I thought I was buying new screws that bolt the rotor to the hub. Now I'm not so sure - they seem a little smaller than what I've seen in pictures.

Under FastLane, 1984 300SD, Brakes, Brake Disc Set Screw, $1.40, 4 per car.

What did I buy, and do I need it to replace the rotors?



Ken300D

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1982 300D at 351K miles
1984 300SD at 217K miles
1987 300D at 370K miles

You bought the screws that hold the rear brake disc to the axle. I believe that you only need two of these (one per side). Normally they are reuseable.

With regard to the cap screws that hold the front rotors to the hub, these are significantly larger. You need five of them for each front rotor. However, you can certainly reuse the ones that you currently have. They don't go bad with time.

Thank you - that clears it up for me. I believe that I now have a lifetime supply of these little set screws. I'm not burning up rear rotors very fast.

Just recently took a close look at the 300SD rotors and knew they had to be replaced immediately. It uses the vented rotor and they are worn down almost into nothing - stopped driving it. Got the new rotors and will start the job soon. I want to get a picture of the new and old side-by-side to post here. Kinda scary.

Ken300D

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1982 300D at 351K miles
1984 300SD at 217K miles
1987 300D at 370K miles

Yep, I just did the SDL two weeks ago. The pads wore a track into the rotor that actually made it quite difficult to get the calipers off. The pistons had to be forced considerably into the bores to get the pads to clear the edge of the groove. But, it sounds like your grooves are even deeper than mine. It definitely is worth a photo.

I've got the first rotor off now and its not as bad as I initially thought. But still well into replacement-need range. Fortunately they weren't as dangerously thin as I thought. With the rotor off I can see the grease seal has been leaking so while its all apart - new grease seals and bearings. Bearings look OK but now is the time if the grease seal has to be changed.

The pry bar against one lug bolt method worked great for me. I'm not sure how much penetrating oil will really help on the rotor bolts, as they are coated with thread locking compound and that generally prevents corrosion as well as penetrating oil penetration. I held the old rotor in a vice for convenience, then used a breaker bar w/10-mm socket on the rotor bolts, and the big tire iron on the other side's lug bolt to hub pry point. Easy.

Do I understand correctly that 80-ft/lbs is the correct replacement torque on the rotor bolts?

I'm looking forward to keeping all my MBs long enough to require rear rotors too. That should be in the 750k mile range.

Ken300D

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1982 300D at 351K miles
1984 300SD at 217K miles
1987 300D at 370K miles

Ken:

You will need rear rotors around 200,000 miles -- the ones on the TE will have to be replaced next pad set (really should have done them this time, I suppose, but they are thick enough).

I've put them on the 300D of my brothers (unknown milage), on the 220D (unknown milage but more than 150,000), and on the 280 SE (unknown milage, but more than 163,000).

They will last the normal two sets of pads, but you only need to replace them about every other front pad change, so 30,000 (for me) on front pads times 4 = 120,000 or so.

I don't expect to replace any more brake parts on the TE any time soon -- Mom only puts about 6000 miles a year on it.

Peter

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1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!