# Handbrake Applied & Released Repeatedly / spots on rotors / deep scoring on rotors



## 91794 (Mar 25, 2015)

*Handbrake Applied & Released Repeatedly / spots on rotors / deep scoring on rotors*

The manual shift is very nice but another favorite things about Cruze is the manual handbrake! 

Q1: Assuming traction is sufficient so tires won't slip, and a bootleg turn is not the goal, is it OK or not OK to use handbrake rear-brakes to save wear on front brakes (when spouse is not in the car)? I've verified that the car evidently lacks an no-squat suspension, so it squats weirdly when handbrake is applied.

Q2: Why are my 2017 cruze diesel stickshift's brake rotors mottled/patchy with couple-millimeter-sized patches, instead of consistently shiny metal as for the other 30+ vehicles I've owned, including 2011 cruze 1.8 stick? Corrosion? Uneven heating or overheating? Intentionally weird metal alloy? I'll post a photo at some point if there is interest and folks would like to compare with their rotors and maybe post photos. There is no actual operational problem that I can detect from the mottling colorations on the rotor.

Q3: On day 2 days of ownership before anything resembling a bootleg turn or handbrake fun, I noticed deep scoring on left rear brake rotor, and the weird spots/mottling on the rotor itself. After 30k miles, the original rotor scoring has worn down and is not so deep. Now two other rotors have newer/deep scoring. Is the scoring bad? Presumably it reduces braking performance marginally? Is it from tiny rocks/sand that get stuck between rotor and pad? Most of car's miles have been in winter including thousands of miles on black ice, sand, huge rock salt chunks. Car has the standard 17s .


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## Robby (Mar 1, 2013)

Using the handbrake to stop the entire car will cause the rear brakes to overheat themselves and the rotors. Parking brake is just that....for parking. Also known as a emergency brake......for emergency stopping in the event a brake failure.

All that to say the parking/emergency brake is not a service brake.

Brake rotor face wear and corrosion: The scoring is not abnormal. It results from highly metallic brake pads. Harmless though as the pad has corresponding score lines that, when applied, have full rotor contact.

Cannot comment on your described 'patches' till I see them.

Rob


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## Ma v e n (Oct 8, 2018)

Why would you not use the brakes to stop the car? I can't imagine a scenario where I'd want to use the parking brake to stop a normally function car before I used the brake pedal unless I was hooning.

Please just use the brakes. 

Whether the scoring is acceptable or requires service depends on the depth of the scoring. Pictures needed for further discussion on rotor condition

If I may ask...How old are you?


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## 91794 (Mar 25, 2015)

Super Rob, thank you for all the info as well as your well-thought opinion and questions and especially for your incentivization! But let's never mention "parking" again unless you come to Boston and attend my "clinic" (PM me!). 
I sure will let you know if the rear brakes overheat at 3F this week or 100F this summer now that I have your kind new incentive to apply the hand brake more vastly and more gratuitously. 
Btw, how do I know for sure if the rear brakes overheat and the fronts do not, or if both fronts and backs overheat, or if the fronts overheat and the backs don't overheat? Will the rotors glow orange or red? That will be totally awesome! Maybe I can photograph a red-hot rotor at speed with one of my old cellphones on a selfie stick. That would be a way better photo than a photo of a mottled rotor. 

Mave, I'd offer thanks but you have offered zero for me to thank you for, so not this time. 
Your first question contains implicit falsehood so there can be no real answer. IIUC, the handbrake uses two of the brakes so I am always using the brakes to stop the car despite you implying otherwise. I'm not Fred Flintstone but he sure did OK ! My understanding is that the rear brakes stop the car no matter whether handbrake or brake-pedal is applied. Your second sentence indicates a weak imagination, but I encourage you to step it up and see if you can imagine a use-case. And until you withdraw the question about my age you can remain 100% sure that I'm old enough to be your dad.


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## Ma v e n (Oct 8, 2018)

Eli said:


> Mave, I'd offer thanks but you have offered zero for me to thank you for, so not this time.
> Your first question contains implicit falsehood so there can be no real answer. IIUC, the handbrake uses two of the brakes so I am always using the brakes to stop the car despite you implying otherwise. I'm not Fred Flintstone but he sure did OK ! My understanding is that the rear brakes stop the car no matter whether handbrake or brake-pedal is applied. Your second sentence indicates a weak imagination, but I encourage you to step it up and see if you can imagine a use-case. And until you withdraw the question about my age you can remain 100% sure that I'm old enough to be your dad.


Please excuse my lack of precision in my speech. I am sure it is in some way related to my lack of imagination, which is in turn likely due to exposure to radon and plutonium.

Using the entire service braking system by engaging the brake pedal to affect a stop is the way to go. This allows the hydraulic brakes as well as the electronic system control to function.

Using only the handbrake results in significantly lower braking force being applied, not only due to the difference in force between the hydraulic apply system as compared the mechanical apply system engaged when using the handbrake. But also due to the fact that the front brake components have a larger diameter, larger swept area and have the benefit of the front wheels being loaded due to weight transfer under deceleration which increases contact patch size, and therefore friction. 

Utilizing the rear brakes via the handbrake in order to reduce wear on the front brakes is a foolish practice. The excessive wear which will be experienced by the brake cables and cable apply mechanism will incur cost which exceed any savings realized due to reduced front brake component usage.

The question regarding age remains, as I was taught it is only rude to ask a woman her age. And as I have no reason to believe you are in fact a biological woman, or identify or express yourself as a woman I see no reason to rescind my query based on social mores. Your age is irrelevant in your ability or likelihood to be my dad, and since I don't know your age I am simultaneously 100% sure that you are able to be my dad and 100% sure that you're not. Only knowing your age, or social security would enable me to verify with certainty either way.


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## 91794 (Mar 25, 2015)

Thanks Maven, that was an excellent reply seemingly void of plutonium or radon effects. May you & yours all remain free of such effects while also remaining younger and better looking than me. 

I'm aware that rear brakes apply less braking force to the road than the fronts and that the cable may stretch and need tightening or (aghast) replacement. That idea is indeed the sort of thing I was looking for in a reply, thank you. The 2017 cruze will not be my first car in which the parking^H^H^H^H^H^H^H hand-brake-cable has required tightening! I've rarely had a mechanic charge to tighten it - they tend to do it as a bonus in 42 seconds after they notice it. 

Were you aware before today that some cars have more rear-brake-bias than others and that some drivers prefer more or less rear-brake-bias and that some cars (trucks) had a valve on a brake line via which the brake-bias could be adjusted? 
In 40+ years of licensed driving my favorite car of 35 is Australian and has huge front rotors and TINY rear rotors, and massive rear brake bias under light-braking. It eats rear brakes much faster than fronts, hooray! Whether it extends life of brakes overall is an interesting question that may be difficult to define/measure/quantify and would seem to involve measuring brake pad & rotor thickness over years, and solving 2nd-order differential equations relating to the engineering tradeoffs. Automotive designers and computer/models do this math when they design braking systems for particular cars. Different cars, different goals, different tradeoffs such as "brake life vs brake performance". 

To specifically answer your original question, yes, you may ask my age. 
As for the gender stuff, there is only one gender that would consider this sort of absurdly nitpicky obsessively detailed analysis without being paid a fat salary to do so. The other gender(s) would tend towards saying "You guys are ridiculous. Get a life. Shut up and drive. Do not touch the handbrake while the car is moving or the next piece I break off will be your hand."


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## Robby (Mar 1, 2013)

Having read your response several times it appears you were not really asking a question or two.
The answers given by me were what you asked for.
Ambient temperature does not have much to do with brake pad crystalizing due to excessive heat at the rotor/pad interface.
This often evidences itself as squealing brakes on application.

Anyways, I have concluded you were looking for a battle of some sort.........sorry, I won't play.

Might want to check my bio.......I'm old enough to be YOUR father.

Rob


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## jblackburn (Apr 14, 2012)

Modern cars bias light braking towards the rear so the car doesn't nosedive. Once you apply harder, it begins to squeeze the front ones harder. 

Why in the world would you use the parking brake to slow the car in normal driving? 

Brake pads are cheap. Just drive the car like a normal person. 

Sent from my SM-G950U using Tapatalk


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