Brake Pulsing
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From: Oakville, Ontario Canada
'89 300E
Brake Pulsing
My 89 300TE tends to shudder, or pulsate, when I put on the brakes. It doesn't feel like ABS pulsing. It feels exactly like my 87 300E did before I had a chance to address the problem, since I totalled it in July, immediately, of course, after buying new rear rotors but before putting them on. I assumed I needed to replace the rotors on the TE, but I just got a service history tonight from the previous owner, and all four rotors and pads were replaced one year ago. I looked briefly at the front left rotor yesterday and it's smooth. However, I get a lot of brake dust on the wheel at the front left, so I may need new pads there. But could the shuddering be due to brake sensors acting up, or ABS, or do I need rotor work? Thanks
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From: Eastern Washington
1991 300E
First: Front or rear wheels? Just one side of the car?
If it is the front, do you feel it through the steering wheel too? And, have you had the rest of the front steering components and suspension checked out?
More likely than not though, what you have is a warped rotor. I had the pulsing through the pedal, and felt it in my seat, driver's side rear. Visual inspection of the disk showed it to look fine, nice and smooth, but once I put a dial gage on it and checked the runout it was obviously warped.
Solution: Replace both rear rotors and pads. Couldn't believe how cheap those rotors were. I have a set of rotors and pads waiting to go on the front, I'm just waiting for either the brake sensor lights to come on or for those rotors to get warped. Remember, the MB rotors are not designed with a whole lot of thickness on them. Less heat capacity due to there physically being less metal. They can't be turned either, just replaced. I think that the front rotors are less prone to warping due to their construction.
I have heard of rotors getting warped due to driving and getting the brakes good and hot, then washing the wheels right away once you get home. (Buddy was a real particular neat freak about brake dust on his wheels.)
If it is the front, do you feel it through the steering wheel too? And, have you had the rest of the front steering components and suspension checked out?
More likely than not though, what you have is a warped rotor. I had the pulsing through the pedal, and felt it in my seat, driver's side rear. Visual inspection of the disk showed it to look fine, nice and smooth, but once I put a dial gage on it and checked the runout it was obviously warped.
Solution: Replace both rear rotors and pads. Couldn't believe how cheap those rotors were. I have a set of rotors and pads waiting to go on the front, I'm just waiting for either the brake sensor lights to come on or for those rotors to get warped. Remember, the MB rotors are not designed with a whole lot of thickness on them. Less heat capacity due to there physically being less metal. They can't be turned either, just replaced. I think that the front rotors are less prone to warping due to their construction.
I have heard of rotors getting warped due to driving and getting the brakes good and hot, then washing the wheels right away once you get home. (Buddy was a real particular neat freak about brake dust on his wheels.)
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From: Oakville, Ontario Canada
'89 300E
Thanks for the reply. I have new 300E rear rotors, as I mentioned above. But I don't think I can put them on the TE. I think the rear wheel bearings on the wagon make for different rotors from the sedan. But I'm not sure. Anybody know? If I can use the sedan rotors I'll put them on ASAP.
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From: Oakville, Ontario Canada
'89 300E
Thanks Rusty. Much appreciated. I actually have two new rotors in the back of the car. I'll probably just return them to the dealer, take the 20% restocking hit, and buy the TEs there.
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From: SLC, UT
1987 Mercedes 300D Turbo
I think it's the ABS
If your brakes are pulsing, it is definately the ABS. If you just feel like your car is unstable when you are braking, it's probably the rotors. You used the word pulsing, so it sounds like your brake pedal is pushing back at you.
My ABS is very over-active.
My ABS is very over-active.
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From: Belfast, N Ireland
93 320CE, 72 280SE 3.5, 55 220A, 05 E280CDI, 88 Mini Mayfair, 90 Peugeot 205GTI, 04 Mini Cooper
Originally Posted by JaredJohnson
If your brakes are pulsing, it is definately the ABS. If you just feel like your car is unstable when you are braking, it's probably the rotors. You used the word pulsing, so it sounds like your brake pedal is pushing back at you.
My ABS is very over-active.
My ABS is very over-active.
Mine does it, but there is no fault with the ABS, discs (rotor).
I've had mine checked both by my mechanic and it went through it's MOT a few weeks ago and the brakes are perfect. (MOT if your not familiar, is an annual government test of car safety, brakes suspension etc. coming in for close scrutiny). The inspector did tell me that the bushes on the end of the anti-roll bars were not long for this life.
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From: Belfast, N Ireland
93 320CE, 72 280SE 3.5, 55 220A, 05 E280CDI, 88 Mini Mayfair, 90 Peugeot 205GTI, 04 Mini Cooper
OK had a quick look on some UK 124 sites and there is reference to the anti-roll bar bushes causing a clunk / judder that can be felt through the pedal.
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MBWorld Fanatic!
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From: Belfast, N Ireland
93 320CE, 72 280SE 3.5, 55 220A, 05 E280CDI, 88 Mini Mayfair, 90 Peugeot 205GTI, 04 Mini Cooper
To the right of the anti-roll bar bracket the bar is "rubbed", this is what I'm told causes the juddering, it's worn but not unsafe. And yes it is normally clean under there but I've been busy lately
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From: Richmond, Va.
1991 300E
If you're still wondering if your brake problem is ABS related or just warped rotors, Drive at slow speed (5 mph) near the edge of the road/culvert and brake hard on a pile of wet leaves. Be careful!!!!! you should be able to make the ABS kick in and "pulse" the front wheel that's trying to skid over the wet leaves. You'll feel it through the brake pedal. If that's the same feeling you're getting under normal braking conditions on a dry road then it's probably ABS, not rotors. Just be safe and watch out for the curb if you decide to try this.
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While I too am not sure of your description "pulsing" I will describe one eliment not already mentioned if this the case, if you feel something close to being called pulsing only at times (usually below 5 mph) coming to a stop, it is almost always one of your 3 ABS brake sensors. One each for right, left front and one for both rear located on the differential.
You cannot tell which one is faulty and they are very expensive. If this sounds more like your problem, have it diagnosed.
You cannot tell which one is faulty and they are very expensive. If this sounds more like your problem, have it diagnosed.
