Today, the 1982 300sd got a new differential mount, new springs and spring pads, new shocks, and new sub frame bushings.

Coming home from the shop, I heard a distinct roaring noise that was not there before coming from the rear end. It sounds like metal on metal or a wheel bearring going bad but not quite the same.

It increases loudness with increase in speed. It decreases loudness with decrease in speed. It really starts about 30mph. Checked differential fluid, it is full. Mechanic put it back on rack and rechecked everything, even ran it in gear off ground, but it does not make noise off ground. He rode with me and heard it, but we cannot diagnose. Please help.

Ride height was restored. It was an inch and a half low. I measured before and after rebuild. The springs, spring pads, shocks, subframe bushings and differential mount brought the car up an inch and a half in the rear. And car does not lean in corners any more. I am going to crawl under right now and see if something is rubbing while car is on ground. Did all repairs change rear end geometry that much???

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1982 300SD Light Blue
2002 Honda Accord SE
1974 Toro Wheel Horse Tractor
2000 Toyota Tundra Pickup

Wolf Walker from the site here came by and helped me diagnose the problem. We went driving and when I applied the parking brake while my foot was still on the gas, the mystery noise became very loud.

I definitely am going to have to replace the parking brake shoes. Hope there was no damage to the drum. We loosened the parking brake cable which was maxed out to let the pressure off. Will test drive in a little bit and see if that temporary fix worked till I can get the parts.

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1982 300SD Light Blue
2002 Honda Accord SE
1974 Toro Wheel Horse Tractor
2000 Toyota Tundra Pickup

Sounds like the parking brake shoes have been fried by improper adjustment -- you adjust them with a star wheel through a lug bolt hole, not with the cable! Using the cable will wear one end off the shoe, and the lining will come off. Also possible it's just old age, or the shoes are off the retainers.

Easy enough to check, just jack it up, pull the rear wheels, remove the calipers, and pull the rotors.

At least you don't have a fried rear end.....

peter

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1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!

Check alignment too, if ride height changed I can bet the alignment is now off.

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Proud owner of ....
1971 280SE W108
1979 300SD W116
1983 300D W123
1975 Ironhead Sportster chopper
1987 GMC 3/4 ton 4X4 Diesel
1989 Honda Civic (Heavily modified)
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I am not sure where the adjustment is for the shoes. We got under the car and loosened the cable to get them to release. I guess I can fix that later when I do the shoes. Is there a picture in the factory service manual?

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1982 300SD Light Blue
2002 Honda Accord SE
1974 Toro Wheel Horse Tractor
2000 Toyota Tundra Pickup

you adjust them through one of the lug bolt holes
I believe the adjustments are at the top and aproximately 10-14 degrees off of straight up on either side.
They are small, but if you take the wheel off and get a flashlight in there, you can see.
Also when you replace the shoes, you will see what I mean. Most likely though the adjusters are frozen from heat and dust and rust.
Mine were....some never cease and heat helped that problem