Analysts calculated the value of the global automotive driveshaft market: $32B. Not bad for a rotating tube! But what makes them so valuable?
The short answer? Driveshafts are a vital component of a vehicle’s internal mechanics. They use torque force to transfer energy from the engine to the rest of the driveline. Without it, a vehicle doesn’t move.
But, for a driveshaft to serve its purpose, it has to be the right size for its vehicle.
Fortunately, the team here at Point Spring & Driveshaft Co. are certified driveshaft specialists. We supply custom-built driveshafts, precision-fit truck parts, and premium materials for all sorts of heavy-duty vehicles.
In this guide, we’ll walk you through situations where measuring your driveshaft is mandatory, the necessary steps to take to get accurate measurements, and a swath of tips and tricks to get your angles set up perfectly.
Quick Review: What Is a Driveshaft?
A driveshaft is a cylindrical component of the driveline. It’s a metal rotating tube, typically enclosing a slip spline, stud yoke, or slip joint. Both ends of the tube have end fittings.
That said, driveshafts can also utilize other joining components, including:
● Flanges
● End yokes
● Weld yokes
● Tripod couplings
● Differential yokes
Within a driveline system, a driveshaft functions to transfer power from the auto engine and transmission to the differential.
The differential ultimately regulates and transmits that energy to the vehicle’s axle and wheels. Driveshafts utilize rotational energy and torque force in this process.
Contemporary vehicles typically use either one-piece driveshafts or two-piece driveshafts. This guide lays out best measurement practices for both commonplace driveshaft types. It also indicates best practices for a range of attachments and end-fittings.
When Should You Measure a Driveshaft?
You'll need to measure a driveshaft when you're replacing it due to damage or wear. On average, a driveshaft lasts for 75,000 miles in a personal vehicle.
But, you can’t rely on averages. If a vehicle has a tendency to drift, emits unusual sounds or vibrations, leaks fluid, or doesn’t easily turn or shift gears, it might need a driveshaft replacement.
You might also need to measure the driveshaft in the course of repairing your car or truck’s drivetrain, or if you’re modifying your vehicle in any significant way.
Custom Driveshaft Services and Modifications
Custom modifications like lightweighting improve the fuel efficiency of heavy-duty vehicles (HDVs). Likewise, popular modifications like converting two-wheel-drive (2WD) HDVs into all-wheel-drive (AWD) systems also require driveshaft measurement.
Complete Driveshaft Measurement Guide
Measuring a driveshaft is generally a four-step process: gather tools, prep your vehicle, measure driveshaft angles, and measure lengthwise.
Note that the lengthwise measurement process varies depending on whether you have a one-piece or two-piece driveshaft.
1. Gather Appropriate Measurement Tools (All Types)
To measure your driveshaft, you will need the following tools:
● Standard tape measure
● 6” scale
● Calipers
● Angle finder tool
An angle finder tool is similar to a carpenter's level. It can be found at hardware stores. You can also use an app to transform your smartphone into an angle finder.
2. Prep Your Vehicle
Set up your vehicle at ride height. The weight of your car or truck should be distributed on its springs. The rear wheels should be firmly on the ground.
This setting is crucial to get accurate measurements. Measurements must reflect the ratio and configuration of the driveshaft within the drivetrain when the auto is in use.
Identify And Assess
Once the vehicle is set up, identify the transmission and the joint or coupling type (flange, yoke, spline, u-joint). If possible, identify the u-joint series.
3. Measure Driveshaft Angles
To discern the right angle for the driveshaft, you need to measure:
● The slope (angle against the “baseline”) of the differential
● The slope of the transmission
● The slope of the driveshaft itself
Set your angle finder tool so its bottom runs lengthwise along your driveshaft. This number is your baseline.
Then, set and measure it against the flat side of the transmission’s output yoke or flange. Do the same to measure the differential’s angle.
To get the correct angle relative to your driveshaft, subtract your driveshaft’s angle from the other readings.
With the correct angle measures, you can adjust the shim or differential angle as needed.
4. Measure Your Driveshaft Lengthwise
To take shaft measurements, follow the directions in the subheading specific to the driveshaft type you want to measure.
Remember to differentiate your tactic according to the driveshaft's specific end-fittings when you take the shaft length measurement.
How to Measure Driveshafts With Different End-Fittings
Measurement procedures vary by end-fittings. The best rule of thumb is:
● Measure driveshafts with splines from the extruded spline-end
● Measure driveshafts with U-joints from the center of the U-joints' loops.
● Measure driveshafts with flanges (including rubber boots or seals over a metal flange) from the flat of each flange’s face.
In some circumstances, it's easier to measure a driveshaft from one flat end of the rod to the other first. Then, measure the extruding splines later, and add the two measurements together.
How To Measure A One-Piece Driveshaft
First, identify the attachments on either end of the cylindrical part of the driveshaft.
Then, measure the shaft lengthwise.
Follow the directions above to ensure you start and end your measurement at the correct points. The length measurement process is differentiated by end-fittings.
Use digital calipers to get precise measurements. Keep your line straight. Only use a measuring tape to get a general view of the shaft length as a whole.
How To Measure Two-Piece Driveshaft
A two-piece driveshaft has center support bearings, to maintain balance.
To measure a two-piece driveshaft, take two lengthwise measurements.
The first measurement starts at the transmission end of the driveshaft, and it ends at the precise center of the central support bearing. You may need to use calipers or a digital compass to determine the exact center of the bearing.
Use the appropriate measurement placement, given the coupling on the transmission end of the driveshaft. Measure the length of the tube from that point to the center.
Then, measure the length of the tube again, this time starting from the central bearing. Move outward to the differential end of the driveshaft. Again, make sure to place your caliper end at the appropriate point, given the end-fitting on the differential end of your shaft.
Get Professional Measurement From Point Spring
There's no single, easy answer to the question, "How do I measure a driveshaft?" We've cultivated this resource to guide you through the process.
Yet, expert guidance is better granted in person, hands right on the vehicle. If you need to measure your driveshaft—whether for a repair, a replacement, or a custom modification—the pros will get the job done right the first time.
Point Spring & Driveshaft Co. Specialists Deliver Expert Driveshaft Measurement—And So Much More
Our team at Point Spring & Driveshaft Co. offers specialist expertise to meet all your HDV, drivetrain, and driveshaft needs. Whether that’s routine maintenance or custom part fabrication, we’ve got you covered!
When you need quality vehicle solutions, call us at 888-787-7746. Or, fill out our contact form, and one of our specialists will reach out to connect.