Rear Brakes Wearing Faster than Fronts

[srmmmm]

Do you tow? I found the more miles I tow during a year, the higher the wear rate on the rear pads. It's usually a 1300 pound PWC trailer on my hitch so there are no trailer brakes.

2002 X5 3.0 332,700 miles
2014 428i 33,000 miles

2004 325i sold at 123,600 miles
2001 325i sold at 66,000 miles

1970 Firebird Under Restoration

[andrewwynn]

That makes a lot of sense


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[PropellerHead]

Originally Posted by 14thbmw

Lots of use of traction control can wear the tears faster then the fronts.

This.

At the BMW Performance delivery center, I have visited (more to visit friends than to get a car- which is only twice) and spoken many times with both delivery specialist and the professional drivers. They cite the continuous interaction with traction control as a cause for rear pads to wear out more quickly than the fronts. And that makes sense if you think ab it.

The rear is usually the end that traction control is trying to wrangle in. It doesn't have to be from aggressive driving- or what we consider it necessarily. Any time you're in a situation in which the physics might require a little rear brake input to keep it from swinging around is a fine candidate for uneven wear on the rears. Think a clover leaf in the rain, a heady left across an intersection with lots of imperfections on the pavement, or even a nice heavy transfer of weight from back to front that lets those rears come juuust enough off the street to loosen grip. The traction control system sits there listening for a chance to squeeze in just the right place and it does it. Often- my bet is most often- we don't even know.

Alas, the OP's experience mirrors my own across nearly 20 years of electronically-nannied Bimmers (17 years with 1 E53, 7+ with each of the other 2). My rears almost always wear out more quickly. In my 1975 '02, the fronts would wear much more quickly.

And there are plenty of others who find the same thing. For as many different drivers to experience the same thing drives home the notion that similar systems in common are the cause.

Premature Rear Brake Pad Wear From Bimmerfest

brake wear (front vs. rear) From E90 post

Searches can reveal more.

[Fifty150hs]

Originally Posted by srmmmm

Do you tow? I found the more miles I tow during a year, the higher the wear rate on the rear pads. It's usually a 1300 pound PWC trailer on my hitch so there are no trailer brakes.

2002 X5 3.0 332,700 miles
2014 428i 33,000 miles

2004 325i sold at 123,600 miles
2001 325i sold at 66,000 miles

1970 Firebird Under Restoration

No, I never tow. Anyone have any other ideas?

[PropellerHead]

Originally Posted by Fifty150hs

No, I never tow. Anyone have any other ideas?

You are experiencing 'normal'. Don't fret. Drive!

[andrewwynn]

+1


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[Fifty150hs]

Originally Posted by PropellerHead

This.

At the BMW Performance delivery center, I have visited (more to visit friends than to get a car- which is only twice) and spoken many times with both delivery specialist and the professional drivers. They cite the continuous interaction with traction control as a cause for rear pads to wear out more quickly than the fronts. And that makes sense if you think ab it.

The rear is usually the end that traction control is trying to wrangle in. It doesn't have to be from aggressive driving- or what we consider it necessarily. Any time you're in a situation in which the physics might require a little rear brake input to keep it from swinging around is a fine candidate for uneven wear on the rears. Think a clover leaf in the rain, a heady left across an intersection with lots of imperfections on the pavement, or even a nice heavy transfer of weight from back to front that lets those rears come juuust enough off the street to loosen grip. The traction control system sits there listening for a chance to squeeze in just the right place and it does it. Often- my bet is most often- we don't even know.

Alas, the OP's experience mirrors my own across nearly 20 years of electronically-nannied Bimmers (17 years with 1 E53, 7+ with each of the other 2). My rears almost always wear out more quickly. In my 1975 '02, the fronts would wear much more quickly.

And there are plenty of others who find the same thing. For as many different drivers to experience the same thing drives home the notion that similar systems in common are the cause.

Premature Rear Brake Pad Wear From Bimmerfest

brake wear (front vs. rear) From E90 post

Searches can reveal more.

Thanks!

[andrewwynn]

Great feedback


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[bcredliner]

Pads do not wear the same on rear, front and AWD vehicles. Pad wear is not necessarily the same when comparing different model or years of X5s.

Some vehicles understeer and some oversteer. The X5 understeers when traction limits are exceeded. If traction limits are exceeded as long as speed is constant or increased, regardless of the how much the steering wheel is turned the X5 will not turn. When that happens the inside rear wheel will brake to offset the understeer, changing the X5 to a balanced condition resulting in safely making the turn. The system reacts to traction changes in milliseconds and most of us let off the throttle so the understeer condition is eliminated very quickly. The pad wear increases depending on what condition is induced and of course the frequency that takes place.

With stock X5 suspension and tires it is extremely difficult for circumstances to cause an oversteer condition. Using your example, if the rear tires lose traction the rear of the X5 would start to rotate, spin out (oversteer). It that were to happen the stability control would apply braking to the front outside wheel.

Brake bias, which is the % of braking by the front and rear wheels, can cause differences in pad wear. Even calipers and size pads front to rear are a factor. Bias setting is set to maximum its contribution to the shortest possible stopping distance.

Towing can change how much the front or rear pads wear. But, what happens to some degree depends on the circumstances such as towing weight, trailer, train speeds etc.

If you read threads about pad wear there is seldom agreement on whether the front or the rear wears faster. It's because of all the reasons about and several more not mentioned.

Traction control involves wheels spinning under acceleration. Electronic stability control is the system that addresses under/oversteering condition.

[PropellerHead]

Originally Posted by andrewwynn

Great feedback

Thanks. I am glad you guys found helpful the first hand experience across many years and nearly 300 *thousand* miles across E53 X5's. Even srmmmm's 322k miles over 15 years of experience is in line with higher pad wear in the rear. Towing or not, the principles of different input needed at different times for the rear are applicable. I dunno about his memory, but across that much time and brake services, I don't even *know* how many times the rear sensors clipped before the front.

So often, we consider it 'normal'.

I am also happy that you found helpful the direct insight from others who used E53's and other BMW's every single day and *millions* of miles as their *job* in boring environments like a shuttle from the museum and extreme ones like the track. Both duties met and exceeded the experiences of those who own and love them so many years later.

We've got more than a few of us who have this direct experience on the E53, but the common thread to their experience is because the forces at work and the application of them know no specific chassis. They know only what they are programmed to do to correct *any* input needed at the rear wheels *every* time they're called upon. This uneven application of brakes across any chassis at any time will cause uneven wear, and has done so- as you and many, many others have directly experienced. Nothing like observation to establish experience.

For a travel back in time, here's a couple pics of the stable at the BMW Performance Delivery Center *fifteen years ago* when we took delivery of the E46 there. Yep, that's a crispy new 4.6is alongside an E65 and a very. very pretty E39 M5. All the rage of the day- and even moreso, the E46 M3's that were everywhere.