[Scudetto]

If there’s one thing that’s really getting on my wick about my Merc, it is its ability to eat front brake pads.

Even though how it’s driven is consistent (slowly, circa 6k a year), its brake pad life is arbitrary. Sometimes, they last 12k. Sometimes 8k. Most recently, the Front pads and the pad wear sensor were replaced in Jan this year. Now, 5k later, and the brake pad warning light is on again. I’m always changing front brake pads on it. Why?

My route to work is five miles. A third of it is stop start traffic.

My route home is maybe seven miles (due to a detour). Two thirds of that journey is stop start. Ok, so I am on the brakes a lot.

But my mate does the same journey in his 2009 E Class - which is much faster and heavier than my car - and since he bought the car in 2018, it’s still on the same front pads.

I’ve never owned a car that munches brakes like this one does. Even if the crummiest brakes available were put on it, surely they’d last more than a few k? Ok, the cost to replace the pads isn’t that much, but I see the pad warning light flash more the low fuel light.

Any suggestions?

 

[Sterzo]

Change the front discs?

 

[symon]

I think the bit where you said that you were on the brakes a lot might have something to do with it.

However that does seem like an excessively short life. The ones I put on the front of our Giulietta look about half worn, and that is after 40,000 miles of fairly spirited driving. We have seemed to get a similar life out of pads on other cars too. Generally I fit half decent OE type pads like Pagid, Textar etc.

Maybe it is a design issue on the Merc? I bet you have lots of dust also.

 

[Scudetto]

Sterzo, the front discs were changed two years ago (circa 12k-ish)

Symon - here’s a pic about one week after it was washed. You can see brake dust already seeping out between the fins. At a guess, that’s 100/120 miles from pristine clean wheel trim to what you see here.

Maybe stop start/stop start driving can be that ruinous to brakes on an auto. But still...

 

[symon]

Have you ever stripped and cleaned the calipers? They might be sticking slightly.

 

[keithyboy]

That does seem like excessive. I don't think I've ever changed pads twice on a car. I've haven't done it once in 15,000 miles in my Saab.

 

[Harvo]

Autos are a bit harsher on the pads but saying that I've done 25k in the 2 tonne Elgrand and the pads are still going strong.

Maybe stop driving it like you stole it Scud?

 

[Scudetto]

Thanks chaps. Maybe the callipers are sticking. Wonder if the sensor has gone a bit nuts? Can’t imagine how though. Anyway, it’s in for a service this week so will bring this up then. Let’s see what that reveals.

 

[Ralf S.]

The most likely thing to go wrong is, by definition, the most likely thing to go wrong.

You have a "vintage" (aka old banger) Merc' so I'd bet any amount of money that your brakes are no longer performing with the supple ease of movement of a 12 year old Swabian gymnast. There's likely to be any or all of; sticky pistons, seized pins, degraded brake lines and corroded calipers.

Ergo, you need a brake overhaul to make sure the beast is grabbing the brakes like a good shephard dog, rather than a moody rottweiler (i.e. it has to "let go" afterwards).

Take the calipers off and fit new flexy pipes, whether yours look in good nick or not. If they're 1991 vintage then they're likely to be falling apart anyway so this is money well spent. If you had a sensible Italian car then they'd cost a tenner each. Old Merc... I'm guessing fifty for the pair.

Dismantle the caliper. If the piston looks pitted and rusty, put a new one in there. Fit new seals. If this sounds like a recipe for an epic car crash/a lot of faffing around/"it costs nearly as much as a rebuilt caliper.." then fit a rebuilt/refurbished caliper... old caliper body but brand new everything else. £80 each.

Take out the sliding pins and marvel how what looks like a pair of rusty nails managed to support the braking energy of your car. Clean out the slides with WD40, a thin rag on the end of a straightened out wire coat-hanger. Buy new pins (tenner a side) and fit them in there with the proper white brake grease (suppled) and new bellows (ditto).

Take the pads out of the caliper/frame and check the springs/anti-squeal looks okay. You may or may not have had new ones with the brake pads you bought in July, so they should be in fairly new/good nick. Poke out the pads and make sure they are "loose" in their mounts. They should fit in and fall out with minimal pressure.

If they're jammed (cheapo pads.... naughty, naughty!) or corroded, get a file out and grind them down till they fit in and out with minimal pressure. Better still, fit Brembo or Ferodo pads that actually have a plate that's accurately cut/shaped. Use copper grease on the ears of the pad and on the anti-squeal springs.

Have a look at the wear indicator sensor on the pads. If it's fitted half way up the pad, rather than near the backing plate then that's why your light comes on so often - the pads are only half worn. If you use quality pads then the sensor is probably in the right place.

Anyways.. fit it all back together again, bleed the entire system (not just the front brakes) and then off you go. If your fuel economy suddenly improves and your car gained "an extra 20bhp" then your pads were sticking for any reason you just cured and it's all good now. If the wear is exactly the same, then sadly it's your driving style and I can't help you with that one...


Ralf S.

 

[Ralf S.]

One more thought.. if your brakes are "serviced" by a garage... when you fit new ones, get some yellow enamel paint and put a big stripe on the back of each pad. Just curious if the next set of "new pads" have a coincidentally identical mark on them. Could be your mechanic is just fertling the old ones a bit but not actually replacing them, particularly ifthe sensor goes off when there's loads of pad material still left.

 

[Scudetto]

The most likely thing to go wrong is, by definition, the most likely thing to go wrong.

You have a "vintage" (aka old banger) Merc' so I'd bet any amount of money that your brakes are no longer performing with the supple ease of movement of a 12 year old Swabian gymnast. There's likely to be any or all of; sticky pistons, seized pins, degraded brake lines and corroded calipers.

Ergo, you need a brake overhaul to make sure the beast is grabbing the brakes like a good shephard dog, rather than a moody rottweiler (i.e. it has to "let go" afterwards).

Take the calipers off and fit new flexy pipes, whether yours look in good nick or not. If they're 1991 vintage then they're likely to be falling apart anyway so this is money well spent. If you had a sensible Italian car then they'd cost a tenner each. Old Merc... I'm guessing fifty for the pair.

Dismantle the caliper. If the piston looks pitted and rusty, put a new one in there. Fit new seals. If this sounds like a recipe for an epic car crash/a lot of faffing around/"it costs nearly as much as a rebuilt caliper.." then fit a rebuilt/refurbished caliper... old caliper body but brand new everything else. £80 each.

Take out the sliding pins and marvel how what looks like a pair of rusty nails managed to support the braking energy of your car. Clean out the slides with WD40, a thin rag on the end of a straightened out wire coat-hanger. Buy new pins (tenner a side) and fit them in there with the proper white brake grease (suppled) and new bellows (ditto).

Take the pads out of the caliper/frame and check the springs/anti-squeal looks okay. You may or may not have had new ones with the brake pads you bought in July, so they should be in fairly new/good nick. Poke out the pads and make sure they are "loose" in their mounts. They should fit in and fall out with minimal pressure.

If they're jammed (cheapo pads.... naughty, naughty!) or corroded, get a file out and grind them down till they fit in and out with minimal pressure. Better still, fit Brembo or Ferodo pads that actually have a plate that's accurately cut/shaped. Use copper grease on the ears of the pad and on the anti-squeal springs.

Have a look at the wear indicator sensor on the pads. If it's fitted half way up the pad, rather than near the backing plate then that's why your light comes on so often - the pads are only half worn. If you use quality pads then the sensor is probably in the right place.

Anyways.. fit it all back together again, bleed the entire system (not just the front brakes) and then off you go. If your fuel economy suddenly improves and your car gained "an extra 20bhp" then your pads were sticking for any reason you just cured and it's all good now. If the wear is exactly the same, then sadly it's your driving style and I can't help you with that one...


Ralf S.

Ralf, surely given the very technical nature of the problem, a much more effective fix would be to hit it - quite hard - with a hammer? 😊