor will come on.

 

The only disadvantages to running the pads down are:
1/you will wear down the brake pad sensors and have to replace them along with the new pads.
2/You do have to pay attention to how much pad you have left.
3/Depending on how you use your car, you may find there is too much brake travel for your taste.

I have read a variety of posts whereby people state that for good rotor life you should change pads when they are at 50%. Gents, this is NONSENSE. I have no idea who started this idea [it must have been someone trying to sell an excess of pads ;->]. The Factory Manuel notes exactly what I stated above.

Your friend's BMW lacks great brakes. That is a known weak spot on them. Especially if you track them the rotors can/will warp. I also have an M car and the brakes are surprisingly puny compared to the better Porsches. My wife has an allroad and it is pretty much gently driven but that didn't prevent the junk excuse for brake rotors from warping. Not all German cars seem to be genuinely built for the Autobahn.
John Rice

 

HEY!!! I can ALMOST post things for sale. This sure took long enough [not enough "RIGHT!" "SWEET" etc posts]
JR

 

Then why is there a brake pad sensor? They are pretty much useless.

 

Why? So that a light comes on before the steel backing hits the rotors.

Best way to tell if you need to change pads is to pull a wheel and measure the remaining pad thickness. You can see the outer pad through the spokes of the wheel, and might be able to get a measurement at the bottom of the pad. Pulling a wheel gives you a chance to see the inner pad.

Change them for sure when you are below 5-7mm.

YMMV

 

We don't let our pads go below 1/4 inch of material. If you allow it to get that thin, the heat transfer onto the rotor will cause heatchecking of the drilled holes to happen in an advanced state.

If you don't want to spend $450 for rotors, replace your pads when they get down to 1/4inch if you drive your car hard.

Mike

 

Excellent - Thanks - much more specific.

Depending on your car and your own driving style, you CAN damage your brakes if you are overheating them. I don't have racing experience with these cars so I don't know if running them thin can carry enough heat over but I suspect that is quite possible. [I seriously doubt you can do this with street driving in a Porsche.] I do confess that I have experienced this when racing of other cars and attempted running to the very last mm of pad material. The pads started breaking up and fading. Still, the rotors were fine. [Tho a stupid way to lose a race when simply putting fresh pads would have insured I still had brakes at the end of the race.]

The wear indicator is ... political. Once most car mfg started using these, they had to determine at what point they would make the units activate. Obviously, they went on the conservative side... In most cases this is extremely conservative. It seems that most people simply have them changed when the light comes on. I know my wife panics when the damn thing lights up. On her Audi I merely note the miles, check the pads and bend the ss contact bit so it won't make contact. I then periodically check the INSIDE pad for thickness.

So--- the pad answer is. If you don't mind replacing them early simply have it done as soon as the light comes on. If you like playing with your cars use this as the point to make sure you have a set of replacement pads ready to go on and either buy a replacement set of sensors or do something so you don't wear your sensors out.

I noted a couple of opinions on how thin is the limit. How you USE the car is probably the most important factor. For the average street driven Porsche I would bet anything that you could go right to the thinnest possible pad and not hurt a thing. Conversely, are there any guys here that drive their cars "normally"? ;->

JR