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  #1  
Old 10-02-2001, 08:55 PM
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Warped Front Rotors--Again!

All help appreciated, including Benzmac's:

I've had my 94 wagon for about 2 years and have driven it about 14,000 miles. Most of it stop and go city driving. When I bought the car from the MBZ dealer they told me they had put on new rotors and pads as part of the Starmark preparation. Within about 8,000 miles the front rotors warped pretty badly. I replaced them with new EBC front rotors and new EBC green stuff pads. Within less than 2300 miles the front rotors warped so badly that I had to take them off (got a full refund, however). I replaced the rotors with MBZ stock rotors and kept the green stuff pads. Now, less than 2500 miles later my front rotors are warping.

I have a torque wrench and use it to set/check for proper torque. I don't spray cold water directly on the rotors when they are hot although I do run it through the car wash every now and then. I do not use Kleen Wheels.

What seems to be the problem here? If it is purely a matter of excessive heat, what would be the best upgrade to make (considering that money IS an object)? I've heard of 500E brake installations on wagons before, is this a straight bolt-on upgrade? What needs to be changed besides the rotors and calipers? I have 17-inch wheels which should be big enough for the 500E brakes.

I've put in a parts request here but haven't heard back yet.

Is there another path to take?

Again, all help appreciated.

Cheers

Bill
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92 300E (Black/Grey interior: wife's car)
94 E320 Wagon (White/Saddle interior, Eibach springs, '96 E420 16 x 7.5 wheels)
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  #2  
Old 10-02-2001, 09:41 PM
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Bill,

I beat the CRAP out of my wagon on the street-the brakes are up to it. NO WAY you should be warping rotors, period. So, I'm thinking you have a stuck caliper upfront-that's where you need to focus. If not, then perhaps your master cylinder is not allowing all pressure to release (unlikely, though)

500E calipers require different hubs, BTW. But I seriously doubt you'd need to upgrade-just fix the excellent brakes you already have. And if front caliper rebuilds don't get you what you want, try cryotreating your rotors-worked for me (I was boiling & warping rotors at track events in my 500E)
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1995 E500 street car
1986 Porsche 944 Turbo S track car
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  #3  
Old 10-02-2001, 10:25 PM
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Join Date: Feb 2001
Location: SE PA
Posts: 63
It may be worth checking the hubs for runout prior to putting on another set of rotors. I've seen this on other vehicles. Severe overheating can warp the hub as well as the rotors. New rotors will eventually conform to the warp of the hub after repeated heating cycles. I put 4 sets on a Saab 900 before figuring this out. It started when a friend drove me (and my car) home from a New Years party without releasing the parking brake. On that car tha parking brake is a mechanical actuation of the regular front pads. It was at least 5 minutes before they cooled enough to stop glowing. You could have read a book by the glow when he first parked it. In your case the underlying cause could be a sticking caliper or a PO that rode the brake a lot at speed.
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  #4  
Old 10-03-2001, 08:17 AM
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All good points.
One question, how do you break in the pads and rotors?
I`ve always braked carefully , no hard stops, gentle on the peddle for at least 200 miles. never had a problem.
Recently I replaced the pads and rotors on my 560 SEC, with ATE power discs and Oem pads. After 2000 miles everything is great.
If your doing this yourself how do you set the bearing preload? I don`t have a dial indicator so I thighten the nut until the rotors will just about turn, then back it off about a third of a turn. check for excsessive play and put it back together. Take it for a ride and check that the hubs are not overly hot. Always repack the wheel bearings,and change the grease in the hub.Use Mercedes Green grease.
Your hubs could be getting to hot and warping the rotors

John
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  #5  
Old 10-03-2001, 12:20 PM
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Location: Saugus, CA USA
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Not to suggest a suppository for a headache, but check your back brakes. If they are not working as hard as they should be the extra load on the front could cause problems.
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  #6  
Old 10-03-2001, 10:15 PM
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Thank you everybody for your advice, I'll get with my mechanic and go down through the list.

I do appreciate the help!

Thanks

Bill
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92 300E (Black/Grey interior: wife's car)
94 E320 Wagon (White/Saddle interior, Eibach springs, '96 E420 16 x 7.5 wheels)
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  #7  
Old 10-04-2001, 04:24 PM
jfujimoto
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I just installed some slotted rotors on my non-MB truck. The most important process (according to the manufacturer), is to break in the rotors gently for the first 200-500 miles. Resist the temptation to "test" the new rotors initially.
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  #8  
Old 10-06-2001, 04:52 PM
Southern_Son
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My last warped rotor (last month) is the result of a caliper being retained too tightly in the caliper bracket. I took the bracket off and filed it in various contact points to loosen the caliper's fit. It now works very, very well. The caliper MUST be able to float freely in the bracket, not TOO LOOSE, but loose.
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  #9  
Old 10-07-2001, 12:29 AM
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Location: Jacksonville Florida
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Exclamation the dreaded rotors

Bill, try the porterfield brake pads,and the frozen treated rotors they WILL fix the problem I have used the porterfield brakes on most all of my cars including my ex 911 turbo cause the factory rotors would CRACK I drive very HARD!!!!! and i installed a treated set from porterfield and no more cracks or pulsating pedal PROBLEM SOLVED one quick note do you change the brake fluid every year?also buy only ate or the factory rotors cause sometines the aftermarket rotors are well JUNK

good luck
MARK

BILL If money is not a issue BREMBO makes a sweet
front set up since you have the 17 inch rims




Last edited by mark cummins; 10-07-2001 at 12:34 AM.
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  #10  
Old 10-07-2001, 12:51 AM
starfighter
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who else is driving the car besides you ?because its strange that everything was fine for about 2300 miles and then the rotors a warped I am thinking that some one may have rode the brake peadel then performed a hard stop to warp your rotors well thats my thought
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  #11  
Old 10-07-2001, 05:20 PM
Southern_Son
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Bill, Mark Cummins has a good idea on using the cryogenically treated rotors for service stability. However, the warped rotor referenced in my post above, is one of the Sport Rotors from Vette Brakes. I put two on the front of my vette for a little over $200 apiece. The right side warped again because of the dragging caliper in the "too tight" bracket.
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  #12  
Old 11-04-2001, 08:59 PM
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Update:

Sorry, I was out of town on business for a while but now I'm back.

I had my mechanic check out the brakes including the calipers, hub runout, etc., and could find no problems. We've removed and replaced the front and rear rotors (the fronts under warranty) and pads with MBZ parts. The left front rotor runout was .004 in; the right front and both rears were out .002 in each.

So, we're starting from scratch and I must say they are very smooth, at least for now. I am being as careful as city traffic allows with the break-in. My mechanic says he has seen bad rotors back-to-back in the past, as I seemed to have experienced, but I'm keeping my fingers crossed.

Thanks for all the input and advice, everybody.

By the way, I had him install Bilstein Sport struts on the front end (I'm not quite ready to tackle the rear shocks yet--$$$$) and I've picked up a little additional compression travel over the stock struts. For those who have lowered their cars without going to the sport struts then you are indeed missing out. Ride quality seems to be as good as before but I get some extra travel and much less "hobby-horsing" than with the stock struts.

Cheers

Bill
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92 300E (Black/Grey interior: wife's car)
94 E320 Wagon (White/Saddle interior, Eibach springs, '96 E420 16 x 7.5 wheels)
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