Because we’ll be running a...
Because we’ll be running a Chassisworks g-Bar system under Track Rat, we decided to opt for their FAB9 housing as well. Since the housing comes with all the suspension brackets precision-welded in place it will be a real time-saver when we go to install the new suspension widgets. The mild steel case was ordered with late-model Torino housing ends.
We’ve been making steady progress massaging our ’68 Camaro’s battered body back into shape over at Best Of Show Coach Works in San Marcos, California, but after a while you get tired of sucking in body-filler dust and crave a change of pace. What better way to break up the monotony of block-sanding than to wrench together some go-fast parts? So we decided to move on to the rearend assembly that will eventually help propel Project Track Rat down the road and through the cones.
We’re not planning on dropping in a big-horsepower engine; most likely something a bit under 500 hp (remember back when 500 hp was considered big power?), so there is no need to kill the budget on parts way beyond what’s required. That’s the secret to building a nice, reliable car on a reasonable budget. It’s all about balance and choosing parts that complement each other. Building a 1,000hp engine and backing it up with a stock 10-bolt rearend is as goofy as putting the strongest rearend available behind a stock 350 small-block.
With that in mind, we opted for a middle-of-the-road mix of parts rated a bit above our target power levels. This way we will be able to pound the snot out of our Camaro without fear of the rearend blowing apart under the back of the car. The rear FAB9 housing was stronger than we needed, but the extra cost would easily be offset by all the hours we would save on installing the rear suspension and as they say, "time is money." Plus it just looks cool. So follow along as we head over to Currie Enterprises to build the first part of Track Rat’s drivetrain.
The welding on the FAB9 is...
The welding on the FAB9 is a work of art. Here you can get a better look at the lower arm bracket that will eventually support our g-Bar rear suspension. The multiple mounting holes will let us really dial in the Camaro’s handling.
We’ve always had great luck...
We’ve always had great luck with Detroit Truetrac units, so we saw no reason to try something else. Its planetary helical side gears and pinions make this the perfect differential for a street car that likes curvy highways and the occasional road course. Under normal conditions the Detroit Truetrac performs like a regular open differential and, when required, automatically transfers torque to the wheel with the most traction. The Truetrac is capable of transferring up to 3.5 times more torque to the high traction wheel. This torque transfer ratio, called the bias ratio, is accomplished by using parallel-axis, planetary helical side-gears and pinions that mesh much like worm gears. Since the Truetrac uses hardened gears against hardened gears and not clutches or cones, there is nothing to wear out, so it won’t need maintenance. Eaton offers a preloaded and non-preloaded version for the 9-inch Ford. Because the preload helps the differential react faster, Currie offers it exclusively.
Next to building a manual...
Next to building a manual transmission, putting together a third member has to be one of the more difficult items to assemble properly. It’s not impossible to do yourself, but it requires a few tools not normally found in the average roll-away toolbox. Items like a dial indicator, a bearing press, and a bearing puller are just a few of the unique tools you’ll need. Currie will completely assemble a third member, and set all the pre-loads and backlash for just $124.95. Doing it wrong can cost you a bunch of time and even more money, so we feel having a pro do it is well worth the extra cash. Besides, this way there’s a warranty.
With the bearings pressed...
With the bearings pressed onto the Truetrac, it was time to mate it to the ring gear. To keep everything in place, we dabbed a liberal amount of red thread locker on the bolts. Since we will be running an overdrive Tremec transmission we decided to go with 3.70 gears.
With the unit reassembled...
With the unit reassembled and spinning freely, Torres started adjusting the backlash. The goal for our unit was 0.010-inch.
With that done, Torres checked...
With that done, Torres checked how the gears were meshing together using marking paint. We were off on the first try (high on the coast), but that’s common when trying to mate new parts to a reconditioned case.