Hey, folks, Cooley here again with another one of your emails about high tech cars and modern driving.
This one comes in from Joe D, who says, when I've owned vehicles with full scheduled maintenance from the manufacturer, at about 36,000 miles they would drop in a new set of brake pads.
Now that manufacturer has dropped brakes from their free schedule maintenance, and they want to replace the pads and rotors at the same time, and of course that's gonna be on his nickle, and he wants to know what's my take on all these, he is smelling something fishy.
And I'm with you Joe, I know this probably doesn't feel real good to have a sudden being totally.
By the way, you need more work than in the past, and you have to pay for it But there could be some good reasons for this going on.
First of all, depending on how much of a different car you're driving now than the last one, you may have a different Pad Material.
And I'm assuming you're still in the same make but maybe a different model and different model year.
And Pad Material could've changed.
Then the Rotor Design could've changed.
We'll learn about this in just a second.
That can also require rotors to be replaced as opposed to being serviced.
And the third thing is just very generally, OEMs are changing their specs on things all the time.
Depending on who they get their parts from, the vendor, the source and how they're designed, they're constantly doing engineering updates and changes.
So you can't necessarily look at one car and another one from years back and say well they should be serviced the same But I think it'll be helpful if we take a look at all these parts and really understand why they wear and cost us money.
Okay, so there are three components that typically make up your brake system at least down around the wheel where the work is actually done.
The first one is the emblematic rotor or disc from which disc brakes get their name.
You see these things all the time through almost any car that has open alloy wheels.
This is mounted to the wheel.
It turns with it.
It's bolted with these boltholes you see right here and it provides the clamping surface that's grabbed on to reduce the cars forward or backward momentum.
Now, the grabbing is done by the pads.
Now this is the part you often think of when I need a brake job.
I need new pads.
This is what we always assume is the wear item.
These are the things, right here, that are used to clamp onto this disc right there and that's what slows the car down.
So, what does the clamping?
It doesn't happen by magic.
Nope, this guy does it.
This is a caliper.
Most folks are less familiar with this.
This is also mounted down around your car.
It sits here, and the pads would be sandwiched inside of it, and when you hit the brakes, the little hydraulic cylinders inside here, those pistons, they press the whole thing together and pinch the pads onto the disc or rotor, and slow the car down.
Now unlike engine oil you don't monitor and service your brakes based on mileage.
You do it based on thickness of materials.
There's a certain thickness here on the rotor, on the disc, of how much metal it has from one face to the other.
And there's also a thickness of these pads of the clamping surface.
That rough, dull part there that does the grabbing, that can only go down so much before the breaks are unsafe.
There's also a time when you'll service the caliper, because those rubber seals inside there, that are part of those two pistons.
Those can go bad and start to leak, but again, that's relatively infrequent.
Some pads are very soft material.
They have a lot of grab, but they also tend to wear quickly and throw off a hellasist amount of that brake dust on your front wheels.
Most brake pads today try and strike a happy balance, to be honest.
Then you've got your rotor here.
Almost always made of steel.
A few cars have them made of ceramic.
They're very exotic and you'll know if you have those.
These guys here have a certain amount of thickness that allow you to put this on a lathe and remove a thin amount of metal and get a new surface.
But some of the most modern cars are taking a different tact.
They're saying no, we wanna save weight.
So they build these rotors as thin as possible and you can only use them once.
And you can't put them on a lathe and machine them down to a new surface.
That could also be a factor in the brake job change that you're seeing on your latest car.
They don't allow it to get too thin because it can't dissipate heat well then.
It may warp when it gets too thin and it also may cause these pistons to have to extend too far for safety, if it gets too thin.
So there you have it.
Those are the things that can wear out on a car's break system.
The rotors are the ones that surprise people, because they may have already had them turned a couple times and don't remember it, and therefore there's not enough rotor left.
So they need new ones or the car was designed to never turn them and always get new ones.
the pads are usually pretty obvious, we expect these to wear.
And then the last thing that we didn't show here is brake fluid.
If your brake system ends up having water in the fluid, that's a very bad situation for a number of reasons.
Corrosion and poor brake [UNKNOWN] Actuation, and that's when they'll request that you let them do a brake fluid flush.
Keep those emails coming.
I'm here to answer your questions about high-tech driving.
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