Last post on Jul 24, 2003 at 12:02 PM
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Mercedes-Benz 280-Class, Wheels, Sedan
Jul 12, 2003 (8:31 pm)
Oops! Sorry, I misunderstood.
Does that have a limited slip differential by chance and have you checked the diff fluid if it does?
I think you are probably correct, but if it has a limited slip differential, I have seen them do some strange things when the additive has given up.
I know, not much help.
#5 of 13 hit some garage sales
Jul 12, 2003 (8:54 pm)
get an old kiddie phonograph, and pull the ceramic phono cartridge and tone arm out of it.
duct-tape the arm so the needle rests lightly on the half-shaft or housing (you don't want this rotating underneath the needle) on the side you suspect. you are going to have to put some bubble wrap or thin foam under the arm so the needle isn't squashed flat against the metalwork and won't have any flex left.
rig an extention cable to go into a boombox line input jack, and set it to record. put headphones on so you can monitor it, and back up.
it's a remoted mechanics stethoscope, and that should either transmit the noise clean as a bell, or not. if not, tape it to the other side.
I've tried to isolate noise with a microphone before, but road noise and air movement drowned it out. it REALLY gets drowned out with my homebrew 45 khz ultrasonic listening rig. this ought to work. the ceramic phono pickup should be a half to 3/4 volt output, so it's line input level.
Jul 13, 2003 (3:53 am)
Find someone who has a Steelman Chassis Ear, secure two of the pickup leads to the outer knuckles, two to the inboard side, and take it for a drive. Might be a trick keeping the leads out of harm's way but it should be doable with velcro or nylon zip ties.
Jul 13, 2003 (6:36 am)
I have a friend who has a chassis ear actually but he was skeptical that we could rig it, as that axle is, of course, a spinning part.
So you guys don't think that the "loading" of the CV joint is a clue? That is, a rear CV is more likely to knock if the car's weight is thrust to that side?
#8 of 13 makes sense, but as you said, which side?
Jul 13, 2003 (9:04 pm)
the noise is being transmitted to the chassis, right? so methinks getting soundings off the hub area is perfectly acceptable, and perhaps even closer to the actual problem, so the noise would be louder.
there is a chance that there's binding on the links someplace, too, and moving a pickup around there could isolate the assembly.
Jul 14, 2003 (7:21 am)
Well at $650 per side + labor (if one were crazy enough to buy new at the dealer), one had better guess correctly.
I can get an axle from the wreckers for $100 but they are rather hard to bench-test unfortunately, unless they are totally wiped out.
Big monster joints, seem more suitable for a panzer tank. You could use them in the weight room at the gym. Why they put them into service with a less than 100 HP diesel engine I don't know, unless they planned for interplanetary travel distances.
#10 of 13 probably had 'em on the shelf already
Jul 14, 2003 (3:12 pm)
which means they might show up in the next little dinky mopar, since DC is very keen on the idea of parts-sharing.
#11 of 13 What body is it?
Jul 24, 2003 (6:02 am)
Jul 24, 2003 (6:32 am)
It's a W123 dawg!
#13 of 13 Rear CV joints
Jul 24, 2003 (12:02 pm)
What's the condition of boots over the CV joints? Are they cracked open? Funny, usually the outer left side wears faster (due to the proximity to the hot muffler and tailpipe). Are you sure it's not in the brakes? The rear brakes on my W116 cars, which are about the same, have been noisy while backing from time to time (especially when new, and yes I use the shims). Also, the parking brake gets neglected quite often, can the shoes be sticking, hence the binding you hear? As for the noise when making left turns at speed, are your rear subframe mounts worn flat? Just food for thought, but diesel and 6cyl cars don't usually have axle problems unless the boots are bad and the joints have been allowed to dry out, get wet, etc.