By now, it’s no secret that fifth-gen Camaro have a weak point once they start making serious power. In fact, we’ve heard of people breaking this one component while producing stock horsepower and torque numbers.
So, what is the weak link? The factory rearend – specifically the axles.
Reliability and streetability have been the goal from the beginning for the Daily Camaro. So, after installing a 2.9L Whipple supercharger in the last segment, we’ve been driving with our fingers crossed…
The Weak Link
In a poll on Camaro5.com, a legendary forum in the fifth-generation Camaro community, 91 voters selected between three options when questioned about the axles in their 2010-2015 Camaro. The first option is “stock and holding up fine.” The second; “Aftermarket: replaced for peace of mind,” and the last is, “Aftermarket: Replaced due to failure of stock components.”
Well, you can count us among the, “better safe than sorry” crowd. While we haven’t experienced any failures since we installed the Whipple supercharger on our LS3, we have a feeling it is only a matter of time until the high-mileage stock components let go. The Daily Camaro is flirting with 200k miles on the odometer, after all. So, we placed a few phone calls and asked the experts to weigh in. After reaching out to the folks at Eaton, Lingenfelter, and The DriveShaft Shop, we came up with a plan to build a bulletproof rearend for the Daily Camaro.
The Remedy – What We Used
We realize we put the cart before the horse by installing the supercharger first, but we wanted to see how the car reacted to boost with the stock 3.45 rear gears before we decided to go full send and swap them out for something more aggressive.
To no surprise, we found the engineers at General Motors knew what they were doing when they put 3.91 gears in the ’13-’15 Camaro Z28, and we are opting to use the same.
As it turns out, Lingenfelter got the contract to produce rear gears for the 5th-gen Camaro and thus we went straight to the source. When they arrived, the box was labeled American Axle, and that’s because, according to Lingenfelter, they are, “Manufactured by American Axle, the original equipment gear supplier for Camaro SS.” Of course, this means buyers are getting OEM-quality parts – more on the importance of this later.
And what would a monster set of gears be without a nearly indestructible differential to match? So, when it came time to upgrade the differential we knew exactly who to call – Eaton. We’ve used the venerable Truetrac in more than a few projects by now, so we know the pros and cons of the clutchless gear-type system well.
“Instead of using clutch packs like a typical limited-slip differential, the Truetrac uses a helical gear design to transfer the engine’s torque equally to both wheels, or to the wheel with the most traction should tire spin occur. The Truetrac has the ability to transfer up to 70-percent of the torque load to the wheel that has the most traction. Let’s say you have one rear wheel on wet grass, and the other on dry concrete and you rev up the engine and sidestep the clutch. Obviously, there is zero rolling resistance on the tire in the grass and it is just going to spin. However, because of the Truetrac’s biasing capabilities, it will send 70-percent of the torque to the wheel on the concrete and move the car forward.” – Clifton Klaverdweiden for Street Muscle Magazine.
Lastly, we reached out to our contacts at The DriveShaft Shop for a set of near-indestructible axles. The set we sourced is rated to handle north of 1,400 horsepower – way more than we intend to make. Then again…
Once we’d come up with a plan of attack to replace the Daily Camaro’s aging differential, gears, and axles, we placed a call to our local experts of all things running gear – Oceanside Driveline in, you guessed it, Oceanside, California.
Before we get into the nitty gritty of the installation, Paul Headrick, gave us a little background on his business.
Paul tells us, “Oceanside Driveline has been in business since 1985. We do a lot of import stuff that other shops don’t want to touch – Euro stuff and cars like that can be difficult. Frankly, no other shop deals with the variety of vehicles that we do. We’ve done everything from Bentleys to industrial tractors. Hell, we’ve even done planes. Anything with a driveshaft, we deal with it.”
Beefed-Up And Bulletproof
With the Daily Camaro on the lift, we began the rearend overhaul by removing the exhaust and driveshaft. With those things out of the way, we were afforded unimpeded access to the rearend, but not before removing the rear wheels. We also took this time to drain the differential of its ancient fluid – probably not serviced since its initial fill.
We removed the calipers and set them to the side so we could pull the axles out, but not before removing the driveshaft.
With all the accoutrements removed, we began the disassembly of the rearend housing. Up until this point, the Camaro was looking great for its age. The bushings didn’t look too bad, and the undercarriage was surprisingly clean. It was only when we opened the differential that we saw the gears were rather aged. Still, the wear pattern was even… just, worn. In fact, the pattern was showing a wear amount of 0.010 inch, while American Axle’s recommended maximum is 0.004 inch.
David, who was handling the rearend rebuild, told us, “aftermarket components usually recommend 0.008-0.010 inch of backlash, but not for factory gears. That’s way worn.”
With the rearend out of the car, we got to disassembly. A few things of note for disassembly – when removing the pinion gear and seal, it’s important to use a gasket scraper to avoid gouging the aluminum housing. Other than that, things are pretty straightforward.
With the rearend disassembled, we took the housing over to the media blaster and gave it a good cleaning. Unfortunately, this is where things got a bit hairy.
We would be doing a great disservice to the Daily Camaro if we put its differential back in without replacing the more-than-a-decade-old bushings. Unfortunately, that simple replacement wasn’t so simple. Removing the factory rubber bushings proved to be difficult, to say the least.
The Camaro’s differential housing is cast aluminum while the bushing sleeves are steel. As such, using a steel punch or chisel to hammer the sleeves was out of the question. Alternatively, we could press the bushings and sleeves out with a press. That is, if the housing had a shoulder beyond the edge of the sleeve… it didn’t. Regardless, we got them out.
Installing the new bushings was, by comparison, much easier, and left us with a clean slate to install our new pinion gear.
New Pinion Gear
Before we could install the new pinion gear for good, we had to press in the races for the bearings. It was quite impressive to watch a master at work – someone who has done this thousands of times. While David whacked on the races with the mallet and die, he listened carefully and could hear the slight tone change once the race was finally seated.
When it came time to fit the new pinion gear, David used a tool he made out of an old bearing for mock-up. He also used the original pinion gear and bearing so he could figure out how to shim the new pinion gear. To craft that tool, he previously filed the diameter of the gear shaft down with a soft stone so the bearing could slip on and off during mock up.
We then put the new pinion bearings in along with the pinion gear and crush sleeve, followed by the pinion seal with silicone applied to both the seal itself as well as the splines on the yoke.
Ring Gear And Differential
Next, David pressed the ring gear on the Truetrac which allowed him to set the carrier and gear in place using the original factory shims. The wear pattern on the gears indicated that the shim was correct and the backlash was appropriate.
David set the dial indicator and it showed 0.004 inch on the first try – exactly where we were supposed to be and the wear pattern was even for a five-cut design like the AAM gears are designed to have.
David explained that this is one of the reasons they love using AAM products – they are made to exacting tolerances and therefore are predictable.
Finally, it was time for the rebuilt rearend to go back into the Daily Camaro.
Axles Go In
With the rearend in place, it was time to install the new DriveShaft Shop axles. From the photos alone, you can see how much more stout the axle shafts are over the stock units, but where the real magic happens is inside the chromoly CV cages. According to DriveShaft Shop’s website, the center bars are full-certified 300M – a special blend made only for DSS using a special heat treat and temper. The CV cages are 4340AQ steel with a redesigned radius on the cage windows. Additionally, the splines are formed rather than cut. By rolling the splines into the axle shaft, no material is removed, which actually increases the strength of both the splines and the shafts. While most people know that forging is extremely strong, these rolled splines are by far the strongest way to form a spline and worlds better than cut splines which, at this point, is antiquated technology.
We slid the beefy new axles into the housing and then reattached the rear spindles. There was some slight difficulty lining up the splines of the axles while also lining up the control arm bolt holes, but after a few minutes, we had it back together. We wrapped up by bolting on the brake calipers and throwing the wheels back on.
Set It Down And Break In…
After filling the differential with 85w-140 gear oil, the only thing left to do was set the Daily Camaro back on the ground and let it eat! Or… not.
David explained the seemingly tedious break-in process to us. “A lot of times we’ll have people leave the shop and want to do a big burnout when they take off, but you can’t do that. Then they wonder why they come back a few days later when their rearend is making noise.”
So, what they recommend, is driving it like a grandma for the first 500 miles or so. David continues, “You have to let it heat cycle. Otherwise, you can get noise caused by an irregular wear pattern – a sort of loud howling.”
So that’s the reason for the heavier gear oil. While most people would expect to run a 75w-90 viscosity gear oil, we elected to run the 85w-140 oil that David and the rest of the team at Oceanside Driveline recommended. David explains, “at the end of the day, it will be quieter, and it’s more compatible with a wide variety of differentials.”
He continues, “You can’t run that heavy of an oil somewhere like Michigan in the winter, but since we are in Southern California, it makes perfect sense.”
What It Accomplished – The Results
He had our initial concerns that the torque multiplication caused by changing the gears would leave us with traction issues around town and at the drag strip. While that may be true; it’s well worth it considering the tread-width tires you can fit on the back of a fifth-gen Camaro. That’s precisely what we plan to do, and make them as sticky as possible.
We effectively added 13-percent more gear ratio with our increase from 3.45:1 to 3.91:1 It’s not as noticeable around town as one might think, though. Even though we were worried about the street manners of the “Daily”, it’s totally manageable. Although, First and second gear don’t last very long now for some reason…Ha!
In the meantime, we’ll break in the new gears, roast off the old tires, and wait for our new sticky rubber to come in.
Until next time…