ATF Speed’s Billet Coyote Main Timing Sprocket Replaces Weak Stocker

IMG_5218

The OEM powdered-metal crankshaft sprocket has the potential to fail in any high-rpm or boosted Coyote. ATF Speed’s replacement cures the problem with its billet construction.

As one of the hottest engine platforms to debut in decades, the powerful 5.0-liter Ford Coyote engine has reinvigorated enthusiasts to build incredibly quick, yet docile cars that are capable of turning in seriously impressive times at the dragstrip or road course, while remaining street-friendly in the process. But in the process, those enthusiasts have discovered a number of weak factory components that can put a serious damper in a racer’s day should they fail.

That’s where the idea for ATF Speed‘s new billet Coyote timing gear came from; longtime engine builder Tim Eichhorn of MPR Racing Engines discovered the need for the product, as a number of his customers were bringing in failed engines with the main timing sprocket destroyed. Eichhorn approached Jason Gatlin of ATF Speed with the idea to partner together and develop a design that would work well without breaking the bank for the consumer. Gatlin, with a background in building supercharger gear drives among many other race-oriented products for many different platforms, jumped at the chance to be involved with the project, and together, they made it reality.

Note the depth of the keyway cut in the center of the gear; with the factory powdered metal construction, this thin spot becomes an issue when power levels are pushed on the Coyote engine.

Note the depth of the keyway cut in the center of the gear; with the factory powdered metal construction (shown at left), this thin spot becomes an issue when power levels are pushed on the Coyote engine. Not so with the billet construction of the ATF Speed gears.

“The crankshaft gears break in the keyway area,” says Gatlin. “They are powdered metal, and the keyway groove is lined up with a deep groove cut in the teeth area, which makes it real thin in that spot. When it breaks, it’s catastrophic.”

Catastrophic, meaning that the heads, the valves, and all of the valvetrain components get wrecked when there’s a failure. And these aren’t old-school two-valve Windsor heads that can be repaired inexpensively — they are four-valve-per-cylinder heads that cost a pretty penny to fix when there’s an issue.

In order to combat the issue of the thin spot where the keyway meets up with the low spot in the gear teeth, ATF Speed relies on a much stronger 4340 chromoly billet material, the same stock that axle shafts are built from. After the manufacturing process, they are also heat-treated and bead blasted to perfect the gearsets.

One might think that with today’s computer-controlled manufacturing processes, that these gears would be made from start to finish on a CNC lathe, but Gatlin says that’s not the case.

The shape of the finished product, including the keyway, is roughed in on a lathe, but then he uses a machine — from the 1940s, no less — called a gear shaper, to finalize the profile of the gear teeth. It was a substantial investment for ATF to purchase the shaper, but Gatlin feels that the gear shaper provides a much more refined finish on the gear teeth and is the right machine for the job in this case.

“The shaper takes approximately twice as long to machine the teeth on each gear, but in the end the part is so much better it’s worth the extra time,” he says.

Alternate views of the stock gear beside the ATF Speed piece; ATF's billet part is easily identifiable as the gray-colored sprocket. ATF uses a gear shaper to perfect the tooth profile before heat treating and bead blasting.

The gear is a direct replacement for the factory gearsets and fits 2011-’14 5.0-liter Mustangs, 2012-’13 BOSS 302 Mustangs, 2011-’14 F-150 with no modifications. 2015 and newer Mustangs, and 2015-newer F-150 vehicles must retrofit the 2011-’14 timing components to allow for the use of this gearset. It also fits a number of Australian Fords–the 2011 Falcon GT, the 2014 FPV Falcon GT-F, and the 2014-’15 Falcon XR8.

At a price point of $250, this lower timing sprocket is cheap insurance for an engine that’s been pumped up with a power-adder or is turning high RPM. Sister magazine Turnology‘s project car, the FFR Cobra Jet Challenge, is using this particular gear in its high-winding naturally-aspirated Coyote, which was built in a previous article series right here.

MPR has been using these timing sprockets exclusively since their debut and has reported perfect durability; if a high-powered Coyote is in the future, considering an upgrade with these is a great idea.

Article Sources

About the author

Jason Reiss

Jason draws on over 15 years of experience in the automotive publishing industry, and collaborates with many of the industry's movers and shakers to create compelling technical articles and high-quality race coverage.
Read My Articles

Horsepower delivered to your inbox.

Build your own custom newsletter with the content you love from EngineLabs, directly to your inbox, absolutely FREE!

Free WordPress Themes
EngineLabs NEWSLETTER - SIGN UP FREE!

We will safeguard your e-mail and only send content you request.

EngineLabs

We'll send you raw engine tech articles, news, features, and videos every week from EngineLabs.

EngineLabs

EngineLabs NEWSLETTER - SIGN UP FREE!

We will safeguard your e-mail and only send content you request.

EngineLabs

Thank you for your subscription.

Subscribe to more FREE Online Magazines!

We think you might like...



Late Model LS Vehicles

Drag Racing

Performance Driving

EngineLabs

Thank you for your subscription.

Subscribe to more FREE Online Magazines!

We think you might like...

  • Late Model LS Vehicles
  • Drag Racing
  • Performance Driving

EngineLabs

Thank you for your subscription.

Thank you for your subscription.

EngineLabs

Thank you for your subscription.

Thank you for your subscription.

Loading