Every time I engage the clutch or shift gears the differential makes a sound like a knock. I am wondering if it is because it might be low on lubricant or maybe its just time to replace the differential??? need some insight on what to do... thanks guys!

 

best way to fix this problem is to take off the diff cover and make sure everything looks ok....if not then your looking at a new rear end/rebuild.

 

[&:] usually this noise will be indicitive of too much backlash between the ring and pinion. this can be adjusted but one must look for excessive wear and make sure that any adjustments made arent just putting a bandaid on a failing component or one that has exceeded its wear limit. the u joint can also cause a similar noise so be sure to check these first. another thing to check is the rear trans mount. if you need help determining how to check each of these come back and see us kurt

 

If it's a posi and I'm assuming most Z28s are it may need posi lube.
I've seen clutch pack chatter from posi rear ends that had the oil changed without adding a tube of posi lube.
just a thought but I'd open it up and have a look before you drive it anymore.

 

[&:] y2k the chatter you speak of will usually be heard during cornering and not during clutch use or gear changes. toledo didnt indicate any of these situations leading to his noise so i doubt this is his problem. good point though remember to add the bottle of friction modifying lube to your diff if you have a posi to prevent chatter kurt