LSD Differential Rebuild

These photos of the diff and axles are as removed from the axle housing condition. During the last track day the diff got extremely noisy under any load. I was expecting to see major damage to the gear set (ie. hard facing damaged and a lot of metal filings in the oil).

There was quite a lot of moisture about the RH wheel bearing (note the rust). There is excessive clearance between the bearing races and will be replaced. The LH bearing is in good order.

An inspection found that the contact surfaces of both the crown wheel and pinion were scuffed beyond repair and were subsequently replaced. Good news is that the LSD centre is in excellent condition. The rebuilt assembly is shown below.

Whilst overhauling the diff centre, the shock absorbers were upgraded for adjustable Koni's....the difference was immediatly noticable.

It was quite obvious that the cause the gear set failure was a loss of lubrication when it was needed the most (ie. when accelerating out of corners). When Mazda ran the first generation RX-7's in the ATCC (Australian Touring Car Championship) they use to run up to 2.0 litres of diff oil and relocate the diff breather. The 626 diff housing is identical to the first generation RX-7 (sans Watts linkage centre pivot) so it was clear to me that the best solution was to increase the diff oil capacity from the standard 1.2 up to 2.0 litres (and Yes I have increased the parasitic loss caused by the higher oil level...but it is better than having another diff gearset failure!!!). Instead of moving the breather location on the diff housing, I mounted a 3 micron breather on the chassis and ran a line to the factory port (custom adaptor was necessary).