Here’s the offending surprise...
Here’s the offending surprise underneath the EcoNova: the dinky 7.5-inch rearend. We honestly had no idea these were put into any V-8 cars, but with barely 140 hp farting from the original 305, they probably weren’t too concerned. Years later with the 275hp LT1 and the 300hp LS1 (in the Camaro), the chickens would come home to roost, sending many a 7.5-inch rear to an early death.
Here’s a bit of obscure trivia for you: all fourth-gen (’75-up) V-8 Novas were equipped with GM’s perfectly adequate 8.5-inch 10-bolt—except the ’76 305 V-8 model. Those cars got the same frail 7.5-inch rearend found in the six-cylinder cars. And guess what our EcoNova project car was originally?
Now when we entered into the E-Rod install, we knew we’d need to at least rebuild the rearend to get it within the spec range needed for the E-Rod calibration—ideally 3.42 gears and a limited-slip differential.
We could get the parts to equip the stock 7.5, but the real problem is the limited power-handling ability of the puny rearend. Unlike the 8.5-inch 10-bolt we would’ve gotten any other year, this one couldn’t be made to work (or more importantly, to last) for any amount of money. Under repeated abuse even with moderate power levels, bearing failures, broken carriers, and mangled gearsets are common with these things. (Just ask fourth-gen F-body owners.) We’ve even had the housing itself bend under hard stress. The stock LS3 in the E-Rod package packs 430 hp (maybe a bit more by some reports), which would be plenty to scatter the best 7.5 if we didn’t keep mindful and baby the throttle. We don’t drive like that, though.
Currie has a great workout...
Currie has a great workout plan for their employees! It may look old-school, but it’s actually extremely effective and requires a carefully calibrated swing to sneak up on the correct width. Backing the tube out is a whole lot harder. Keeping everything in place while the dead blow hammer does its work is an alignment bar that is centered off bushings pressed into the carrier bearing location in a mock-up third member and in the axle bearings. Once satisfied with the measurements, the tubes are tacked into place.
No, we’re notoriously hard on our project cars and known for putting our parts through their paces. We needed something strong and reliable in a fairly heavy car and easily serviced should the worst happen. And rather than junkyard scouring, if we could lay hands on a properly spec’d piece with a fresh set of brakes with just a few clicks online, even better. That’s where Currie Enterprises comes in with their crate rearends designed for muscle cars.
Currie has built tens of thousands of custom spec rearends over their 53-year history. What they’ve discovered is the vast majority of customer inquiries on custom-ordered rearends shared the same basic housings, axles, and specs. This is why they launched the new crate rearend database that allows hot rodders to order up a Torino-style large-bearing 9-inch housing already tailored as a bolt-in for 27 popular muscle cars. That means anyone can get the benefits of a 9-inch in most muscle cars without having to make a single calculation or measurement. All you have to do is pull up Crate-rearends.com, select your car, your third member, gear ratio, brakes, and you’re done. But that doesn’t mean you’re completely locked in; since we’re starting from scratch with a known set of specs, minor alterations can easily be substituted to tailor the rearend to your car. You’ll see what we mean.
Standard practice is to ship out the crate rearend in pieces with final assembly up to the buyer and his choice of shop. That does save on shipping, but for a very small fee Currie will handle all the assembly for you and stand behind the work. As vast as their resources may be, believe it or not, Currie’s Brian Shepard told us that to his knowledge they never built a crate 9-inch for a fourth-gen Nova. The good news is that after measuring and verifying, we discovered that ’75-79 X-body Novas and their brethren have identical specs to the previous ’68-72 generation. And just like that we helped create a new part number for Currie. So if you’ve got big plans for your own ’68-79 Nova, a fully setup 9-inch rearend is just a few clicks away.
Once the angles are set and...
Once the angles are set and the measurements verified, the tubes and spring plates get fully welded externally and tacked inside the housing as well. It takes a talented welder to handle this in one pass as the housing spins slowly.
The crate 9-inch starts with...
The crate 9-inch starts with Currie’s 9-Plus heavy-duty housing. Unlike the 10- or 12-bolt GM housings, 9-inch axletubes are wedged and welded to the housing. That means the third member isn’t laden with the torsional loads from the axletubes.
Currie has a great workout...
Currie has a great workout plan for their employees! It may look old-school, but it’s actually extremely effective and requires a carefully calibrated swing to sneak up on the correct width. Backing the tube out is a whole lot harder. Keeping everything in place while the dead blow hammer does its work is an alignment bar that is centered off bushings pressed into the carrier bearing location in a mock-up third member and in the axle bearings. Once satisfied with the measurements, the tubes are tacked into place.
That much heat warps steel...
That much heat warps steel and the tubes are guaranteed to go askew. To set everything back to straight, the housing spends time with a technician and a big press. A go, no-go fixture is used to verify that the tubes are within spec before proceeding.
Speaking of the axletubes,...
Speaking of the axletubes, they start with slices from a much longer section of tube. We stayed with the stock length of 60.25 inches overall, but Currie will slice a little more off if needed at no extra charge.
Here’s one of those minor...
Here’s one of those minor alterations; we’re planning to lower the EcoNova quite a bit in the future, so to compensate for the large change in driveline angle we’re adjusting the location of the heavy-duty multileaf-spring pads to yield a 2-degree pinion angle rather than the 4 degrees, which would be standard on this application. That will help with getting our front and rear angles on the driveshaft more closely matched. Watch for more on this in a future issue of PHR.
With the dirty work finished,...
With the dirty work finished, the housing spends 10 minutes in the “abrader” to create a nice consistent satin finish.
Currie is a stickler for quality...
Currie is a stickler for quality control and everything you see here, except the Motive Gear ring-and-pinion and Timken bearings, is specifically manufactured to Currie’s demanding specs and only available through them. The Lock-Tite splashed bolt are even marked CE. If you need anything for a 9-inch, Currie is who to call.
The Torque Sensing Differential...
The Torque Sensing Differential (TSD) is essentially an improved version of a stock clutch-style Ford limited-slip unit that will handle more power and abuse. Open diff, spool, Detroit Locker, and Detroit Truetrac are also options for Crate 9-inch rearends.
Our one upgrade over the standard...
Our one upgrade over the standard package is Currie’s heavy-duty Daytona-style forged aluminum big-bearing pinion support instead of the standard cast iron. This Daytona support has improved oiling capabilities perfect for street cars that will see strip or track time.
With the bearings and seals...
With the bearings and seals pressed into place, the new 1350 yoke was torqued into place and the whole assembly dropped into Currie’s own redesigned and strengthened version of the famous Ford nodular 9-inch gearcase. These cases will handle much more horsepower and abuse than our stock LS3 E-Rod will be able to dish out.
To ensure proper alignment...
To ensure proper alignment and no noise, the Motive Gear ring-and-pinion are spun with dark and light grease splotches so our tech Ruben can check the meshing pattern of the teeth. We went with a 3.50 ratio, which will be close enough to the ideal 3.42 E-Rod spec.
All crate 9-inch rearends...
All crate 9-inch rearends use Currie’s popular Cut-To-Fit (CFT) 31-spline performance axles. All it takes is a quick slice from a chop saw, and then a light spin on a grinder to put a chamfer on the edge to go from generic to application-specific. Ours are drilled for a stock GM 5 on 4�-inch wheel bolt pattern.
With the case sitting in a...
With the case sitting in a fixture, this simple gauge is used to make sure the axles have the proper amount of clearance.
There we have it, a crate...
There we have it, a crate 9-inch rearend that’ll be a direct bolt-in for our fourth-gen Nova project. Even with photos slowing them down, Currie went from loose parts to a complete unit in less than four hours. Want one for yourself right now with no changes versus stock? Summit Racing keeps Currie’s Crate Rearends stacked up like cord wood.
Stock-style drums are available,...
Stock-style drums are available, but a $100 upgrade gets you a set of 11-inch Explorer disc brakes with an integral parking brake. For us it was a no-brainer considering the performance and aesthetic improvements. Want more? Big and aggressive Wilwood options are available as well.
The reliable little PBR calipers...
The reliable little PBR calipers are fully loaded and equipped with hoses. Shephard says the trick to connecting everything cleanly is to use the hard line and junction block from a ’69 Torino, since they have tabs that will bolt right onto the gearcase. That’s what we’ll be doing when we get the rear installed.