Hi all-
I hope that I dont get flamed for posting such basic brake questions, but this forum seemed more appropriate for basic questions than the e36 m3 list. And I did search the archives, but I didnt really find direct answers. So those with patience, please indulge me.

Here's the deal: I have a 98 m3/4 with 39.4K miles on it and the brakes started squealing about 500 miles ago. The car has always been a very conservatively driven (meaning slooow) and has never been tracked or autox'd. The pads/rotors have never been changed.

So here is basic question #1: Does it seem reasonable that the stock pads should be giving out at under 40K miles if the car has always been driven slowly? Seems like I've usually had pads last longer than that on other cars, but maybe the stock m3 pads are just really soft. How long would you normally expect m3 pads to last?

I expect that the answer to #1 is "yes, your pads are wearing out". That being the case:
Basic Question #2: Whats the likelihood that I will need to replace the rotors (along with the pads) at 40K miles? How long do e36 m3 oem rotors usually last? I'm wondering if I should go ahead and order the rotors along with the pads.

Here is the final Basic Question #3: I've read a lot about brakes/pads/rotors, but have never actually done a brake job. I have basic mechanical experience, having done oil changes, plugs, wires, etc... and I have a pretty well stocked tool set. Would you guys recommend that I do the brake job myself given that this is an e36 m3 (anything special here?)? If so, how long would it take for a newbie?

Thanks for the bandwidth, guys...
dan

BMW brakes are optimized for performance and thus the pads & rotors tend not to last as long as other makes. The pads are a bit on the soft side so that you have really good cold friction and low noise levels and the rotors are relatively thin to minimize unsprung weight. So it would be possible for the car to need a brake refresh at 40k, depending on driving conditions.

The noise, per se, isn't necessarily an indicator of worn out brakes. It may just be due to a build up of pad material on the rotors. Pulling the wheels and inspecting the brakes will tell how worn they are. And if you wait long enough the brake pad wear sensors will eventually contact the rotors and illuminate the warning light. That assumes that the previous owner left the wear sensors intact.

When changing pads one measures the thickness of the rotors and decides whether to replace the rotors based on that. The total allowable wear of BMW rotors is on the order of 2mm (1mm per side), so it's pretty normal to need new rotors when the pads are worn out.

Doing the brakes is a fairly easy DIY job. It doesn't take much in the way of tools and it isn't difficult. There are lot's of How-To's out there for this.

thanks for the excellent response. So it sounds like what i need to do is inspect the brakes. Coupla questions:

What does the brake material build up look like on a rotor? Is it obvious? I know that normally you'd expect to see the shiny metal. With material buildup is it not shiny anymore?

What's the allowable pad depth? That is, when do i need to replace the pads?

dan

Pads can last less than 40k. Actually, 40k for an M3 is pretty good. Fronts usually last less than rears. As for the noise, pads make a screeching when the pad material wears down to a metal in the pad or to a metal wear indicator. The BMW's have a wear indicator (plastic sensor) which sets off a light on your dashboard. They may also have the metal in the lower portion of the pad to enable a screeching noise. Look at them and see if theu are low (low would be roughly 2 nickels thickness). Pads also make a minor screeching when they get wet, like after a rain or something like that. OEM pads screech a lot less than Metal masters or other aftermarket pads.

As for the rotors, my general rule is to change them at about 100k unless there is some sort of abnormal damage or wear. So far 100k has been working fine.

Can you do them yourself? Absolutely. They are very easy and designed to be idiot proof. In other words, you can only put them in one way, so you dont need much intelligence to figure them out. You will need, however, a sturdy jack and a means to hold the car up firmly.

What does the brake material build up look like on a rotor? Is it obvious? I know that normally you'd expect to see the shiny metal. With material buildup is it not shiny anymore?
Usually one just sees a difference in color and the rotors will look a bit darker than plain steel.

As for the rotors, my general rule is to change them at about 100k unless there is some sort of abnormal damage or wear.
You really can't go on mileage. It is the thickness of the rotors that matter. Because so little wear is permissable, it turns out that a noticable ridge about the thickness of a dime indicates replacement rotors are needed.

OEM BMW pads suck. :buttrock