After re-building a 5, I had an annoying (not much, but enough) whine from the diff. We had refurbed the original diff, but only with new seals, gaskets etc. There was a little play as expected. The original diff must have done 85K+, but we felt it was worth just putting it back to see what sort of condition it was really in. Well it it whined especially, around the 50mph mark on or off load, it was much the same.
Anyway a while back, I had my 6 diff re-built. That was whining too, I took it to a specialist (I won't shame them yet) but it was re-built with a new crown wheel and pinion. It cost around £1200 and it still whined. I took it back, he checked it, said all OK. Re-fitted, and it still whined. Very, very dissapointed to say the least.
So with trepidation I thought I would try Hardy Engineering in Leatherhead, after getting some positive recommendations. A while ago I bought a complete unknown 3.45 diff off Ebay for around £100. So thought I've got nothing to lose to get Hardy Eng to evaluate and advise, which they duly did. This diff needed a new crown wheel and pinion, new bearings etc etc. Hardy Eng supply their own crown wheel and pinion, made to their spec. I'm no expert, so I don't remember everything they told me, except the teeth on their crown wheel and pinion are made with a slightly bigger curve, which apparently provides a quieter engagement. Well I have just fitted this diff to the 5 and taken her for a test drive. - Only 10 miles or so. But whine gone, really quiet, no clonking, nothing. Well pleased and it cost £700.
I'll be taking the original 5's diff to them next and then after that my TR6's diff.
I know, in the past, there have been quite a few frustrations expressed on here over diff repairs like mine. So I thought I would pass this on.
No connection, just a happy customer