Brake thickness reference guide?
- Thread starter The_Eric
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Doesn't that vary for every car? The manufacturer will tell you what the minimum thickness should be; many rotors have this stamped into the backside or hub, actually.
Yes, a service manual for your vehicle has the value.
I have a spec guide for that, got it from the raybestos rep. I know these exist, just finding them is one of those things you need to know someone.
Originally Posted By: dparm
Doesn't that vary for every car? The manufacturer will tell you what the minimum thickness should be; many rotors have this stamped into the backside or hub, actually.
I'm referring to brake pad and shoe thickness, not brake rotor and drum thickness.
Originally Posted By: Eddie
Yes, a service manual for your vehicle has the value.
Yes, I'm aware it can be found there, but it isn't cost effective to buy a repair or service manual for every car or truck I work on. I'm also aware that All Data, Motor or Mitchell will likely provide them too, but again, for now, it isn't cost effective for me to subscribe to their services.
Originally Posted By: EricF
I have a spec guide for that, got it from the raybestos rep. I know these exist, just finding them is one of those things you need to know someone.
You may have given me my answer. I'll go hound a few parts rep buddies and see what comes of it.
Doesn't that vary for every car? The manufacturer will tell you what the minimum thickness should be; many rotors have this stamped into the backside or hub, actually.
I'm referring to brake pad and shoe thickness, not brake rotor and drum thickness.
Originally Posted By: Eddie
Yes, a service manual for your vehicle has the value.
Yes, I'm aware it can be found there, but it isn't cost effective to buy a repair or service manual for every car or truck I work on. I'm also aware that All Data, Motor or Mitchell will likely provide them too, but again, for now, it isn't cost effective for me to subscribe to their services.
Originally Posted By: EricF
I have a spec guide for that, got it from the raybestos rep. I know these exist, just finding them is one of those things you need to know someone.
You may have given me my answer. I'll go hound a few parts rep buddies and see what comes of it.
If you're just looking for a general guide, get a feeler gauge. Its used to measure brake pad/shoe thickness. Its color coated green, yellow, and red.
Example: http://www.amazon.com/Brake-Feeler-Gauge-Measure-Thickness/dp/B0038P70DO
Example: http://www.amazon.com/Brake-Feeler-Gauge-Measure-Thickness/dp/B0038P70DO
I have asked a few vendors for the brake rotor/pad thickness guide numerous times the past few years for my techs. They all say that the aftermarket companies don't make them anymore, which is hard to believe.
Kestas
Staff member
On my car, per service manual, new pads are 11 mm, discard is 2 mm.
I don't see how it would be much different for other cars.
I don't see how it would be much different for other cars.
It's not rocket science. If you want to be safe, always discard under 3mm, don't wait until the metal hits metal. Also, some people say it's not a good idea to ride with completely worn out brake pads since this will cause the cylinder to come out "too much" (I don't know if this is bad in any way).
Kestas
Staff member
I've heard thin pads can also transfer heat better to the fluid, resulting in boiling fluid and loss of brakes in marginal situations.
Quote:
If you want to be safe, always discard under 3mm, don't wait until the metal hits metal.
Also keep in mind that they don't always wear evenly. The side in view might be OK, and the side out of view might be too close to metal. Look very closely. And, of course, metal rubbing on metal gets expen$ive.
If you want to be safe, always discard under 3mm, don't wait until the metal hits metal.
Also keep in mind that they don't always wear evenly. The side in view might be OK, and the side out of view might be too close to metal. Look very closely. And, of course, metal rubbing on metal gets expen$ive.
When pads wear unevenly its usually due to a stuck caliper pin or pad. The pad next to the caliper piston will usually wear faster if something is stuck, so thats why the pad wear indicator (noise maker) is put on that side. If there is a wear indicator, I would consider that to be the minimum thickness for any point on any of the pads.
Now having said that, there is no substitute for pulling the pads out on regular intervals for inspection and cleaning the brake parts (caliper pins, pad contact points) and lubing where required.
Now having said that, there is no substitute for pulling the pads out on regular intervals for inspection and cleaning the brake parts (caliper pins, pad contact points) and lubing where required.
The guide was meant to be a reference, not an absolute. Naturally I'll look at both pads and inspect the slides. I don't aim to tell a person that their brakes are fine and send them packing with only a brake thickness measurement, but I DO want them to take full advantage of what they've paid for.
Pads seem to be - discard at 3ish mm? Shoes, ????
Pads seem to be - discard at 3ish mm? Shoes, ????
Originally Posted By: The_Eric
The guide was meant to be a reference, not an absolute. Naturally I'll look at both pads and inspect the slides. I don't aim to tell a person that their brakes are fine and send them packing with only a brake thickness measurement, but I DO want them to take full advantage of what they've paid for.
Pads seem to be - discard at 3ish mm? Shoes, ????
Usually 1-2mm for pads and 1mm for shoes.
The guide was meant to be a reference, not an absolute. Naturally I'll look at both pads and inspect the slides. I don't aim to tell a person that their brakes are fine and send them packing with only a brake thickness measurement, but I DO want them to take full advantage of what they've paid for.
Pads seem to be - discard at 3ish mm? Shoes, ????
Usually 1-2mm for pads and 1mm for shoes.
Measure the thickness of the new lining and don't let it get below 10 percent. You may have to be vigilant below 25% if your car is hard on linings or you may go metal to metal.
When I worked on cars for a living, my policy (which evolved from many shop policies) was to inform the customer at 25%. Hard sell at 15%. That gave them leeway for arranging the time and finances and gave them a cushion if their driving took a turn for the hard.
When I worked on cars for a living, my policy (which evolved from many shop policies) was to inform the customer at 25%. Hard sell at 15%. That gave them leeway for arranging the time and finances and gave them a cushion if their driving took a turn for the hard.
^^^Sage advice as usual. We like the 10% rule. No way I am running anything to only 1 mm!
I have also had pads that the wear rate varied as the pad wore. They can wear faster or even much slower as they age.
I have also had pads that the wear rate varied as the pad wore. They can wear faster or even much slower as they age.
The percentage rule is not accurate. The problem is you have no idea what the starting thickness was on the pad. If you want a real total generic rule, replace pads when the lining is at or below the thickness of the backing plate.
Originally Posted By: bdcardinal
The percentage rule is not accurate. The problem is you have no idea what the starting thickness was on the pad. If you want a real total generic rule, replace pads when the lining is at or below the thickness of the backing plate.
The percentage rule would only apply if you know the original thickness of the lining.. which I stated in my original post.
The percentage rule is not accurate. The problem is you have no idea what the starting thickness was on the pad. If you want a real total generic rule, replace pads when the lining is at or below the thickness of the backing plate.
The percentage rule would only apply if you know the original thickness of the lining.. which I stated in my original post.
My, am I the only one with a caliper slide ruler in my pocket when I'm working?
The pads are generally the same thickness, but the figures go in the service log in the vehicle.
The pads are generally the same thickness, but the figures go in the service log in the vehicle.
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