I'm about to do the front and rear rotors and pads on the GL.

I think I know the answer, but asking just to be sure before I get in a world of hurt unnecessarily.

Does the x164 have SBC?

MB II has a tips option for deactivating SBC, but did not have anything to say about that on the GL and I haven't found anything online to indicate SBC must be deactivated before taking the brakes apart.

 

No.

its dirt simple.

use blue lock tite on the caliper bolts.

 

Thanks! Looks like it. I've done brake jobs on other cars, the GL looks like most others with mono piston calipers. I sort of wish MB used monoblock calipers for the fronts at least like the AMG cars. Wishful thinking

Here is a link with steps/pics for anyone who runs into this thread in the future.

https://www.rmeuropean.com/mercedes-...placement.aspx

 

Since they are sliding calipers, I believe it is recommended to lubricate the sliding parts.

I have been shocked by the longevity of ceramic pads.

 

Yes, lubricating the sliding components is indeed a must for these types of brakes.

When you say "shocked", do you mean they last longer than OEM which I believe are metalic, or shorter?

I'm going with Brembo rotors and Akebono pads. I was leaning towards Brembo pads as well, but decided to give Akebono a go based on some past threads.

 

Shocked was the wrong word. Pleasantly surprised. The EBC pads have been on there for 60K miles now. Haven't checked them lately but pretty sure they still have pad thickness remaining.

The ceramic pads, EBC at least, have a good tendency to do the "bedding-in" (layer deposition). I think this contributes to the longevity of both the pads and rotors. If the rotors aren't gray - if they are shiny - you aren't doing it right. Not many people know to do this.

 

I can't agree more about the bedding process for pads and using the correct process. Different pads require a different bedding approach. I learned the hard way when I bedded (and ruined) street pads with a track rated pad procedure. Those pads and rotors were scored beyond fugly within a couple of years and less than 30000 kms when they should have been good for 50-60000 (softer pads, which should not have been eating the rotors as much as harder compounds, aka pads with lifetime warranty).

Akebonos were seemingly harder than the Brembos when was doing some light research and I'd rather have a longer lasting pad and not having to replace them too often. Bonus for the Akebonos was lest brake dust as well.

 

A big thumbs up from me for the Akebonos. Virtually no dust and they last a long time. The only drawback is that they aren't quite as grabby as the stock pads, so more pedal pressure is required to get the same braking force, but it is not a big deal.

 

Yeah I was overly enthusiastic when bedding in the EBC Redstuff and ended up with blotches in the deposited material and crazing on the rotors. I put semi-metallic pads in for a couple of years to scrub down the rotors. The blotches returned but it seems more benign than before; the effect is to make the brakes groan when stopping.

I put cheap Detroit Axle rotors and ceramic pads on my daughter's Jeep; bedded them in while driving around on a Sunday morning, and the rotors are a beautiful smooth gray.

Properly bedded-in pads and rotors are so rare that I roll my window down and compliment the driver when I see them.

Tip: If you mess up rotors, you can resurface them yourself with garnet sandpaper. I haven't tried it, but supposedly you just put a sheet between the pad and rotor and then free spin the rotors with the end of the vehicle jacked up. It needs to be garnet because other compounds (aluminum oxide) deposit grains that join the crystalline structure of the iron, like the cementite that forms from overheating.

This is a great article on the dynamics of pad-rotor interaction: https://www.clublexus.com/forums/mai...disc-myth.html

 

Thanks for reminding me about that tidbit. It was one of my minor concerns when I read through others' experiences. I haven't used Akebonos before so I am sure there will be some adjustment on my part. On my VWs I opted for Mintex Red which worked well for street and light track use.

Seems like my street driving style should work with the Akebonos alright. Most times I tend to brake lightly and early compared to most drivers, plus I downshift to scrub some speed. Brake use is mostly for drivers behind me to get the message that the car is slowing down with downshifts. The vacuum on the 5.5L motor is ginormous and combined with the gearing, I am always impressed with the deceleration just by downshifting. I don't think it will be hard to get used to the new pads' characteristics.

 

Interesting, and good to know that a light resurfacing job can be DIY with sandpaper. I might give that a try if I botch another bedding job.

I thought I might have been the only one staring at people's wheels, although in my case it's to admire the brakes they are sporting. I am a sucker for a good looking and solid monoblock brake system that can stop a car in no time flat. Yes, tires and suspension also contribute enormously to the brakes' ability to do that. I used to run a custom setup with Porsche monoblock calipers, bigger rotors, and stainless steel lines on my VW's front axle. The rear was light and didn't need anything more than stock calipers, but I did use matching pads front and rear. Especially important when running the car on the track. I was in love with the brake pedal travel, so minimal with that setup. I think I only used 10-15% of the pedal travel before I would reach the ABS engagement point. Tempted to sort out the GL's brakes too with something from the AMG line, but not high on the list of "mods". I'd rather do something with the Command first, although with the amount of use currently (not very much), I can't justify that expense. But enough about my side bar.

 

Um isn't that putting extra wear on the clutches in your transmission? Personally I'd much rather burn through $50 pads than a $5000 transmission.

 

This!

 

I definitely see your points. I makes sense to wear out the cheap parts and protect the pricy ones. I've done engine braking on most of my other cars (with manual transmission), so the habit just kicks in. Speaking of habit, I don't do it on automatics with Manual mode without the paddle shifters because it's counter intuitive without the clutch. But the paddles in the GL negate that counter intuitiveness, I suppose. I have a VW with 300000+ km on the original clutch and both the motor and manual transmission are rock solid. I've done a lot of engine braking in that. I also have a diesel VW which was in my buddy's hands before me. He's a trucker and I am sure he's done lots of engine braking and probably double clutching when he was learning to drive semis. That one also has 300000+ kms and original clutch/powertrain. Maybe the manual transmissions are more tolerant towards the extra work.

I get that the automatics are more sophisticated and the MB units even more so, plus more coslty when it comes to parts/replacement units. Perhaps it's time to rethink the braking habit.

 

You know your stuff.

My second car was a Volvo 242 GT. 4-speed manual (with electric overdrive, which the manual said I didn't need to clutch for but always did anyway). Had a new acquaintance in the car, driving on ordinary city streets. Literally the only guy who ever observed: "Do you always double clutch?"

It was a habit I got into thinking about the poor synchromesh gears, but it has a nice side effect of keeping the engine revs up during the shift, though of course it slows down your shifts.

I was in the front passenger seat of a bus driven in New Zealand. I noticed a big sign above the manual transmission stick: DO NOT DOUBLE CLUTCH. I watched the driver try to downshift into a gear. GRRRT. Tried again. GRRRT. Double clutches, vroom, pops right in.

The drive-by-wire throttle does a good job of backing off the throttle imperceptibly when upshifting (there are six gear changes, but I defy you to observe them with masking tape over the tach), but I'm pretty sure it doesn't do anything when downshifting. I suspect liability prevents the designers from doing anything that opens the throttle without the driver instructing it to do so. You'd have to keep on the throttle when slowing to go into the corner, stabbing the throttle whenever tapping the left paddle. When you feel the lurching as you paddle-downshift, that is the engine inertia change buffered by the the torque converter ... and the transmission internals.

I did my first fluid change the other day on my rebuilt transmission, and there was this fine gray silt in the bottom of the pan. I asked the rebuilders about it, and they said it was mostly junk trapped in the oil cooler from the old tranny. That's all clutch wear from inside the trans. Blech.

Wouldn't it be great to reprogram the drive-by-wire to handle downshifts, from lockup to lockup, with the gear change in between? Flip it into a super sport mode, and it keeps the revs between 5 and 7. One can dream.

 

I don't know how much I really know my stuff lol There is always more space in my head for more stuff

If the MB is anything like the VW engine (also drive by wire) which I suspect it is and more, when you're braking and pressing the accelerator at the same time, the accelerator input will be negated. You'd see the tach drop to idle, no matter how much you're pressing the accelerator while you're also on the brake. "Stabbing" the accelerator as you described might help as the accelerator input is not constant and the ECU is probably ignoring them if they're sufficiently short. This confirms your thoughts about the drive by wire not taking any action during downshifts.

If I had my way, I'd have a manual 8 speed in this truck mated to the 5.5L. It's the first Auto transmission I have owned in a looong time. It will replace the VWs. My wife's car is auto as well, no paddles on her steering. I guess I just have to accept defeat so to speak and go along with the auto tranny needs. I am tempted to do the transmission fluids myself now rather than task the dealer, just to see what condition the oil and pan are in. The last time it was replaced was approximately 90000KM ago so it's time.... one day when I am motivated to get splashed by transmission fluid and the weather is enjoyable enough.

How did this thread go from brakes to fluids? HA! I guess brakes have fluid too, so not too farfetched.

 

The ECU has a funny response to throttle-and-brake-simultaneously. i tried bedding in pads by dragging the brake, and the engine thrust clearly sagged, but not to zero.

Doing the tranny fluid really isn't bad. Maybe you saw my thread on my invention. The rebuilder I got my tranny from advocated changes every 25k mi. I guess that's 40k km (40 Mm?). I lagged on it for fear of what I was getting myself into, and put it off until 40k mi. He said it was a very good transmission, and if you change the fluid regularly it will last a long time. 90k km isn't that long of an interval; that's 55k mi.

I strongly advocate doing it yourself, or at a dealer. I took it to a tranny shop and am not convinced they refilled it correctly, because it was just 10k mi later that it took a dump on the highway. Could easily be coincidence, too. I hadn't been super kind to it, having only changed the fluid - did a flush - at 90k mi.

I also was doing aggressive downshifts. For what it's worth. Not too much, though; only a few times when my brake discs were making the steering wheel shake.

 

This idea has been posted a few times on this site. I'd like to learn more about the basis for the extra wear comment.

 

You can infer it from the comments up-thread. If you tap the left "paddle shifter" button, you feel a lurch as the engine rpm jumps upon the downshifts. If you were managing a manual transmission, and were a respectable driver, you'd tap the gas pedal to get the engine revs up to match speed before letting the clutch pedal back up. This is especially true with a racing clutch, without the passenger vehicle's springs in the clutch disc that absorb the shock.

When I was first getting into cars, back in the day, I looked at a picture of a clutch disc and asked my more knowledgeable friend what the springs were for. He smiled and said, "That's so the tires don't go BIRP every time you change gears - and then the cops come after you." True story.

A really good driver (which I'm not) is able to smoothly match the engine rpms at every shift, so as to never apply a burst of torque to the drive wheels.

Because the automatic transmission program is (I think) unwilling to open the throttle without the driver telling it to, the transmission has no choice but to take the speed difference between the transmission and the engine and take it out on the transmission clutch discs and bands, buffered by the the torque converter. Conceivably you could do some tricks like tapping the accelerator while downshifting, but I don't know if those work.

Heck, I can't even get the tranny to preemptively downshift when exiting the corner. I stab the pedal ... and wait ... and wait. "Couch on wheels", am I right?

It's complicated, but worth understanding: The "torque converter" is literally nothing more than a liquid coupling that buffers the difference between the engine output speed and the transmission input speed.

The reason manufacturers were suddenly able to make these complicated transmissions with 7-10 gears is because of drive-by-wire throttle management. If the driver stomps the gas pedal, the computer lets off the gas when the shift happens. This is an automatic version of the driver lifting the gas pedal every time he pushes the clutch down. It would be awesome to have a computer that was willing to goose the gas when you downshift, but I guess liability prevents it.