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#1
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WARPED ROTORS
I have a 1980 300cd. When I bought the car it made a very noticeable pulsing noise that was most evident while making left right turns at highway speed. The speed of the pulse was determined by vehicle speed. When stopping the brake pedal would pulse also. I took it to Midas for a complete brake inspection. The inspection showed that the left front rotor was warped. So, I had both the front rotors turned and the wheel bearings repacked. The noise was gone, and the brake pedal was back to normal. It's been about 2-3 thousand miles since then and the noise is starting to come back along with the slight pulse in the brake pedal. The car still stops straight even upon hard braking. Is it the rotor getting warped again? Does anyone know what could have caused it? I would like to fix it one more time. But I would like to fix the cause for my rotor being warped. The rest of the initial inspection showed everything else to be fine. I would appreciate any and all advice on this matter. Thank You, andy
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#2
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andy, do you drive it hard with a lot of use of the brakes then wash it? I have heard that if the brakerotors are real hot and you spray cold water on them (like in a car wash when you wash the wheels) then there is a possiblity that they can warp. I have never tried it so I do not know if it is true or not. Seems logical though.
Jim '95 E320 '97 Honda CRV |
#3
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Warped Rotors - Andy 1980 CD
Andy;
According to MB, factory rotors cannot be turned as they are case hardened. The only acceptable approach is to replace them. After market replacemnts are available at about half the cost of the OEMs. I have a pair on my 88 300SEL and I have had no probs. |
#4
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Buy a torque wrench.
Rotors often warp because someone "repairs" your car and then proceeds to put the wheels back on with the nearest impact wrench. This either applies too much torque to the nut, applies torque unevenly to different nuts, or both. Wheels MUST be bolted down in a criss-cross pattern using a torque wrench. Final torque is probably around 75-80ft/lb, but work your way up from 20 to 40 to 60, etc. I would check with your manual to be sure of final torque specs. Do it yourself too, because I have actaully seen people who didn't know how to use a torque wrench, so even if they say they used a torque wrench, be suspicious.
g Greg |
#5
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Midas!!!!????
At the risk of offending any one, I have never been impressed by Midas or most any other franchise shop. Under trained, under experienced, commission based maintenance sales, etc. In general, I do not recommend turning brake rotors. Braking turns kinetic energy (moving energy) into thermal energy (heat). The heat needs to be absorbed and dissipated. This is one reason there is a minimum thickness on rotors and drums. You have to have enough steel mass to absorb the heat energy during the stop and then get it cooled off before the next stop. Also, for the cost of turning etc, new rotors a usually worth the money, especially if you are planning on keeping a car for a while.
Good luck! |
#6
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Thanks for the replies. I live in Washington state. Most of the time I drive my wheels are getting wet from the rain. I took my car to Midas to get an inspection. I wasn't sure how thorough the brake inspection was anyplace else. I am going to get a new set of front rotors. I will also torque the wheels myself according to the manual. I hope the problem goes away after doing that. Thank you, andy
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#7
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If you need/want a total brake inspection, for peace of mind, go to a good independent Tech or the dealer. Lots of horror stories out there about Midas, my sister took my Dad's truck to a Midas shop for front pads. They ended up talking her into almost $600 (1979 dollars) worth of work. Within 50 miles the right front wheel nearly came off. The "brake specialist" never tightened the spindle nut.
That loose nut caused the new rotor to be eaten up, as well as the bearings and the spindle. The only piece I was able to salvage was the caliper. Another $400.00 in parts and a little bit of my time, the truck was on the road and my Dad was beating on the Midas managers desk. He did get his money back.
__________________
Mike Tangas '73 280SEL 4.5 (9/72)- RIP ![]() Only 8,173 units built from 5/71 thru 11/72 '02 CLK320 Cabriolet - wifey's mid-life crisis 2012 VW Jetta Sportwagon TDI...at least its a diesel Non illegitemae carborundum. |
#8
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If it were my car, it would have without further ado, a new pair of front discs and new pads both sides ! Machining front discs is almost as expensive as new parts and will never recover the original spec. of the discs.
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#9
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Why don't you check prices on the rotors at the partsshop here.
I could get new front and rear rotors, pads, sensors, and all for very good prices on partsshop here for my car. And believe me, I'll be buying from here when the time comes. Alon
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'92 300CE - Sold 2004 C240 - 744 - C7 Wheels - Android Radio 2002 C320 - 816 - Sport Wagon |
#10
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I made the guy
at the tire store pretty mad yesterday. I took it to a local tire store and had my tires balanced.
First I would not let the guy put it on the rack because there would have been an interference between his rack and a section of the exhaust system. I insisted that he use manual jacks. Watched in interest as the guy started to try to find a place to put the jack underneath the rear end. He got pretty hot saying that "I know where they need to go", while eyeballing the largest strut that he could see, when I insisted that he put the jacks at the jack points. He finally gave up and walked away when I pulled out the lug wrench and started removing the tires. A Mexican dude came out, took the tires and balanced them (did a good job by the way) and brought them back out to me where I proceeded to remount them. We lowered the jacks and I completed tightening the lug nuts. The guy cooled off and came back out to the car and understood "whatever it takes to serve the customer". I will go back there the next time I need balancing done. I do not have a balance machine at the house. Jim '95 E320 '97 Honda CRV |
#11
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How do you figure turning rotors is as expensive as new ones? I get them done for $6 + tax in upstate NY. I had the fronts done on my '79 300SD and the brakes are as smooth as silk and it was done 27,000+ miles ago. I will agree that if the rotors are warped they may warp again so new are sometimes needed. The rotors can warp form excessive heat so down shift going down long hills.
P E H |
#12
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By the book?
Turning rotors is a lot less $ than buying new ones. No comparison. But Mercedes says you cannot turn the rotors. I have heard that they need the thickness to absorb heat or they will warp. MB's have STRONG brakes. Lots of heat. You might get away with turning rotors. If hard stops from high speeds is a possibility I wouldn't take the chance.
I have done brake jobs to every car and motorcycle I have ever owned, except my MB because it doesn't need any work done yet. I changed the brake fluid last year. When I bought it there was a terrible brake squeel from one rear wheel. Changed to new MB rear pads and no more problem. The brakes were done at a franchise by the previous owner. The Mercedes manual clearly states that the rotors cannot be turned. Sure, anyone can cut corners, but for my money, get the right parts. I have had numerous recommendations to use the OEM pads and new rotors. They last a long time. This is no place to scrimp. Steve '85 500SL Euro |
#13
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refacing rotors
Don't know where everyone got info on MB suggesting that rotors are hardened or that they can't(shouldn't) be refaced, but we do that every day. Benz issued bulletin on subject in 1996 suggesting that under warranty that rotors must be refaced as long as there would be at least 1mm over min material after re-machining. If fact the W220 rear rotors are an almost every day happening!! 2000 Model that is! On early cars the bearing pre-load is important & critical!! On later cars, rotors can be done w/out touching the bearings.
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MERCEDES Benz Master Guild Technician (6 TIMES) ASE Master Technician Mercedes Benz Star Technician (2 times) 44 years foreign automotive repair 27 Years M.B. Shop foreman (dealer) MB technical information Specialist (15 years) 190E 2.3 16V ITS SCCA race car (sold) 1986 190E 2.3 16V 2.5 (sold) Retired Moderator |
#14
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Wrong again, and I hate that.
Perhaps I misunderstood, but I thought the CD stated no turning. I'll look again to satisfy my curiosity but am sure M.B. DOC is right. I may hate to be wrong, but I love to know the truth. This is one of the reasons that I camp out on this site. Thanks again.
Steve '85 500SL Euro |
#15
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I am going to purchase a new set of front rotors and brake pads. I will also torque the wheels myself with a torque wrench according to my owners manual. I appreciate all of the replies. The one thing I am curious about is why only the left rotor has warped and not the right? I'm just worried about going through the expense of new parts and possibly ruining them. Since owning my M.B. and with the help of this site and it's members, I'm am becoming familiar with the DOs and DONTs of M.B. car care. Thanks for you help. I would still like to know why only the left rotor has warped? andy
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