2001 3g GT Project Car Differential: Booty Overhaul

For those just tuning in, our '01 3g GT Mustang project is all about forces--g-forces to be exact. Our mission is to achieve 1g of cor-nering, 1g of braking, and 1g of acceleration using bolt-on parts. So far, we've updated our screaming Zinc Yellow banana with an ATI ProCharger P-1SC supercharger, a Steeda suspension (including the company's five-link rear setup), Steeda 13-inch front brakes, and a Cervini's Cobra R body kit (hey, it has to look the part too). We've also spruced up the inside with Ford Racing Performance Parts leather seats, NR Auto Accessories electroluminescent gauges, MGW billet hardware, and a Year One brushed-aluminum dash kit.

Thus far, the performance parts we've installed have given the 3g GT a whole new feeling, turning a decent stock Mustang GT into a performance machine anyone would love to have. But we're just getting started. Later in 2003 (it's only September 2002 as this is written), we'll begin a Phase Two scenario with our project Mustang. Look for even bigger brakes, more engine enhancements, more handling improvements, custom paint with graphics, and much more. With the addition of Phase Two, the 3g GT will undoubtedly be able to post the g-force numbers we're seeking.

Up to this point, the rearend--one of the most important areas of the drivetrain--hadn't been upgraded to handle the current power of this Mustang, let alone what we plan to throw at it in the future. While the 3g was busy being hustled from show to show during 2002, we had just enough time to get its rearend built up by LaMotta Performance, with the proper goodies from Reider Racing, before heading to the NMRA World Finals in Bowling Green, Kentucky.

After discussing the project with Tom Reider, we agreed that a Zexel Torsen T-2R differential with Precision Gear 3.73 gears wrapped around it would be the best answer for cornering and straight-line acceleration. To complete the upgrades, Tom suggested Moser Engineering custom alloy axles since the Torsen is a 31-spline case. We also contacted Kenny Holcomb at Holcomb Motorsports for an FRPP aluminum driveshaft because if you've ever driven a Mustang with one of these bad boys under it, you know every Mustang should have one. Finally, we cracked open a fresh case of Red Line synthetic gear oil to lubricate the 3g's new parts.

The installation wasn't complicated, but there were a few extra steps due to the Steeda five-link suspension mounting points. As we've said before, we don't expect you to perform your own gear swaps, but we want to show the progress our project car is making. Come out and see the 3g at driving, racing, and show events in 2003.

It's much easier to understand... read full caption It's much easier to understand how the Zexel Torsen differential works if we simply show you an exploded view of the differential instead of trying to describe its internal operations. Suffice it to say, the differential works instantly and offers great traction and cornering abilities for a street or handling car. Just don't punish the Torsen with big slicks and extreme drag-race use.	LaMotta Performance technician... read full caption LaMotta Performance technician Jay Meagher drew the short straw and was the lucky winner to work on our 3g Mustang (special thanks to Jake LaMotta for fitting us in so quickly before the NMRA World Finals). To access the differential cover, Jay removes the right Panhard bar mounting assembly from the axlehousing since one of its support legs ties into the differential-cover mounting-bolt area.	With the Steeda five-link... read full caption With the Steeda five-link Panhard bar and mounting bracket out of the way, Jay removes the rest of the differential cover bolts and drains the barely used synthetic fluid from the differential housing. He then completely removes the cover.
For the differential to be... read full caption For the differential to be removed, the rear axles must be disengaged from the differential side gears. Jay removes the brake calipers and mounting brackets (wiring them to the frame so as to not hang from the brake hose). He then removes the delicate ABS wheel speed sensor so the sensor isn't damaged during axle removal.	With only the bare axles left,... read full caption With only the bare axles left, Jay removes the differential cross-shaft retaining bolt and then slides the cross-shaft out of the differential. This allows the axles to be pushed inward so the C-clip retainers can be removed from the ends of the axle, allowing complete axle removal.	Use caution not to drag the... read full caption Use caution not to drag the axle on the axle-bearing seal (located at the extreme outer edge of the differential housing) or you will damage the seal and cause a gear-oil leak all over the brakes and rear wheels. Not good.
With the axles removed, the... read full caption With the axles removed, the differential can be extricated from the housing. Jay removes the two differential main-bearing caps (noting their sides and the directional arrows on them) and then carefully pries the differential out of the housing.	The stock steel driveshaft... read full caption The stock steel driveshaft will have to be removed to access the pinion gear still mounted in the differential housing. The four 12-point, 12mm bolts that retain the driveshaft are secured with thread locker. The bolts are tough, so be sure to use the right tools. Jay takes care of the bolts with a swivel impact socket. Once the driveshaft is out of the way, he uses an impact gun to remove the pinion gear retaining nut. The pinion gear, crush sleeve, and pinion shims are now removed from the housing.	The first order of business... read full caption The first order of business for our new parts is installing the new pinion gear. The pinion depth is measured with the tool shown here. One part of the tool is installed in place of the pinion gear and the other part is installed in place of the differential. Then, shims from the Precision Gear installation kit are added to the pinion area until the clearance is within the tool's specs.
The shims from the pinion-depth... read full caption The shims from the pinion-depth tool used in the previous caption are transferred to the new pinion gear, along with a new pinion bearing (also from the installation kit). The shims simply slide over the pinion-gear shaft, but the bearing must be pressed on.	The pinion gear is installed... read full caption The pinion gear is installed into the differential housing, and a new crush sleeve and pinion retaining nut--which are also included in the installation kit--are installed. The pinion crush sleeve has to be crushed by tightening the pinion nut until a certain amount of torque is required to turn the pinion gear. Here, Jay checks the torque needed to turn the pinion gear with a dial-type torque wrench.	After installing the new differential... read full caption After installing the new differential bearings supplied in the Precision Gear installation kit, Jay carefully presses the ring gear into place on the differential using old ring gear bolts to maintain alignment.
Once the ring gear is seated... read full caption Once the ring gear is seated to the differential, Jay installs the original ring gear bolts from the factory differential (you can order new bolts as an option) and then torques them to the specs in Precision Gear's installation instructions.	Now comes the fun part. Jay... read full caption Now comes the fun part. Jay temporarily installs the new differential and ring-gear assembly into the differential housing with the original shims. He checks for proper wear pattern on the gear teeth as well as the gear backlash settings. It takes about four tries of swapping shims and setting the differential back in place, but he finally gets the whole setup within the specs he likes.	To install the new Moser 31-spline... read full caption To install the new Moser 31-spline alloy axles, the ABS sensor rings must be pressed off the old axles and transferred to the new ones. The rings are made from powdered-metal castings and are somewhat fragile. It isn't uncommon that at least one of these rings will have to be replaced in '94-'02 ABS cars that are getting axle upgrades. Jay carefully extricated both rings and installed them on our Moser alloy axles without a problem.
This photo of the factory... read full caption This photo of the factory axle and the new Moser 31-spline alloy axle demonstrates how much beefier the Moser axle is, especially in the axle-bearing and stud-flange areas. Notice too the special machined section where the ABS ring is pressed on. When ordering axles, you will have to specify if the axles are for ABS use so that this special section can be machined into the axle.	Jay slides the new Moser axles... read full caption Jay slides the new Moser axles into place and secures them with the original C-clip retainers. He then installs the Torsen's specially designed cross-shaft/ thrust block to retain the C-clips.	Though the Precision Gear... read full caption Though the Precision Gear installation kit comes with a paper gasket, Jay prefers to use a solid bead of silicone sealer on the rear cover, which is exactly how the cover is installed at the factory. If you use silicone sealer, be sure to run the bead of sealer on the inside of the bolt holes, otherwise your fresh gear oil will leak from the bolt holes in the cover.
With the cover in place and... read full caption With the cover in place and the Steeda five-link bracket reinstalled, the only steps left are to reinstall the brake components, install the driveshaft, and fill the differential with oil. The rear brake system and ABS sensors are reinstalled first and then the wheels are reinstalled. Jay snugs the lug nuts with an impact gun, but he does the final tightening with a torque wrench--and we didn't even have to ask!	Our new FRPP driveshaft is... read full caption Our new FRPP driveshaft is a complete, ready-to-install assembly with strong 1330 U-joints, a slip yoke, and a companion flange mount. Just slide it in and bolt it down. What could be easier to make your Mustang run more smoothly?	We took this photo after Jay... read full caption We took this photo after Jay tightened the driveshaft bolts. These are the pesky 12-point, 12mm bolts of which we spoke earlier. Using the correct tools to secure these will prevent damage to you, the bolts, and the driveshaft. To finish our day at LaMotta Performance, Jay followed up the driveshaft install by adding the Red Line gear lube. It's also worth noting we had to send our EEC V processor back to Steeda Autosports to have it reflashed in order for it to work happily with our new 3.73 gears.
Our 3.73-geared 8.8 differential... read full caption Our 3.73-geared 8.8 differential is now ready to put some serious power to the ground. The wonderful marriage of 3.73 gears, a Torsen T-2R dif-ferential, a Steeda suspension, and an ATI ProCharger make for one exhilarating driving experience. Of course, we'll want more soon, and then it will be time for more cubes, more blower, and who knows what else. So keep reading, or you might miss something! 5.0