Hey does this rear end make me look fat?

The one place on the build I did not spare any expense is the rear end. Why? Because twice last summer I exploded the Camaro rear end and had to drag the car home from the track.

Now when say exploded I really mean exploded. The gears inside and housing looked worse than the cover.

So I choose the biggest baddest rear end that would fit in the Miata then replaced every serviceable part in it with genuine Ford Racing parts. I didn’t plan on doing that when I started so I blew the rear end budget by twice the budgeted amount. But the more I thought about last summer the more I did not want to repeat that with the Miata!

The rear end is an 8.8 locker out of a 96 Thunderbird. Dale and I had some fun tearing it down and pressing the new bearings on carrier in his shop. Back on my bench I rebuilt the locker with new carbon fiber clutch discs.

Next up a new set of 3.55 gears. The Tbird gears were 3.27 but that is too low for 6^th gear and good launches at the starting line. Hopefully they are not so radical that they don't just turn tires into smoke!

I put the new pinion in but did not press on the new pinion bearing yet. Instead I ground down the old one so it would slip it on and off the pinion easily. That way I can swap shims with no press during the set up process.

And a good thing I did because my first pattern the pinion is WAY too shallow so I need a thicker shim.

This is where the story takes a turn for the worse. With how far off the above photo is I knew the shim would have to be quite a bit thicker but all the shims from the install kit only added up to .011 and no way would that be enough. Well with no other options I put them all in and much to my surprise the pinion hit the carrier and would not rotate. I tried fewer shims and a number of combinations but there was no way to get the pinion deep enough without hitting the carrier.

Now I knew there were going to be scratch your head how am I ever going solve this problem situations in the build but using all top end Ford parts in a diff overhaul is not where I expected it!

So it was off to Google to see where I went wrong and sure enough I found it. The ring and pinion sets from aftermarket gear makers like Motive and Richmond fit all 8.8 rear ends from Mustangs to Thunderbirds to trucks. But for whatever incredibly stupid reason the Ford racing ring and pinion only fits Mustangs. I’m not sure if it’s because I missed quite a bit of sleep trying to figure this out or because I’m stuck with a set of Mustang gears I can’t return but am a little bit crabby about this situation. It's bone head engineering like this that let the foreign car makers shut detroit down!

Well forever forward. I ordered a set of Motive 3.55s and the Fords will go on ebay.

Psalm 121:1-2

I lift up my eyes to the mountains— where does my help come from?
My help comes from the Lord, the Maker of heaven and earth.