Thai
Elite Member
Advice:
Noisy brakes? It could be rust.
by Phil Bailey
A pattern has developed in recent weeks. People are phoning in to make an appointment for a brake inspection. We started to wonder why this unusual activity had become so frequent and it turns out that noises from the brakes upon application are the motivation. But why this year and why now? Some quiet questioning of clients in the waiting room produced a pattern of circumstances.
In almost every case, the car owner had been on holiday for an extended period of two or three weeks and had left the car sitting in the driveway. With the exceptionally high rainfall we’ve experienced this year, the humidity has been above normal and the problem that causes those terrible brake noises is RUST. No matter where you drive, with the possible exception of Arizona, leaving your car to stand for a long period of time will allow a film of rust to develop on the brake rotors and even inside the brake drums, if the car is so equipped. This rust makes a truly terrible noise on the first several applications and then tends to disappear as the brake pads remove rust from the discs and the nice shiny surface appears once more.
In some cases however, the rust has penetrated sufficiently to produce high spots, or to have worn the pads so badly that the brakes continue to be noisy and to vibrate under hard braking conditions. In the case of our clients, we were able to reassure most of them that nothing very serious was amiss and that they could continue to drive for some time to come before brake work would be necessary.
Most brake rotors are equipped with cooling fins in the centre that direct cooling air right down the centre of the rotor. If you cut open an inexpensive rotor, vertically, you will find that the number of cooling fins varies according to quality. The cheaper the rotor, the less cooling capability it has. I’ve had people come through my door offering to sell rotors for as little as $10 each. I won’t bite, because such rotors usually need machining right out of the box and the labour cost of replacing them after a month or two, under warranty, simply makes them too expensive to contemplate in the long run. In the auto industry, you always get exactly what you pay for. These cooling cavities, even in very good quality rotors, will eventually fill with rust and can no longer force cold air into the rotors. The first application of the brakes from high speed, say as one is leaving an autoroute down the exit ramp, will overheat the rotors and cause a permanent distortion that manifests itself as a pedal vibration that gets steadily worse until the car starts to shake like a wet sheep dog.
Needless to say, this tremendous amount of dynamic force, then goes to work on such items as tie rod ends and ball joints. Is there an easy solution to this problem? Not really, although parking the car indoors will certainly help a lot. I’ve never tried it, but I can’t help feeling that a little light oil applied to the brakes, after the car is parked for its long stay in one place, might be better than rusty rotors. The lubricant will affect braking distances for the first few applications and may cause a bit of pad wear, but all of that would be far less expensive than a new set of rotors.
Apart from cost, there are obviously good engineering reasons why stainless steel doesn’t work as a brake rotor. From what I remember from my machine shop days, stainless steel galls very easily and is difficult to machine. I really don’t think cost is a factor, or someone out there would have already figured out that there is a sales opportunity, as has already happened in Europe with replacement stainless exhaust systems.
Racing car rotors don’t rust, because they are made from carbon fibre, but they don’t work very well either unless they are red hot! They wear down very fast too, as anyone of us who watches Formula 1 pit stops can see for themselves as large clouds of black brake dust emanate from the wheels as they are removed.
Maybe someone out there has a solution to the rusty rotor problem, but at this time, I haven’t seen one mentioned in all the technical magazines I read.
Noisy brakes? It could be rust.
by Phil Bailey
A pattern has developed in recent weeks. People are phoning in to make an appointment for a brake inspection. We started to wonder why this unusual activity had become so frequent and it turns out that noises from the brakes upon application are the motivation. But why this year and why now? Some quiet questioning of clients in the waiting room produced a pattern of circumstances.
In almost every case, the car owner had been on holiday for an extended period of two or three weeks and had left the car sitting in the driveway. With the exceptionally high rainfall we’ve experienced this year, the humidity has been above normal and the problem that causes those terrible brake noises is RUST. No matter where you drive, with the possible exception of Arizona, leaving your car to stand for a long period of time will allow a film of rust to develop on the brake rotors and even inside the brake drums, if the car is so equipped. This rust makes a truly terrible noise on the first several applications and then tends to disappear as the brake pads remove rust from the discs and the nice shiny surface appears once more.
In some cases however, the rust has penetrated sufficiently to produce high spots, or to have worn the pads so badly that the brakes continue to be noisy and to vibrate under hard braking conditions. In the case of our clients, we were able to reassure most of them that nothing very serious was amiss and that they could continue to drive for some time to come before brake work would be necessary.
Most brake rotors are equipped with cooling fins in the centre that direct cooling air right down the centre of the rotor. If you cut open an inexpensive rotor, vertically, you will find that the number of cooling fins varies according to quality. The cheaper the rotor, the less cooling capability it has. I’ve had people come through my door offering to sell rotors for as little as $10 each. I won’t bite, because such rotors usually need machining right out of the box and the labour cost of replacing them after a month or two, under warranty, simply makes them too expensive to contemplate in the long run. In the auto industry, you always get exactly what you pay for. These cooling cavities, even in very good quality rotors, will eventually fill with rust and can no longer force cold air into the rotors. The first application of the brakes from high speed, say as one is leaving an autoroute down the exit ramp, will overheat the rotors and cause a permanent distortion that manifests itself as a pedal vibration that gets steadily worse until the car starts to shake like a wet sheep dog.
Needless to say, this tremendous amount of dynamic force, then goes to work on such items as tie rod ends and ball joints. Is there an easy solution to this problem? Not really, although parking the car indoors will certainly help a lot. I’ve never tried it, but I can’t help feeling that a little light oil applied to the brakes, after the car is parked for its long stay in one place, might be better than rusty rotors. The lubricant will affect braking distances for the first few applications and may cause a bit of pad wear, but all of that would be far less expensive than a new set of rotors.
Apart from cost, there are obviously good engineering reasons why stainless steel doesn’t work as a brake rotor. From what I remember from my machine shop days, stainless steel galls very easily and is difficult to machine. I really don’t think cost is a factor, or someone out there would have already figured out that there is a sales opportunity, as has already happened in Europe with replacement stainless exhaust systems.
Racing car rotors don’t rust, because they are made from carbon fibre, but they don’t work very well either unless they are red hot! They wear down very fast too, as anyone of us who watches Formula 1 pit stops can see for themselves as large clouds of black brake dust emanate from the wheels as they are removed.
Maybe someone out there has a solution to the rusty rotor problem, but at this time, I haven’t seen one mentioned in all the technical magazines I read.
