Muscle Mustangs & Fast FordsHow To Drivetrain
Installing a Bulletproof Strange Engineering 9-Inch Rearend in a S197 Mustang GT
Drag racing is a brutal sport. Launching a car on a sticky track is hard on drivetrains and losing is hard on egos. If something breaks, not only does it hurt your wallet—it means you’re loading up and going home.
Extracting ludicrous levels of torque from today’s engines is ridiculously easy. Most owners are just a blower or turbo away from quadruple-digit power levels. Any weakness in the series of parts between the engine and tires will be a lost round, and send the driver home.
The rear axle assembly is one of the most critical components in the drivetrain, as it translates the twist of the driveshaft to each of the rear wheels. On a solid axle car, all of the tractive and suspension forces go through the rear axle housing. The shock loads are immense, especially from a high-strung naturally-aspirated, nitrous, or supercharged engine. During each launch, the engine is trying to twist the axle multiple ways.
Luckily, Morton Grove, Illinois’ Strange Engineering offers mega-duty rear axle options for the most demanding applications. When the time came to replace our 2011 drag race Mustang’s 8.8-inch rearend, Strange Engineering built us a Ford 9-inch-based assembly—and dared us to break it.
That’s going to be a tough challenge, as Strange Engineering’s decades of rear axle experience are incorporated into this bolt-in assembly for 2005-2014 Mustangs. Strange started with the same axle housing they supply for Ford’s Cobra Jet program. The housing incorporates a few tricks, including moving the upper control arm mount up 0.400-inch and forward 0.400-inch, and the shock mounts are relocated inboard 1-inch and narrowed 1.25-inch per side, making it trimmed perfectly for 15-inch wheels.
A heavy duty aluminum center section holds a 3.50:1 Pro Gear set that spins on a heavy duty 40-spline spool machined with Strange’s lightweight option. The corresponding 40-spline axles are gun-drilled to remove about four pounds of weight. Strange then finished off the housing with their Pro Series rear brake kit.
To see how we swapped the Strange rearend into our 2011 Mustang GT, check out the following photos, where Saul Gutierrez from GEAR Driven Automotive in Northridge, California handled it with ease. With this seriously built Strange Engineering 9-inch Cobra Jet rear axle, we’ll happily say that it’s ready for everything we can throw at it.
• Strange Engineering Heavy Duty 9-inch Mustang Cobra Jet axle housing
• Lucas 85W-140 gear lube
• HD Pro Aluminum Case Assembly
• HD 40 Spline Lightweight Spool
• Chrome Moly Pinion Yoke
• 3.50:1 Pro Gear
• Pro Race Axle Package
• 40 Spline Gun Drilled Axles
• 3.150 Axle Bearings
• 5/8 Stud Kit
• Pro Series Rear Brake Kit
1. We’re in the middle of completely revamping our 2011 Mustang GT and while the built 8.8 has served us well for the past eight years, it was time for a complete replacement.
2. After unbolting the rear driveshaft, we disconnected the axle ends of the rear trailing arms and the panhard bar.
3. With the third link and brake lines disconnected, we lowered the axle from the chassis.
4. Our Strange Engineering Cobra Jet 9-inch axle assembly arrived with all the necessary provisions to bolt into our 2011 Mustang GT (see “What’s Inside” sidebar). We opted for the Cobra Jet housing because it already has the factory shocks moved 1-inch inboard and narrowed 1.25-inch per side. This setup would also give us the perfect fitment for our choice of Mickey Thompson Drag Radials on a set of 15x10 Weld Racing drag wheels, but we’ll have more detailed info on that in the next segment of our build.
5. Before lifting the axle off the shipping pallet, we swapped out the upper control arm bushing into the Strange Cobra Jet rear axle housing.
6. With the Strange axle assembly on the jack, we filled the housing with the supplied 85W-140 gear lube.
7. With the fluid topped off, we jacked the axle assembly into position.
8. First, we reattached the lower trailing arms to the axle housing. (Note that the Strange Engineering axle housing includes multiple mounting to tune the instant center for harder or softer launches.)
9. Before attaching the shocks, we installed our BMR rear drag lowering springs.
10. Our BMR rear anti-roll bar attached to the rear axle housing using weld-on tabs (verses the stock mounting method).
11. We welded on a fresh set of tabs to the Strange axle housing.
12. After the welds cooled, we attached our BMR sway bar’s end links to the Strange axle housing.
13. With everything buttoned up, our 2011 Mustang’s rearend is ready for serious track duty.