If you plan on really abusing this 8.8, we'd suggest adding Ratech's solid-pinion bearing spacer that replaces the stock crush sleeve. This solid spacer adds strength, but does require a little more time to properly set the pinion preload. At this same time, you could also get rid of that small stock U-joint in favor of a larger, more robust 1350-style U-joint. This will require changing the pinion yoke, which Currie, Moser, and Strange make out of steel instead of cast iron. This works best with a larger-diameter, stronger driveshaft. Moser offers a main-cap stud kit that may offer some additional strength along with the reinforced aluminum rearend covers that offer preload help for the main caps to prevent deflection, although these covers are a bit pricey. Also, if you feel the need, Mark Williams makes steel-billet rear main caps for the 8.8 Ford. Other ideas that are common upgrades for other Salisbury-style rearends include having a professional shop weld the axletubes into the centersection to increase strength. Ford merely plug-welds the tubes in two spots for each tube, which can easily be twisted and broken with a high-torque car on sticky tires. A tube-welded housing with strong 31-spline axles, a good limited slip, professionally installed gears, and larger housing ends is plenty strong enough to take the abuse that any street car can dish out.
Five-Lug Axle Swap
The very first thing to change on a Mustang 8.8 is the lame four-lug axles. In typical Ford fashion, this four-lug pattern isn't even the same as the early Mustang six-cylinder stuff from the '60s, so you can't even reuse the old wheels. The least expensive swap is the classic Ranger switch. Search the boneyard for a couple of late '80s to early '90s Ranger pickups. You'll need to find two trucks because you'll have to pull the left-side (driver) axles from these two trucks, which are the same length as the stock Mustang axles but have the five-lug pattern. One little red flag Jeff Stange of Strange Engineering informed us of is that once an axle takes a torsional set, it does not like to suddenly be twisted in the opposite direction. So the Ranger axle that goes on the right side (passenger) could fail if subjected to enough abuse.
When yanking the Ranger axles, if you can find two serviceable drums you might want to snag them too since you will need five-lug drums to match the axles. This is also a great time to install new axle bearings in the housing. The bearings are pressed into the housing using the axleshaft as the inner bearing race, just like a 12-bolt Chevy. This also means that when you pull the Ranger axles, inspect the bearing surface carefully. If there are pits in the axle-bearing race area, avoid that axle because it will soon fail, even with a new bearing. Of course, another alternative is to invest $235 for new axles from Moser that will bolt right in.
 Welding new housing ends on...  Welding new housing ends on an 8.8 allows the use of a much larger axle bearing to dramatically increase the load-carrying capacity. This photo is of a 12-bolt housing using the larger Ford 9-inch- style bearing. Typical labor charge for this service is between $100 and $140. |
 Welding the tubes into the...  Welding the tubes into the cast-iron centersection on an 8.8 is a great way to add strength, but this should be done by a professional shop. This is usually done at the same time that the housing ends are welded on. Cost for this procedure is between $100 and $140. |
 When you add 31-spline axles,...  When you add 31-spline axles, you also have to change the differential to accommodate the larger axles. This is a Detroit Truetrac gear-style limited slip for a 31-spline 8.8 Ford rear that offers excellent traction even in high-g cornering situations. |