Hello, everyone... I am a relatively recent Mopar convert from Volkswagen land, and as such have never had to deal with a rear end before (please keep chuckles to yourselves). When i bought my 76 Swinger, it made a rather loud howling sound from the rear, which i chalked up to low/no oil in the diff. But now, it has progressed to a cyclical 'scrape/roar' (at the speed of the driveshaft, not the wheels) with intermittent 'clunks' around 15mph. It seems to be worst at low speeds, better at 40mph+. I'm trying my best to find a new rear end for it (it's a 7 1/4", 2.76 with 10" drums) but haven't had any luck yet. Hopefully this weekend... may have to drive to LA. I found one on car-parts.com but it's a loooong drive...

My question is, when this fails, will it lock up and kill me, or just kind of crap out and spin freely? It's wednesday now, and i have to get to work till the weekend when i can fix it. Should I be fixing my bike first?

Thanks!

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76 Dart Swinger, 225 /6

You might check the U-Joints, one or both could be gone. If as you say it
seems to follow the drive shaft RPM, and seems to get better at higher speeds.

Please make sure it isn't either rear axle (wheel) bearing. When mine went in my 7 1/4" rear, I thought it was just diff noise at first, too. It was exactly as you described...clunks at low speeds, then it would go away. It turned out to be a rear axle bearing. How do I know? I was called into work on a Sunday morning, hit the highway and a half hour later while merging from a ramp onto I-95 North, I heard a grinding sound and saw the right rear wheel, axle shaft attached, rolling past my car.

The culprit: broken ball bearings in the 7 1/4". I was inexperienced then, but I know now to really make sure all my wheel bearings are good, and to check them the minute I suspect something.

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'68 Dodge Dart 4dr Sedan

Thanks for the suggestions, i will definitely look into both possibilities. How would I check the U-joint? Is there a diagnostic procedure?

Thanks again! This is a great forum, lots to be learned!

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76 Dart Swinger, 225 /6

The only certain way to check the U-joint is to take it out and inspect it. A quick check is to hold the yoke still and try to twist the driveshaft back and forth. If you see any movement at all in the drive shaft relative to the yoke then your joint is shot. Also look for signs of rusty red dust around the rubber seals on the end caps. If your U-joint is bad enough to make the kind of noise you describe then you'll almost certainly see signs of rust and/or metal shavings and also movement in the joint itself.

Just a side note, U-joints don't typically "howl;" that kind of noise is usually a mismatch in the pinion to ring gear mesh. It can also be caused by bad pinion and/or carrier bearings. A cyclical scraping/grinding noise could well be the rear wheel bearings. It's very difficult if not impossible to diagnose the problem just from the noise; about all you can do is generalize. At some point you've got to get your hands dirty. A mechanics stethescope can help to isolate the source of the noise but in the end you've got to tear it down to see for sure.

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David Kight
'62 Valiant Signet, White
'98 Dodge Dakota
'06 Jeep Liberty

Growing older is unavoidable but growing up is strictly optional.

Patrick, you were dead on. Took the axles out and it was the passenger axle bearing. Totally shot, balls missing... I opened the diff and everything looks fine in there, so i'm going to have new bearings pressed on and hopefully be back on the road soon.

Thanks for your help, everyone!

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76 Dart Swinger, 225 /6

Good to know. I'm glad you were able to find out the easy way (and not the stranded-on-the-highway way)!

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'68 Dodge Dart 4dr Sedan