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Tech: 2015 Mustang Halfshaft Upgrade

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By EditorTurner

Tech: 2015 Mustang Halfshaft Upgrade

Race Ready

Lethal Performance bolsters its 2015 Mustang IRS for the drag strip

By Steve Turner

If you have been following along with our coverage of Lethal Performance’s 2015 Mustang GT build, you know that the company has taken an aggressive path with its mods. Eventually that path leads to the drag strip, so it was time to take a break from adding power and fortify the drivetrain to withstand drag launches.

Before heading out to the drag strip with a power adder or two, the Lethal Performance 2015 Mustang was in need of some fortification. Team Lethal didn’t want a track outing cut short by a broken halfshaft, so they called The DriveShaft Shop for a set of 2015 Mustang 800hp Direct-Fit Axles (PN RA8505X4 and RA8506X4; $1,199.98).
Before heading out to the drag strip with a power adder or two, the Lethal Performance 2015 Mustang was in need of some fortification. Team Lethal didn’t want a track outing cut short by a broken halfshaft, so they called The DriveShaft Shop for a set of 2015 Mustang 800hp Direct-Fit Axles (PN RA8505X4 and RA8506X4; $1,199.98).

From what we have learned, the stock halfshafts won’t last long when they are wedged between sticky tires and elevated horsepower levels. Anywhere from 10-20 hits, and you might snap a shaft. It could be even sooner if that hit packs the instant torque wallop induced by nitrous.

“The next steps of our build will be to beef up the rearend with some Driveshaft Shop axles, a Driveshaft Shop driveshaft, a full American Racing Headers exhaust, and a big ol’ front-feed, 2.9-liter Whipple Supercharger kit,” Lethal Performance’s Jared Rosen told us after the nitrous install. “Of course all of the supporting mods such as a fuel system, injectors, clutch and flywheel will be part of the equation.”

Jake Long of Power by the Hour gets started by unbolting the factory brake caliper.
Jake Long of Power by the Hour gets started by unbolting the factory brake caliper.

As such, Lethal selected a set of the company’s 2015 Mustang 800hp Direct-Fit Axles (PN RA8505X4 and RA8506X4; $1,199.98).

For those of you that have high-powered Terminators, you know the tale of weak halfshafts. The good news is the S550 shafts are sturdier from the jump. Of course, that doesn’t mean that they can’t be improved to support the kind of power that you plan to add to your new Mustang.

You don’t have to disconnect the brake line, but you will need to hang the caliper safely so it doesn’t dangle from the brake line and damage it.
You don’t have to disconnect the brake line, but you will need to hang the caliper safely so it doesn’t dangle from the brake line and damage it.

“First we started with both the inner and outer splines going into the hub and the differential. We have been working with Ovaco steel out of Sweden and they came up with a material called Ovaco 300 that has been used by D.S.S. in each and every IRS/CV driven world record breaking car to date,” the company explained. “So each spline is now made from this amazing 300m material (on both the 800hp and the 1400hp versions). We then made 4340 billet CV mounts and are using our proven 108mm CV with full 300m billet chrome-moly cages and races (with the 1400hp axles using the larger 30-spline bars). This along with Neo HPCC1 grease and with a higher durometer Neoprene boot, it will handle just about anything you can put to it.”

Jake removes the shaft retaining nut with an impact gun.
Jake removes the shaft retaining nut with an impact gun.

Besides the materials, the manufacturing process is designed to further improve the durability of the shafts.

“We didn’t stop there, the center bars we made are done with our CNC spline-rolling process, which most people ‘in the know’ will tell you that a rolled spline is significantly stronger than one that was done with material cut away because it is actually forging the spline and compressing the micro structure to make it even stronger,” D.S.S. says. “So what we have here is a proven design, and if that’s not enough so we also have taken the time to put end caps on the end of the CV housings in case they are ever taken apart (you guys pulling the diff will love this, as the six bolts come off and the diff will come out, try this with a stock axle) and the caps have blue RTV inside to ensure a perfect seal.”

While the shafts are rated for up to 800 horsepower, thus far D.S.S. reports that they haven’t found the limit of the shafts just yet. We are pretty sure that Lethal will try to find that edge with its car. With that in mind, we checked in at Power by the Hour in Boynton Beach, Florida, to document the installation of these shafts.

Next, Jake removed all the fasteners holding the spindle in place.
Next, Jake removed all the fasteners holding the spindle in place.
He then removed the spindle. You can sneak the halfshafts in and out with the spindle in place, but this makes the operation a little smoother.
He then removed the spindle. You can sneak the halfshafts in and out with the spindle in place, but this makes the operation a little smoother.
The stock Super 8.8 was marked with the letters SV, and each diff cover fastener is position is marked as well. Jake had a little fun by adding on a T.
The stock Super 8.8 was marked with the letters SV, and each diff cover fastener is position is marked as well. Jake had a little fun by adding on a T.
The stock halfshaft is retained by an internal C-clip. Unlike the clips on the old-school 8.8 rears, these clips will expand as you pry out the stock shaft.
The stock halfshaft is retained by an internal C-clip. Unlike the clips on the old-school 8.8 rears, these clips will expand as you pry out the stock shaft.
The fluid is filled right up to axle level, so you shouldn’t lose enough to require refilling the diff. In the case of the Lethal car, none came out on the driver side, and just a small drop came out on the passenger side.
The fluid is filled right up to axle level, so you shouldn’t lose enough to require refilling the diff. In the case of the Lethal car, none came out on the driver side, and just a small drop came out on the passenger side.
Lethal Performance’s Jared Rosen decided to sneak in a little workout with the D.S.S. and stock halfshafts. As you might expect, the beefier D.S.S. shaft is a bit heavier.
Lethal Performance’s Jared Rosen decided to sneak in a little workout with the D.S.S. and stock halfshafts. As you might expect, the beefier D.S.S. shaft is a bit heavier.
It’s easy to see the DriveShaft Shop halfshafts (bottom) are more robust than the stockers. Where the stock shafts neck down at the ends, the D.S.S. shafts retain a consistent diameter. They feature 108mm CV joints with 300m billet chrome-moly cages, while the center bars are built from Ovaco 300M alloy steel and the splines are cold-rolled. The stock shaft may only last 10-20 passes with more-than-stock power and sticky tires.
It’s easy to see the DriveShaft Shop halfshaft (top) is more robust than the stocker. Where the stock shafts neck down at the ends, the D.S.S. shafts retain a consistent diameter. They feature 108mm CV joints with 300m billet chrome-moly cages, while the center bars are built from Ovaco 300M alloy steel and the splines are cold-rolled. The stock shaft may only last 10-20 passes with more-than-stock power and sticky tires.
With the path clear, Jake slides the D.S.S. halfshaft into place.
With the path clear, Jake slides the D.S.S. halfshaft into place.
The C-clips expand, like a piston ring, when the shaft is installed and compress once they are inside the differential to lock the shaft in place. Make sure you feel them click into place and be sure they are seated before you bolt everything back up.
The C-clips expand, like a piston ring, when the shaft is installed and compress once they are inside the differential to lock the shaft in place. Make sure you feel them click into place and be sure they are seated before you bolt everything back up.
The D.S.S. shaft definitely has a more robust look, and it is said to be able to handle up to 800 horsepower.
The D.S.S. shaft definitely has a more robust look, and it is said to be able to handle up to 800 horsepower.
Now that the new shaft is in place, Jake reverses the process by reinstalling the spindle, brake rotor, and brake caliper.
Now that the new shaft is in place, Jake reverses the process by reinstalling the spindle.
With the parking brake set, you can start tightening the axle nut with an impact gun, but be sure follow up with a torque wrench set to 125 lb-ft.
With the parking brake set, you can start tightening the axle nut with an impact gun, but be sure follow up with a torque wrench set to 125 lb-ft. Then you can complete the process by reinstalling the brake rotor, brake caliper, and wheel.

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