FD Differential Remove and Replace - Writeup

[jkstill]

The gearset installed is the 4.77 KG (Garage Kagotani) gearset. These gears are not actually made specifically for the FD RX-7. That is apparent when you consider that the pinion requires a bushing to bring the diameter up to the correct size for the bearings, and the ring gear requires a spacer to get in the the correct backlash range.

Nonetheless the gears work fine. One potential problem with this gearset is that the ring gear spacer may not be thick enough. The setup on my diff required the 6.50mm shim on the left side of the diff to get the backlash set correctly. As 6.50mm is the largest shim Mazda makes, if the 6.50mm ring gear spacer had not worked a new spacer would need to be made.

I didn't measure the ring gear spacer thickness, but it should probably be another 0.2mm (0.008") thicker.

Were I to do this again I would probably just get the 4.77 RX-8 gear set.

Next: Pinion race install