I am replacing wheel bearings on a 81 300D and noticed that both contact springs are broken. Can anyone tell me what they are for and are they really necessary.

Greetings Snipe,

Are you talking about the radio suppression sping steel as you remove the wheel bearing cap? If these are the ones you speak about I think they were used to keep noise out of your radio reception as it keeps a constant ground to your tires. I don't have them on my diesel. They might have come with them, but radio reception is great without them. I could see their purpose if this was a gasoline car with a typical ignition system. On a diesel I see no purpose for them.

Charles

__________________
"Tell me and I will listen, Teach me and I will learn, Show me and I will accomplish, Involve me and I will succeed."
'84 300SD 256,000 Gold on Brown (Mileage Award)
'86 300E 246,000 Blue on Tan

Thanks for the reply can-do. The spring is what I was talking about. I don't really understand how that can help radios. So I guess I really don't need them. Thanks again

Snipe

i recently replaced a front rotor on my 84' 280e,,,i don't recall the suppression springs being there,,,but i'm sure the hubs have been off enough times by now someone could have tossed them!!! then again my car wasn't ordered with a radio so it may not have had them installed,,,

its my understanding that the suppression springs would be for electromagnetic noise induced into the circuitry of the radio wiring,,,this noise would easily be induced to the wiring if not grounded,,,it would affect the sound in the same way the alternator does as revolutions in the winding increase,,,the difference is that the noise induced through the spinning of the wheels is not directly hard wired into the electrical system,,,the springs help disapate the interferance through the chassy,,,the rear wheels are probably far enough away that the noise in completely degredated,,,but they could have springs as well,,,the car being a diesel or not shouldn't make any difference,,,

my guess is that this is an example of MB engineering overkill,,,you probably won't notice the sound in the radio if you don't reinstall the springs but remember the assembly was designed with all parts installed,,,leaving out a part because you don't see a need for it may affect the function of another,,,

this is just my thoughts,,,i hope it helps,,,

Certain models of tires tend to cause a buildup of static electricity when rolling. Sometimes this is audible from the radio when listening to an AM station with a weak signal. An extreme case would be when you get a little static shock after driving when your feet hit the pavement. Toll booth attendants sometimes get zapped this way also.
When I did the wheel bearings on the 300D, I found one of the springs with it's tab broken off, sitting in the grease. The possibility of loose parts getting ground up and mixed in the grease concerned me enough that I took the spring out of the other side also.

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Palangi

2004 C240 Wagon 203.261 Baby Benz
2008 ML320 CDI Highway Cruiser
2006 Toyota Prius, Saving the Planet @ 48 mpg
2000 F-150, Destroying the Planet @ 20 mpg



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Just a quick thought. Keeping static electricity from building up has far more serious implications than just radio interference or an occasional little zap to your hand. A spark jumping between the fuel filler neck & the pump nozzle doesn’t sound like much fun to me.

RTH