Jag Diff Noise

[kyleb]

I have a 3.54 jag power loc fitted to my cobra and am about to pull it out for the third time .... First drove the car a few months ago which was a great feeling but the rear end shook like a dog crapping tacks, so after a lot of investigation decided to remove supposed reco (albeit sat idle for many years ) diff and found the wrong dia pinion bearing was fitted therefore allowing pinion to float which also added some unwanted metal to the oil... Okay no probs we can do this, fit new bearings change ratio from 3.07 to 3.54 ( opportune time ) and re-fit diff, easy right.. Ahhh No.. Put diff back in was good initially then after a few K's started to whine and graunch on gear change and transfer of power, got worse as oil heats up then eventually chopped out pinion seal and bled to death .. Check oil and you guessed it, full of sparkles.... BUGGER. OK remove diff take it to jag specialist and $1900 poorer I get the nice newly reco'd diff back assured was good to go forever.. Apparently forever is about 60 K's.. Noise and graunching back, get home and pull a sample of oil and yep sparkly, diluted the sample with fuel and put a magnet in and it came out looking like a porcupine...Hmmm... Ok, thats great get to the point you say, Well my question is this, Have I screwed something else up to cause stress on the pinion ? It has a TKO 600 fitted in line with the centreline of the car and the diff centre is offset somewhat to the drivers side and the driveshaft is about a foot long ( typical for a cobra I thought ). Could excessive angle on the tailshaft cause vibration and failure? Or is it just plain bad luck and the fact that we are all re-using second hand parts that are now getting past their useby dates? Whaddya Reckon..