Is there a mechanical test? This mechanic drives the car and tells me warped rotor(s). But it's too hard to tell which one or how many by driving it, he says. So, now I must remove and resurface all the rotors based on a braking shimmy. This just doesn't sound right to me. Couldn't the mechanic determine if a rotar was warped by running a micrometer around it? If so, would he have to remove it first or could he do it while still on the car?
Process for determining warped rotars?
- Thread starter GR8VIII
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magic_marker
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RE: Process for determining warped rotars?
You can mic rotors on the car, but all that will tell you is the thickness *at the point you measure*. I suppose he could spin the rotor and note the presence of high/low spots by the amount of rubbing on the mic calipers, but I think we are talking .00x measurements, here. It would be pretty tough to eyeball the "warpage", I would guess.
As far as being able to tell if it is the front or back ones that are warped, I just drive at a high speed (>50 mph), and slowly apply the parking brake (not the normal brake). If I feel vibration, I know that it is isolated to the rears.
NOTE: USE EXTREME CAUTION when using this method, and make sure that your parking brake is fully functional *prior* to doing it!
You should always replace rotors in pairs, BTW.
Hope this helps,
Scott
You can mic rotors on the car, but all that will tell you is the thickness *at the point you measure*. I suppose he could spin the rotor and note the presence of high/low spots by the amount of rubbing on the mic calipers, but I think we are talking .00x measurements, here. It would be pretty tough to eyeball the "warpage", I would guess.
As far as being able to tell if it is the front or back ones that are warped, I just drive at a high speed (>50 mph), and slowly apply the parking brake (not the normal brake). If I feel vibration, I know that it is isolated to the rears.
NOTE: USE EXTREME CAUTION when using this method, and make sure that your parking brake is fully functional *prior* to doing it!
You should always replace rotors in pairs, BTW.
Hope this helps,
Scott
Neontail97
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RE: Process for determining warped rotars?
Typically you can feel a vibration or more of a thumping through the steering wheel that changes with speed when applying the brakes. If can stop from cruising speed without feeling anything either through the brake pedal or steering wheel your rotors are probably fine. 99.9% of the time on a Mark warped rotors are up front since they do a bigger percentage of the work. A dial indicator can be used to check rotor run-out or warpage...a micro measuring device with a pin connected to a micrometer dial gage. The pin is placed on the rotor surface at a right angle and as the rotor is turned the pin moves in and out based on trueness of rotor. Driving the car is usually all that is required to diagnose warped rotors.
I would not recommend spending money to resurface the rotors if they are warped or you wil have the same problem in as little as 2 months. Buy new ones from NAPA or OEM. Some 1st gen owners purchase 2nd gen rotors as they are believed to be of a more robust design and more resistant to warping.
Typically you can feel a vibration or more of a thumping through the steering wheel that changes with speed when applying the brakes. If can stop from cruising speed without feeling anything either through the brake pedal or steering wheel your rotors are probably fine. 99.9% of the time on a Mark warped rotors are up front since they do a bigger percentage of the work. A dial indicator can be used to check rotor run-out or warpage...a micro measuring device with a pin connected to a micrometer dial gage. The pin is placed on the rotor surface at a right angle and as the rotor is turned the pin moves in and out based on trueness of rotor. Driving the car is usually all that is required to diagnose warped rotors.
I would not recommend spending money to resurface the rotors if they are warped or you wil have the same problem in as little as 2 months. Buy new ones from NAPA or OEM. Some 1st gen owners purchase 2nd gen rotors as they are believed to be of a more robust design and more resistant to warping.
RE: Process for determining warped rotars?
Jason,
Thank you. I had heard or read, can't remember which, about the 2nd Gen rotor being a better investment. Your confirmation sealed it. I also had it in my knowledge box that I should ask for the 98 LSC rotor. Is that correct, or will any year of that generation fit? Also , whats the scoop on cross-drilled/slotted rotors? I know they're good for heat dissapation, but is there a chance they will wear the pad unevenly and lead to premature failure? Appreciate your help.
Lee
Jason,
Thank you. I had heard or read, can't remember which, about the 2nd Gen rotor being a better investment. Your confirmation sealed it. I also had it in my knowledge box that I should ask for the 98 LSC rotor. Is that correct, or will any year of that generation fit? Also , whats the scoop on cross-drilled/slotted rotors? I know they're good for heat dissapation, but is there a chance they will wear the pad unevenly and lead to premature failure? Appreciate your help.
Lee
RE: Process for determining warped rotars?
Damn, you guys are good. Guess I'll have to invest in new rotars then. New rotars equal new pads too, no? And all because the kid at the tire store didn't torque down the lug nuts properly. Thems the most expensive tires I ever bought. sizzle.......
Thanks alot for the replies.
Damn, you guys are good. Guess I'll have to invest in new rotars then. New rotars equal new pads too, no? And all because the kid at the tire store didn't torque down the lug nuts properly. Thems the most expensive tires I ever bought. sizzle.......
Thanks alot for the replies.
RE: Process for determining warped rotars?
How many miles are on the pads?
Since I have been taking car to make sure that the lugs get torqued to 95 ft/lb in a star pattern I have had no warping issues. I also upgraded to the autospecialty cross drilled rotors, so I believe that has helped as well.
How many miles are on the pads?
Since I have been taking car to make sure that the lugs get torqued to 95 ft/lb in a star pattern I have had no warping issues. I also upgraded to the autospecialty cross drilled rotors, so I believe that has helped as well.
RE: Process for determining warped rotars?
Specs for thickness, runout, etc., from the manual('93):
FRONT DISC BRAKE DIMENSIONS
Component................................Specifications
Lining Material..........................JB-FA00-FF
Lining Wear Limit (from shoe surface)....1.00mm(0.040inch)
Caliper Cylinder Bore Diameter...........66mm (2.598 inch)
Front Rotor Nominal Thickness............26.0mm (1.024 inch)
Front Rotor Minimum Thickness(a).........24.75mm (0.974 inch)
Front Rotor Diameter.....................94mm (11.57 inch)
Front Rotor Allowable Runout on Vehicle..0.076mm max. (0.003 inch)
Front Rotor Finish.......................0.4-3.2 micro-meters(10-80 micro-inch)
Front Rotor Thickness Variation..........0.009mm max(0.00035inch)
Note the extreme tolerance on thickness variation(about 1/3rd of 1 thousandth of an inch). Runout is allowed to be 10X the variation of thickness.
Specs for thickness, runout, etc., from the manual('93):
FRONT DISC BRAKE DIMENSIONS
Component................................Specifications
Lining Material..........................JB-FA00-FF
Lining Wear Limit (from shoe surface)....1.00mm(0.040inch)
Caliper Cylinder Bore Diameter...........66mm (2.598 inch)
Front Rotor Nominal Thickness............26.0mm (1.024 inch)
Front Rotor Minimum Thickness(a).........24.75mm (0.974 inch)
Front Rotor Diameter.....................94mm (11.57 inch)
Front Rotor Allowable Runout on Vehicle..0.076mm max. (0.003 inch)
Front Rotor Finish.......................0.4-3.2 micro-meters(10-80 micro-inch)
Front Rotor Thickness Variation..........0.009mm max(0.00035inch)
Note the extreme tolerance on thickness variation(about 1/3rd of 1 thousandth of an inch). Runout is allowed to be 10X the variation of thickness.
Neontail97
Registered
RE: Process for determining warped rotars?
Jason,
Thank you. I had heard or read, can't remember which, about the 2nd Gen rotor being a better investment. Your confirmation sealed it. I also had it in my knowledge box that I should ask for the 98 LSC rotor. Is that correct, or will any year of that generation fit? Also , whats the scoop on cross-drilled/slotted rotors? I know they're good for heat dissapation, but is there a chance they will wear the pad unevenly and lead to premature failure? Appreciate your help.
Lee
[/quote]
I have not personally confirmed the 2nd gen rotors are of a superior design. My information comes from the topic being covered many times in the past and many references by others being the case.
My part number listing shows the same pn for 96-98 models but it does start with F8 which means there was some sort of change in 98 so I'd go ahead and order rotors for the 98. LSC or base model does not matter.
From what I have read crossdrilled rotors are more for performance applications and they need coupled with the right pad material recommended by the manufacturer to avoid premature wear or reduced braking ability from the reduced surface area.
Rotor problems among owners vary wildly. Some can't go 10k without warpage while others go 50-80k. I am up to 40k with no problems on my 97 OEMs. They were replaced under warranty at 30k miles right before I bought the car, no doubt with the updated part number. I do not trust anyone else to torque my own lugs. Even if a shop uses a torque wrench, that doesn't mean the wrench is working right or they know how to use it correctly.
Jason,
Thank you. I had heard or read, can't remember which, about the 2nd Gen rotor being a better investment. Your confirmation sealed it. I also had it in my knowledge box that I should ask for the 98 LSC rotor. Is that correct, or will any year of that generation fit? Also , whats the scoop on cross-drilled/slotted rotors? I know they're good for heat dissapation, but is there a chance they will wear the pad unevenly and lead to premature failure? Appreciate your help.
Lee
[/quote]
I have not personally confirmed the 2nd gen rotors are of a superior design. My information comes from the topic being covered many times in the past and many references by others being the case.
My part number listing shows the same pn for 96-98 models but it does start with F8 which means there was some sort of change in 98 so I'd go ahead and order rotors for the 98. LSC or base model does not matter.
From what I have read crossdrilled rotors are more for performance applications and they need coupled with the right pad material recommended by the manufacturer to avoid premature wear or reduced braking ability from the reduced surface area.
Rotor problems among owners vary wildly. Some can't go 10k without warpage while others go 50-80k. I am up to 40k with no problems on my 97 OEMs. They were replaced under warranty at 30k miles right before I bought the car, no doubt with the updated part number. I do not trust anyone else to torque my own lugs. Even if a shop uses a torque wrench, that doesn't mean the wrench is working right or they know how to use it correctly.
RE: Process for determining warped rotars?
You should have heard the guy at the NAPA store when I ordered '98 rotors and admitted I was putting them on a '93. "This ain't some kind of 60's car where the same brakes work for ten years in row!" he screams.
I said "And you call yourself a parts man!?" and hung up. Now I gotta find another NAPA and they're getting few and far between.
You should have heard the guy at the NAPA store when I ordered '98 rotors and admitted I was putting them on a '93. "This ain't some kind of 60's car where the same brakes work for ten years in row!" he screams.
I said "And you call yourself a parts man!?" and hung up. Now I gotta find another NAPA and they're getting few and far between.
Neontail97
Registered
RE: Process for determining warped rotars?
I've had similar experiences when ordering other parts under these circumstances. Something so simple can become so complicated. This is one time when giving the parts person too much information can be a bad thing.
I've had similar experiences when ordering other parts under these circumstances. Something so simple can become so complicated. This is one time when giving the parts person too much information can be a bad thing.