Can squealing be caused by the failure to insert the shims or to spray the blue non-squeak stuff on the back of the pads?

Just wondering.

I have installed brand new brake pads before which started squealing really fast. Replaced with another set of same brand pads and the squeal went away. So maybe there is sometimes a quality issue with pads. Not sure.

Never heard of hard pads causing squealing. Did he pull the pad of the grooved rotor to see if he could determine the cause?

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

No i brought it up again but he wouldn't do anything until saturday.
(steam rises from forehead)

i called him again in my frustration and he called back a half hour later to tell me that..
he's ordered all new rotors and pads and is installing them saturday all for free.
He said, "different style of rotor," and "i spoke with the sales rep and got pads that are meant for the mercedes." whatever that means.
So, i'm placing faith in some sort of better knowledge he somehow acquired, or maybe he truly got screwed by his supplier, or maybe he was just being cheap before. i don't know.
But man what a lot of wasted time and supplies. Every single component they've ordered and put in, pads/rotors/pins, is now completely being replaced.
I don't know what to think of this situation. Oh well i guess it'll be resolved eventually.

If it were me, I would raise the car up, take off the wheel, remove the spring pins, remove the pads, apply anti-squeal grease to the appropriate places on the back of the pads, and reinstall. These guys seem to have you on the hook. I'd try to sever the ties asap.

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1982 300CD Petrol/Black Leather

Bits of steel, brass, I've had a hard spot or two on pads before.


I've seen this before, new brakes don't grip as well as ones that have been bedded in, this coating increases initial grip. https://www.bendix.com.au/sites/default/files/news-uploads/how_titanium_stripe_saves_you_time_and_money_technical_bulletin.pdf

There are even some pads that are laser burned.

Brake pads work best when the binder very near the rotor is cooked so outgassing does not interfere with braking. When a pad overheats, hot gas comes out of the pad further towards the backing plate causing a hydroplaning effect. If the pad was cooked all the way through, it would tend to crumble.

i kind of doubt they are hooking me in to further work given that if this was sorta intentional they sure wasted a lot of time and money of their own. if they were able to quickly solve it without doing another full install then yeah i'd be a victim.
they know that i will be there to check out the process. i live one block away. i was already present for a few minutes here and there previously so i do think they have to put new stuff on since i'd notice if they weren't.
they also are the only shop in the middle of a small town, and everybody knows them and goes to them. i think maybe they are just not very good at what they do.

anyways, i do have one advantage i can take which is to have them install new bearings in the front since they will have to repack them anyway. can't i just and them new bearings and they will be doing the same amount of work?

would someone be so kind as to give me a hint as to what to get? i will want to act quickly so that they can arrive friday or saturday.

Can't recommend bearings but once my front passenger wheel began to make scraping noises.
Turned out to be a ripped brake pad spring. Pins were still in place. (ATE calipers).
That metal spring broke and twisted, cutting the brake sensore wire and touching the disc.. ergo noise...

Well, you are getting a bunch of new stuff, afterward get a new mechanic !!

__________________
1979 300D 220 K miles
1995 C280 109 K miles
1992 Cadillac Eldorado Touring Coupe 57K miles SOLD
********************
1979 240D 140Kmiles (bought for parents) *SOLD.
SAN FRANCISCO/(*San Diego)
1989 300SE 148 K miles *SOLD

bad idea to have this mechanic install the new front bearings?
1163300051 I found the brand "fag" to be the most reputable and can have them arrive in time for the brake REDO.
Should I just avoid letting them touch the bearings up front and do it myself? Or is packing bearings pretty straight forward and i should just let them do it....
After this, hoping the brakes will behave, i'm totally done with this establishment.

I don't recall ever getting into the bearings when I replaced rotors on my 1984 & 85 300D's. The rotors just pull off the hubs, after you remove the retaining screw (common on Euro cars). If that screw snaps, don't worry since it isn't needed. Most U.S. cars don't have one, as the wheel secures the rotor. I did replace one front outer bearing, probably on my 1985. It had the typical symptoms of a whining sound at 50+ mph. The rollers were pitted. The front bearings are very common (Timken SET3 & SET5 or National A3 & A5, I recall), also used on GM trucks. A little tricky to do yourself since best to also replace the race (knock out) and must know how to tighten the nut just right. Re "best bearing", most name brands today come w/ "Made In China", which doesn't always mean bad. I have lucked into "Made In Germany", Japan, on U.S. from ebay or surplus.

I wouldn't worry about that little groove. Some rotors have intentional grooves or holes for better braking, so consider it a "feature". Probably just some grit in the pad. If it doesn't wear flat in 20K miles then wonder. The vibration when turning could be due to too much play in the wheel bearings allowing the wheel to shift so the pads touch the rotor. If so, you will feel it in the brake pedal. Next time you turn, press your foot slightly on the pedal to feel for that. Many rotors are slightly wavy so you might feel a little pulsation especially as the pad barely touches. Sounds like the shop is a stand-up place and hard to find today, so don't go fussy on them based on half-baked ideas. If you had read the Owner's Manual, it would have been obvious that the brake lamp you were seeing was different than the "worn pads" lamp.

A lower ball joint would have to be severely worn to cause vibrations when driving. The weight of the car acts down on it to keep it tight when driving. When the front end bounces over speed bumps or railroad tracks, then you might feel worn ball joints and bushings shifting and clunking. Anyway, isn't rocket science, just jack the front up by the frame and wiggle the wheel around looking for play. More likely vibrations would be from play in the steering linkage or gearbox and that is easy to observe as someone turns the steering back & forth. The W123 steering boxes are notorious for wear. I have yet to find one in the junkyard which isn't at the limits of the sector adjustment screw, just like my 2 cars.

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1984 & 1985 CA 300D's
1964 & 65 Mopar's - Valiant, Dart, Newport
1996 & 2002 Chrysler minivans

I've only replaced the front rotors a couple of times, but when I have the bearings are right there. They fall right out, so you can't help but get into them. Maybe you can get by without cleaning and repacking, but it's recommended you do it. Giving them fresh bearings would actually save them the time and mess of cleaning anything. The repacking is not complicated. The real issue is setting the preload on the bearings. They probably don't have the correct gauges, so they'll end up using the "tight, then back off 1/3 turn" method. Unless you have better plans, might as well let them do it, I guess.

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1982 300CD Petrol/Black Leather

Well i've been thinking about getting them a good new set of bearings but I think i'll not. They seem to think the bearings are healthy, and it would be best to just move on from their shop. I know i'll have to open up the rotors to do it myself later on but i trust my commitment to accuracy/gauges/techniques more than theirs at this point. I'd rather take my time to do it right and there's no point in having them install them if i don't trust their commitment to the details. I also do not want to enter into yet another conversation with them about a new topic of technique. The owner does not have a good temper and told me yesterday on the phone "you come in here and sit down and i'll tell you what this is all about," verbatim, about my two or three questions and concerns of pads/rotors/grooves/squealing.

And just this morning, per the suggestion of BillGrissom, i isolated the rumbling issue to occurring even while in park and reving up to high rpm and turning the wheel. So it's not the bearings or anything to do with driving motion, it's probably the power steering. Thanks bill. Tomorrow i refresh the power steering fluid and filter. Maybe it's the belt or pump.

But those brakes that are currently still on the car are still squealing a lot. I don't know anything about pads or rotors but hopefully they came up with some kind of new understanding about what to order. The groove is strange. I didn't get to inspect the other rotors. Maybe they all are grooved a bit now. So we'll see what new rotors and pads does.

Just a thought. During DIY replacement of front rotors, noted scraping on Left front new rotor. Was dust shield scraping rotor. Tried to bang dust shield to different shape but this did not end scraping. Eventually sawed a cut in part of dust shield enough to bend shield slightly to avoid scraping. Did have to remove and repack bearings to remove rotor.
Had one noisy front outer bearing. Sounded as if right side when driving. Wrong. Was left. One way to diagnose which side. Before taking rotor off, turn rotor or even whole wheel, and put hand on part of front suspension or spring and feel for vibration in some part of front suspension. Should feel scraping vibration on the bad side. Bad bearing almost always outer bearing. Used Autozone bearing as needed quick fix on evening on a weekend and was fixing my daily driver. Same outer bearing as old 1985 Chevrolet Impala and other GM vehicles. '85 300SD


PeachPartsWiki: Front Brake Pad & Rotor Replacement

http://www.benzworld.org/forums/attachments/w126-s-se-sec-sel-sd/335719d1286632269-front-rotor-replacement-1983-300sd-wheel-hub-front-126-33-310.pdf

Well the second round of pads and rotors have performed pretty much flawlessly. One time braking after backing up I got a tiny squeak, but other than that they have been silent.
Next time I'll take it to a brakes specialist or just learn enough to do it myself.