Tip: To get the calipers over the raised "lip" at the edge of the disc problem.

You can use regular calipers instead of micrometer, by grabbing a couple of common washers and hold one to each side of the disc and caliper that thickness. If you zero your caliper on the 2 washers alone, you don't even have to do any math to subtract the thickness of the washers to arrive at the disc thickness.

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Cheers!
Scott McPhee

1987 300D

You do not have to change out both unless they are worn below minimums. The FSM states a value above the minimum that when your changing out the pads the rotors should also be changed.

I haven't recently priced rotors, I've just changed the pads and all was well, rotors were above minimums. Sometimes it's more cost effective to change the pads and the rotors vice having the rotors turned.

Personal choice i guess. The FSM doesn't say you can't turn the rotors.

Attached Files

Checking brake rotor pad thickness.pdf (203.5 KB, 240 views)

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92 300D 2.5L OM602 OBK #59

In practice, I replace the W123 rotors with every second pair of brake pads (both front and rear). The W123 rotors are just too inexpensive to bother machining, and my experience indicates that a new set will outlast two sets of pads without any performance issues. In this case, I believe the OE recommendation is excessive.

That is a totally subjective evaluation and says nothing about the technical feasibility of the practice. Clearly, anyone who finds the practice a "bother" is free to avoid it.

From a technical standpoint, it is entirely possible that a rotor machined on the hub (in the case of front brakes) might have less runout than a new one just installed.

I agree, it can be done. For me, it would be more trouble than it's worth. The new ones are very cheap and work well for me; but it's not the only way.

I typically change the rears every other time.

I can only remember changing fronts once... they are much thicker than the rears

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1989 300ce 129k
( facelifted front,updated tail lights, lowered suspension,bilstein sports, lorinser front spoiler, MOMO steering wheel, remus exhaust,stainless steel brake lines). (Gone)

1997 s320 154k (what a ride). Sold with 179k miles. Replaced with Hyundai Equus

1994 e320 Cabriolet 108k



1972 280se 4.5 153k Owned for 12 yrs, sorry I sold it


[/SIGPIC]

I know at least 2 people who have said they would never again have their Rotors turned while they were still on the car because they had problems with them later.
I suspect the reason is may Cars have a lot of Wheel Blearing end play/clearance. If you do not remove the end play/clearance before you turn the Rotor I do not see how the turning job can be accurate.
I also do not see how they can line up the Machine accurately either.

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84 300D, 82 Volvo 244Gl Diesel

"On the hub" is not the same concept as "on the car."

Sorry, I did not catch that detail.

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84 300D, 82 Volvo 244Gl Diesel

Machining a rotor should cost about $15.

You have e-mail.


Have a great day.

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1985 300SD
1983 300D
2003 Volvo V70

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What a timely thread. I have started to feel the pulsing from the brake pedal that would be caused by a warped rotor. If my memory serves me the issue of not turning the rotors was the same on my 89 range Rover (I bought it with 58,000 miles on it) I never saw it writing however everyone I spoke with on that forum said to change them not machine them. So I did. I may go ahead and turn these ( I have access to a quality brake lathe) and report back. The only issue I can see is that I need to tun them and wait while that process is going on. If I buy a new set the whole thing goes smoother and faster. Of course they is only because mine are warped without a doubt. If they were not and were found to be within spec I would just resurface/dress them and save the money.

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92 500E Silver 66k
82 Porsche 911SC 84K
68 Cadillac ( Gone Now )
03 Suburban Z71 200K
85 300SD 217k From Original Owner ( Dad )

I'm pretty easy on brakes. I only change them if they are warped or too thin. I use standard pads or ceramic. The ceramics will last longer but might reduce rotor life. The clean wheels are worth it though. I haven't tried turning any in decades.

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

I'm on the original front rotors at 400kmi on my 1977 300D. I use Pagid soft pads, commute gently on highways, brake gently, and have driven this car for ~305kmi. There's essentially no lip on the rotors, but when it comes time to renew the rotors, the new ones are so cheap and easy to install that it's foolish money to machine them. Actually, I have an almost new pair of rotors in the garage attic from a wreck I bought for the engine. Pads are cheap and easy to replace. I've got the wheel covers so brake dust is not a big issue.

'77 300D 404kmi
'95 C220 190kmi
'83 Dodge B150 336kmi
'72 Norton Interstate 169kmi

There are undoubtedly those who would argue that any money spent on a 33 year-old, 400k miles car is "foolish money." You won't get your money's worth out of those new rotors unless the car lasts another 400k miles.