Stopping Brake Squeaks

For some reason I associate brake squeak with old junker cars. It was embarrassing for me when my Z3 started making those annoying high pitched squeaks every time I came to a stop sign. After some research the solution was cheap and easy.

The first thing I learned was that I misunderstood what brake squeaks were. I thought it was the friction between the brake pad and the disc that caused the squeak. Turns out that most brake squeaks are from the brake pad moving around and rubbing against the caliper.

I had heard of anti-brake squeak stuff before but I always dismissed it because I thought anything between the brake pad and the rotor was a temporary solution at best since it would wear away quickly. Once I learned this stuff was for the back of the brakes everything made since. The guy at the NAPA store laughed and said “can’t tell you how many times I’ve seen this stuff used on the wrong side”. NAPA’s CRC Brake Disc Quiet was roughly $3 a bottle, and it was more than enough for two cars.

It comes out as a thick rubbery goo, and dries in about 10 minutes. Once dry, simply reinstall the brake pad then wipe down the excess red goop that squeezes out. It’s a little messy, but you’re probably wearing rubber gloves when working with brake pads anyway.

Once installed the difference was night and day, no more brake squeaks.

Changing Brake Pads In My BMW

The very first step is verify that you have a 7mm allen wrench, it wasn’t part of my little allen wrench kit so I had to make a quick run to the local hardware store. While you are there you may want to also pick up some rubber gloves. As you know the stock brakes spread break dust everywhere. Once I had the right tool for the job replacing the pads was pretty easy.

The first (and possibly hardest) step was getting the car up on a jack and jack stand. Especially considering the BMW M roadster does not come with a jack. Once that small task was done and the wheel was removed the rest was fairly easy.

If you are working with the right rear wheel or the left front wheel there will be a brake sensor (blue arrow). This sensor is clipped into a notched out area of the brake pad. Get your fingers as close to the brake sensor as possible and wiggle-pull it free.

The next step is to remove the retaining spring. I used a few choice curse words to aid in its removal, you will want to squeeze and push in on the clip (red arrows) while lifting and pulling out on the back (yellow arrows).

On the back side of the brake, there are two plastic caps that cover the 7mm hex bit guide screws. The plastic caps can be pulled off with your hands, they are snapped into a rubber housing. Once the caps are out of your way use the 7mm allen wrench to remove the guide screws. The screws should be completely removed.

The only thing holding the brakes in place now is brakes themselves. If you are having trouble working the caliper free apply constant even pressure on the brake piston by pull on the outside of the brake (use caution – remember your car is up on a jack and jack stand). You are not going to be able to compress the piston with a single yank, just use medium sustained pressure and you will feel the piston loose pressure and release. It took me about 40 seconds of medium pressure for this to happen.

Once the caliper is removed, replace the inner and outer brake pad. The inner brake pad is clipped into the brake piston, pull straight out to remove.

The outer brake pad was just kind of stuck there. Note the sticky stuff on the stock outer brake pad, if the new pads you are installing do not have this you will probably want to take a look at my Stopping Brake Squeaks article.

Once you have the new pads in place, you may have to put some more pressure on the piston in order to reinstall the brake caliper since the new brake pads should be thicker than the worn ones you just removed. The rest of the installation is just retracing the steps you took to remove the caliper.

TWO VERY IMPORTANT NOTES: You will need to pump your brake pedal several times to get pressure back to the brakes. Use extra caution the first time you drive after replacing the pads.

When new, brake pads have a slightly rounded surface that ensures once broken in you get a maximum contact patch. But until they get fully broken in you are concentrating the friction to a smaller patch. This means that when brand new the friction/heat is in a smaller area so you should avoid overheating the rotors.

Porterfield Brake Pads

Pros: Possibly Better Performance, Almost No Brake Dust Mess
Cons: Initial Brake Squeal, but Easily Fixed
Cost: $94 Front, $75 Rear from MyRoadster.net

After 60,000 miles on the stock brake pads I assumed I was getting close to needing to change them. I’ve been pleased with the performance of the stock BMW brake pads, but the brake dust was always a mess. The photo to the right is for real, this is how my wheels usually look. I wanted to find some replacement pads that offered equal performance but without all the brake dust mess.

The Porterfield brand caught my attention, it appeared it may be what I was looking for. MyRoadster.Net carried the Porterfield brand so I asked some questions via their info@myroadster.net address. I learned that Porterfield makes three different kinds of brake pads depending on your needs.

* R-4 for track use only

* R-4S for street and light competition

* R-E for endurance racing events

The “Porterfield R4-S Carbon/Kevlar Street Brake Pads” matched my needs, and the feature list impressed me.

* Low Dust

* Light Pedal Effort

* Rotor Friendly

* High Friction, Hot or Cold

* Low Wear Rate

* Fastest Stopping Road Pad Available!

* Friction Coefficient:

* OEM: Between .2 and .3

* Porterfield: .4

* Temperature Tolerance:

* OEM: 500-700 degrees F

* Porterfield: 1,100 degrees F

After installing the pads (see ///MZ3.Net’s brake pad installation article for details) I resisted the urge to make any judgements until I knew the pads were really broken in. I was also cautioned to avoid excess hard breaking during this initial period. When new, brake pads have a slightly rounded surface that ensures once broken in you get a maximum contact patch. But until they get fully broken in you are concentrating the friction to a smaller patch. This means that when brand new the friction/heat is in a smaller area so you should avoid overheating the rotors. At least that’s how a BMW tech explained it to me, it wasn’t something specific to the Porterfield brand, just a general caution for all new brake pads.

8,000 Mile Update: How does the saying go, if I knew then what I know now….

I put up with the stock brakes and their mess for 60,000 miles. From my experience, the Porterfield R4-S brakes offer at least equal performance (maybe even a little better) but with almost no brake dust mess. That was exactly what I was looking for so I am very happy with the Porterfield R4-S pads brakes. My only complaint with them was some initial brake squeal, but that was easily fixed (see Stopping Brake Squeaks article for details). For the cost ($94 front, $75 rear) and backed with MyRoadster.Net’s money back guarantee, the Porterfield R4-S pads seem to be what most Z3 owners should be looking for when either they need to replace their stock pads, or are just fed up with cleaning up after the BMW pads.

ABS, ASC, AST, ASC+T, DSC – What Does it All Mean?

With all the new and improving technology BMW is putting into the Z3, it’s easy to get lost in the ever-growing sea of acronyms. When the Z3 was first introduced in the 1996 model year, BMW included Antilock Braking System and that technology has stayed in the Z3 ever since.

The next technology to be added to the Z3 was All Season Traction. There is a lot of confusion on this technology because it appears it goes by several different names. Sometimes called Anti Slip Control or Anti Slip Control + Traction, when you are talking about a Z3 you must realize that all of these names are for the same technology. The rumored story behind this confusion is that ASC was the initial name, but someone didn’t like the word “slip” since it suggested the car was susceptible to slipping. So they renamed it ASC+T, adding the word “traction” to the end. Later, the word “slip” was removed altogether and they started calling it AST. If you visit BMWUSA’s webpage, AST is the official name they used to describe the technology (but the buttons on the dash are still labeled ASC).

Well, whatever you want to call it, it was initially an option on the Z3 in 1996, eventually becoming a standard feature a couple months into the 1997 model year. The AST technology has continued to be a standard feature in all Z3 models with the one exception of the 1998 model year M roadster. The entire 1999 model year Z3 line up (including the M roadster and M coupe) once again featured both the ABS and AST technologies as standard features. This duel technology made the already nimble Z3 safer and easier to control in panic situations than the majority of cars on the road.

According to reports, starting with the 2000 model year the Z3 gets another new technology. With the addition of Dynamic Stability Control, the newest BMW Z3 now has three distinct technologies working for it making it an even safer vehicle to drive.

Antilock Braking System (ABS)

BMW antilock braking system (ABS) helps prevent wheel lock-up under hard braking or slippery conditions. This helps you stop while retaining steering control to avoid objects or potentially dangerous situations. The technology works on all four wheels and it is always turned on (can’t be turned off).

All Season Traction (AST)

a.k.a. Anti Slip Control (ASC)

a.k.a. Anti Slip Control + Traction (ASC+T)

BMW All Season Traction (AST) continuously monitors the rear wheels for wheel slip. If slippage occurs at the rear wheels, AST controls the brakes and the engine to restore traction. AST can be disabled with a push of the button, and there are times when it is recommended you do so (like when using the mini-spare tire).

Dynamic Stability Control (DSC)

Dynamic Stability Control works with All Season Traction to detect and correct abnormal under or over steer conditions that can result in a loss of control. By monitoring steering angle and individual front wheel speeds, DSC logic can immediately recognize loss of lateral stability. When this occurs, the DSC system selectively applies the brakes and adjusts engine power to help restore directional control (think of DSC as AST for the front wheels).

It is my opinion that BMW’s continuous commitment to improvement and safety should be applauded. The technological balance of power and control built into the BMW Z3 is ahead of the other roadster vehicles on the market today and should be considered one of its most important features.