Building ERA Slabside #3012

[AndrewB]

5 or 6 years ago I was browsing craigslist and found a complete 1973 XJ12 rear assembly that had 74k miles on it and it had the ratio I wanted (3.31). So even though I didn’t have a car on order at the time, I knew it would come in handy some day . After doing tons of research, buying mics, dial gauges, magnetic bases, blah, blah, blah, we set out to rebuild the rear end.

Too late to turn back now


We decided to change out the Jag carrier to a Dana 44 Auburn Gear LSD. Dana 44 uses smaller 3/8” ring gear bolts, and as I already had the ring and pinion ratio I desired, we had the carrier drilled out to use the larger 7/16” Jag bolts – having a friend who works in a machine shop is invaluable! Here it is mounted with new bolts and lock plates.


All new bearings, races, shims, crush sleeve, seals, etc. After days of research, and going back and forth on shim pack size only to assemble and find out we were wrong, we finally got the proper backlash and pinion settings dialed in. After it was all assembled I was happy with both the drive and coast mesh pattern on the three areas we tested.


The stub axle seal surface had a bit more pitting than I was comfortable with so we installed some speedi-sleeves to give it a nice fresh surface. I hear this is the area notorious for leaks so I’d rather be safe than sorry.


As this is an early version of the Jag differential, it uses these crazy double ball stub axle bearings that are shockingly expensive.


New calipers, pads, and rotors being trial fit. Got pretty good at safety wiring too!


Here are the control arms and axles back from ERA and painted. We’re going to be loading them up with the Jaguar Classic bronze bushing kit.


The hubs were another exercise in patience. I don’t have any good pictures of those, but they now have all new guts, and with quite a bit of trial and error on shim sizing, we were able get the proper end float dialed in.

We still have to get the center section mounted in the subframe, control arms and axles fit, and the parking brakes installed, but we’re almost there. Its funny, when I write this up it all seems so easy and I almost forget about all the frustration involved. I knew we were taking on a significant project by rebuilding the rear end ourselves, and it certainly ended up as such, but overall it was a good experience even if it was a big PITA.