I just finished a lapping day at the local gokart course and noticed after getting some gas that there is a curious noise coming from the rearend that wasn't there this morning. The noise sounds like a groan and sometimes a clunking. This is while going straight no turns. Best heard off throttle but can hear it from 2-4.5k rpm when accelerating. I had changed the oil to Mobil 1 75w-90 about 50 miles before the event. Any ideas?

 

Talk to Puddy, you need a new diff.

 

Could it be anything else you think? I'm assuming it's the diff...

 

You could have a broke axle maybe??

Easy thing to do is…Drain the diff oil and check the drain magnet for junk also check the oil for heavy metallic sheen. If you only have a bit of fuzz on the magnet and a light metallic sheen then the diff maybe ok. Good luck

 

Check the axle nuts and make sure they are properly tourqed. There is a TSB out about the early model cars axle nuts, a quick search should find it.

If you broke an axle, it should be very very very obvious when driving.

Good luck!

 

How obvious is obvious? I was just reading about that tsb. I did have a click accelerating from a stop a couple of weeks back. At first it was on one side but now they alternate on whether each side does it or not. Hopefully it's the axle nuts. Though ive read that if left not fixed then the bearings or axle could fail.

After driving it today I noticed that it is speed dependent. Ill jiggle the axle tonight to see if there is any play besides side to side (left to right) instead forward and backward.

Little info on the car if it helps: 74k, lowered .75 inches with Koni yellows/gc combo about 1k miles ago. Everything else is stock.

 

Oh and I REALLY appreciate everyones help!

 

Obvious axle failure should be stupid obvious. If the axle failed, it would no longer we turning that wheel. I've never really heard of axles failing on N/A cars though, typically the diff fails before that.

 

Heh. I should drink coffee earlier in the morning. That was painfully obvious.

 

When I drained the diff oil it had quite a bit of floating particulate (shiny silver and gold) in the drain pan. Some fuzzies on the drain plug. This was on the second flush. I actually had to do it twice after maybe 15 miles since I didn't have a differential washer which caused a slight leak. The first flush had more fuzzies on the plug but didn't see any particulate in the oil.