i just installed new Brembo rotors and Bendix pads on the front of 05 Sport Sedan. I followed the break-in procedure as advised by stop-tech which indicated 2 sets of 10 60mph-10mph braking sequences coupled with cooling exercises. I followed this procedure the next day with another set of braking sequences. However, i am noticing a soft pedal feel and very little initial pad bite. At high speeds, after one usage of the brakes under load, I am feeling vibration and some shimmy. Looking at the rotors, their appears to be a glaze over the entire rotor and the sheen does not resemble the shine of say my rear rotors. also, the drills in front are filled with brake dust already. should i look into a brake fluid change? are the pads not adequate or do i need to give them a few hundred miles of break-in? i am really hoping i have not begun weakening the rigidity of the rotors and that is the reason for the slight vibration after heavy loads. any help would be greatly appreciated

 

For initial bite, stainless steel brake lines will help. I'm unfamiliar with that brake setup so I'll let someone else chime in. I would doubt that by just following the stoptech procedure that you would have warped your rotors.

Did you replace the rotors in the back also? Could you explain the glaze? Does it look like there's a chemical compound there or is it a metallic sheen?

 

i have always thought about stainless lines, especially now that my car has some miles. the setup i am unfamiliar with as well, but i have tried many different variations over the last 3 years and have struggled to get a brake setup that really "feels" good. the OEM setup has been the best so far (rotors being brembo as well), but the pads chew through the rotors too quickly and dust too much. as for the coating, the sheen seems more like a chemical resin over the face of the rotor (its not a shiny metal complexion like the rear brakes). Also, i had to brake really hard today and experienced some alarming sensations: the car started vibrating and shuttering very badly and the back end started fishtailing out. i have no idea whats going on considering these brakes are new and of high quality. It also doesnt seem to have the braking power it used too. Maybe i shouldve stuck with stock

 

sounds like your pads are leaving too much material on your rotor. That's probably causing the vibration/pulsation in your brakes. May want to try different pads.

 

The first three questions I have are:

Have you use a dial indicator to measure the runout of the rotor? Often installation of the rotor is not according to good practices, and results in excessive wobble.

Have you changed the brake fluid with the specified Mercedes brake fluid? Should be done every two years to avoid excessive copper absorbation. I have seen a few cars with poor brake performance because the owner used ATE Blue racing brake fluid. It does not play nice with the ABS system.

Did you use alcohol to remove the protective shipping coating from the rotor surface? You might have imbedded it into the surface of the pads. It should wear off in a few miles.

 

+1 - excellent advice & you won't mess up Brembo rotors that easily but you will if they are not running true.

Secondly regarding soft pedal - some causes

1) Ballooning brake hoses - fit SSteel armoured hoses as recommended above.

2) Repacing only front pads with semi worn - but lot's of life left - rear pads not changed. If one light pump on the brakes brings the pedal up and firms it then you should replace rear pads as well to regain proper travel of pedal & firmness thereof. Common Benz problem.

3) Calipers over-returning - which causes no 2 - & if the front is doing the same thing as the rear then you have a real mushy pedal. The pistons in the calipers have a D shaped cross section seal. When you brake this seal partially distorts with the movement of the piston toward the rotor. If the seal does not slide down the bore of the caliper - when you lift off the brakes the pistons over return as the seal regains it's natural shape requiring more than usual pedal travel to re-engage the brakes. - The only guaranteed fix for this is to strip all the calipers - clean them of all brake fluid internally - and reassemble them dry with pads & all back on the car. Then blow them hard with compressed air via the flexible brake pipe inlet on the caliper so that the pads seat hard against the rotors & the D seals on the pistons orientate themselves correctly in the caliper bores. Then you introduce brake fluid & bleed the brakes normally. You will have a rock solid pedal - Hoses that balloon exacerbate the problem of over-returning calipers.

Technicians often cause this problem by pushing the pistons back too far in the caliper when changing pads.

 

Replacing my front disk and pads on Wednesday... anything I need to look out for or can I trust the MB Techs to to a good job... should the fluid be replaced aswell and what about the stainless steel brake lines

 

Fluid should be replaced every 2 years. If you don't ask they never do it under the maintenance plan. Just tell them not to push the pistons back any further than they have to to get the new pads in. If you suffer a spongy pedal after they have done the job that corrects with one pump of the pedal - make them replace the back pads as well. I'm still running standard lines. Stainless will give a firmer pedal but it's not major if the pads are correctly installed & calipers not over returning.

If you talk to the average Tech about this they will look at you as though you are mad. They don't begin to understand these things & brake pad replacement is usually left to the unskilled labour - don't allow this unless you are watching & advising. Orbit Culemborg - do the best job but since Stanley - the Service Manager - has gone to Bentley their standards are dropping. He was the finest Service Manager I've ever experienced. His attitude was that if you bought a car from them you owned a couple of bricks in the building - how refreshing!

 

I dont know how to measure runout so that could be a problem. what would i say to my tech to check this?

I had my fluid changed last spring and i usually do it every spring. perhaps i may need to do it sooner. i think SS brakelines is a good option since i have the larger Brabus wheels (which have added some unsprung weight)

I dont know what the tech did while installing or if he cleaned them at all. but there is a chemical coating on the rotor so thats a possibility.

to me if appears to be a pad issue and not a rotor issue. However, the over-returning caliper could be an issue as well, coupled with the rear brakes not having been replaced. how difficult is it to do the procedure to fix for over-returning? i may ask my tech to do it while replacing these pads for the OEM ones. However, i am still confused about the fishtailing/shuttering during heavy braking (it occurred also during the break-in procedure). could this be a result of the caliper or the pad?

 

If you change your brake fluid every spring that's fine & often enough.

The only way to check run out properly is with a dial gauge. If your Tech does not have one find a competent Tech.

I would not run standard pads - messy things - fit a decent set of ceramic pads like Porterfield.

You are going to have to get whatever is on the rotors off. I would fit a decent set of ceramic pads - they will wear off whatever is on the rotors.

Doing a dry rebuild of the calipers is a bit af a pain in the butt but I've done it often (not on my Benz but endless Alfas with Dual boosted Lockheed Bonaldi brakes). It's like taking the car back to when it was built prior to the addition of brake fluid to the system. I would only do it as a last resort.

I think your juddering/fishtailing after new pads & rotors was due to uneven braking. Probably because the discs/rotors were not clean & dry - could have been the shipping anticorrosive coating. You must check to see that the rotors are running true.

 

A true motor enthusiast indeed... I was told you can only call yourself an enthusiast once you have owned an Alfa... and by the sound of things, you have owned more than one...

I will speak to the tech about not pushing the piston back more than need be

 

Yep! Had 5 Alfa's in a row in my younger years. In those days they were some of the quicker vehicles on the road.

 

my w203 does similar when breaking.
The breaking was sharp before I changed the front rotors. The only problem I had was the steering wheel shakes slightly when breaking, so I changed them out. (free of charge from the dealer I bought it from, since it was under warranty within 30 days).
After they changed the front rotors, I have to step on the break harder, and I do NOT feel the sharp breaking anymore. It feels more like the break paddle is pushing back out more whenever I step on it. The new rotors have been driven almost 300 miles.
I remember one hard break on the freeway, the steering shakes slightly again. From about 70mph to 40mph.
The new rotors still look new, with fine circular lines.

 

Are these standard rotors & pads? or did the dealer fit some cheap rubbish? Once bedded in your braking should be the same as before & there should be no shake. Report this to the dealer before the warrantee runs out.

 

Wheel vibration and squealing can be an indication that the pads have deposited too much material in one spot on the rotors during break in. Sometimes you can look at the rotors and see the outline of the pad on the rotor. As the rotor passes this spot the coefficient of friction changes and you get the wheel speeding up and slowing down....an oscillation that you feel as steering wheel vibrating back and forth or hear as squealing. If you apply pressure to the brakes at a stop and force the pads against the rotor for any length of time (like at a stop light) during the break in this material transfer can take place. I use the parking brake to hold the car when at a stop during the break in period to avoid this problem. You can dress the rotors with sand paper and try the break in again if this happens. Did you have the same/Bendix pads before? The soft feel could just be the different pads. Unless you really push the car hard, do a lot of mountain driving, or track it I doubt stainless reinforced lines will do anything for you.

 

I do push the car hard, and with the Massachusetts roads its hard not too! however, i have noticed some deposit on the rotor itself and i used the parking brake to stop during the break-in procedure. nevertheless, i think these pads are not what i am looking for. I have yet to find the right pad for my application aside from OEM because it gets so cold here some pads, like EBC redstuff, take too long to heat up during normal driving and i had no braking power until they reached optimal temp (scary!). i thought about porterfields but have had trouble finding them anywhere and they are expensive for brake pads. i think i am going to try sandpaper on the rotors and try new pads and see what happens. the SS lines will be something i look into but for now i just want my car to be braking like it should, especially now since its winter and very cold. any suggestions on a different break-in procedure that may not be as violent on my pads/rotors?

 

I've been using Porterfield pads and they require slightly more foot pressure than the stock pads, a couple of stops to get to operating temp (nothing scary, just more foot pressure), and are slightly less smooth coming to fnal stop. Not enough difference to be a bother and with the no dust and fact that they'll go 100K miles it's worth it. I'm guessing the Porterfields are more fade resistant but I've never pushed them or the stock ones enough to make either fade.

 

The first thing I would do is put your car on MB approved fluids instead of all the crap you are running.

Secondly - If you don't like the brakes the way they are & don't like Porterfield's then go back to OEM. They are excellent if you can live with the dust like I do.

 

BTW - 99.9% of the world never go through any brake run in/bed in procedure & never incur any braking dissatisfaction

 

All of my cars have either had squeeling brakes or shimmy until I started bedding them in properly. I'm not a late braker, speedster, or do I drive a lot in the mountains. It's the freeway stop and go driving.

 

I've never bedded in a set of brakes on any Benz I've owned or on any car in our race team. Benz Germany & our Benz dealer recommends no such thing - I've never experienced squeal or shimmy on a road car & I've never heard of a Benz owner in this country with OEM discs or pads that has experienced these symptoms.

 

I lie - I had shimmy on a Holden Berlina 3.8 V6 that was my company car in Australia at 19,000 Kms while braking at 60 to 80 Kms/h - discs were skimmed & problem resolved. Diagnosis - driving into car wash with very hot discs frequently because it was free to me at our Service Stations. Problem never recurred

 

Very common problem in Southern California. Freeway driving is the culprit. Here's a great explanation of what's going on....
http://www.stoptech.com/tech_info/wp...akedisk.shtml#

 

Thanks & very interesting. I've heard many theories on this subject & all are in a similar vain & probably partially true. This articles comments on brake fluid are not 100% correct. Comments on cast iron suggest the composition is all the same - inclusions & all - which it is not. etc. I would like to see all this backed up with some decent materials & surface analysis & some good electron microscopy. Comments on hard materials wearing soft materials are not altogether accurate. We have all seen what an elastomer seal can do to a steel shaft.
The article also harks back to the past when materials & treatment were somewhat different to today - eg. some discs today are treated in a process similar to plasma nitriding but deeper,(Honda & others) which changes the surface characteristics of the disc somewhat.

All that said I believe that the standard OEM brake set up allows for proper bed in under fairly normal driving conditions over the first 10 to 20 Kms of use.
I certainly agree that you don't want a hard clamping dead stop on a very hot disc.

In a racing scenario you are probably achieving close to what is recommended inadvertently. A driver will normally take a car from the pits. Do some brake warming before hitting the first corner fast. & then go through progressive heating & cooling cycles as he or she completes the lap. One big difference being they would never slow down to 5 mph & equally would not come to a dead stop.

You have raised my interest & I intend doing some more reading & research. I'm afraid I'm not one of those people that believes everything that I read in black & white purely because it has been committed to text. I've trained my staff for years to challenge conventional wisdom.

My cars brakes are great, they have always been great. It's just had it's first set of new pads (OEM) under the maintenance plan & they are still great - never had any concious bedding in - don't squeal or judder. I suspect - in fact know, that most people are like me in this regard

 

Great! Maybe open a new thread with your findings? I have researched as well and the StopTech explanation seems universally accepted and is easy to understand so I referenced it. One thing I found interesting is that abrasive pads are made to clean pad deposits off of rotors. I still use the OEM rotors but the brake dust bothered me too much with the OEM pads. I must admit though, the OEM pads are more linear and smoother than the Porterfields, but they wear much quicker.