Project Vapor Trail Gear Swap - Gear Drive

Time to gut the stock 8.8. Dave removes the pinion-shaft bolt, pulls out the shaft, removes the C-clips, and slides out the axles enough to clear the differential. Next he removes the bearing caps, and pulls out the stock diff and ring gear.

Be sure to set the bearing caps aside in the same way they came out. They need to go back on just the way they came off.

After unbolting and removing the pinion gear, Dave taps out the pinion bearing and flushes the pumpkin with brake cleaner.

Dave says this pinion depth gauge is critical to properly setting up a gear. This tool allows you to mock-up the new bearings in the housing and check for the proper shims before you install the differential for real.

The FRPP install kit includes numerous shims. Depending on your setup, you might need to stack two to achieve the proper measurement. Dave prefers to use a single shim, and had the proper shim in his cache of shims collected from years of setting up 8.8s.

Dave finds a good use for old bearing races as buffers for pressing on new bearings. This practice is seen here as he pressed the new FRPP carrier bearings onto the fresh Torsen T-2. Once again having the proper tools, like a press, really expedites the job.

When it comes to someone working on your 'Stang, you want a systematic, detail-oriented type. Dave fits that bill. He has a routine that helps him make sure that he doesn't forget a crucial step. Here Dave is bolting the ring gear to the Torsen in a star pattern before torquing them into place at 85 lb-ft.

After pressing on the new bearings, Dave installs the pinion gear and the new pinion flange from Axle Exchange. The new flange is required to install the AE driveshaft, and it looks far more robust than the stocker. It takes a long wrench or wrench with a prybar to torque the pinion-bearing crush sleeve, but do it in small increments to get it just right.

After torquing the pinion into place, Dave checks the preload on the pinion. It should be 30 in-lb. Since many aftermarket S197 driveshafts require a new pinion flange, swapping a driveshaft and gears at the same time dovetails nicely. Dave says it's really tricky to get this preload correct when you just swap the flange.

After bolting in the Torsen and torquing the bearing caps to 75 lb-ft, Dave checks the backlash with a dial indicator. The proper range is between 0.008 and 0.015 inch. Thanks to Dave fastidiously selecting the proper pinion shims with the depth gauge, PVT's new FRPP 3.73s came in right in the sweet spot of 0.012 inch.

FRPP's install kit includes the white lithium grease to test the pattern of the newly installed gears. I knew it must have been a good install when Dave exclaimed, "Wow!"

He then proceeded to show me an ancient Ford document that showed a pattern just like the one on PVT. These gears are set up right!

The T2 is a perfect fit for the GT500, as it is compatible with 31-spline C-clip axles.

After Dave pops in the C-clips, he bolts the thrust plate in to wrap up the Torsen portion of the install.

After liberally coating the mating surface of the FRPP girdle with high-temp sealant, Dave bolts on the cover. He torqued the cover-retention bolts to 25 lb-ft, and then he installed the drain plug and load bolts. To provide extra room for a socket, Dave replaces the standard load bolt nuts with smaller fasteners for increased clearance. The load bolts only are only torqued in the 5 to 10 lb-ft range. Too much torque is not a good thing. Once they are within spec, the nuts lock them in place. With the cover installed, Dave filled the rear with some inexpensive 75W-90 conventional gear lube for break-in. He recommended that I drain it out after 1,000-2,000 miles before making the move to synthetic gear lube.

If you ever plan to drive your car in anger, it's a good idea to install a driveshaft safety loop. I expect trouble-free service from the Axle Exchange 'shaft, but the loop provides peace of mind. It also keeps you on the good side of officials at the racetrack. This simple, elegant solution from BMR Fabrication bolts to the transmission crossmember. The BMR front driveshaft loop (PN DSL010; $109.95) is slotted so you can easily center it up before permanently installing it. With stock two-piece driveshaft you'd need a loop out back too; BMR has those as well.

With the BMR front driveshaft loop loosely installed, Dave installed the Axle Exchange one-piece aluminum driveshaft. This driveshaft is a thing of beauty, with gorgeous welds and quality hardware, and it's proven to be vibration free. It also eliminated that tell-tale tick-tock noise that the stock shaft exhibited after PVT's suspension upgrade. We weighed the AE shaft and it was about 18 pounds, or about 20 pounds lighter than our stocker. You could definitely feel the difference in heft.

With the installation wrapped up, Dave carefully reinstalled PVT's Steeda Watt's link without disturbing any of its settings. While it did require a strategic installation plan, the Watt's does clear the FRPP girdle. Whew!