Hey everyone, I have a question about the brakes on my 1971 220D.
Recently, it has developed a problem when braking that the front end seems to groan/shudder.
Generally, this is at slow speeds like in a parking lot, or right before stopping at a traffic light, but it will also do this somewhat at higher speeds if I apply the brakes harder. There is a very low pitched deep vibration/noise. I don't really feel it, but I HEAR it, it makes the entire cabin resonate. It NEVER feels like the car will have any problem stopping, and it is not like warped rotors.
My first thought first was wearing through the brake pads, but those are fine.
I have also noticed that it NEVER does this when the car is in gear. It will start right away when I put the clutch in while braking. I don't think it is the clutch though because it continues even if I put it into neutral and let the clutch out.
The car does not pull either.

I came across some info in my service manual about having to have the caliper pistons at the right orientation, like it was designed to press at a bit of an angle on the pads. Could this be it? Is it possible for the pistons to rotate while the vehicle is in service?
Any other ideas? This is getting annoying. The car is so smooth riding except for this...

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1971 220D/4-speed ~250K mi. Family owned (dads side) through three generations since <5K miles.
1992 Chrysler LeBaron, 3.0V6 125K. Family owned (moms side) through three generations since new.
1977 Chevy Camaro Continual hotrod project
1970 Cadillac Sedan DeVille 472ci and nearly 19' long
1974 Fiat Spider Still needs work

Not rotors and not pads? Might be callipres partially frozen. First thing I'd do is bleed off alot of the old fluid, its probably black with dirt. Another possibility might be the flexible brake lines are shot and swelling when you apply pressure.

Actually, I was talking with a friend recently who is into diesels, and he suggested the vacuum pump, said I should raise my idle speed.

I used the dash adjuster and cranked it up to 1500rpm at idle, and the braking went completley back to normal. Explains why it would be just fine if stopping in gear, but got wierd the moment I put the clutch in.

I've been swamped with homework lately though. Keep meaning to check the checkvalve and the vacuum produced by the pump and see which is at fault.

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1971 220D/4-speed ~250K mi. Family owned (dads side) through three generations since <5K miles.
1992 Chrysler LeBaron, 3.0V6 125K. Family owned (moms side) through three generations since new.
1977 Chevy Camaro Continual hotrod project
1970 Cadillac Sedan DeVille 472ci and nearly 19' long
1974 Fiat Spider Still needs work

Engine mounts

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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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