My next issue was the annoying sound coming from my Mazda RX7 rear axle. Although super beefy and having LSD and big rear disc brakes the whine was unbearable. Kind of like going to the dentist for a filling. It was fine under load or off accelerator but on cruising it was horrible. I had bought the axle used as it was already narrowed but the PO had set up the back lash and pre-load wrong and permanently damaged the ring and pinon gears. I had a hard time finding used gears (3.909) at a reasonable cost. When I did find some I found a shop that specialized in swapping gears and removed the pumpkin and took it into them to do the delicate work. I supplied them with a new crush sleeve, all new bearings, and seals. They finished their work in one day.
I had never replaced gears before and had no idea how hard it is to remove and re-insert that 50 pound of metal. The housing mating surfaces are machined to a very tight tolerance, and with liquid gasket drying and me laying on my back, I worked up a sweat going from side to side to seat it home before my sealant dried. My first drive with the new gears proved it was all worth it. What a relief to cruise along with just the sweet sound of the muffler. Thanks to Proven Force in Osseo Minnesota for the gear swap.