w124 front brakes wear more one side

[scottmcphee]

Driver's side is eating through brake pads at 2x the rate of the passenger side. Each pad pair is wearing equally per disc (inside and outside pads equal wear), so it's not a seized caliper on either side. Just that the driver's side now has no meat, has eaten clean through the pad sensor, while passenger side is about 50%.

Most recent are MBenz supplied pads. They give off a lot of dust and seem to be friendly to rotors, as the rotors are holding up about equally, but are both now under minimum limits and both due to be changed. SO that's on my list.

Stopping power is still fine, good and short, no funny brake feel or pulse. ABS kicks in sooner on the driver's side. It's obviously doing more of the work to stop. More dust.

When I lift the car after parking and spin each front wheel, there's no evidence of calipers holding firm on driver's side, wheels spin by hand freely.

I could just go through life doing pads more often... or I've heard of old rubber lines "valving" shut inside causing slow release. New hoses are on the list just to be sure.

Calipers causing this? Is the driver's sticking closed, or passenger sticking open? What's most likely here? They're both doing work and wearing, just one side 2x the other.

I got original Girling calipers on the car. A bit hesitant to throw these away to get reman Fenco's or whatever god knows what quality for $110 / side. Girlings are in good external physical shape, sans rust... is it worth me having them rebuilt and keeping them?

Other choices for calipers from online sites run the range of brands and prices right up into MBenz OE territory from the dealer. (I haven't checked that price yet but will sit down before I do.)

What's reasonable these days for w124 calipers out there?

[Diesel911]

I am sort of assuming that this is happening on the Front.

On sides Wheel bearings could be looser than the others.

The excessive but equal Pad wear could still be casued by sticky Caliper Pistons. Caused by the Calipier Seals loosing elasticity and not retracting the Pistons, Gunk in the Calipers or as you mentioned the Rubber Brake Hose "Valving".

Jack up the Wheel and have some one step hard on the Brake Pedal and see what type of resistance to rotation you get when the Brakes are released.

[scottmcphee]

Your assumption is confirmed in the title of the thread w124 front brakes wear more one side.

I don't understand what the bearings would have to do with this. Anyway, they're both recently done, smooth turning, and good. Wheels spin freely to a hand push and continue for 1/4 rotation after letting go... perfect, no resistance from the hub/bearing, or brakes for that matter, while parked.

I'll do as suggested and get a helper to use brakes as I check spin just after release. With car off, and then again running, see if there's any difference testing each way.

There's no brake fluid loss, I don't think the seals are weeping. Maybe one is packed with mud or crust that prevents good retraction, is torn, or is not as elastic as it once was 25 years ago. I have a close look at rubber when I go in with the pads.

For the money I'll get the caliper rebuild kit (rubber) to have on hand for re-doing seals and rings. If there's no obvious problem with the calipers / corrosion I will run them again resealed with a new set of pads, rotor, and hose...

[t walgamuth]

If the car is stopping true and not pulling I might be tempted to just live with it. Replacing calipers and or rotors will get expensive quickly.

Are your pads an exact match side to side? If you had different manufacturers one side might be harder.

Also is it possible someone else changed the caliper and pads on one side of the car and not the other?

[Zacharias]

My first though was that you have a partially collapsed flex brake line on one side that isn't allowing the caliper to release as fast as the other, incrementally increasing wear on that side. If it were a caliper issue that bad I would think you'd notice it when changing the pads...?

[tjts1]

Originally Posted by scottmcphee

Driver's side is eating through brake pads at 2x the rate of the passenger side.

Do you do most of your driving alone? If so, its normal. I would check the passenger side front brake hose to see if its bulging or leaking.

[Diesel911]

See if there is anything in the below site that matches:

FIXES FOR COMMON BRAKE PROBLEMS

[Alastair]

What state is the dust shield/backplate behind the disc in?

Damaged, holed or missing, and thats your problem....

[qwerty]

Originally Posted by scottmcphee

ABS kicks in sooner on the driver's side. It's obviously doing more of the work to stop. More dust.

One possibility is air in the passenger side brake line.

[scottmcphee]

The parts are equal, same pad brand all across, dust shields in place.

I'm thinking air or hose weakening power on the passenger side is most likely, next most likely is hose valving is causing binding on the drivers side.

Don't see how single occupancy would affect left / right wear... Can't tell me sitting on one side affects or requires more braking on that side. Not with the weight of a car behind you.

Also, whats the thinking on how would a missing dust shield affect wear?

[Zulfiqar]

loose bearings can cause this - I just repacked the bearings on my car and one side which used to black out a lot was the side with the super loose bearing. It causes the disc run crooked. It also causes the ABS (if equipped) to act real funny.

[scottmcphee]

Hmm interesting about loose bearing, I'll be careful to check not only free spin (which is fine) but also looseness of the thrust nut holding the wheel onto the axle. I guess some side/side and in/out tugging on the rim while jacked up that side will tell? Or do I have to uncompress the caliper away from the disc to tell...?

[scottmcphee]

Just changed the brake rotors and pads.

No loose bearings or any funny play. Smooth turning.

FYI - Old front brake pads just changed out were Mercedes parts, also marked "Pagid", and the tri-star logo and word "Mercedes Benz" on them. So I guess Pagid is an OE manufacturer for real.

The double worn side (driver's) had rotors that were down to 19.1mm (below the stamped 19.4mm minimum thickness), and the brake material on that side's pads was down to last 1-2 mm thickness, nearly on metal soon but still stopping the car like a trooper. Old rotors were Mercedes Benz branded part (logo). The less worn side rotor was about 19.8mm, and about 5-6 mm of material on pads.

I put in Zimmerman rotors and TRW pads.

The calipers were inspected, original Girling's. No rust. Both still floating nicely, not seized.
Both allowed the piston to be squished in easily with a C clamp, no binding.

I did notice some brake fluid moisture had oozed out of the affected side caliper near the piston as I was reassembling them. Might have had to do with the amount of travel all in one motion and less that perfectly square push with the C clamp (?). The fluid level in the reserviour is now reading back at the top/max line after the job, and I've never "topped up". So I'm not losing fluid there habitually.

The hoses are looking perfectly fine, no cracking, hardness, wetting, or anything. Mechanic friend says try new hoses too even though no visible signs of wear. Says they can inner restrict and cause delayed release action that adds up as extra wear over time. He also says that some cars just have a wear characteristic that you can't fight to solve. As a GM mechanic he says the right rear inner pad on their half ton trucks are famous for burning through a pad before anything else is worn.
(e.g. Rear Inner Brake Pad Wearing Out - Fullsize Truck & SUV - GM-Trucks.com)

Car is still stopping straight and true and ABS works with new parts in. Less grinding sounds on the driver's side, though ;-)

I held off on the fluid change, because I think I do a caliper rebuild on both sides, then fluids so I'm not doing that twice.

[Zulfiqar]

The wheel bearing play is best checked with caliper piston compressed and the wheel mounted back on, this gives you more leverage to rock the hub/disc.