I appreciate that there has been significant discussion regarding the BMW LSD but I’m afraid I can’t find a suitable answer so here we go again. Ignoring the horrendous whines, clunks and embarrassing kangaroo characteristics, (they all do that sir!) my 2012 differential having only travelled 9000 miles in a 140 Supersport, seems to have significantly more backlash than when it fell into existence. Before I take it apart to investigate what’s going on, I’d appreciate any wise words from the world of Blatchat.
I have measured the free rotation of the input flange against the handbrake and have approximately 23 degrees (20mm around the flange circumference). I know there is a small amount of free play in the driveshafts but this is minimal. 23 degrees in the diff seems colossal.
I have also tried to assess the free play by jacking up one wheel and rotating it against the gearbox in 4th gear (straight through). I marked the movement relative to “CR500” on the tyre. I would attach a photo but ain't clever enough. It goes from the start of the 'C' to nearly halfway through the first '0'.
My first question is whether anyone knows the specified backlash for this diff. Secondly, I’d really appreciate it if you also have this diff and can measure what backlash you have. I measured a friend’s and his circumferential measurement on the diff flange was 16mm which means mine is 25% greater. It would be good to get a number of measurements for comparison.
Thanks for your help.