Premature rear brake rotor wear

[HeyBales]

If you do a Google search for rear brake pads wearing faster - you'll see many forum entries for all kinds of cars for decades ago, and nothing to do with hybrids.
That's when I discovered it, at least 10 yrs ago.
Light braking is the culprit - which the hybrid just encourages.
Well, and smaller pad depth usually on rear, so it's actually noticeable.

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[MakinDoForNow]

If you do a Google search for rear brake pads wearing faster - you'll see many forum entries for all kinds of cars for decades ago, and nothing to do with hybrids.
That's when I discovered it, at least 10 yrs ago.
Light braking is the culprit - which the hybrid just encourages.
Well, and smaller pad depth usually on rear, so it's actually noticeable.

Yes to light braking in past. I had more than one friend over years who would drive with foot on brake pedal supposedly not pressing it until needed. They invariably need brake work in 1/3 +/- % time of the expected frequency.

 

[Cherokee]

I’d ask my Ford dealer at my next service then reported back in here on what they said.

 

[Cougar70]

I haven’t read every post in this thread, so what I’m thinking may have already been suggested.

As you’re slowing down, initially when you take your foot off the gas pedal, the regen is effectively braking, then when you actually put your foot on the brakes, the regen is still active and is working to slow the truck from the front wheels where the regen generator is connected and the actual application of brakes is more on the back brakes.

I would think this wear on the back brakes would be increased when actively trying to use the regen system and when using a drive mode that favors the regen system to slow the truck down.

Couple these actions with “inexpensive” rear rotors and I can see them wearing in a way that would be considered premature.

I’m curious if with a 25 hybrid AWD that in AWD, whether the regen braking works on all wheels or if it only works to same as the FWD hybrids.

 

[todd92]

The rotors scoring and wearing has nothing to do with the rear brake pads wearing faster than the fronts. If the road salt is Magnesium Chloride it will absolutely destroy brake rotors if the vehicle is not frequently washed.

 

[Cougar70]

The rotors scoring and wearing has nothing to do with the rear brake pads wearing faster than the fronts. If the road salt is Magnesium Chloride it will absolutely destroy brake rotors if the vehicle is not frequently washed.

I’m sure that type of road salt can affect a brake rotor, but you normally expect something like that to affect both front and back rotors somewhat evenly.

And it sounds like it’s affecting more than just people’s trucks in salt environments.

 

[greycat]

Yes to light braking in past. I had more than one friend over years who would drive with foot on brake pedal supposedly not pressing it until needed. They invariably need brake work in 1/3 +/- % time of the expected frequency.

I'd hate to be stuck behind that person.

 

[MakinDoForNow]

I'd hate to be stuck behind that person.

In HS there were 635 in my graduation class and not sure how many but about 10-12 seemed to be doing this, so say 1-2% of drivers. But who knows for sure. There were several over the next 30 years who complained of rear brake wear. The rear brakes are normally applied first and/or at greater pressure to help prevent "fishtailing" (the main reason if you only purchase two tires the shop will normally recommend the better tread is on the rear wheels, better grip for ice/water hydroplaning).

 

[HeyBales]

So I did some slippery brake testing, well in normal too first.

Whether I was coasting, or braking lightly at top of regen, or aggressively in bottom of regen.
There was at no time brake pressure to any brakes, including the rear.
So regen was only regen.

I'll have to review the logs for an instance of hitting the brakes harder to pop out beyond regen, to see the wheel axle application.

Now what I did see - is when you reach that final 10 mph and the pads start getting pushed in and even more about 5 mph and less.
The rear has more pressure initially applied and kept higher until stopped.
This I'll have to compare with Normal to see if it happens then.

It was never a big difference - but it was there. Like this. Some of the differences is for sure the laggy time of readings from ABS module. But rear always higher than front. This was a straight stop, not a corner.

 

[ricklee4570]

I am interested to see if this is a rare occurrence or will most of us experience accelerated wear?

 

[jdavidr]

So I did some slippery brake testing, well in normal too first.

Whether I was coasting, or braking lightly at top of regen, or aggressively in bottom of regen.
There was at no time brake pressure to any brakes, including the rear.
So regen was only regen.

Awesome data, thanks so much. Good to know that the regen green zone achieved by pressing the brake pedal isn't actually riding the brakes, even in slippery mode.

Any chance you could collect some data using the L button to "brake"? My impression is that hitting the L button with your foot off the accelerator and off the brake performs the equivalent of precisely pressing the brake pedal to maximize either regen or engine braking (depending on the state of the hybrid battery charge) without actually using the brakes.

The left dial gauge seems to indicate that's what it's doing, as it will pin the needle right at the edge of the green zone... but given our brake wear, and the amount I use that L button to slow down (quite often), I'm now skeptical.

BTW, it seems you have to be going above ~10-15mph for the L button to do what I'm describing.

 

[MakinDoForNow]

Awesome data, thanks so much. Good to know that the regen green zone achieved by pressing the brake pedal isn't actually riding the brakes, even in slippery mode.

Any chance you could collect some data using the L button to "brake"? My impression is that hitting the L button with your foot off the accelerator and off the brake performs the equivalent of precisely pressing the brake pedal to maximize either regen or engine braking (depending on the state of the hybrid battery charge) without actually using the brakes.

The left dial gauge seems to indicate that's what it's doing, as it will pin the needle right at the edge of the green zone... but given our brake wear, and the amount I use that L button to slow down (quite often), I'm now skeptical.

BTW, it seems you have to be going above ~10-15mph for the L button to do what I'm describing.

I use L button to maximize Regen from 65-70 mph quite frequently.

 

[HenryFord]

This is a rather disturbing thread if this turns out to be a common issue. Chewing up brake pads every 30k is not my idea a of a good time.

 

[HeyBales]

I am interested to see if this is a rare occurrence or will most of us experience accelerated wear?

If you do the Google search I suggested - you'll see you will likely experience this as many have been for over the last 10 yrs on all makes and models.

Probably less than them though, since our brakes really only brought on at the end if doing regen decently.

If you are always gently just barely going past regen into the pads - then probably faster wear will occur. Back off just a bit.

 

[HeyBales]

Appears it could be a strong result of slippery mode.

Normal mode braking within the regen area also causes no brake pressure.
But when you get slow enough for it to occur - the axles that get the most pressure are different than in Slippery mode.
This was pretty consistent among the stops, and as the pressure was increased the difference remained.
Again - only talking from about 5mph to stopped.

Now - mid-drive braking at 35 mph hard enough to grab pads, not really the same thing.
Still not talking really hard here just enough to go past regen, only down to 28 mph while no one happened to be behind me. Here's a snippet, close enough pressure, though perhaps swapping from front to rear.
I'll for sure include this in my drive mode braking tests. Still trying to figure out how to make the differences due to drive mappings stand out.

Also - here's why I know it's laggy from the ABS to the display or log file.
Slowdown braking about 13 mph the front brakes do get pressure while the back get nothing.
Around 8 the rear's are brought in.
But you can see from the diagonal effect the millisecond delay.
The fronts still came on first in Normal mode. The backs in Slippery mode, with a difference in pressure.

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