This one isn’t a sexy swap. In fact, you might say it’s pretty mundane when looking through the list of mods for Mustangs. However, it’s also routinely rated as one of the most seat-of-the-pants noticeable upgrades.

We’re going to show you how to install an aluminum driveshaft in an S197 Mustang.

But first, let’s take a quick look at why and when a driveshaft swap can help, because it might not match the reasons you’re thinking of.

(Image/Christopher Campbell)

From the factory, 2005-14 S197 Mustangs are fitted with a roughly 38 pound, two-piece steel driveshaft supported in the middle by a carrier bearing. Two-piece driveshafts are inherently more expensive to manufacture, so why did Ford opt for a heavy multi-jointed beast?

There are three main reasons for using multipiece driveshafts: chassis length, driveline angle optimization, and reduction of NVH (noise, vibration, harshness).

S197 Mustangs are reasonably short wheelbase cars with a 52 inch driveshaft, so we know that length wasn’t the issue. For Ford, it was mostly about driveline angle optimization and reducing NVH. A long, single-piece driveshaft is more prone to NVH than two shorter pieces.

The main reason most enthusiasts look to aluminum driveshafts swaps is weight savings. Typically, switching to an aluminum shaft on any vehicle will reduce the driveshaft weight by anywhere from 10 to 20 pounds. On an S197 Mustang, it’s about 16 pounds. Less weight is always good when you’re chasing performance, right? Yes, but the actual performance gain just from the loss of weight is not that high.

Let’s look at why.

The assumption is that this decrease in driveshaft weight benefits the engine’s ability to accelerate under load. That’s because weight is magnified when it needs to rotate. This is known as the moment of inertia (MOI).

In physics, MOI is the measure of the opposition that a body exhibits to having its speed of rotation about an axis altered by the application of turning force (torque). The amount of torque needed to cause angular acceleration is proportional to the MOI of the body. The heavier something is, the more torque is required to accelerate it. The faster you try to accelerate it, more torque is required. Also, the larger the diameter of the object, the higher the MOI.

So, if you’re trying to accelerate a very heavy, large diameter object very quickly, a lot of torque is required.

However, driveshafts really aren’t that heavy or large in diameter. If we spin up a very large diameter mass, or a very heavy mass, (such as a large flywheel) and we do it rapidly, it requires notable power. However, spinning up a small diameter mass, especially over a longer period, such as accelerating from stop to quarter mile costs much less power. That relatively long spin-up time combined with a small diameter and light weight, means that driveshafts don’t actually cost much horsepower.

If you do the math with an energy storage calculator, a typical three inch diameter one-piece steel driveshaft consumes less than one half horsepower. A two-piece steel driveshaft has more mass and more joints, so the consumption will be somewhat higher.

So, by losing weight and simplifying to only two joints, we are reducing the amount of power stored and consumed by the driveshaft.

Does that mean you’ll see an increase in horsepower at the tires due to less parasitic loss? Maybe, but we’re talking rather low single digits at best. We’ve seen tests show two to three horsepower on the dyno after swapping to lighter one-piece shaft and others show absolutely zero change.

But even if the potential power gain isn’t huge, there are several great reasons to swap to a lighter driveshaft.

While the small possible horsepower gains aren’t going to make much difference for quarter mile times, a lighter driveshaft does help notably in a road race or autocross car like our project, since this type of racing requires instant, repeated changes from acceleration to deceleration. Also, once the miles pile up, more joints in a driveshaft (plus a carrier bearing mounted in a rubber isolator) can mean more flex in the driveline, so a one-piece driveshaft often feels “tighter” or “more responsive” vs. a worn factory two-piece.

This is the seat-of-the-pants improvement most people feel.

When it comes to sustained high speeds, like you see on a road course or open road racing, performance driveshafts like our Ford Performance Parts unit also have an important safety edge because they’ve been designed to have higher than stock driveshaft critical speeds. Critical speed is the speed at which a spinning shaft encounters its natural frequency of vibration and will begin to bend or whip and is dependent on shaft length, weight, diameter, and rpm. This is important to keep in mind for whatever type of racing you do—and believe it or not, the answer is not always a one-piece driveshaft.

Here’s the basic formula for computing critical speed using our 3.55:1 rear gear and 26.2 inch tall rear tire to calculate engine rpm at 140 mph. Note, this is for 1:1 final drive in fourth gear, since we never use fifth on track. For true top speed, you would need to calculate for OD since it actually increases driveshaft speed while decreasing engine speed:

  • Engine RPM = (MPH x Gear Ratio x 336) / Tire Diameter
  • Engine RPM = (140 x 3.55 x 336) / 26.2
  • Engine RPM = 144,883 / 26.2
  • Engine RPM = 6,373

Since this Ford Performance Parts driveshaft has a critical speed of 7,500 rpm, we’re well within a safe range.

Ok, enough math and physics, let’s get this thing in the car!

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Click below to see details on the specific driveshaft in the article:

Ford Performance Parts 2005-10 Mustang GT One-Piece Driveshaft – FMS-M-4602-MGTA

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Strength and beauty. The Ford Performance Parts shaft is made from 3.5 inch diameter 6061-T6 aluminum tubing with 0.125 inch wall thickness. (Image/Ford Performance Parts)
How strong? With a maximum horsepower rating of 940 and maximum torque rating at a staggering 4,231 ft.-lbs., we’ll never even come close to challenging this driveshaft’s strength. (Image/Christopher Campbell)
No lift in our shop, so we’ll be doing this on ramps and jackstands up front. We started here but ended up using jackstands in the rear and allowing the axle to droop to create the most room to make the swap easier. (Image/Christopher Campbell)
If you’re using jackstands, make sure to place them in the proper locations. This diagram shows common jacking points for an S197 chassis. We ended up using the red dots on the chassis. (Image/Ford & Christopher Campbell)
Our rear end probably looks a little different than yours thanks to the CorteX Racing watts link and torque arm hanging below our driveshaft. The good news is that if you have a similar setup, there is enough room to work around it once the axle is dropped. If you’re using a stock style three-link, you’ll have even more room to work with. (Image/Christopher Campbell)
The key to creating a little more space is simply to unbolt one side of the axle-back exhaust and slide it away from the mid-pipe. You don’t technically need to do this if you are running a stock style suspension, but we do recommend it since it only takes a couple minutes to loosen the clamp and creates a noticeably larger amount of space. (Image/Christopher Campbell)
Now with the pipe shifted down, we can see the driveshaft above the torque arm, so let’s get started! (Image/Christopher Campbell)
 Starting at the transmission side, set the parking brake to hold the driveshaft from rotating. Using a 12-point 12mm socket (or ratcheting wrench), remove the four bolts from the transmission output flange. Release the e-brake and put the trans in Neutral to rotate the driveshaft as necessary to gain access to the bolts. Save these four bolts, they will be reused. (Image/Christopher Campbell)
We don’t intend to reinstall the factory driveshaft, but we still marked the shaft and flange clocking just in case. This will also be our reference point for the new aluminum driveshaft in the unlikely case that we discover any vibration during testing. The driveshaft should come loose from the flange with a slight bump. If it seems stuck, use a pry tool to wedge in the gap between the flanges near the bolt hole. The driveshaft should compress slightly and allow it to disconnect from the transmission flange. (Image/Christopher Campbell)
Hopefully your transmission flange will look as clean and rust free as ours. If not, take time to clean up the surface with some light sanding. (Image/Christopher Campbell)
On the rear end side of the driveshaft you’ll be removing six 10mm CV joint bolts. It is helpful to have a partner here since you’ll need to rotate the driveshaft and then relock the parking brake (or have a helper turn the rear tire and lock the brake) to access all the CV bolts. We got lucky and our rear end flange was just as clean as the front flange. If yours is rusty, be sure to clean it up thoroughly as the driveshaft flange on this end is a very tight fit. (Image/Christopher Campbell)
The middle, only two bolts are holding the carrier bearing to the car. These bolts are easy to reach with a six inch extension and a 13mm socket, just be ready to catch the driveshaft. Note the large amount of squish and distortion in the rubber isolator. That level of distortion can result in higher NVH and even movement that can alter the shaft’s critical speed. This could be the source of a driveline vibration we’ve felt on track. Ignore the brackets hanging down to each side, those are part of the front mount for our torque arm. (Image/Christopher Campbell)
With the shaft out of the car, we can see the uncompressed top side of the rubber around the carrier bearing. It’s worth noting that the youngest S197s are already eight years old, and the earlier ones are nearing twenty. The carrier bearing on two-piece driveshafts does have a service life, and many cars are probably running up against it. (Image /Christopher Campbell)
Time for a little side-by-side comparison! Where most of the weight decrease happens is obvious. Note that the aluminum shaft is 3.5 inches in diameter all the way down while the stock two-piece alternates between three inches at the rear piece and 3.5 inches on the front piece. Since the aluminum is lighter, the diameter had to increase to achieve the desired critical speed. Fun fact, a properly designed and installed two-piece performance driveshaft will always have a higher critical speed due to the shorter shaft lengths. (Image/Christopher Campbell)
Check out the size difference on the 1350 series Dana Spicer 5-1350X solid body universal joint vs. the stock one. These parts are stronger than the 1330 series version originally on 2005-10 Mustangs. (Image/Christopher Campbell)
Doesn’t look like much, but that tab is part of the balancing process that keeps the shaft stable all the way to 7,500 rpm. (Image/Christopher Campbell)
The bolts included in the kit for the rear end flange include four Allen head and two cap screws. All have some threadlocker pre-added, but we’ll be adding some fresh thread locking compound before installing. (Image /Christopher Campbell)
Nothing worse than worrying about a driveshaft bolt backing out, so we’re going with a dab of Permatex Threadlocker Blue on all the bolts. (Image/Christopher Campbell)
The spline and slip design of the driveshaft makes the install easy since the driveshaft length adjusts with just a tug. Using an X pattern, torque the transmission flange bolts to 76 ft.-lb. (Image /Christopher Campbell)
We particularly like that no adapter is required for the rear end flange; the shaft just bolts directly to it. It may be a snug fit, so be prepared for a little effort to get it seated. The two cap screws go in first followed by the Allen heads. All of them are torqued to 41 ft.-lbs. This would be a great time to get a set of hex sockets if you don’t have them; an Allen wrench is a tight fit. (Image /Christopher Campbell)
Installed and ready to spin! Thanks to our CorteX torque arm’s front mount, the driveshaft is nicely captured for safety. This is a great time to mention that while not a necessity, it’s a good idea to add a driveshaft safety loop if you plan to drive your car on track. (Image/Christopher Campbell)

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Christopher Campbell has been heavily involved in the automotive world since he began building his first car, a 1967 Ford Ranchero, with his dad at the age of 14. That started a lifelong passion with custom hot rods and muscle cars. After graduating from Cal State Long Beach, he went to work for HOT ROD magazine as Associate Editor. From there he became Technical Editor at Popular Hot Rodding magazine. Currently he creates freelance content for OnAllCylinders as well as many diverse enthusiast magazine titles such as HOT ROD, Muscle Mustangs and Fast Fords, Mopar Muscle, Super Chevy, Mustang Monthly, and 8-Lug.