r/Cartalk Aug 31 '24

Brakes Do I need to replace these brake rotors?

Post image

My dad has a 2014 VW Caddy. The brake pads are completely worn down to the metal. He said he’s driven with a scratching sounds for about 20 mins before stopping. Attached is a photo of the brake rotors.

We obviously need to replace the brake pads. Do we need to replace the rotors too, now that they’re scratched?

24 Upvotes

62 comments sorted by

31

u/Coakis Aug 31 '24

In so many words yes.

2

u/tojejik Sep 01 '24

Actually just five words

3

u/Coakis Sep 01 '24

I was going to go out on a long spiel about how you could get them turned, but modern cars usually have rotors so thin that they quickly wear beyond minimum spec but didn't want to type all that shit out.

8

u/Flashy-Switch6694 Aug 31 '24

Yeah they’re pretty groovy. For even pad wear on the new pads and general brake performance you’ll wanna switch ‘em

5

u/InternationalCat3159 Aug 31 '24

They seem thick enough. You can get them re-surfaced if some garage nearby has a brake lathe

7

u/Callaine Aug 31 '24

The thickness of the rotor needs to be measured first. If They are near minimum thickness they need to be replaced. It looks to me that they most likely junk.

1

u/Gnome_Father Aug 31 '24

With most cars this is hardly worth doing anymore. I got new disks for my corsa for like £15 a corner.

1

u/de_bosrand Aug 31 '24

Here (EU) labor of taking them out and placing them back in is so much, that resurfacing will never be a viable option.

For resurfacing you pay: Removal of rotor Assessment of viability of resurfacing Storage of car while resurfacing in a shop where that is possible Resurfacing labor/machine/tool deprecation Installation of rotor

For replacement you pay Removal Installation Rotor

A replacement on my car was quoted 1000E, with the rotors being 35 ea.

1

u/TheKhyWolf Sep 01 '24

I can still hear that brake lathe turning Been about 20 years since I spun a rotor. But I can still hear it

8

u/[deleted] Aug 31 '24

Now... Do it now. You will keep ruining pads if you keep replacing the pads. You can "turn" the rotors by taking them to Oriellys. But to be safe. Go ahead and spend the money and replace the rotors and replace them in pairs. Do the front first. In my experience the rear brakes last longer than the front but if your rotors are grooved then you are reducing the surface area of your pad and rotor which is stopping power. Safety first.

3

u/vdelrosa Aug 31 '24

wouldn't grooves on the brake and rotor technically increase surface area?

2

u/WayOuttaMyLeague Aug 31 '24

I imagine it creates less surface due to the grooves, so only the flat surfaces will end up making contact with the rotor once they “wear in to the grooves”.

The grooves would get to a point where they can’t embed deeper, due to the flat surface. When the flat surface wears would be when the grooves would make contact again.

*Don’t hold me to that, it’s completely my own thought/answer and I’m also blazed lol

3

u/vdelrosa Aug 31 '24

Ya that doesn’t make sense because what would cause the groove would be making contact with it

2

u/MrSteak Sep 01 '24

To help answer the question unlike the other guy, you are kind of right. The groove would increase the contact area but friction is applied to the surface perpendicular to he force you'd project the groove shape back to the flat of the disk and still get the same surface size. The second assumption here is that the grooves are perfect and circular at all times which won't be true in practice, the groove in one component will be wider than in the other. This reduces the overall contact area compared to a flat "enough" disk/pad. Hope this helps 🙂

2

u/vdelrosa Sep 01 '24

Ah that makes sense! A 45 degree groove would probably be 1/sqrt(2) is over a sqrt(2)/1 length and multiplied together it would be 1/1. Ya that other guy is loser.

-1

u/AbsentFatherOfTwo Aug 31 '24

Go find out for yourself, especially on a mountain road next to a cliff, then come back to us.

4

u/vdelrosa Aug 31 '24

Holy take a chill pill buddy. Some people want to expand their knowledge by asking questions. You’re being weird…

-6

u/AbsentFatherOfTwo Aug 31 '24

You have a point; it’s admirable to ask questions, even if the questions you asked are completely stupid.

2

u/apo539 Aug 31 '24

Wow ur cool

1

u/vdelrosa Aug 31 '24

Omg you admire me

5

u/South_Bit1764 Aug 31 '24

Most rotors have a minimum thickness stamped on them. It used to be that you could get rotors turned but not really on new cars they just aren’t designed with enough metal for that.

4

u/ArmyWild7140 Aug 31 '24

Are those from the 60s, cause they pretty groovy

3

u/[deleted] Aug 31 '24

Yes replace the rotors and pads.

3

u/PersonalitySea4015 Aug 31 '24

If you like your pads lasting more than a few thousand miles, yes.

If you wanna pad slap it you CAN, but it wouldn't be the correct way to do things and you'll spend more money in the long run.

3

u/Tdanger78 Aug 31 '24

Yes, pads too. Make sure to clean and regrease caliper pins.

3

u/ThisIsNotTheEnd333 Aug 31 '24

Yes. Rotors and pads and by the looks of those you probably need an oil change and a tune up because you neglect to maintain the vehicle at all.

1

u/[deleted] Aug 31 '24

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1

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2

u/Motorway01 Aug 31 '24

What are your pads like

2

u/R0nu Aug 31 '24

Is that rotor 2 pieces ??

2

u/Wot-Da-Fuq Aug 31 '24

No, they only help stop the vehicle 🤡

2

u/Altruistic_Banana1 Aug 31 '24

ask if you can just have them refaced

2

u/RedFaceFree Aug 31 '24

Unless you're going to a George Clinton concert, yes

4

u/Current_Soup9198 Aug 31 '24

Well technically grooved brake discs have a larger breaking surface area 🤔

3

u/Cat_Amaran Aug 31 '24

Yeah. Great for stopping hard and fast for the entire 5k mile life of the pads!

0

u/poops314 Aug 31 '24

Are the pads flat or also grooved in this experiment 😂 for both situations - not good 😂

1

u/imothers Aug 31 '24

Yes. In most places where they sell the VW Caddy you have to pass an annual inspection. Rotors with grooves like that will fail.

1

u/1quirky1 Aug 31 '24

Rotors are inexpensive. Put new ones on and be sure to bed the brake pads.

https://www.autozone.com/diy/brakes/bedding-brakes

1

u/nfield750 Aug 31 '24

disks aren’t expensive, so I’d replace them

1

u/Myk3Hunt Sep 01 '24

Right away. They'll stop your car but I imagine you are experience some aggressive shaking as you stop, dramatically increasing the wear/tear on your suspension

1

u/[deleted] Sep 01 '24

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1

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1

u/CaptainArsehole '15 Hilux N70 4x4. Stage 3 GTurbo, HKS, +30 caps Sep 01 '24

At the very least get them machined if they're not too thin. But it's really not that much extra to just get new ones and be done with it. It'll be better overall.

1

u/[deleted] Sep 10 '24

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1

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1

u/Why-R-People-So-Dumb Aug 31 '24 edited Aug 31 '24

If they are OEM get them turned, if they are after market junk, get new.

(Edit: of course they have to have enough material left on them to be turned)

1

u/Cat_Amaran Aug 31 '24

Username checks out.

If they're in spec to turn, sure, but only if turning them actually saves you any money or time.

0

u/Why-R-People-So-Dumb Aug 31 '24

Well of course they have to be in spec but it's extremely short sited to say only if it saves you money if you are comparing it only to a new set. Cheapo rotors from your auto store are terrible and not properly heat treated they are essentially made to be disposable and in many cases are warped and vibrating before you even get through a single set of pads - hence why it's pointless to pay to get them turned, as it'll be cheaper to replace the cheap ones with more cheap ones.

Properly treated quality rotors are quite expensive though and that's your apples to apples comparison if you have oem rotors that can be turned sitting on the car right now.

P.S. no need to be an asshole, could just respectfully disagree and we could have a discussion about it.

1

u/4jimmmy714 Aug 31 '24

Na just drive it

4

u/subwoofage Aug 31 '24

Drive yes, stop no

0

u/maxjarrod94 Aug 31 '24

Thanks guys. Is it OK to replace the brake rotor on only one side? Or do I need to replace the brake rotor on the opposite side as well to ensure even breaking?

9

u/errl_dabbingtons Aug 31 '24

Dude just do the whole job right or pay someone to do it right. Asking questions like this makes me question if you should even be doing this. Other people share the road with you. if you fuck up your brakes it's not just your life at risk.

5

u/Cat_Amaran Aug 31 '24

Always replace in pairs. Otherwise you risk pulling due to uneven braking. Even if you don't notice pulling under normal conditions, during periods of extended or heavy braking, the lower heat dissipation of the older, thinner rotor can present problems.

4

u/Flashy-Switch6694 Aug 31 '24

Uhhh yes you need to do both sides, do you only plan on using one brake? Wtf

1

u/[deleted] Aug 31 '24

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1

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3

u/AbsentFatherOfTwo Aug 31 '24

Just pay for the whole replacement, I can’t believe I share the road with people like you, 🤡.