"For a bit over $1000, within a week we had our new driveshaft."
It never gets cheaper to race, does it.
After installing our engine and putting the car on the ground, we found some bad news: Our driveshaft was about two inches too short.
How could a Mustang driveshaft not fit into a Mustang? we asked.
As with most issues surrounding our Mustang’s drivetrain, the answer revolved around the Roltec transmission. This Chevy-based transmission is some 1.75 inches shorter than a Top Loader or Ford-based T-10.
After getting on the phone with Mark Williams Enterprises, they walked us through the process for measuring out a new driveshaft. (One tip: bury the yoke into the tail shaft and then backing it out 5/8 inch.)
Final answer: We would need a 55 3/8-inch driveshaft.
The next question: steel, aluminum or carbon fiber?
The steel driveshaft would weigh 19.8 pounds, aluminum would check in at 11.8, and the much more expensive carbon fiber shaves a couple more pounds.
Shaving eight pounds doesn’t sound like much, but it is nearly 50%. The static weight isn’t the real issue. Like a lightened flywheel, a lighter driveshaft helps the engine accelerate. Based on the horsepower rating of our engine and its intended use, the shop calculated that a 3.5-inch-diameter driveshaft would be best for us.
The price difference between aluminum and steel is about as much as the weight difference–imagine that. For a bit over $1000, within a week we had our new driveshaft.
Mark Williams Enterprises shipped us a beautifully made driveshaft that was perfectly balanced and built to withstand at least 1000 pounds of torque in a violent drag racing scenario. We feel competent it will serve our needs quite nicely.
"For a bit over $1000, within a week we had our new driveshaft."
It never gets cheaper to race, does it.
One thing made of carbon fiber that can be had fairly cheaply is tubes, makes you think about chopping up a junkyard shaft and affixing a carbon tube cut to length where the steel used to be...
Edit: Looks like Robbie had similar thoughts:
I made a similar faux pas with the Datsun. In my case I'd found a driveshaft via Dave at Futofab, sadly I'd measured wrong and was off by about the same 1.75"
Fortunately I simply moved the motor and tranny back in the chassis.
"Pounds of torque"? Why not the simpler "torques"?
Is that second picture just a demo of what the old one looked like when it was too short??
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