Marginal Brakes On Modern Cars

[chimpvalet]

I've been running a '21 Nissan Rogue since new, now clocking about 15k miles many of which were easy highway. Just completed several trips inland over mountain passes where braking from over 70 mph was in order from time to time and over the journey the car developed a vibration felt more in the structure than in the steering wheel and not at all in the pedal when hauling down from those speeds. I'm no kid so rather judicious when running a bit hard, therefore it seems the brakes are a bit marginal. Thoughts?

[Chris_Hamilton]

Shuddering would indicate something mechanical as opposed to marginal. Fade would indicate that they were marginal.

[PackardV8]

Vibration upon application of brakes is often an indication of warped rotors.

If you're a DIY, put the front wheels off the ground, remove the tires/wheels and place a dial indicator perpendicular to the rotor face. Spin the rotor and observe any wobble. If the rotors are in otherwise good shape, it's sometimes possible to shim them back to plane.

FWIW, back in the bad old days of fixed calipers, shimming rotors was part of a brake job.

[FC-Pilot]

In the development world we could can change the rotor run out just by adjusting torque of certain lug nuts. The pulsating in the pedal is actually what we called DTV. (Disk Thickness Variation). Often the felt vibration is due to uneven thickness in rotors that is felt as they heat and therefore due to the uneven thickness in the cast rotors you get that pulsing. Then as they cool they cool in a “warped” fashion. The manufacturers have an internal struggles as the brake guys want thicker and bigger rotors, but drivetrain wants no rotors for weight and handling wants no rotors due to corner weight. It is a constant battle. Some manufacturers generally have better brake packages than others. The Rogue is not Nissans best offering for sure. But as least it is not a Toyota. Their brake packages are poor ( and I say that after working in the US development team for Toyota for 5 years). We had jutter so bad I. The trucks in testing we honestly thought we would damage suspension parts or even the frame. It would rip the wheel out of your hands.

Paul

[dfarr67]

My Accord was a POS, Hawk pads and EBC rotors fixed it but good.

[chimpvalet]

Getting some good feedback here, thanks!

We had a 2015 Accord Coupe which was generally a nice enough car and performed well but also produced the vibration when driven over the same mountain highway. I'd passed a series of cars while a passing lane was available and braking from about 80 MPH the most terrible drumming vibration arose, feeling like something big had broken in the front end. I've never experienced anything like it. After some further miles at a calmer pace I relaxed somewhat thinking it had been down to something in the brake temperatures, this confirmed further on down the road when again pulling down from speed. My veteran mechanic suggests it's perhaps a function of the many compliance bushings in the front end getting out of synch with higher braking forces. Seems worth a thought.

In any case both the current Rogue and that Accord stand as marginal in some measure when it comes to putting the brakes to work.

[Stranger]

Years ago when I was atca toyota dealership we would have cars coming in with brake shudder (mainly Camrys) after replacing tyres from the wheels being tightened with a rattle gun. Most of the time it was a simple matter of backing off the buts and doing them up with a torque wrench. The excessive cranking up from the ugga dugga gun was distorting the thin rotors

[modok]

I think some of it is from OE's prefering to use "low dust" ceramic friction material, because people don't like brake dust on the fancy wheels.
So the main problem is fancy wheels.
10-20 years ago I would advise to put on some metallic pads and let the rotors wear themselves straight, and that seemed to work just fine.
But at that time the rotors were so cheap they were almost disposable, it didn't even really make economic sense to turn them.
Or, just turn the rotors, IF it seems like they were decent. SEASONED rotors will stay straight better than new ones, just like flywheels and clutches, same way.
But if the problem is that the casting of rotor itself is uneven, then, it will just do the same thing again, so, when in doubt about that better to replace.
The cost of a new rotor would be the determining factor for me.
I can turn or grind rotors at home or at work so it doesn't really cost me anything, but my time and suffering has a value.

[PackardV8]

Today, the vast majority of replacement rotors are of chicom manufacture. The good news is most of them function well enough.

[FC-Pilot]

Today, the vast majority of replacement rotors are of chicom manufacture. The good news is most of them function well enough.

Yep. Most are oe grade or just under. Which means they are as crummy as what comes from the factory.

My old body style Tahoe falls into this category. It’s brakes were undersized to begin with, and then towing or driving poorly in traffic will get some judder at times. Nothing you can do without upgrading the whole front brake setup (which requires new spindles and everything which it’s not worth for a $2,000 truck).

Either tolerate it, change vehicles or driving styles. Engine braking helps greatly. We forget we can do that in our automatics these days.

Paul

[lefty o]

most peoples "warped" rotors is just pad material build up on the rotor itself. rebed the pads.

[PackardV8]

Engine braking helps greatly. We forget we can do that in our automatics these days.

Paul

Yes, No, Maybe, It Depends. With today's small V6s and turbo fours, downshifting just produces more noise, not more retardation.

[FC-Pilot]

Very true Jack!

Paul