|
|
Mopar Rearend Replacement - Project B3 Gets Rear EndedBuilding And Installing A Bulletproof Strange 60 Rearend In Our Bracket Racer From the July, 2007 issue of Mopar Muscle By Dave Young Photography by Dave Young
|
|
Whether your Mopar is a street car or a dedicated race car, chances are it's overpowered. Tire shredding, axle snapping, u-joint exploding torque is something even stock Mopar engines are known for. While too much power is not necessarily a bad problem to have, the driveline behind the engine must be built to withstand the power, or reliability will suffer. Since reliability is one of the keys to our bracket racer project, we had to decide what rearend would best suit our needs. While an 831/44 differential would probably suffice if built properly, it still wouldn't be as tough, or last as long as a 60-style rearend. Since we showed you how to narrow and assemble your own Dana previously, in this issue we'll give you another option. Strange Engineering is fabricating an all-new 931/44 rearend housing called the Strange 60, and when stuffed with their tough internals, the Strange 60 is virtually indestructible. If you've been following project B3, you know that our engine is a 451ci, low-deck big-block that makes well over 600 hp. While a properly built 831/44 rearend would handle this kind of power for a while, we're looking for years of reliability from this bracket racer, so we decided to spend a few more dollars and upgrade to one of Strange Engineering's Strange 60 differentials. The Strange 60 is based on the same Dana 60 rearend that Chrysler installed in their most brutal Hemi and 440 Six-Barrel-equipped street cars, and features the same, massive, 931/44-inch ring gear. The Strange 60 can be custom ordered for any application from a stock street car to the wildest race car. our car is a dedicated racer, so we had the guys at Strange set up the rearend to take some serious abuse. If your car is a street car, you can save a few bucks by ordering your rearend with more economical components.  Since we knew we'd quickly...  Since we knew we'd quickly destroy the 811/44 differential in our bracket racer project with more than 600 hp and a sticky set of slicks, we decided to talk to the guys at Strange Engineering and see what it would take to build one of their indestructible Strange 60 rearends.  Before we can install our...  Before we can install our new rearend, we had to get the 811/44 out of the way. We actually sold this rearend for $150, which we'll add to the budget for this build.  The crew at Strange Engineering...  The crew at Strange Engineering fabricate and assemble their Strange 60 rearends in-house, ensuring a quality finished product. Here our housing is drilled and tapped for the factory-style vent and brake line T-fitting. There are several reasons a drag car needs heavy-duty components in the rearend. First, race engines simply make more power and torque than the average street engine. Second, race stall converters are usually far looser than street converters; our Dynamic 8-inch converter will flash in the neighborhood of 5,000 rpm, again applying more torque to the rearend. The third, and most important factor, is the soft compound slicks that adorn the rear wheels of most race cars. Slicks, unlike street tires, won't spin when the car is launched, and, therefore, incredible forces are transferred to the car's driveline. Street tires will spin when overpowered, relieving the stress on the rearend, axles, and driveshaft, but slicks grab and hold, exposing any weakness by breaking driveline parts. Since we'd rather be at the track racing than in the shop repairing the rearend, we asked the guys at Strange to use some of their best components when building our Strange 60. A nice feature of all Strange 60 housings is, unlike factory Dana 60s, the axle tubes are fully welded to the center section of the rearend. This prevents the tubes from twisting in the housing under high loads. Since it is imperative a drag race car's rear wheels turn at the same speed throughout the run, we decided to run a spool in our rearend. A spool, unlike a Sure grip, is simply a solid connection between the ring gear and both axles, forcing the rear wheels to spin at the same speed. We don't recommend a spool for street applications for obvious reasons. Around corners, especially in the rain, the inner wheel will spin at the same rpm as the outer, but since it has less distance to travel, it will slip. This causes traction issues that could lead to loss of vehicle control, so if you're building a rearend for a street car, we recommend a Sure grip differential. Since our Barracuda will be raced for years to come, we chose Strange's lightweight Pro Spool for our application. This is a tough piece, and when matched with a pair of 40-spline race axles it should give us years of reliable service. Our 40-spline axles are solid, and we had them fitted with 51/48-inch wheel studs for extra durability. Since we'll be running this car in the quarter-mile, we opted for 4.30-ratio Pro-gears, which should match our tire size and power combination well, pulling us through the traps at some 7,000 rpm. our Barracuda will retain its factory suspension component locations, so we had our new rearend built to factory A-Body dimensions. If your car is back-halved, mini-tubbed, or otherwise narrower than stock, Strange can custom build your rearend to fit your application.  Although using new parts,...  Although using new parts, Strange takes every precaution, even scuffing the back of the ring gear with a honing stone to remove any burrs or high spots which could affect the setup.  The ring gear was bolted to...  The ring gear was bolted to the spool, and the fasteners were all torqued to 120 lb-ft. Red Loctite was used to ensure these fasteners stay in place.  Using a special driver, the...  Using a special driver, the pinion bearing race can be installed in the housing. To complete our rear suspension, we'll be installing Mopar Performance Super Stock leaf springs, an adjustable pinion snubber, and Strange double adjustable rear shocks. This is not an exotic setup, but a reliable suspension package that should get our project car hooking up well enough for some sub-1.50-second sixty-foot times. But enough about theory, let's install our new rearend.  One of the many improvements...  One of the many improvements Strange has made over the factory Dana 60 design is the addition of adjuster nuts to set preload and backlash. This makes the process far easier than the trial-and-error shim method, which must be used to set backlash on the factory-style Dana 60 rearend.  The front bearing journal...  The front bearing journal of the pinion gear was polished before the bearing was pressed in place, and the pinion gear was installed in the housing.  With the components installed...  With the components installed and the main bearing caps torqued to 80 lb-ft, the backlash is checked using a dial indicator. If the backlash was not within the 0.008- to 0.010-inch range, the adjuster nuts are used to achieve the required tolerance.  The gear contact pattern was...  The gear contact pattern was checked by painting several teeth of the ring gear with marking compound. The ideal contact pattern is a central pattern on the drive side of the tooth, or shifted slightly towards the toe or inside diameter of the ring gear. The contact pattern is adjusted by changing backlash or placing shims under the rear pinion bearing race.  To determine the thickness...  To determine the thickness of the pinion preload shim, Strange uses a technique that saves time and effort. By placing a piece of 0.090-inch flux core solder around the pinion, and installing it and torquing the yoke until 25 lb/in of drag is achieved, the solder is crushed to the thickness of the required shims. The assembly is then disassembled, and shims of the proper thickness take the place of the solder.  Once all the tolerances were...  Once all the tolerances were setup, a billet yoke was installed, again using Loctite. We opted for a 1350 series universal joint, commonly used in full ton or bigger trucks, because of its strength and durability. Strange will build your rearend with a factory-style yoke if desired.  We opted for Strange's 40...  We opted for Strange's 40 spline, solid race axles for our build and also upgraded to 51/48-inch wheel studs. These studs are basically unbreakable, but must be used with aftermarket wheels as they won't fit in the bolt holes of factory wheels. Strange uses nonadjustable sealed bearings on all their axles.  Once built, the cover was...  Once built, the cover was installed and the rearend was crated up and ready to ship. When received, we'll simply be able to bolt on our brakes, bolt the rearend in place, and be ready for the track.  In the interest of our budget,...  In the interest of our budget, we decided not to have our rearend powdercoated, but rather to paint it ourselves to keep the bare metal from rusting.  Using new U-bolts, bushings,...  Using new U-bolts, bushings, and hardware, we bolted our new Strange 60 in place. We're using Mopar Performance Super Stock leaf springs for our build; Mopar has these springs in several rates depending on the weight of your car.  Unlike factory Dana 60s, the...  Unlike factory Dana 60s, the axle tubes of the Strange 60 are completely welded to the center section. This prevents the tubes from twisting under high loads.  In the interest of saving...  In the interest of saving money, we used factory Chrysler 11-inch drum brakes on our rear, so Strange manufactured it to accept factory brakes. If rear disc brakes are more your style, Strange can accommodate you by placing the proper tube ends on your housing.  For maximum chassis tuning...  For maximum chassis tuning ability, we used Strange double-adjustable race shocks in the rear. These shocks will bolt to factory locations, but a spacer must be used on the bottom to prevent the adjuster from interfering with the lower bracket.  Huge 1350-series universal...  Huge 1350-series universal joints were used because of their durability. U-bolts, instead of straps, were utilized on the rearend yoke because of their superior strength.  Using an angle finder on both...  Using an angle finder on both the driveshaft and the mounting pad for the pinion snubber, and subtracting the difference, we found the pinion angle.  Leaf-spring cars usually require...  Leaf-spring cars usually require between four and eight degrees of positive pinion angle (nose of the pinion toward the ground) to hook up properly off the line.  To adjust the pinion angle,...  To adjust the pinion angle, tapered shims were used between the leaf spring and the pad on the housing. These shims are available in various angles from Summit Racing Equipment and are fairly inexpensive. For our application, we used a 2-degree shim to achieve a pinion angle of 6 degrees.  Another key rear suspension...  Another key rear suspension component is an adjustable pinion snubber. As the rearend tries to rotate under acceleration, the pinion snubber engages the floor, forcing the rearend downward and improving traction. Always set the pinion snubber with the cars weight on its wheels, leaving about 31/44 to 1 inch of space between the rubber snubber and the car's floor. With the back half of our suspension installed in our project car, we're a little closer to making it to the track. Be sure to follow future issues as we'll continue our project by installing the engine and transmission, front suspension and brakes, wire and plumb the car, lighten it up with fiberglass body parts and polycarbonate windows, then finally finish up the interior. We're still a long way from the track, but each step is getting us closer. The car is just about to achieve "rolling chassis" status and that should help motivate us to quickly complete our bracket racer.
|
|
|