Heavy or Light Braking

[MiketheEngineer]

Will you get more brake and tire wear if you quickly apply the brakes or "drag" them coming to a stop say from a set speed of 50 mph??

Obviously - the slower method allows aero and engine braking to help out longer but all things considered - does it make any difference? The theoretical work is the same - so would not the wear be the same??

Just a dumb old Structurual here that likes fooling around with old cars.

 

[evelrod]

Well, we have danced about the issue sufficiently...In my experience, an automobile or truck that is "lightly used", i.e., no high speed stops or 'aggressive' driving tend to have their brakes last many thousands of miles further than industry 'norms'. I come by this from personal observation and from the observations of my racing sponsor, a tire and auto center.

Obviously, many other factors enter into the equation, not the least of which is "engine braking". Cars driven gently will usually outlast ones that are driven aggressively.
Exceptions to the 'rule'? You bet, especially considering the desperate build quality of some aftermarket parts.

Rod

 

[patprimmer]

I have seen a difference of 400% between brake wear on cars with hard and soft drivers. There are many factors including number of brake applications and total speed reduction as well as engine braking, aero and drag proportion of braking effort and instantaneous contact surface temperature and pressure.

Regards
Pat
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[izzmus]

On the flip side, in certain climates, people who always brake lightly will have to replace their brake rotors and pads once per year or so, because they never burn overnight rust all of the way off. Rear brake rotors on small cars are the worst for this.

I make a point to get the brakes nice and hot about once a week. I never have rotor rust issues.

 

[dgallup]

How does that increase rotor life?

 

[NormPeterson]

Perhaps the little dislodged rust particles are more abrasive than the pad material that scrapes them off?


Norm

 

[HRHtex]

Or the slightly pitted surface on the disc caused by the rust?
Slightly off the subject - the early model VN Commodores have noticeably shorter brake pad life than comparable cars due to the lack of engine braking caused by the overdrive top gear in the automatic gearbox.

 

[FeX32]

Of course being light on the brakes dissipates less energy per unit time. Thus, less wear should be induced.

But my VW pads certainly get hot now and then ..... especially after the turbo was a whining.


Fe

 

[FeX32]

BTW, the average material removal rate (assuming linear abrasive model) is dependent on 2 factors => The velocity, and pressure applied. Keeping pressure down significantly reduces MMR.


Fe

 

[Jimwahhh]

Do you think heat plays any significant role? I am typically a light braker, but say on a large hill where engine braking is not enough I try to do small bursts of braking rather than sustain a lesser pressure the entire way so the heat can dissipate. I was told to do this when I was learning though the reason was more that the lower temp is less likely to distort the rotor.

 

[MacGyverS2000]

BTW, the average material removal rate (assuming linear abrasive model) is dependent on 2 factors => The velocity, and pressure applied. Keeping pressure down significantly reduces MMR.

Wouldn't keeping pressure down simply mean you have to apply a lighter pressure for a longer period of time?

Dan - Owner

http://www.Hi-TecDesigns.com

 

[FeX32]

You are right Dan. That's what it's MMR in g/min for example.
It is usually not linear, from my understanding. As we heat the material the rate of removal of particles also increases.

So say the MMR in braking from 50mph to 0 in 5 seconds is 12mg/min, the MMR for braking from 50mph to 0 in 20 seconds may be 8g/min.
This is my understanding of this.


Fe

 

[rmw]

First off, brakes and brake parts are cheap compared to engine, transmission and driveline parts, so saving a little brakes by a lot of engine braking is false economy. That doesn't mean I don't do it-I just know that it is false economy when I do, but it was the way I was taught. The wife on the other hand, maintains her foot on the fuel feed until the moment she has to throw on the brakes. Maddening.

Second, The difference in the 'braking per unit time' concept mentioned above is heat. Heat is usually the enemy of most everything. I think I remember that the wear rate of brake material goes up significantly as material temperatures increase.

If you are asking this question because you have drum brakes, the cooler you keep the drums, the longer you have brakes. If they are Disc's, then the preceding doesn't hold true.

If you have an older vehicle and you haven't changed the brake fluid in your lines and calipers (or cylinders) heat can boil the moisture that your brake fluid absorbs and then you have no brakes whatsoever. I've had that fun at least twice in my life at the most inopportune times, usually on some mountain pass with a vicious name like Wolf Creek Pass or one of his sisters. Terrifying.

Funny how the thread changed from technical to philosophical a while back.

rmw

 

[evelrod]

Threads tend to do that on any tech subject that is rather 'open ended', leaving much room for interpretation. In this case, I don't see all that much difference in the tech and the philosophical.

Funny, though...your first paragraph sounds like me in the late 50's talking to my 50 something year old dad!!! I was into sports car racing where brakes were much better than production cars of the era. Now, all I drive are antiques in which I always "gear down"...Full circle...bet he's smiling.

Rod

 

[rmw]

Rod,

You have become your Dad.

rmw