snub disphenoid

I've been trying to figure out what this noise coming from my car is. I can't really pinpoint where it's coming from, but when I let one of the guys at Rotorsports drive my car, he said it felt like something was wrong with the driveshaft/rear end. The noise is sort of a loud clicking, sometimes it's more of a thudding. It gets more frequent the faster I go, so when it starts happening at 60mph or so, it feels like I'm in a cheap massage chair.

The noise only occurs when I'm accelerating or slowing down. If I pop the car in neutral and let it coast, it makes the sound. If I brake lightly, it makes the sound. If I'm maintaining my speed either on a downhill (engine braking slightly) or keeping speed on a flat highway, it makes the sound.

When they put my car on the lift, the tech (aaggh, forgot his name) said that I had excessive play in the driveshaft. It did appear to rotate quite a bit with the ebrake on and the car in gear (I believe that's the test, right?). So does this herald the demise of my stock differential? As far as I know, it's original, so it would have 137,000 miles on it at most. I did take my car do the drag strip and I did have some issues with wheel hop, so i guess I killed my differential, unless...?

I dunno, if anyone could confirm this diagnosis for me I'd appreciate it. I don't want to slap in a new differential and still have this annoying *** noise.

dgeesaman

iTrader: (7)

Differentials have a pinion that connects directly to the tail end of the drive shaft. The carrier bearings for this pinion can go bad, and if you don't wait long to fix it, it will be a reasonably simple rebuild. The general symptom is that if you grab the rear flange at the diff, you can push/pull and find a little bit of play in it. On my truck the diff made a whining noise, especially when coasting down or on the throttle (although the redneck mudder tires howl so loud the mechanic had to point it out to me). I would start by looking for play at the driveshaft flange and then draining the diff oil and looking for flakes of metal in it. Tiny flakes usually come from the worn out bearings.

It may be cheaper to install a used stock diff than rebuild yours. Fortunately differentials are pretty basic equipment, so any shop with RWD car experience can probably give you very good service.

Dave