BMWs have always had good brakes. Most models have all round discs but some smaller engined cars have rear drums even now. ABS been an option since the early 80's but wasn't standard on on cars until about '92.

Wear and Tear

You can check the condition of disc brakes by looking through the wheels. Signs of light rust are a sign of little recent use and shouldn't worry you. If there is a pronounced outer rim which is thicker than the rest of the disc then you'll need a new set soon, they aren't dear unless you get them from a dealer.

If you can get under the car check for weeping master cylinders and damaged flexible hoses. Rusty metal brake lines may need replacing and this can be expensive, get a quote before settling a final price. Brake lines normally run down one side of the car under the floorpan, the fuel lines are often next to them. Genuine BMW pipes and hoses often have a higher pressure rating than aftermarket parts.

If you hear a slight rattle over low speed bumps it could be a badly adjusted or loose hand brake mechanism. The hand brake has it's own pads which grip the inside shell of the read discs.

ABS

BMW ABS is self checking. Turn the ignition to position one, most of the dashboard warning lights should come on including the yellow ABS one. If it doesn't the ABS won't work on older cars and may have been disabled rather than fixed! The light should go out once the engine is started.

ABS can fail due to wiring, control unit or sensor problems. A bad ABS pump relay can also cause a fault.

By far the most common problem on early BMWs is corrosion of the speed pickup stators. Each wheel carries a toothed ring an inch wide with lots of metal splines on it. These splines are pickup by a magnetic sensor when they move. If the ABS light flickers it's often caused by rusty splines, a ten year life is about right. New stators cost my 25 GBP each for the back and 45 for the front as they include the front wheel bearings.

Brake Pads and Dust

BMWs always have dirty front wheels, depressing but true. Cars put more strain on the front brakes due to weight transfer and they're larger to compensate for this. Brake pads produce dust which bonds itself to the wheels.

If this bothers you you can buy low dust pads or fit shields behind the wheel to stop dust getting out. Don't fit shields on cars in very hot climates or which see a lot of hard braking as you'll reduce cooling airflow and cause brake fade. They are OK for commuting and town cars.

I use PAGID brake pads as they offer improved braking power .

Hydraulic Accumulators

Some older BMWs like the 1980s five, six and seven series use a hydraulic pressure accumulator. It's often known as The Bomb as it's black, the size of a large grapefruit and resembles the kind of bomb the Pink Panther used to throw at people! If it fails the brake pedal can feel dead and offer poor response to emergency braking. New ones aren't horribly expensive and aren't too awkward to fit.

I was driving along in my '85 635CSi once, at a high speed I won't mention, when I heard a snap and saw a drive belt disappear into the distance through my rear view mirror. The steering went heavy and the hydraulic pressure warning light came on. Despite having no hydraulic pump I stopped normally with no fuss thanks to the pressure left in the accumulator. These are the best engineered cars in the world, nothing else has the same depth of engineering effort and I'll never drive anything else.

Sticky Brakes

All BMWs were designed to be left hand drive. For the UK and other right hand drive markets a metal bar was added to transfer the braking effort from the brake pedal (on the right) to brake booster (on the left). This bar runs at the top of the firewall in the engine bay and is about 9mm in diameter.

The problem is that the mounting points and pivots can foul with dirt or mild rust. This causes the brake pedal to stop returning to the normal height once pushed. An early sign is that the brake lights don't go off when the pedal is released. Solution is to clean the pivots. E28 five series and E24 sixes have this mechanism and it's very common on older cars. Sixes seem less prone than fives though and for all I know other right hand drive BMWs may have the same fault.

Brake Judder

Go to 50-60mph and brake hard. Do the brakes judder? If so it could be several things. A common cause on lower mileage (<100.000 mile) BMWs is warped brake discs, new ones are fairly cheap. Be sure they a torqued correctly and that the wheel nuts are also at the correct torque. Be sure to have the wheels balanced correctly and at equal pressure too.

On higher mileage cars you need to check for worn ball joins and thrust arm bushings. On many BMWs you've be advised to replace worn bushings with stiffer ones from a 750i.

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