Custom Ford Driveshafts For Increased Power - Shaft
If You're Going To Step Up The Power, You're Going To Need A Custom Driveshaft
From the December, 2006 issue of Modified Mustangs & Fords
By Jim Smart
Photography by Jim Smart
Driveshafts just don't give us that eye washing thrill of a powerful new engine, a fresh coat of paint, or a striking set of wheels. But they're just as important as horsepower, paint, and rolling stock. We don't give driveshafts much thought when we're planning our projects. And unless the driveshaft or a universal joint fails, it just isn't going to get much of our attention.
It's good practice to think about the driveshaft and universal joints when you're planning more power underhood. As horsepower and torque increase, the demands on a driveshaft, universal joints, and yokes rise accordingly. If you are stepping up to a 9-inch rearend, the difference in driveshaft length is probably going to mandate a new driveshaft anyway.
How do you order a new driveshaft, and what do you need to know before doing so? Before we get into driveshaft fabrication, let's look at driveshafts, universal joints, and yokes.
There are three basic types of driveshafts available for classic Fords: steel, aluminum, and carbon fiber (composite). Classic Fords and Mercs were fitted with steel driveshafts from the factory. Some were of a two-piece design, with an outer shaft and an inner shaft separated by a rubber vibration absorber. This design was common with automatic transmission cars to improve driveline smoothness. Manual transmissions were a single steel tube shaft only. Some applications were fitted with a slip-yoke/harmonic balancer design, also intended to absorb vibration. There were many variations in vintage Fords to begin with.
From left to right are the...
From left to right are the three basic types of drive shafts available from Inland Empire Driveline: steel, aluminum, and composite. Composite is the shaft of choice when you're going to throw a lot of power at the rearend. Aluminum driveshafts can take up to 500 hp. Steel shafts can take even more depending on which tube size and universal joint you choose.
Aluminum driveshafts offer...
Aluminum driveshafts offer reduced weight and less rotating mass. The weight advantage is what makes the aluminum shaft desirable. The 3.0-inch aluminum shaft with a .125-inch wall thickness will take up to 500 hp. Outside tube diameters of 3.5 and 4.0 inches are also available.
Opting for a steel driveshaft...
Opting for a steel driveshaft is going with the solid and reliable. Steel shafts can tolerate greater amounts of torque better than aluminum shafts, depending on wall thickness and tube diameter. Inland Empire Driveline can steer you straight on sizing.
In any case, be it one-piece steel or two-piece, we suggest replacement of your factory driveshaft with a new one-piece steel shaft for your vintage Ford. We make this suggestion not to help these folks sell driveshafts, but for you to get into current universal joint technology, availability, and installation. Many original Ford driveshafts use inside snap-ring universal joint cup retainers. These clips have been known to fly out (if improperly installed), causing the cup to fly out, which throws the driveshaft off center. If this happens at 70 mph, it can be catastrophic. When a driveline company builds you a new shaft, it uses the outside snap ring cup retainers, which are more secure and safer. But like the inside snap ring, they mandate close attention to detail during assembly. Another issue surrounding the inside snap-ring universal joint is availability. They are harder to get these days from auto parts stores for classic-style driveshafts.
Composite driveshafts look...
Composite driveshafts look decidedly different than their conventional steel or aluminum tube counterparts. Composite shafts are carbon fiber wrapped up in a liquid resin that, when it cures, is super strong. What's more, it is much lighter than the aluminum shaft. If you're building a show car that's going to have mirrors underneath, the composite shaft is a showstopper. If you are going racing, it will take darned near anything you can throw at it.
This is a two-piece, steel-around-rubber-around-steel...
This is a two-piece, steel-around-rubber-around-steel tube driveshaft-original equipment in classic automatic transmission-equipped Fords and Mercurys. It's a good idea to replace this type of driveshaft with a steel or aluminum shaft for safety and security.
You will find this universal...
You will find this universal joint on older Fords, where the caps are tied to the different yoke with bolts instead of U-bolts. This is a Spicer 2.5R x 2C joint.
We visited Inland Empire Driveline for this story, and when Inland Empire Driveline builds a new shaft, you get new universal joints and a new slip-yoke, which eliminates all worn out parts. With the driveshaft come other issues that need your attention if everything is to work smoothly. Replace the transmission tailshaft sleeve bushing and tailshaft seal, which improves fit around the new slip-yoke, getting everything back in proper tolerances for driveline smoothness.
Here's a Spicer 1310 with...
Here's a Spicer 1310 with 1.063-inch caps on all four sides (PN 5-153X). We know it's a 5-153X because it is permanently lubricated and void of grease fittings.
When we order the 1310 with...
When we order the 1310 with grease fittings and 1.063-inch caps, we get the 5-1201X.
Here are the 1330 with 1.063-inch...
Here are the 1330 with 1.063-inch caps and grease fittings, known as the 5-1203X. The 1330 is obviously larger than the 1310, more meat for that powerful mill you have planned. If you want a permanently lubricated 1330, ask for 5-791X.
In the '90s, aluminum driveshafts started showing up in new Fords, as well as the automotive aftermarket. Aluminum driveshafts offer us reduced weight and less rotating mass than steel. They are not tolerant of extremes of torque. They twist and break when we exceed their design limits. Aluminum driveshafts call for the use of special universal joints with coated caps designed to prevent dissimilar metal corrosion that comes when steel and aluminum make contact with each other. Aluminum driveshafts are also subject to distortion and irregularities we don't normally see with steel driveshafts. This calls for extraordinary attention to detail during manufacture. Inland Empire Driveline features custom-made aluminum driveshafts in 6061-T6 aluminum for strength. What's more, each shaft is state-of-the-art welded for consistency and strength, passing Spicer's reverse-torsion testing. This makes Inland Empire Driveline an authorized Spicer driveshaft builder.
Composite or carbon-fiber driveshafts are featherweights, the lightest driveshaft you can buy. They are also the strongest. Composite shafts offer unprecedented strength coupled with lightweight construction, making them perfect for high-stress applications that could break a steel or aluminum shaft. The composite shaft is designed to tolerate 3,900 lb-ft of torque. Rotation is smooth and stable up to 14,000 rpm. Composite driveshafts are common in late-model GM cars, such as the Camaro and Firebird, where composite material is wrapped around the aluminum shaft. Composite driveshafts are available from Inland Empire Driveline on a made-to-order basis. They are not an off-the-shelf item and do not come inexpensively. Where off-the-shelf steel and aluminum shafts cost anywhere from $350 to $500 each, a composite shaft for the same application can run upwards of $1,000. That's the price you pay for solid driveline integrity when you are going racing.
When presented with the choice...
When presented with the choice of greaseable versus lifetime-lubricated universal joints, consider this. Greaseable joints aren't as strong because they have been drilled through to accommodate the grease galleys. Lifetime-lubricated universal joints are solid, and you never have to sweat lubrication.
When you are shopping universal...
When you are shopping universal joints for aluminum driveshafts, remember that you need special caps for the aluminum shaft. These caps are coated to prevent corrosion between the steel caps and the aluminum driveshaft.
Here are the two basic slip-yoke...
Here are the two basic slip-yoke sizes: the 31-spline unit (left) for big-blocks and the 28-spline piece (right) for small-blocks. Both are of iron and steel construction, easily identified by their sizes.
If you want to reduce rotating weight, composite driveshafts make sense. Unless you want your street Ford to be decidedly different than the rest, and are willing to pay the price, you do not need a composite driveshaft for your street warrior. If you just have to have one, be prepared to pay the price.
When you are ordering a driveshaft, expected power output is very important to know. Most applications will live happily with a 3-inch tube. When you are going to pump greater than 500 hp through the shaft, you're going to need a 3.5-inch shaft with larger universal joints and yokes.
Universal joints are installed at each end of the driveshaft to allow the shaft to articulate with the rear axle. These little guys have a big job to do. They have to keep power going to the rear axle under some very adverse conditions. The more power we throw at the driveshaft and universal joints, the larger and beefier these items have to be.
A driveshaft consists of six...
A driveshaft consists of six basic components: the tube, ends, universal joints, and the slip-yoke. The ends are precision fitted and welded to the tube. The shaft build begins with the universal joints installed in the ends along with the slip-yoke. This enables us to set the shaft up in the jig.
Driveshafts are measured lengthwise...
Driveshafts are measured lengthwise from center-to-center, meaning from the center of each universal joint cap. It's simple to make a driveshaft if you are going on measurements from an existing shaft.
Our original shaft is a one-piece...
Our original shaft is a one-piece unit with the external C-clip universal joints. It becomes more challenging when you custom order a driveshaft for an unusual application.
Most Ford applications call for a Spicer 1310 universal joint at each end of the shaft. The 1310 vary according to cap size, meaning being able to tie the driveshaft to different applications. Most original Ford applications call for an inside clip universal joint that is numbered differently from the 1310. Your local Spicer dealer or Inland Empire Driveline will have the necessary information if you choose to rebuild your original driveshaft. If you're stepping up to more power, you will want to consider the 1330 or 1350, which are larger universal joints for more heavy-duty applications.
When we speak of 1310, 1330, and 1350 universal joints, we are talking about the basic joint body with each number without the caps. A basic 1310, for example, has the same size cap on all four sides: 1.063 inches. The same is true for the 1330: a larger universal joint, also with 1.063-inch caps in on all four sides. The 1350 joint is a super heavy-duty piece with 1.188-inch caps.
When we go with different cap sizes on the basic 1310, 1330, or 1350, we are then dealing with a conversion universal joint. For example, you want to install a 9-inch rearend in your Mustang with an 8-inch rearend. If driveshaft length works out, or you are able to go with a different yoke, all you need is a conversion 1310 with the correct 1.125- or 1.075-inch caps opposite the 1310's native 1.063-inch caps. With an 8-inch rearend, we would have the smaller 1.063-inch caps on all four sides.
|Inland Empire Driveline Steel Replacement Driveshafts |
|Part Number ||Description |
|U-Joint - Tube ||Dia. x Wall Thickness |
|SK-31-31-83 ||1310 - 3.0" x .083" |
|SK-33-35-83 ||1310 - 3.5" x .083" |
|SK-35-30-95 ||1350 - 3.0" x .095" |
|SK-35-35-83 ||1350 - 3.5" x .083" |
|SK-33-30-83 ||1330 - 3.0" x .083" |
|SK-35-30-83 ||1350 - 3.0" x .083" |
|SK-35-30-95C ||1350 - 3.0" x .095" |
|Inland Empire Driveline Steel Replacement Driveshafts |
|Part Number |
U-Joint - Tube
Dia. x Wall Thickness
|1310 - 3.0" Tube - |
Polished Shaft, Chrome
U-Joints, Slip-Yoke &
|ALU-1310 ||1310 - 3.0" x .125" |
|ALU-1310-3.5 ||1310 - 3.5" x .125" |
|ALU-1330-3.5 ||1330 - 3.5" x .125" |
|ALU-1330-4 ||1330 - 4.0" x .125 |
|ALU-1350 ||1350 - 3.5" x .125" |
|ALU-1350-4 ||1350 - 4.0" x .125" |
A side-by-side comparison...
A side-by-side comparison of the 31-spline slip-yoke shows us the factory yoke on the left and the Quick Release, CNC-machined steel forging from Inland Empire Driveline on the right.
For those of you running small-blocks,...
For those of you running small-blocks, here is the 28-spline yoke with the factory piece on the right. To the left is the Quick Release forging.
These are pinion yokes (from...
These are pinion yokes (from left to right): aluminum, steel forging, and the factory cast-iron piece. Factory castings vary in length.
Driveline yokes present their own set of challenges because there are several variations. It is up to the informed enthusiast to choose the right one. The slip-yoke slides back and forth at the transmission's tailshaft, hence the name. There are two basic slip-yoke types (although there are many variations of the two types): 28-spline for small-block transmissions such as the C4, Top Loader, T-10, and T5; the 32-spline (larger) for big-block applications such as the C6, big-block Top Loader, T45 (if you're running a Modular V-8), and Super T10. The factory slip-yokes are made of cast iron and machined steel alloy.
The factory shaft is a 2.749-inch...
The factory shaft is a 2.749-inch outside diameter tube. This calls for a 3.000-inch tube from Inland Empire Driveline. Be it aluminum or steel, we want 3.000 inches. The aluminum tube has a .125-inch-thick wall. Steel is .083-inch thick. Because aluminum isn't as strong as steel, it calls for a thicker wall to give us strength. In some instances, we need a 3.5-inch or 4.0-inch outside diameter aluminum tube when serious power gains are expected.
Each end of the shaft is fitted...
Each end of the shaft is fitted with its universal joints.
The front of the shaft gets...
The front of the shaft gets the slip-yoke. Universal joints are pressed into the ends, and the C-clips are installed and checked for securtiy.
When you are pumping up the power, you're going to need more yoke and the corresponding universal joint. When horsepower rises above 500, a 1310 joint will not stand up to the torque. And because we like to see a measure of safety demonstrated here, we suggest stepping up to a 1330 or 1350 when horsepower goes above 400. With this kind of increase in power, we suggest going with one of Inland Empire's CNC machined, heat-treated forgings with the quick-release cap design for easy maintenance. These 1350 Quick Release yokes will withstand brutal amounts of power. If you are planning huge gains in power, you will want this yoke, along with 1350 joints.
Inland Empire Driveline measures...
Inland Empire Driveline measures each end to the center of the universal joint cap. Then the tube is measured to proper length before it is cut with a bandsaw.
We take the total length of...
We take the total length of the original shaft and figure in the end dimensions to arrive at total length, center-to-center.
That means our aluminum shaft...
That means our aluminum shaft must be the exact same length from center-to-center before it is welded together.
Inland Empire Driveline offers a couple of differential pinion yokes for high-performance Ford applications. The 1350 steel pinion yoke, like the 1350 Quick Release, is designed to take a lot of punishment. a 7075 T-6 aluminum pinion yoke (1310 and 1350) is also available.
When you study the slip-yoke and pinion-yoke part numbers, choose your yoke based on the transmission type, differential type, and the universal joint you intend to use. The universal joint number is incorporated into the yoke part number. So is your transmission type.
Let's Build A Driveshaft
When you walk into Inland Empire Driveline or Mustangs Plus to buy a driveshaft, you can count on the shaft being an "in-stock" item if you are building a commonplace driveline package. Shafts are available in stock for applications such as a '67 Mustang with a 289, C4 Select-Shift, and an 8-inch rearend. If you are building something out of the ordinary, such as a 5.0L EFI small-block, Tremec TKO, and a 9-inch rearend, you will have to order the shaft. Inland Empire Driveline can build a driveshaft to your specifications and have it on your doorstep in a matter of days.
Each end of the tube is machined...
Each end of the tube is machined on a lathe to create an improved end taper for the welding process.
The driveshaft ends and tube...
The driveshaft ends and tube are set up in an assembly jig first. A buddle level is used to get the shaft close and to ensure proper alignment with the jig.
We decided to have Inland Empire Driveline build us two driveshafts for our project cars: one steel, one aluminum. We learned there isn't much difference in price with steel and aluminum, both are competitively priced.
The seam between the end and...
The seam between the end and the tube is cleaned with a wire wheel for purity. Contaminates in the metal can disturb the welding process, adversely affecting the integrity of the weld.
Once the shaft assembly is...
Once the shaft assembly is set up in the jig, it is checked for run out, which is not only tube and tube-end alignment, but tube straightness.
Aluminum shafts are impossible...
Aluminum shafts are impossible to straighten. Distorted and bent tubes are discarded. Run out is checked at both ends and at the center. The shaft is rotated and checked at these three locations, and adjusted until run out is less than .005-inch.
|Guide To Ford Universal Joints |
|Series ||Width ||Cap Diameter |
|1310 ||3.218" ||1.063" |
|1330 ||3.625" ||1.063" |
|1350 ||3.625" ||1.188" |
|Permanently Lubricated Universal Joints |
|Series ||Part Number |
|1310 Spicer ||5-785X |
|1330 Spicer ||5-791X |
|1350 Spicer ||5-447X |
|Greaseable Universal Joints |
|Series ||Part Number |
|1310 ||5-153X |
|1330 ||5-1203X |
|Conversion Universal Joints |
|Part Number ||Cap to Cap ||Inside to Inside ||Cap ||Cap |
|5-3022X ||3.218" ||1.125" ||1.125" ||1.063" |
|5-788X ||3.218" ||2.125" ||1.075" ||1.063" |
|5-794X ||3.625" ||2.563" ||1.125" ||1.063" |
|5-797X ||3.625" ||2.625" ||1.125" ||1.063" |
|Applications ||Part Number |
|SY-C4-1350Q ||Ford 1.219 inch, 27 on 28-spline for C4, FMX, Top |
Loader three- and four-speed, T5 Light-Duty,
AOD and AODE
|SY-C6-1350Q ||Ford 1.390 inch, 30 on 31-spline for C6, Tremec |
T45, big-block Top Loader four-speed
|Pinion Yokes |
|Applications ||Part Number |
|PY-9 ||Steel 28-spline for 9-inch |
|PY-9P ||Steel 35-spline for 9-inch |
|PY-8.8 ||Steel 30-spline for 8.8-inch |
|PY-9-1310-A ||Aluminum 28-spline for 9-inch |
|PY-9-1350-A ||Aluminum 28-spline for 9-inch |
|PY-9P-1350-A ||Aluminum 35-spline for 9-inch |
Once perfect alignment is...
Once perfect alignment is achieved, each end is welded to the tube in a timed pattern that ensures a perfect union. Heat is concentrated to prevent distortion from heat across the tube. The shaft is again checked for run out at three points to ascertain alignment.
The shaft is spun and dressed...
The shaft is spun and dressed with 180-grit paper to improve its appearance. you can order a polished-aluminum driveshaft from Mustangs Plus or Inland Empire Driveline.
Driveshafts are dynamic balanced...
Driveshafts are dynamic balanced just like your car tires or engine assembly to eliminate vibration. Each weight is tied to the shaft and welded in place, then balance is checked again.