When it comes to many — not all, but many — things mechanical, there’s a game of tradeoffs to be played. The material or the design that’s most lightweight may not be the strongest, or vice versa. But when it comes to driveshafts for the most powerful and violent of drag racing machinery, there’s little tradeoff to be had.
All of Strange Engineering’s tubular driveshafts are made from chrome-moly steel, with diameters of 3-inch and 3.5-inch, with the primary difference coming in the weld ends and u-joint styles for varying applications.
Your options, of course, are aluminum, carbon fiber, chrome-moly steel, and pure steel. Chrome-moly steel is widely regarded as the single strongest material a driveshaft can be constructed from, particularly for vehicles producing horsepower measured in the thousands.
“The strength of chrome-moly is superior, without a doubt, to any type of composite or aluminum,” says Strange Engineering’s J.C. Cascio. “Those materials definitely have their purposes and are beneficial from a rotational weight standpoint, but we do believe that those shafts have their limitations as far as horsepower goes, and ensuring that they’re utilized in the right applications, and the chrome-moly shafts take that out of the equation. For your street cars, they serve the purpose well, but when you get into your high-horsepower drag cars, you begin exceeding those limitations.”
As such, with their central focus on the hardcore drag racing market, Strange Engineering utilizes chrome-moly steel on all of their tubular driveshafts, with variances in welding techniques and u-joint designs to cater each model to specific uses, from those intended for high horsepower street and strip cars all the way up to Pro Modifieds producing 4,000 horsepower.
The strength of chrome-moly is superior, without a doubt, to any type of composite or aluminum. – J.C. Cascio, Strange Engineering
Strange’s lineup begins with a 3-inch outer diameter, .083-inch wall, seamless 4130 chrome-moly shaft (PN U1699) that sports Spicer cast weld ends and heavy duty u-joints, which Cascio says would lend itself well to your typical street and strip machine.
From there, the next step up is the exact shaft that we chose for our Project Evil 8.5 Mustang — a similar 3-inch by .083 wall, which sports forged chrome-moly weld ends and a heavy duty u-joint (PN U1702). Strange considers this perhaps their best all-around shaft for cars in our horsepower range (1,600-1,800) and applications both higher and lower, with no restrictions on horsepower, per Cascio. These are in fact used by some Pro Modified racers.
Strange TIG welds all of their driveshafts, providing for the ultimate in strength.
A larger diameter 3.5-inch chrome-moly shaft (PN U1704) with forged 1350 weld ends and u-joints fits into Strange’s line as an excellent choice for those needing a longer driveshaft, where factors like critical speed (the point at which a driveshaft becomes unstable, or distort itself) come into play. The larger diameter increases this critical speed RPM, producing a safer piece all around.
Strange carries the larger 3.5-inch diameter into their big-boy driveshaft (PN U1706), which is likewise .083-inch wall, 4130 chrome-moly, but sports the large, virtually bulletproof 1480 series u-joints, delivering a prime piece of hardware for Pro Modified and Radial vs The World cars and those that shell out similar degrees of abuse on a driveline.
The shaft we’ve chosen for our Project Evil 8.5 sports forged chrome-moly weld ends with some heavy duty u-joints to take the punishment of over 1,200 horsepower.
Cascio notes that radial cars tend to be the most abusive of the vehicles they see, given not only the power on tap, but the vehicle weight and the unforgiving tire and track prep they run under. Given that, they tend to lean toward recommending the “beefy” driveshafts and driveline components for those applications.
The installation of the driveshaft in our Evil 8.5 Mustang is pretty straightforward for a slip yoke-style shaft. The only additional step we had to take was puling the transmission bracket to drop the Turbo 400 transmission down low enough to slide the driveshaft into the driveshaft loop, as there wasn't enough clearance with our two driveshaft loops to get it in there otherwise.
“It’s always hard to put a horsepower number on something, because obviously a 4,000-pound car is going to be harder on driveline parts than a 2,000-pound car, so there’s a tradeoff in weight and horepower and the tire that factor into it, so that makes it challenging,” Cascio says.
All of the shafts are Tig-welded, which provides not only a better but a stronger weld, and are also electronically balanced before going out the door. “We go through a process when the shaft gets welded up where it’s checked for straightness, within eight-thousandths or less runout, at various points along the length of the shaft and end-to-end. Once that’s complete, we then fully balance them,” says Cascio. In addition, Strange uses solid spacer u-joints, which per Cascio, means they don’t contain any grease fittings and are non cross-drilled.
Each shaft, it should also be noted, is fully SFI-certified.
While overall driveshaft length will cause a variance, Cascio shares that complete driveshafts, with weld yokes and all, typically come in around 22-23 pounds, give or take a pound or so. “We definitely don’t push it in regards to weight with these driveshafts,” Cascio explains. “For us, we design and intend these more for strength purposes, for durability.”
Our driveshaft, which measures 47-3/4-inches center to center to fit the Fox body Mustang chassis, mates our ATI Performance Products two-speed Turbo 400 transmission to the Strange center section.
With the engine assembly in its final stages at Steve Morris Engines, we’ll be putting the new driveshaft to the test in the coming months under Project Evil 8.5, and with the research and engineering that Strange has put into their lineup of shafts, it’ll be one less thing we need to worry about failing on us when we release the transbrake.