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#1
09-15-2002, 05:52 PM
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Front rotor thickness
Hi
Someone please tell me what are the minimum allowable thickness on the front rotors of 1985 300D Turbo before they should be replaced. Thank you David __________________________ 1985 300D Turbo 165,000 miles 
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#2
09-15-2002, 06:28 PM
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It may be stamped on the rotor itself...
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#3
09-15-2002, 09:13 PM
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It is stamped on the edge, but good luck finding it now!
Actual spec is, I think, 0.42". this is AFTER they are turned, if you were thinking of doing so, and minumum thickness at any point, not average or largest. Two quick and dirty ways to tell -- How many sets of pads on this set of rotors? MB recommends new rotors every third pad change. Is there a visible/palpable lip at the outer edge, and is the inner edge worn down to the level of the hub? If so, replace, they are too thin. Not much meat on these things, keeps unsprung weight down. Also, how close were the backing plates on the old pads to the anti-rattle spring? If it looks as though they would touch the spring before the lining was gone (especially if they would touch before the slot was worn off), or they DID touch, get new rotors, the old ones are too thin. Don't take a chance on underthickness rotors -- they will cause the pistons to lock up in the bores after the new pads wear down, hit the spring and cock. Doesn't stop worth diddly then, either (and it's costing me $250 in parts on the 280 right now!) Peter
__________________
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!
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#4
09-15-2002, 09:23 PM
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I would not turn them if in doubt change them they are not too expensive unlike Honda or Toyota.
MVK
__________________
One penny saved is three penny earned. 1985 300D Turbo 179,000miles Last edited by MVK; 09-16-2002 at 06:14 PM.
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#5
09-16-2002, 02:41 PM
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Thank you for your responses.
This morning I made some measurements on the thickness of the rotors. My front rotor thickness is about 0.450". This is after I took away the 0.025" ridge on each side of the edges. (0.500"-0.025"-0.025"=0.450"). Other than the ridges, the rest of the surface on the rotor are very smooth. The minimum thickness stamped on the front rotor says 10.5 mm which is about 0.413". So I think I am ok until the next time changing the front pads. The question I have is the "0.025" depth ridge on the edges tolerable? What causing the development of the ridges? The rear rotor thickness is about 0.400". The minimum thickness stamped on the rear rotor says 8.3 mm which is about 0.327". So I think I am OK on the rear rotors. The rear rotor ridge is about 0.010". Thank you David ____________________ 1985 300D Turbo
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#7
09-16-2002, 07:36 PM
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Plan on new rotors next set of pads.
The ridge is a result of the fact that the pads don't cover the complete surface of the rotor -- I suspect so that crud and rust don't interfere with braking. I've never seen rotors on an MB that were anything but pretty smooth until they are worn out -- wavy, but not grooved. Very rare for someone to actually run the backing plate down to the rotor, anyway. Peter
__________________
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!
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#8
09-16-2002, 11:35 PM
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Quote:
__________________
1995 S-350 370K + SOLD 1952 220B Cabriolet 39K kilometers + SOLD 1998 E300D 310K + 2012 E350 BlueTec 120K
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