Strange S60 & Moser M9 Rearends - Bullet Proof Backends - Tech

Up under the car, a screw jack is used to support the transmission and its stock crossmember is removed. The stock trans mount comes off of the transmission tailshaft (as does the factory torque arm mount) and a supplied relocation bracket is bolted to the bottom of the trans. This helps move the mount slightly rearward and to the passenger side so that it will line up properly with Moser's new chrome-moly crossmember, which we see here being tightened to the frame. By the way, new bolts and nuts to attach the trans mount to the adapter plate are not supplied, so be ready to dig some up.

We dump in some 80W-90 conventional gear oil before putting the rear in place (it ends up taking almost four quarts before the stuff begins to dribble out of the plug in the driver side of the pumpkin). The rear is raised up and the shocks, LCAs, and Panhard are connected. The latter two cannot be torqued without the car on the ground, of course, and, as an aside, some powdercoating had to be removed for our Panhard to slip into its bracket on the M9. Further, the Moser brackets for the LCAs were a tad wide, so a washer was used so that they could grab onto the metal part in the center of the LCA bushings when tightened (they're said to work perfectly with LCA relocation brackets, though).

Time for Moser's beefy, fully adjustable torque arm to go in. Its front slider must be removed, greased, and reinstalled before doing this. Insertion of the torque arm is best accomplished with the axle sitting just below ride height. We need to loosen the jam nuts on the torque arm's two rear attachment points and screw in/out to get everything to line up with the mounting points on the housing (though these appear to be spherical rod ends, they are not-there is only one, at the front of the torque arm slider). This is easily the most advanced torque arm system this author has ever seen and, though difficult to tell from the photo, it is constructed in a three-dimensional fashion to follow the contours of an F-body's tunnel perfectly.

Speaking of the front of the torque arm slider, we were advised to install it into the third hole up in the crossmember for our horsepower application (this turned out to be very fortunate, as any lower would have caused the torque arm to hit our Dynatech Y-pipe). We ensure that the slider is not quite fully in right now, as we want to give a little leeway for in-and-out movement as the suspension goes through its travel (not to mention any forward movement under load).

Observant readers may have noticed that the springs have not been mentioned yet. We have left them out temporarily to ease installation of the torque arm, and also so that we can run the rear through its suspension travel and check clearances everywhere. Lifting the rear up all the way, we discover that although most parts of the assembly are a good distance from contacting anything under the car, the upper mount of the torque arm is getting within a couple of inches of the body above (just ahead of the gas tank). But when attempting to go up further, the rear suddenly stops prematurely, before hitting the bumpstops. We discover that the aluminum fluid fill plug on the top of the M9 contacts the underside of the gas tank. The solution? Rig up some 1.5-inch bumpstop spacers, which we weld on after putting the springs in place.

After loading the suspension and measuring the required length of the driveshaft, Inland Empire Driveline Service hooked us up with a sweet 3.5-inch aluminum unit (right). This is a big improvement over the stock 3-inch aluminum piece, which, among other things, is too long to work with the M9. MSRP for such a shaft (PN ALU-1350C) is $470, and it comes complete with U-joints compatible with the 1350 Moser yoke. IEDLS says the maximum horsepower such a unit can support depends on the length of the shaft, but it is not uncommon to run it in cars with up to 1,200 hp!

With the driveshaft in, the final odds and ends are taken care of, including: hooking up the parking brake cables (and zip tying them as appropriate), adding a small piece of hose to Moser's barb-style breather fitting, connecting and bleeding the brake lines, and putting the antiroll bar in place. That'll do it. The M9 is easily the coolest-looking rear-axle assembly (and torque-arm system) ever seen on the pages of GMHTP!