Interesting info about turning brake rotors and the effect on braking performance.
http://www.oeqf.com/techinfo/index.htm
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Interesting info about turning brake rotors and the effect on braking performance.
http://www.oeqf.com/techinfo/index.htm
http://www.oeqf.com/techinfo/index.htm
They want to sell rotors by scare tactics. A lot of people who claim to be "in the know" recommend not turning rotors but using a stiff 3M burnishing pad in a die grinder to rough up the rotors. Another solution is to find a shop that grinds the rotors with a tool similar to this http://www.etoolcart.com/browseproducts/Disc-Brake-Rotor-Grinder-T-1074.HTML
What they purposly left out is burnishing the pads prior to road operation. This step is usually ommitted by brake shops and in most cases, they give out false information in the form of "use your brakes lightly for a few hundred miles" This is totally WRONG.
If you properly burnish your brake pads, even with a turned rotor, stopping distances will be significantly reduced.
IN any case, new pads should be burnished by this process.
Find a large parking lot with no obstructions. Accelerate to 60 MPH and slam on the brakes. Immediately repeat this 2 to 3 more times.
Hopefully, the brakes should be producing a lot of smoke. Let them cool, with your foot off the brake pedal for 3 minutes. Repeat the 60 to 0 stops 3 times. Let them cool for 5 minutes with your foot off the brakes then 3 stops from 40 to 0.
That's usually enough to burn off all the glue resins and the outcome is this, the brakes will work better and last longer
What they purposly left out is burnishing the pads prior to road operation. This step is usually ommitted by brake shops and in most cases, they give out false information in the form of "use your brakes lightly for a few hundred miles" This is totally WRONG.
If you properly burnish your brake pads, even with a turned rotor, stopping distances will be significantly reduced.
IN any case, new pads should be burnished by this process.
Find a large parking lot with no obstructions. Accelerate to 60 MPH and slam on the brakes. Immediately repeat this 2 to 3 more times.
Hopefully, the brakes should be producing a lot of smoke. Let them cool, with your foot off the brake pedal for 3 minutes. Repeat the 60 to 0 stops 3 times. Let them cool for 5 minutes with your foot off the brakes then 3 stops from 40 to 0.
That's usually enough to burn off all the glue resins and the outcome is this, the brakes will work better and last longer
Larry - you just described how I typically drive through the Wal-Mart parking lot during normal business hours.
I agree with Larry about the "use your brakes lightly for a few hundred miles..." is not sound advice, at least not for any car I've ever owned. I think that they tell people that so they protect themselves in case a customer goes blowing out the door 100 mph and the brakes are burnished in (hit a tree, pedestrian, a square dancing police officer, etc).
I also question the validity of the entire experiment. Here's why: The experiment is conducted by OE pads (an aftermarket manufacturer) to attempt to get the same results as factory pads and rotors.
Most after market makers of brakes and rotors try to EXCEED the factory performance. OE experimented to match the performance. Match it exactly. Hmmm.
I suspect the "spring back" theory is solid however.
angela
I also question the validity of the entire experiment. Here's why: The experiment is conducted by OE pads (an aftermarket manufacturer) to attempt to get the same results as factory pads and rotors.
Most after market makers of brakes and rotors try to EXCEED the factory performance. OE experimented to match the performance. Match it exactly. Hmmm.
I suspect the "spring back" theory is solid however.
angela
Good thoughts Angela.
I reacted differently to OEQF
I reacted differently to OEQF
Prior to retirement from the L.A. County Sheriff's Dept. in 2003, I was assigned as the Sergeant in charge of our fleet of 4,400 vehicles.
(Nice job as I managed a 13 million dollar contract, got to drive fast on our 1.57 mile road course to test the performance of police vehicles, conduct brake tests, mileage tests and work with Ford, Chevy and Chrysler as they developed police cars and, I didn't have bullets flying over my head)
Every year, in October, we had our annual Law Enforcement Vehicle Test.
Michigan State Police and my Department were the only agencies in the US that conducted tests.
Ford, Chevy and Chrysler participated and we invited law enforcement agencies from all over the USA and on occasion, we would get members from foreign agencies.
I conducted many brake tests and found that if the rotors were ground, not cut and the pads burnished as I described above, brakes would work great with no adverse problems. If the rotors were ground, they would last as long as new rotors with the same performance. I also found that if the rotors were cut, (fine) the pads would chatter until they were burnished. Once the burnishing was conducted, the pads and rotors worked well.
Grinding proved to be the best way to recondition rotors so unless the rotor was "severely damaged" we would have them ground by our vendor and re-use them one time then make paper weights out of them.
(see below regarding Performance Friction Corp. Rotors)
By the way, after extensive tests, I wrote paper requiring that Performance Friction Corp. pads and Rotors were the only components that could be installed on a black and white patrol car.
We found that in most cases, PFC Rotors didn't need to be ground when changing pads.
I have a close friend who now manufactures Porsche racing drivetrain parts and, he also maintains Porsche race cars for some serious club racers. He uses PFC rotors and pads. He said that their rotors are usually good for 3 or 4 races before they replace them.
Unfortunately, PFC doesn't make a rotor that will fit any of the VW based brake systems currently being used on Speedsters or Spyders.
In regards to the test conducted above. I don't like the method they used (applying the brakes at a given land mark) Too much chance for driver error. We used a $10,000 light sensor that measured speed, distance and time and was activated the moment you put your foot on the brake. All of our tests were conducted with the brake pedal mashed to the floor to provide maximum pressure within the mastercylinder.
(Nice job as I managed a 13 million dollar contract, got to drive fast on our 1.57 mile road course to test the performance of police vehicles, conduct brake tests, mileage tests and work with Ford, Chevy and Chrysler as they developed police cars and, I didn't have bullets flying over my head)
Every year, in October, we had our annual Law Enforcement Vehicle Test.
Michigan State Police and my Department were the only agencies in the US that conducted tests.
Ford, Chevy and Chrysler participated and we invited law enforcement agencies from all over the USA and on occasion, we would get members from foreign agencies.
I conducted many brake tests and found that if the rotors were ground, not cut and the pads burnished as I described above, brakes would work great with no adverse problems. If the rotors were ground, they would last as long as new rotors with the same performance. I also found that if the rotors were cut, (fine) the pads would chatter until they were burnished. Once the burnishing was conducted, the pads and rotors worked well.
Grinding proved to be the best way to recondition rotors so unless the rotor was "severely damaged" we would have them ground by our vendor and re-use them one time then make paper weights out of them.
(see below regarding Performance Friction Corp. Rotors)
By the way, after extensive tests, I wrote paper requiring that Performance Friction Corp. pads and Rotors were the only components that could be installed on a black and white patrol car.
We found that in most cases, PFC Rotors didn't need to be ground when changing pads.
I have a close friend who now manufactures Porsche racing drivetrain parts and, he also maintains Porsche race cars for some serious club racers. He uses PFC rotors and pads. He said that their rotors are usually good for 3 or 4 races before they replace them.
Unfortunately, PFC doesn't make a rotor that will fit any of the VW based brake systems currently being used on Speedsters or Spyders.
In regards to the test conducted above. I don't like the method they used (applying the brakes at a given land mark) Too much chance for driver error. We used a $10,000 light sensor that measured speed, distance and time and was activated the moment you put your foot on the brake. All of our tests were conducted with the brake pedal mashed to the floor to provide maximum pressure within the mastercylinder.
...kinda like the braking tests I perform routinely in the Wal-Mart parking lot on any given day of business!
Good stuff Larry.
I agree re OEQF's test method. That's one reason I'd like to see an independent test. But even if they missed the fire hydrant brakepoint by ten feet either way, the differences with coarse or fine turned rotors would still be significant.
I agree re OEQF's test method. That's one reason I'd like to see an independent test. But even if they missed the fire hydrant brakepoint by ten feet either way, the differences with coarse or fine turned rotors would still be significant.