# Rear brakes wear out - adjust brake balance?



## tmarino (Aug 15, 2004)

I've got a 2001 VW Jetta 1.8T with ABS. The car now has 90k miles on it. The rear brake pads wear out every 20k miles. The front brake pads have never worn out and, at last check 2k miles ago, are less than half worn. On top of this, I have to clean the brake dust off the rear wheels every two weeks whereas I never clean the dust off the fronts. This is backwards from every other car I've seen or owned.
It's obvious to me that this car has a problem with front/rear brake balance. But the service manual states that Jettas with ABS do not have a brake pressure regulator, the ABS performs this function. So the question is, what could be the problem with the brakes on this car and how can I fix it???
TIA,
Tony


----------



## phatvw (Aug 29, 2001)

*Re: Rear brakes wear out - adjust brake balance? (tmarino)*

Its not a problem, its actually by design. If you'd like to correct the brake balance, put some higher cF pads on the front axle only. Hawk HPS works well. Leave the rear with OEM pads.
Seems counterintuitive, but this will prolong the life of the rear pads and reduce ABS activation on hard stops.
If you'd like to learn more, I've written a couple articles about this specific issue: http://forums.vwvortex.com/zerothread?id=2357867


----------



## Mohudsolo (Feb 25, 2004)

*Re: Rear brakes wear out - adjust brake balance? (phatvw)*

Note that VW also specs two different pads, one softer and one harder. They put the harder ones on if someone complains about wear rate and the sofer ones on if someone complains about brake noise. I've had people try and convince me it is a feature but as far as I am concerned, it is just cheapness on VW's part. Note that lots of other cars do this too. It also means that if the ABS is not working, the brake balance is way off and spinning on low traction surfaces is a very good possibility.


----------



## tmarino (Aug 15, 2004)

*Re: Rear brakes wear out - adjust brake balance? (phatvw)*

No, it's definitely a problem. If it's by design then they need to fire their designers and get a whole new team. What kind of design puts big honkin beefy rotors in the front and then sets the brake balance so the puny rotors in the back (which I've now had to replace 3 times) take all the load???
This is the last piece of crap VW I'll ever own.


----------



## phatvw (Aug 29, 2001)

*Re: Rear brakes wear out - adjust brake balance? (tmarino)*

My Gillette Mach3 razor is dull after 2 or 3 shaves - but I keep buying more...


----------



## Mohudsolo (Feb 25, 2004)

*Re: Rear brakes wear out - adjust brake balance? (phatvw)*

Do all three blades get equally dull or is there a blade balance issue?
I've seen all sorts of reasons given in press releases, brochures, etc about why the lack of a proportioning valve is "feature" rather than a cheapening of the brake system. I've yet to see one that actually makes any real sense. I'll also bet there are more new cars being built today without a proportioning valve than with. If anything goes wrong with the ABS system and it shuts down, the rear brakes will be locking up first. This would seem to be a no-brainer for an ambulance chaser but what do I know.


----------



## phatvw (Aug 29, 2001)

*Re: Rear brakes wear out - adjust brake balance? (Mohudsolo)*


_Quote, originally posted by *Mohudsolo* »_Do all three blades get equally dull or is there a blade balance issue?
I've seen all sorts of reasons given in press releases, brochures, etc about why the lack of a proportioning valve is "feature" rather than a cheapening of the brake system. I've yet to see one that actually makes any real sense. I'll also bet there are more new cars being built today without a proportioning valve than with. If anything goes wrong with the ABS system and it shuts down, the rear brakes will be locking up first. This would seem to be a no-brainer for an ambulance chaser but what do I know.


The center of each blade wears out first because it cuts more whiskers due to the contour of my face So I'm wasting the edges of the blade








I totally agree with you. They could have easily shifted the bias forward a little, but I suppose its more important to optimize for full load scenario where the extra weight has a bigger impact on stopping distance and handling? 
Also I reckon all that testing at the super-cool Bosch facility in Northern Europe shows that the ABS electro-hydraulic control units are more reliable than the mechanical proportioning valves. Just look up posts in the MkII forums about folks having trouble adjusting their valves. BTW I don't think the failure mode of a proportioning valve is particularly great either.

Just thought of something - are there any cars that have both ABS and a separate mechanical valve? Maybe on the old 2-channel/3-channel ABS systems from the Late 1970's/Early 1980's?



_Modified by phatvw at 8:09 PM 2-18-2008_


----------



## a2gtinut (Dec 2, 1999)

*Re: Rear brakes wear out - adjust brake balance? (phatvw)*

modern cars have electronic brake prop. valve which works together with ABS.
In old cars with out ABS rear brakes were made "weaker" for safety.
With modern ABS systems, rear brakes can do a lot more braking and at the same time do "anti-dive". Side effect is rear brakes wearing out faster than in older cars.
BTW. this electro-hydraulic system is so good







that Benz had to redesign their cars (R , ML, GL) to have standard hydraulic brakes. Those cars were originally designed to have electro-hydraulic brakes but after discovering reliability problems in E class, they stopped development of this system. Siemens VDO now part of Conti developed "wedge" caliper. but this is topic for another thread.


----------



## phatvw (Aug 29, 2001)

*Re: Rear brakes wear out - adjust brake balance? (a2gtinut)*


_Quote, originally posted by *a2gtinut* »_
BTW. this electro-hydraulic system is so good







that Benz had to redesign their cars (R , ML, GL) to have standard hydraulic brakes. Those cars were originally designed to have electro-hydraulic brakes but after discovering reliability problems in E class, they stopped development of this system. Siemens VDO now part of Conti developed "wedge" caliper. but this is topic for another thread.

Are you talking about an electro-hydraulic brake caliper? Is that the same as "brake by wire" or "sensotronic" - everything seems to be -tronic these days eh?
Anyway the ABS control units are all still electro-hydraulic and protected under the dashboard right? No vibration and road grime to worry about there


----------



## tmarino (Aug 15, 2004)

*Re: Rear brakes wear out - adjust brake balance? (a2gtinut)*

My statement still stands:
"What kind of design puts big honkin beefy rotors in the front and then sets the brake balance so the puny rotors in the back (which I've now had to replace 3 times) take all the load???"
If you design a system that puts more load on the rear brakes, then design the rear brakes to take the additional load. Brake wearout every 20 ~ 25 kmiles is nowhere near acceptable.


----------



## a2gtinut (Dec 2, 1999)

*Re: Rear brakes wear out - adjust brake balance? (phatvw)*


_Quote, originally posted by *phatvw* »_
Are you talking about an electro-hydraulic brake caliper? Is that the same as "brake by wire" or "sensotronic" - everything seems to be -tronic these days eh?
Anyway the ABS control units are all still electro-hydraulic and protected under the dashboard right? No vibration and road grime to worry about there










ABS module is under the hood. Benz canceled their brake by wire system for ML, GL, R, and others.
regarding small rear rotors- thermodynamics and not so perfect weight distribution on VWs.
THERE IS NOTHING WRONG WITH THIS DESIGN. 
if you look at (ex. BMW) car with 50/50 split hen rear rotors are not vented (may or may not) and they are bigger in size and as big as front.
Front end heavy VW-small in the rear.
Do you understand vehicle dynamics?
Under braking rear tires become unloaded and big rear brakes are not needed. So stop trying to redesign something that you do not understand.


----------



## Darkgryffin (Jul 1, 2009)

*Re: Rear brakes wear out - adjust brake balance? (a2gtinut)*

"Under braking rear tires become unloaded and big rear brakes are not needed. So stop trying to redesign something that you do not understand"
Ok, so the design needs no improvement, but the rear pads, now on my 08 Jetta, are worn out at 34k. So if there is nothing wrong with the design, why are they wearing out so quickly, and so unbalanced from the front pads and rotors?


----------



## germancarnut51 (Mar 23, 2008)

*Re: Rear brakes wear out - adjust brake balance? (Darkgryffin)*

I think the point that needs to get across here (that has already been stated) is that: On modern cars with ABS braking systems by design, the rear brakes are now able to contribute more to the overall braking force available than on earlier designs where the front brakes did most all of the braking. On those early cars, the rear brake material, whether drum shoes or disc pads lasted much longer.
Newer design cars with ABS systems are able to brake harder and stop shorter than earlier designs without ABS, and as a result, the rear brakes no-longer last as long.
BUT, people have become spoiled to read brakes last a long time, you used to be able to put a long wearing low noise rear brake in, and it lasted forever. But now, people are still using the cheap rear brake shoes or pads and are complaining about short brake life.
The ANSWER? Use high quality rear brake shoes or pads (equal or better than that used on the front brakes), and drive smoother without roaring from traffic signal to traffic signal and stomping on the brakes.
Facts of life. Cars with ABS braking systems will have shorter usable rear brake service life than cars without ABS rear brakes. AND, brake shoes and pads DUST. That's a part of driving. If you don't like brake dust, don't drive your car. 


_Modified by germancarnut51 at 9:54 AM 8-30-2009_


----------



## dr_spock (Feb 16, 1999)

*Re: Rear brakes wear out - adjust brake balance? (tmarino)*

Replace your rear rotors and pads with drum brakes. They'll last a lot longer than rear disc brakes that are exposed to the environment and gunk that the front wheels throw towards the rear of the vehicle. And with drums you don't have to worry about cleaning brake dust off the rear wheels.








You can also try the harder OEM VW pad in the rear. They'll take longer to wear down than the soft version of the OEM pads and generate less dust. I installed them on mine last year and there is no layer of black dust between car washes. The down side I get noise when there is rust on my rotors but that usually goes away after a couple of braking stops.


----------



## GTijoejoe (Oct 6, 2001)

*Re: Rear brakes wear out - adjust brake balance? (tmarino)*


_Quote, originally posted by *tmarino* »_My statement still stands:
"What kind of design puts big honkin beefy rotors in the front and then sets the brake balance so the puny rotors in the back (which I've now had to replace 3 times) take all the load???"
If you design a system that puts more load on the rear brakes, then design the rear brakes to take the additional load. Brake wearout every 20 ~ 25 kmiles is nowhere near acceptable.










I completely understand your fustration, and I agree that the RR worn pads is an issue. Although you don't even understand anything about the bias, your making an uneducated visual inspection...since we weren't included in the design, we dont undertand the obsticals they encountered. 
For example, do you perfer dusty brakes over annoying ear piercing noise?
Noise is some of the highest warranty claims, so the design will always choose increased wear over noise....wear is normal, noise is not.
OEM vehicles by design are not easy to dimension, unlike race cars where the weight and decel levels are always the same (neglection of downforce) and no body cares about noise and brake dust. 
A passanger vehicle is always a balance, a compromise of many different factors. Since your decel range will vary 0.1-1.0G and your weight will vary curb weight to GVWR ~+600-1000kg its very difficult to design a brake system that will be able to operate safely and efficiently within that entire range to perfection. Than you even add GCWR in there and combined with towing weight.
One of the factors that no body has mention is not bias but pad area. Pad area will greatly effect the wear characteristic, but in design its difficult to countermeasure on 1pot calipers, super large area with only a single small piston makes all kinds of other problems, so its always easier to change friction compound. But like everything else in a brake system there is no special friction, you can't have it all. Changing to a harder compound will also not give the cold bite performance that a OEM vehicle needs, and harder compounds are notorious to noise......


----------



## spitpilot (Feb 14, 2000)

*Re: Rear brakes wear out - adjust brake balance? (GTijoejoe)*

Hey...look on the bright side..pads and rotors for the rear are signifcantly cheaper than the fronts...you're savin $$'s by not having to replace fronts twice as often as rears (that's the ratio my ol Golf with drum rears had..replaced pads twice, rotors once..brakes shoes once drums never...in about 110K miles of ownership)...Of course it didnt' stop with anywheres near as quick as either my Passat or Rabbit..


----------



## 2000Jet1.8T (Mar 25, 2009)

You shouldn't have to change the pads at 20k. Even though they wear quicker than the fronts (which I have no problem with) they should last at least 40k. So, maybe there is something wrong. As far as expense is concerned I'd take changing the rears more often than the fronts any day.


----------

