pulsating brakes and noise(help me please!)

Aug 15, 2003 | 11:45 AM

duron

Thread Starter

Almost a Member!

Joined: May 2003

Posts: 39

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From: Charlotte, NC

1993 400E

pulsating brakes and noise(help me please!)

Hello,

Some time ago, I had a problem with my brakes pulsating when coming to a stop around the 20mph area. The feeling was like someone pumping the brakes ever so slightly. I was told by my mechanic that my rotors my have been warped(spelling?)

I then once it was time to change out, had them change front pads to porterfield dustless(works great) as well as the front rotors which was as rotor they had in stock that had holes drilling into them. I also changed back rotors and pads, but with OEMs.

The first few days were fine exept for the fact that now and currently when slowing from say 55 once I get to about 40 I get a low tone noise that sounds like rough tire noise (not squeel) and that tone gets deeper as the car slows. That is one issue.

The next is after a few day of no pulsating, it returns. The guys check the rotors and inform me that after placing them on either a machine or putting some kind of tool to them that measures rotor(I am not a mehanic) depth or straightness. They tell me that my rotors are fine, but I may have something going on with ABS.

so, to recap:

1. noise at low rpm stopping(I think it is drilled rotors)
2. pulsating

Any ideas at all from you guys, as I would like to solve both issues at my 150K service coming up in a week or two.

I have '93 400e

Thanks,

Duron

Aug 20, 2003 | 06:32 AM

john.clarke

Newbie

Joined: Apr 2003

Posts: 11

Likes: 0

Hi ..thank goodness someone has the same problem, this has been driving (braking) me mad for a good month now.

....1995 W124 E220 auto.

.....Happens at all speeds above 45 Km.

.....Slight braking pressure gives a pulsating of all brakes.
......this is clear because no deviation or pulling effect is apparent at any time. It follows that the braking on all wheels is perfectly synchonised.

..... hard braking at +/- 100Km results in serious pulsing / vibrating with resultant accompanying noise, but not like an ABS function.

.....today I noticed that a sqweaky brake at the rear perfectly mimicked the pulsating frequency of the brakes, which leads me to believe there is a pulsating pressure in the brake hydraulic lines.

I have previously negated the ABS unit, disabling same by removing all relays and the whole electrical connection block.

My latest theory is a slight leak in the brake pressure assist unit which causes the internal pressure to collapse and recover, producing a pressure pulsation effect. No chance to investigate this yet.......

...Does this spark any ideas Duron.......

........Tyke in South Africa.

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