Let's face facts: General Motors just can't get things right in the rearend department. From the weak 9- and 10-bolts found in L98/LT1/LS1 F-bodies, to shattered C5 and C6 Corvette diff cases (and the absolutely F.U.B.A.R. rear of the early CTS-V), it's pretty safe to say that GM hasn't done an axle assembly correctly since the turbo Regal. The problems aren't just for owners who drag race, either: many such failures occur during spirited (or in some cases, totally normal) street driving.
This issue, GMHTP is focusing on the particular problems that plague our favorite musclecars, the LS1-powered Camaros and Firebirds. Though it's possible to substantially beef up these vehicles' factory 10-bolts to handle added torque or abuse, there are limits to the effectiveness of this-limits that are often well below the needs of many high-horsepower 6-speed cars, particularly those with grippy clutches and sticky tires. There are a few aftermarket companies out there that offer attractive solutions-namely, bolt-in, heavy-duty rear axle assemblies. We're going to perform separate installs of tough axle assemblies on two GMHTP project cars and compare and contrast the results in the hopes of providing enthusiasts with the background information they need to start shopping!
First up is Strange Engineering. When Strange was approached with a request for a suitable rearend for Rick Jensen's project 1SC-YA (a car whose stock bottom-end LS1 is already making good power and will be producing a whole lot more in the future), the company's S60 was the hands-down recommendation. A derivative of the renowned Dana 60 that can be found in many GM, Ford, and Mopar trucks built over the last few decades, this is one heck of a beefy axle assembly design that plays well into the needs of powerful Camaros and Firebirds. The Strange S60 comes totally assembled, carries PN PRSF05, and retails for $2,349. Beefy 35-spline axles are standard, and it can come ready for either version of ABS you might have, be it three-channel (add $150) or four-channel (add $69, or send in your old reluctor rings for Strange to press on). The company even goes so far as to include new brake backing plates. While there is no charge for 1993-1997 backing plates, 1998-2002 cars will need to shell out an additional $269 for new ones (or, you can send your old backing plates to Strange and they will be installed at no cost). A Truetrac differential comes standard, and a locker can be had for $70. As to the gears, a Spicer (the OEM supplier) set with your choice of ratio is included, and though we don't have them in our unit, softer, drag-only 9310 gears are also available. With that bit of background information in mind, let's get going on the installation!
The Strange S60 as-shipped:...
The Strange S60 as-shipped: fully assembled and ready to be installed. One small caveat is that this rear is only available bare, so we had to spray it the gloss black you see here. Our options include an aluminum cover ($45.50), the aforementioned new brake backing plates, and provisions for this car's three-channel ABS system (Jensen likes his cars sans traction control or other "pansy-ass" equipment). Strange also supplied a heavy-duty driveshaft (PN U1702), a 3-inch seamless tube chrome-moly unit with solid 1350 series U-joints and a forged chrome-moly trans yoke ($295 plus $179 for the yoke). Finally, though stock brake rotors would work just fine with this unit, we're installing Brembos on the back to match the ones we put up front in the November 2007 issue ("Street Car, Track Car: Part I").
The folks at TT Performance...
The folks at TT Performance Parts (Passaic Park, NJ), late-model GM specialists who now also offer complete race car fabrication services, are chipping in for the install. Jay Partyka puts the '01 Z28 on the lift and pulls off the rear wheels. Here's the stock 10-bolt in all its 7.625-inch, C-clip-axled, rust-encrusted glory. (As just one comparison of strength, the S60's ring gear is a whopping 9.750 inches in diameter.) Let's get this piece o' crap outta here!
The driveshaft comes out first....
The driveshaft comes out first. The stock U-joint clamps are removed and the shaft slides out the back of the trans. Have a drip tray ready under the tailshaft because you may lose a bit of ATF during this process. The factory unit in this stripper Z happens to be steel, and quite rusty at that. The torque arm then comes out, and this is easier if one undoes the sandwich clamp at the front first. Use caution, as the axle assembly will want to tilt backward and push the front of the torque arm up higher into the tunnel. It helps to keep the Panhard rod connected during this time-by limiting tilt, it also prevents putting undue stress on the lower shock bolts once the torque arm is out. A screw jack can also be used under the rear to take the rest of the tension off of the two large bolts securing the torque arm to the rear.