We have this 71 Electra that we are attempting to re-gear for demolition derby use. I have the rear end all stripped down. It's a 12 bolt open carrier. 30 spline semi-floating axles that bolt-in to the housing endcaps. The ring gear bolts are reverse thread and seem to be 1/2-20 on first glance but I did not put calipers to them so don't hold me to that. The outside of the ring gear measures about 9" as expected. The inside of the ring gear measures 6" 15 teeth on the pinion so I assume this is a 2.73 gear set, but I did not count the ring gear. Is this a 3 series carrier? Can I use regular Chevy 12 bolt gear sets? The reason I ask is that I purchased a 12 bolt 5:14 gear set on eBay and it does not match up to the carrier. The ring gear I received has a 5.5" bore and looks to use 3/8 or 7/16" bolts (again, did not measure, but they are certainly smaller than what I took off the rear end I am re-building). The pinion came with the large bearing already pressed into place as the gears are pre-run. I set the pinion down into the center section and I also noticed that the large pinion bearing is smaller than the bearing on the 2.73 pinion. The bearings are only riding in about 1/2 of the race that's installed in the housing. What do I have here? What more do I need to go measure so someone can help me figure out what I need to get this rearend re-geared?
The rear in that car is a 9 3/8" ring gear. There are no gearsets made for it. You'll only find (if you're lucky) at most a 3.42 set, and those are in the Riviera GS models 71-72.
Even if you could find a 9 3/8 3.42 Buick ratio gearset it would cost more than you paid for the entire car you are going to use.
Thanks for the heads-up guys. Looks like this one is just getting welded up solid and run as-is then.
