When I had the alignment/steering knuckle job done at the MB dealership, they alerted me to the fact that my front brakes need attention. Specifically, they told me that not only do I need to replace pads/rotors but also that the wiring harness at the pad wear sensor has been damaged by someone who, they think, did the last brake job improperly. They told me this is why my pad wear sensor is not lit, while it should by now.

Anyhow, I've been riding on these brakes for 3+ years, and the front rotors look perfectly smooth even now.

I'm not really comfortable doing the front brake rotors myself, after reading about packing the bearings and setting tolerances, etc... I was hoping they are as easy as removing calipers, bolting off the rotors, and bolting new ones on like in my old Saab, but they are not, obviously... I can't really afford getting the new rotors and especially paying someone to do it right now. So instead as a *temporary* fix through the Winter, I was thinking about just replacing front pads and perhaps the sensors/wiring if that is easy. What kind of rotor thickness can I get away with on '84 300SD, at least for several months on new pads?

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84 300SD - bought in April '06 with 237,000 mi

Install some inexpensive organic pads and your future rotor wear going forward will be almost nil. If your rotors are thick enough for thin pads, they will get you by for a while with new pads.

Thanks, tangofox!

I looked up what Autozone has, and they offer Duralast organic pads for like 13 bucks! Wow....

Here it is:


Part Number: D145
Notes: Non-asbestos organic
Friction Material Type: Platform specific friction
Wear Sensor: No
Friction: No

Question: when they say "wear sensor: No" is that still suitable for my car which does have a wear sensor? Or, perhaps I should be asking - how/where does the pad sensor attach?

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84 300SD - bought in April '06 with 237,000 mi

I'd check minimum rotor thickness at one of the parts stores. Its stamped on the rotor in case they can't look it up. You can also look on yours but the edges may be rusty & need to be cleaned. OK to pad slap it if you're broke but get the pad with speed sensor if that is what you have. There are still a few stores (NAPA & perhaps Orilley's) that turn rotors. Rotors can be removed easily as they are held on by the wheel & lug nuts. Have them turned if they are in specs. You can borrow calipers from the store or take them with you when you go for pads.

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85SD 240K & stopped counting painted, putting bac together. 84SD 180,000. sold to a neighbor and member here but I forget his handle. The 84 is much improved from when I had it. 85TD beginning to repair to DD status. Lots of stuff to do.

I'm in a similar situation, '84 300SD and attempting some front brake work. On my W201, the front rotors came right off & were easy to turn or replace as mentioned earlier. However on the W126 I've been reading that to pull the front rotors the entire hub assembly has to be removed? Looks like there are screws from the back that hold the rotor on?

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1987 190E: 288K & counting: daily driver
1971 TR-6: complete reso.
2001 GMC Duramax: 120k
1988 Saab 900 Turbo: 190k
2003 Hyundai 350GL: wife's daily driver
1984 300D (225k+) & 1984 300SD (400+k) owed by the wife's parents since new.

The photo of the pad shows the notch in the backing plate for the sensor. The other necessary feature is a hole drilled into the side of the pad. (My money says that the hole is there.)

The "No" may be referring to a "scraper" type of wear indicator. Or the fact that the electrical sensors are not included with the pads, which normally they are not.

I don't remember the details but I did my 85SD brakes lest summer & had no problems. The rotors may have been slightly rusted on but a BFH took care of it with no cursing involved.

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85SD 240K & stopped counting painted, putting bac together. 84SD 180,000. sold to a neighbor and member here but I forget his handle. The 84 is much improved from when I had it. 85TD beginning to repair to DD status. Lots of stuff to do.

Do I need to replace any other hardware along with the pads such as anti-rattle clips, etc? Where is the brake paste applied?

Also, what are the steps involved in replacing pad wear sensors and their wiring? Maybe it is self-explanatory once I'm in there, but I'd like to know some pointers from people who've done this.

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84 300SD - bought in April '06 with 237,000 mi

You can probably reuse everything when you replace the pads. They should have a hole in the top to press in the sensor, follow the other end, plug new sensors in there too, very simple.
The anti squeak grease is applied to the back of the pad, where the caliper piston comes in contact with it, also on the metal sides front and back, just don't get any on the pad itself.
I forget the minimum rotor thickness for the 126's and my cd-roms no longer work.

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83 SD

84 CD

Thank you - that's very useful info, and I will check the pads for those sode holes when I get them.

But grief... Those wear sensor cables are $45-a-peach!

I believe I'm just gonna do the pads and hold off on the cables until later. If the brakes are looked after, it's not critical to have the properly working sensor, is it? I mean, it isn't now and it's not doing me any harm or good ;-)

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84 300SD - bought in April '06 with 237,000 mi

There are millions of vehicles on the road with no brake pad wear sensors.

LOL. So true. Still, I like to have things working properly on my car, but there are better ways I can spend money on it at this time. :-P

I ordered those organic Duralast pads from Autozone for about $14. They seem to be the only local place to have 'em this cheap. I will update when I get to the repair.

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84 300SD - bought in April '06 with 237,000 mi

The item that generally needs replacement is as follows:


http://www.allpartsexpress.com/ShopByVehicle.epc?q=1984-MERCEDES--BENZ-300dt--/--L5--998cc--3.0l--Diesel--Fi--Turbo-Brake--Components--Wheels&yearid=1984%40%401984&makeid=MERCEDES+BENZ%40%40MERCEDES+BENZ%40%40X&engineid=1193789%40%40300DT++%2F+L5-2998cc+3.0L+DIESEL+FI++Turbo%40%40300DT&catid=Brake+Components+%26+Wheels%40%40Brake+Components+%26+Wheels&subcatid=Front+Brake+Pad+Wear+Sensor@@Front+Brake+Pad+Wear+Sensor&mode=PA

The part that you are referring to is the cable that begins inside the firewall and ends at the brake caliper. This cable eventually suffers from damage to it's insulation, however you might get by with a good application of friction tape. I recently replaced these on the SD, however, most just use the original part.

FYI, the low limit on the thickness for the front rotors is .764"

^Thanks, Bri, those are the sensors I was referring to, not the cable harness.
BTW, .764 is what in mm?

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83 SD

84 CD

It's 19.4 mm as a minimum.