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Old 09-04-2012, 06:32 PM   #12
paul8f
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Join Date: Sep 2012
Location: IRL
Posts: 1
My Ride: PhysicsLab on wheels
I'm not an E46 owner and this is on old thread, but I thought I'd post my own experience on having no option but to drive a car with a sticking caliper.

First and foremost, I must emphasise that doing so is not all that safe. Only do this if you have no other means of transport, and the trip is absolutely necessary.

* If your car has hub caps, remove the wheel cover on the affected corner. This will let in more air to cool the caliper, pads and rotor.

* Before you set off, shed any unnecessary cargo. The heavier your vehicle, the more braking force will be required to stop.

* Plan your journey carefully. If possible, drive on quiet roads very early in the morning. The fewer times you must press the brake pedal the better (..It's almost like getting into the "Hypermiling" mindset.) Avoid heavy traffic, as stop/go driving will never give the brake piston a chance to retract back into the caliper bore.

* Leave an extra large-large gap between you and the car ahead, thus reducing the number of times you brake.

* If the brake pads are permanently rubbing, then try to keep the speed under 40MPH. The lower the speed, the less heat will be generated from the friction.

* If you drive a manual, use the gearbox to perform "engine braking", i.e. shifting down early through all the gears (taking care to avoid over-reving the engine). For example: when slowing down, if you normally change from 3rd gear into 2nd at about 15MPH, instead change down into 2nd gear at 35MPH. This will help kill off some of the speed, reducing the pressure required on the brake pedal. You will need to keep an eye on the rev counter, and also on the rear view mirror (if there is traffic following behind. Lightly touch the foot brake as you gear down, just enough to bring the brake lights on. This shows drivers that you are decelerating.)

* Engine-braking can also be used for descending long hills. Leaving the gearbox in 3rd instead of the usual 4th gear, will hold the car back. Again, the revs will be higher than usual (around 3.5 to 4 thousand RPM). With the car held back, it will tend less to run away as you go down the hill, therefore requiring less force (if any) on the brake pedal. If you have an automatic transmission, select the "2" or "L" position for the long descent. If your vehicle has selectable 4 wheel drive, it's probably better to have power going to all 4 wheels for the long descent for maximum resistance.

* If the sticking caliper is on the front, and your handbrake (parking/emergency brake) activates the rear brakes, then a slight pull on the lever will also aid in killing off some speed when slowing. Only do this on a good dry road, and in a straight line. If you are not happy doing this with the E-brake, then SKIP THIS TIP . . . as incorrect use of the parking brake could cause a loss of control.

* If the caliper sticking is an intermittent problem, it might be worth stopping the car, getting out, and rocking the wheel or car body forcefully from side to side. (Watch out for a hot wheel rim!) Using the manufacturing tolerance of the car components to your advantage, the rocking motion might be just enough to push the pad away from the rotor by the fraction of a millimeter necessary to reduce the pressure. This rocking action could also help free up a stiff self-centering slider on the disc brake.

* As you drive, running the affected wheel over the odd cat-eye in the road might be worth a try. This could be totally futile, but the shock may just help the brake piston slide in it's bore a little.

* If it's a front caliper that's sticking, you may feel the car juddering slightly under you, or even some vibration on the steering wheel. If this happens reduce your speed. If it continues to vibrate, pull over and let the brake cool for an hour.

* Do not rest your foot on the brake pedal if stopped in traffic, and avoid pulling up the parking brake if the bad caliper is on the rear. (Obviously, ensure your car dosn't roll into another car.) Give the caliper piston every possible chance to retract.

* Don't get too carried away with trying to avoid using the brake pedal. If driving circumstances call for a firm push of the pedal, do it. Don't run into the back of someone else. Unless your rotor is glowing red, your car should still have good stopping power.

---> After reaching your destination, have the braking system fully inspected by a mechanic. It may seem like more money initially, but always replace calipers in pairs. If the left side sticks, there is a very high probability that the right side will give you trouble in a few thousand miles, and at the very worst time once again.. If the opposite side does give trouble later on, that's a second pair of brake blocks you will need to buy, and the newer caliper may differ slightly to the first one, leading to your car pulling to one side under braking. Not good at all. Get the brake fluid changed as you're at it, to extend the life of your new calipers.

As a preventative measure, do as little driving on salted roads in the winter as possible. Gritting salt in one of the main factors involved in the corrosion/pitting of the brake-piston's surface. Inspect the little protective rubber boots at regular intervals too.
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