The way the cardan style universal joint works is as follows (and this is very important to understand):

First - why do we need to use a universal joint in the first place? The answer is easy, and can be surmised from the above definition.

So, we have two different shafts, connected by a universal joint operating at an angle. Because of this, the ends of the U-joint in each of the yokes in the 2 different shafts (the t-case output yoke, and the yoke at the transfer case end of the driveshaft) both travel in elliptical paths, but the paths are 90° offset (out of phase) from one-another. In the pic to the left, the blue ellipse represents the path of the input shaft (t-case yoke) and the red ellipse represents the path of the output shaft (driveshaft yoke). Because the 2 shafts are connected to opposite bearing caps, their elliptical paths are offset 90°, as can be seen in the pic.

Now, the problem is, the t-case output is driven from the crankshaft by gears and/or chain drive at a fixed rate (angular velocity) - let's say 1000 rpm for example. Of course, because the driveshaft is mechanically connected to the t-case output, it also must be rotating at 1000 rpm. In the pic, the green arrows show where the two elliptical paths cross, the points of intersection. At these points, the 2 shafts must be in the same place at the same time (otherwise the assembly would come apart.) In order for this to happen, you can see that at times the driveshaft's elliptical path (red ellipse) is longer than the t-case yokes (blue ellipse) and vice versa. So, in order for the assembly to remain together and driven at a fixed rpm, the driveshaft must have to speed up and slow down at different points along it's path in order to match the t-case yoke that is being driven at 1000 rpm. The black arrows show where this happens. In this case, the driveshaft will speed up and slow down a total of 4 times per revolution. That is, it speeds up, slows down, speed up, slows down, then repeats. This is the reason why we say a cardan style universal joint transmits rotation/torque with a "variation in angular velocity between the input and output shafts".

This speeding up and slowing down can cause vibration of the driveshaft and significant wear on the universal joints if not properly accounted for in the driveshafts design. This "accounting for" is what we call driveline geometry and will be discussed in great detail in part 2.

For now, remember that a U-joint must be used because there's an angle between the t-case and pinion (and often a very big angle in the case of lifted 4x4s - which is why this whole driveshaft business is so important to us in the first place). When a U-joint is used, and operates at an angle, the bearing caps on the input and output shafts will describe elliptical paths offset by 90° from one-another because of the difference in geometry between the two opposing bearing caps in the U-joint. Since they travel in elliptical paths, and yet must remain fixed together driven at a constant rpm the driveshaft must therefore speed up and slow down twice each per revolution. This difference in angular velocity between the 2 shafts causes noise, vibration, and U-joint wear, and must be accounted for in proper driveshaft design.

The speed changes are not great when the angle is less than a few degrees, but as the operating angle of the joint increases so do the cyclic vibrations of the driven shaft as well as the back and forth motion in the joint itself.

Constant-Velocity (CV) Universal Joint:

Their common use in fwd cars is because the joints in the half shafts must accommodate being driven at high speeds for long times as well as changing compound angles due to the front wheels being steered and the front wheels cycling up and down with the suspension. As such, the inner and outer joints in a fwd car half shaft often operate at different angles. Whenever the wheels are turned the outer joint runs at a much higher angle than the inner joint. This upsets the offsetting relationship between inner and outer joint angles that’s a necessary requirement for ordinary U-joints. What’s more, the front wheels are required to steer at angles of up to 45 degrees—which puts too much strain on a U-joint.

A CV joint, by comparison, always splits the operating angle in half so the driven shaft turns at the exact same speed as the input shaft. So no matter what the joint angle, there are no changes in speed -- thus the name "constant velocity."

Driveshafts:

A driveshaft is a device that connects the transfer case to the axles, transmitting torque from the engine to the driving wheels. It is also called a propeller shaft or prop-shaft for short (mostly by Brits and Aussies). Virtually all driveshafts (certainly all that I know of) fit into one of two often misunderstood broad categories. They are:

EITHER

Cardan-style universal joint driveshafts, subdivided into:

• Single-Cardan-style universal joint shaft; or
• Double-Cardan-style universal joint shaft

OR

Constant Velocity (CV) joint style driveshafts.

This is an important distinction, if only academically. You see, true CV joint driveshaft are rare in 4x4 driveshafts (some earlier Jeeps came with GKN CV style front driveshafts that were tiny and weak)

There are many different types of CV joint, including Fixed Ball, Single Roller Tripod Plunging Joint, Ball Plunging Joint, etc. You can read about them at http://www.gkndriveline.com/ None have anything to do with our needs and heavy-duty 4x4 driveshafts.

WHAT???? You cry. But everyone's always talking about CV driveshafts - heck the title of your own article is "1 Ton CV driveshaft" you hypocrite!

You're right - you see, the very common double-cardan-style universal joint shaft (pictured above, upper shaft in pic), is properly called a "near constant velocity, double-cardan-style universal joint shaft." (incidentally, this "velocity" we keep referring to is the angular velocity of the joint in the shaft). Now, what has happened is that because "near constant velocity, double-cardan-style universal joint shaft" is such a huge mouthful, it has become common practice to drop the "near" , "double-cardan-style", and "universal joint" and what we are left with is common convention leading to a double-cardan-style universal joint shaft simply being referred to as a CV shaft.

There - now you know the truth, and you can amaze your friends (or getting soundly beaten by them for being a nerdy smart-ass) at the next trail-side campfire!

So, we know that true CV joint driveshafts are of no interest to us, so forget them now. That leaves us with either single or double cardan style driveshafts. The latter, I shall bow to convention, an henceforth refer to them as CV driveshafts, simply because everyone does.

Now, whether a 4x4s driveshaft is single cardan (also called "regular' or "single-joint" or simply "U-joint) or CV, there is one more distinction to make.

All driveshaft's must have some way of changing length, allowing the driveshaft to shorten or lengthen as required, to accommodate suspension movement. This is because suspension movement will cause the distance between the output of the transfer case and the yoke on the axles pinion to change somewhat. How much the distance changes, and therefore how much "accommodation" you need in your driveshaft will depend on a lot of different factors, including suspension geometry, amount of wheel travel, whether the diff on the axle is centered or offset, etc. For example, a 4 link coil sprung rear axle with center limiting strap will require significantly less length change accommodation than a soft leaf-spring-over-axle front axle with shackle reversal, offset diff, and no limit straps. The former may require only an inch or 2, the latter many inches. The only way to know for sure is to flex the suspension and measure.

The 2 common methods of accommodating this length change, or slip, are:

Type 1 - Slip-yoke shaft. This style is a very common late model rear driveshaft factory style. It comes stock in a great number of 4x4s, including Jeeps, Chevy's, and many others. The slip-yoke is an internally splined tube that slips into the rear output of the transfer case. As the name implies, the slip yoke slips in and out of the transfer case output housing, to accommodate driveshaft length change. generally, this type is not favoured by the hardcore crowd as it's drawbacks generally include:

• Small U-joint size (stock)
• Small tubing (stock)
• Limited travel in the slip yoke
• The fact that the transfer case output is sealed by the slip yoke, meaning that if you break a U-joint or the shaft, and have to remove the slip yoke, you have to have some sort of method for plugging the transfer case output hole, otherwise the t-case will lose all its fluid.

Driveshaft U-joint Series / Sizes

So we know all about the different types, and all the parts, the last thing we need to know before we can fully and accurately describe and talk about driveshafts is the relative size (and therefore strength), normally determined by and referenced to, the size (series) of the U-joints used in the driveshaft.

A U-joint "series" is a number that describes a group of cardan style universal joints by common dimensional grouping. A series number is not an actual specific part number.

The common U-joint series used in light truck and 4x4 driveshaft construction, with dimensions listed corresponding to the diagram are:

Glossary

• Bearing Cup Assembly — Consists of a bearing cup with needle rollers generally held in place by a seal guard and bearing seal. Sometimes the assembly includes a thrust washer.
• Bearing Cup — A cup-shaped member used as the bearing bore of a bearing cup assembly and for positioning a thrust end of a cross trunnion.
• Bearing Seal — A flexible member of a bearing cup assembly which prevents the escape of lubricant from or entry of foreign matter into a bearing.
• Boot — A flexible member which prevents the escape of lubricant from or entry of foreign matter into the slip member assembly.
• Boot Clamp — A thin adjustable band used to hold the boot in position on the slip member assembly.
• Boot Seal — See Boot.
• Companion Flange — A fixed flange member that attaches a steering shaft (intermediate shaft) to a steering gear box or steering column shaft.
• Cross — See Journal Cross.
• Cross Hole — A through hole in each lug ear of a yoke used to locate a bearing cup assembly.
• Ear— One of two projecting parts of a yoke symmetrically located with respect to the yoke’s rotational axis.
• End Fitting — An end yoke or companion flange that attaches a driveshaft to a transfer case or axle (pinion).
• End Yoke — A yoke that attaches a driveshaft to a transfer case or axle (pinion).
• Flange Yoke — A full-round style yoke which attaches a driveshaft to a transfer case or axle (pinion).
• Glidecote® — The blue, nylon, wear-resistant coating on Spicer yoke shafts.
• Grease Zerk (Nipple) Fitting— The fitting on the shoulder or center of a journal cross that allows for lubrication.
• Inboard Yokes — Yokes that make up the ends of a driveshaft.
• Intermediate Shaft — See Steering Shaft.
• Journal Cross — The core component of a universal joint which is an intermediate drive member with four equally spaced trunnions in the same plane.
• Lug Ear — See Ear.
• Needle Roller Bearings — See Needle Rollers.
• Needle Rollers — One of the rolling elements of a bearing cup assembly.
• Outboard Yokes — Yokes that are not a part of a driveshaft (i.e. yokes that are part of a transfer case output or axle (pinion) input.
• Phasing — The relative rotational position of each yoke on a driveshaft.
• Pinch Bolt — Bolt used to compress slotted end fittings for retention.
• Purge— The act of flushing old grease and contaminants from universal joint kits with fresh grease.
• Slip Member Assembly — Combination of slip spline, slip yoke and boot assembly.
• Slip Spline— A patented tubular-type, machined element consisting of internal splines in a driveshaft assembly.
• Slip Yoke — A slip member yoke with a female machined spline used for axial movement.
• Slip Yoke Plug — See Welch Plug.
• Snap Ring — A removable member used as a shoulder to retain and position a bearing cup assembly in a yoke cross hole.
• Snap Ring Groove— A groove used to locate a snap ring.
• Spline — A machined element consisting of integral keys (splined teeth) or keyways (spaces) equally spaced around a circle or portion thereof.
• Trunnion(s)— Any of the four projecting journals of a cross.
• Universal Joint — A mechanical device which can transmit torque and/or rotary motion from one shaft to another at fixed or varying angles of intersection of the shaft axes. Consisting usually of a journal cross, grease zerk (nipple) fitting and four bearing cup assemblies.
• Universal Joint Kit — See Universal Joint.
• U-Joint — See Universal Joint.
• Welch Plug— A plug in the slip yoke face that seals off one end of the spline opening. Also known as a slip yoke plug.
• Yoke Lug Ear Cross Hole — See Cross Hole.
• Yoke Shaft — A slip member yoke with a male machined spline used for axial movement.

So now that we know all the terms and definitions regarding Driveshafts, what else do we need to know to get the best, world class, bulletproof driveshaft under our truck?

Well - the answer is ....depends. It depends on what kind of person you are. If you just want the job done, so you can get behind the wheel, the answer is NOTHING. You simply call up Jess at High Angle Driveline @ (530) 877-2875 and have a nice chat with him about your needs. He will help you with whatever you need, discuss your options with you, and be pleased to talk to you about driveshaft tech, and his customer service is second to none.

However - if you're a tech-geek like me - you want to know more.

Part 2 - Driveshaft Geometry

Proper driveshaft geometry is critical to getting the most from your driveshafts. Improper geometry will cause vibration, excessive wear, and premature failure. Even the best driveshaft in the world will suck if it is not installed with proper geometry. We also need to know about proper geometry in order to select the best type of shaft for our application.

Before we discuss geometry, a couple more definitions of some terms are in order. For the purposes of this article:

Terms

When talking about driveshafts, we say that a slope is down if, when viewed from the side of the vehicle, it is higher at the transfer case and lower at the axle (i.e. it descends from the center to the rear of the vehicle for a rear driveshaft or descends from the center to the front of the vehicle for a front driveshaft). The slope is up if, when viewed from the side of the vehicle, it is lower at the transfer case and higher at the axle (i.e. it rises from the center to the rear of the vehicle for a rear driveshaft or rises from the center to the front of the vehicle for a front driveshaft).

Phase:

We say that 2 U-joints are in-phase if they are fitted to yokes that are fixed on the same shaft, such that the 2 opposing bearing caps in the U-joint that are held captive by the yoke on the shaft (the inboard yoke's U-joint caps) are both in the same orientation.

Note that this means that they would be in phase if you rotated one or the other 90° (by cutting and re-welding the shaft). Note also that 90° is the most they can ever be out of phase, for as you pass through 90° difference between the two joints orientation, you begin to come back into phase.

U-joint life span.

As we learned in part 1, there are 2 types of driveshaft that interest us, each with their own separate geometry requirements.

Single-Cardan-style universal joint driveshaft geometry

Most of the equipment that uses driven shafts in a broken-back configuration though, are fairly low RPM (but not all). The reason is, due to the nature (geometry) of the configuration (again, have a look at the picture above) with this setup, there's a lot more inherent strain on the slip member as it rotates. because of the opposite angles, the shaft "wobbles" the slip member back and forth as it rotates - like a skipping rope being swung. At high rpm, with anything but the tightest slip-joint assembly, this would cause a horrible vibration - that's why Spicer light duty driveshafts do not normally come factory in this arrangement. Note however, that some Land Rovers do have stock driveshafts in the broken back configuration, so it can work! I don't have any experience with these Rover's, but I imagine that the angles in the stock configuration are pretty darned small. As with the more standard single-cardan setup - start increasing the operating angles of the U-joints and the elliptical paths get more and more elliptical, the angular velocities (amount the shaft speeds up and slows down each revolution) get greater, and when you spin that shaft at 1000rpm, the more likely it is that the shaft will be noisy, harsh, and vibrate - EVEN IF the angles are matched. Again...time for the double cardan CV shaft!

Double cardan (near) constant velocity driveshaft (commonly known as a CV driveshaft) geometry.

Measuring and calculating universal joint and driveshaft operating angles

So, we know what the geometry is supposed to be - how do we find out what ours actually is, and what do we do about it? This section discusses measuring your geometry, calculating the results, interpreting the results, and making necessary adjustments.

The first 2 steps, measuring slopes of components, and calculating operating angles are the same, regardless of whether you have a standard single-cardan shaft or a double-cardan CV shaft. The third step, interpreting the results, will differ, depending on the style of driveshaft.

Before attempting to measure angles ensure that tire air pressure is correct, that the vehicle is at the correct trim (chassis) height (i.e. suspension loaded, operating weight in/on the vehicle, etc.) and the ground surface is perfectly level. The driveshaft also needs to be installed and torqued to spec.

Step 1 - Find the slopes of the components involved.

Recall that the slope is the angle formed between the component in question, and the horizontal. To find these slopes, we measure them with a protractor as follows:

If your transfer case has an output flange, the best way to measure the slope is to temporarily remove the shaft from the flange,place the angle finder against the flat machined surface of the flange, then add or subtract 90° from the reading taken. Remember to re-attach the driveshaft so that you can correctly measure its slope.

Remember that the slope is "down" if it is higher at the t case than at the axle.

Remember that the slope is "down" if it is higher towards the center of the vehicle, and lower at the end of the vehicle.

Step 2 - Find each operating angle between each pair of slopes as follows:

In the special case of calculating the operating angle at the pinion in a CV shaft application, assign the pinion slope a (+) sign if it is DOWN and a (-) sign if it is UP, then always subtract the pinion slope from the driveshaft slope, regardless of their relative sizes, and make note of the resulting sign (+ or -), as this will help in deciding any possible corrective action.

Step 3 - Interpret the results

Assuming a fairly standard 4x4 setup with no pillow blocks or intermediate shafts, once you have measured all the slopes of the components, and calculated all the operating angles, you should have a piece of paper that has 3 slopes and 2 operating angles written on it. It helps to have a sketch too, like those shown below on the left.

Standard (single cardan) Shaft:

The first operating angle must be less than the maximum operating angle of the series of U-joint used, and preferably less than half the maximum (remember - you need to allow for increase in operating angles while off road due to suspension movement, and also how the higher the operating angles, the more likely vibration, even if geometry is correct). If it is not, you have only 2 choices: lower the suspension or drop the drivetrain (lower t-case); or switch to a CV style shaft.

The second operating angle should be within 0.5° (1/2)° of the first AT CRUISE THROTTLE. This is a critical point. virtually every axle (to a greater or lesser degree, depending on power and suspension) will experience some "axle wrap" or pinion rotation ( pinion rotates up in rear axle, and down in front axle) depending on acceleration and to some extent braking torque. This will of course alter the geometry of the pinion, and therefore the whole driveshaft! Since the driveshaft will presumably spend most of it's time (and therefore the effects of it's vibrations will be most annoying and damaging) in a cruise throttle condition, it is standard practice to set driveshaft geometry for this state (If you have a highly specialized vehicle, like a drag car, this may not apply - and you will want to discuss your needs with an expert like Jess at High Angle Driveline). Generally, for most truck rear axles, at cruise, the pinion will rotate up 1-2° from its static position. As such, it is common practice to shim the axle or adjust the links, rotating the pinion and changing the pinion slope at rests, such that the pinion slope is 2° lower than that required to achieve equal operating angles at rest. Read that bit again, carefully! It's a bit of a juggle, because as you adjust the pinion slope itself, so you also actually alter the driveshafts slope, and therefore the transfer case operating angle as well. Once you get close though, you will easily end up at the correct balance point. the point I'm making is, don't just make a whopping 20° change to the pinion angle, then weld those spring perches on and call it done. That big of a change will have effected things, so you'd have to measure and re-calc all the slopes and operating angles again, as you hone in on the final setting.

We can see that the front operating angle is 12°. Assuming we are using a 1350 series U-joint, and the vehicle is not a frequent, long-range freeway cruiser, nor does it have a super-flexy suspension with monstrous travel, we decide that this is satisfactory. The axle joint operating angle is 11°. Because it is a rear driveshaft, the rear pinion will rotate up, let's say 2° under cruise throttle. Since our measurements and calculations were done at static, this means that in reality, under cruise throttle, the pinion slope would change from 6° down to 8° down (even though the pinion wraps "up" - remember we describe slopes as up or down depending on orientation between t-case and axle). This would make the axle joint operating angle actually 17° - 8° = 9° at cruise. Since we need it to equal 12° at cruise, we need to rotate/shim the pinion at rest down 3°. This will result in a static pinion slope of 3°. the would net a cruise throttle pinion slope of 3° + 2° = 5°. That would make our axle joint operating angle now 17° - 5° = 12° - A perfect match for the front!

Of course - we would need to make this adjustment (rotate pinion down 3° at rest) and then re-measure and re-calc everything to get it perfect, as the change may effect driveshaft slope and therefore t-case joint angle too. However, this is unlikely with the magnitude of the changes in this example.

Double cardan CV shaft

The first operating angle, the CV joint op angle, must be less than the maximum operating angle of CV joint used. Remember - you need to allow for increase in operating angles while off road due to suspension movement. How much you must allow will depend entirely on your suspension design and the terrain driven. If it is not, you have only 2 choices: lower the suspension or drop the drivetrain (lower t-case); or switch to a higher angle capable CV joint shaft.

The second operating angle, the pinion op angle, should be within 0.5° (1/2)° of zero (0°) AT CRUISE THROTTLE. This is a critical point. virtually every axle (to a greater or lesser degree, depending on power and suspension) will experience some "axle wrap" or pinion rotation ( pinion rotates up in rear axle, and down in front axle) depending on acceleration and to some extent braking torque. This will of course alter the geometry of the pinion, and therefore the whole driveshaft! Since the driveshaft will presumably spend most of it's time (and therefore the effects of it's vibrations will be most annoying and damaging) in a cruise throttle condition, it is standard practice to set driveshaft geometry for this state Generally, for most cars and trucks rear axles, at cruise, the pinion will rotate up 1-2° from its static position. As such, it is common practice to shim the axle or adjust the links, rotating the pinion and changing the pinion slope at rests, such that the pinion slope is 2° lower than that required to achieve an operating angles of zero at rest. Read that bit again, carefully! It's a bit of a juggle, because as you adjust the pinion slope itself, so you also actually alter the driveshafts slope, which directly affects what your pinion angle must be, in a feedback type loop. Once you get close though, you will easily end up at the correct balance point. The point I'm making is, don't just make a whopping 20° change to the pinion angle, then weld those spring perches on and call it done. That big of a change will have effected things, so you'd have to measure and re-calc all the slopes and op angles again, as you hone in on the final setting.

We can see that the front CV operating angle is 22°. Assuming we are using a High Angle 1350 series CV shaft, we are comfortably within the proper operating spectrum here. The axle pinion joint operating angle is -1°. Because it is a rear driveshaft, the rear pinion will rotate up, let's say 2° under cruise throttle. Since our measurements and calculations were done at static, this means that in reality, under cruise throttle, the pinion slope would change from 28° down to 30° down (even though the pinion wraps "up" - remember we describe slopes as up or down depending on orientation between t-case and axle). This would make the axle joint operating angle actually 27° - 30° = -3° at cruise. Since we need it to equal 0° at cruise, we need to rotate/shim the pinion at rest down 3°. This will result in a static pinion slope of 25°. This would net a cruise throttle pinion slope of 25° + 2° = 27°. That would make our cruise throttle axle joint operating angle now 27° - 27° = 0° - A perfect setup for a CV shaft!

Note that, in the case of a CV shaft, since we always calculate the angle the same way driveshaft slope minus pinion slope, the sign of the result tells allows us to write an equation, the result of which tells us whether we need to rotate the pinion at rest down or up.

The equation is RR=DS-PS-WA. Where RR = rotation required (of the pinion at rest), DS - driveshaft slope, PS = pinion slope, and WA is the estimated pinion wrap angle. If the result is (-), we must rotate the pinion down at rest that many degrees, if the result is (+) we must rotate the pinion up that many degrees.

Of course - we would need to make this adjustment (rotate pinion down 3° at rest) and then re-measure and re-calc everything to get to perfect, as the change may effect driveshaft slope. However, this is unlikely with the magnitude of the changes in this example.

How to chose a Driveshaft for your Rig.

This is actually a fairly easy one to answer.

First - buy the absolute best you can possibly afford. Why? It is almost impossible to overstate the massive annoyance of a bad driveshaft. Driveshaft vibration is horrendously annoying - street queen or trail-only rig. Believe me, I know. My current buggy, the Wolf, is always trailered, and spends 90% of it's time below 10mph - occasionally it may get to 40mph. I had NO IDEA how bad my cobbled-together shaft was until I replaced it with a High Angle driveshaft. Even at slow speeds, a crappy driveshaft will EASILY suck the fun out of driving your rig. I figured - it's trail buggy - it's loose and noisy anyway - who cares. Well, I learned....it is Sooooooooo much nicer with a decent balanced shaft, operating within it's angle capabilities - and of course - the peace of mind for the components that actually put the power to the axles is priceless.

Do you need a a CV shaft, or will a standard single-cardan style do? Well, in my opinion, unless your rig is only an inch or 2 over stock suspension height, with minimal wheel travel / flex, the answer is definitely YES!

The CV driveshaft offers several HUGE advantages to the off-road vehicle.

First, the pinion and pinion yoke can be rotated up out of harms way, where it will be less susceptible to damage from rocks and other obstacles.

Secondly, the only limit to our operating angle at the CV joint (and thus how much suspension height we can run) is the limit of the double-cardan joint itself. A stock Spicer double cardan CV joint can run successfully at about 22°, and a High Angle Driveline double-cardan CV joint can be run successfully at as much as 32° !!! This allows for successful driveshaft installations in vehicles with much more suspension height than a simple single-cardan shaft can accommodate. Even if you matched the angles on a single cardan shaft exactly, you could never run it safely and vibration free at 30°!

Thirdly, the double-cardan CV joint assembly is simply better and more efficient at reducing or eliminating driveshaft vibration. Even at smaller angles, and even with correct matched-angle geometry, the single-cardan shaft is still susceptible to vibration. The CV shaft will always run smoother, quieter, and with less stress on the U-joints, and transfer case and pinion shafts, bearings, and seals.

The only advantage the single-cardan shaft has is that it is cheaper to manufacture / buy, and you don't have to buy a centering yoke or a third U-joint when rebuilding it. As always - the best costs a little more!

Part 3 - Driveshaft maintenance.

Driveshafts should be carefully inspected and lubricated (as applicable - some components, and even some entire driveshafts are non-serviceable and cannot be re-greased) at recommended original equipment vehicle manufacturers’ service intervals and/or at Spicer recommended lubrication intervals OR you can use my recommendations, which are:

Severe use (wet, muddy, or high-torque carrying use, extreme low gears (80:1 and lower), large tires(35" and over)) 3000 miles, 2 months, or 250 Hrs, whichever comes first

Moderate use (dry conditions, on and off road use) 5000 miles, 3 months, 500 Hrs, whichever comes first

Mild use (mostly street duty - some off-road) 8000 miles, 6 months, whichever comes first

Before undertaking any of these procedure, be sure to read and heed the section on Safety.

Driveshaft Safety

CAUTION

Caution – Under no circumstances should individuals attempt to perform driveline service and/or maintenance procedures for which they have not been trained or do not have the proper tools and equipment. See warning below.

WARNING

WARNING
Failure to release all parking brakes and failure to place transmission in neutral can result in torque being applied to the driveshaft. Disconnecting a driveshaft with applied torque can result in property damage, serious personal injury or death.

WARNING
Failure to take commonsense, precautionary measures when working on a vehicle or other machinery could result in property damage, serious personal injury or death. In order to avoid property damage, serious personal injury or death, you must:

1. ALWAYS wear safety glasses when performing maintenance or service. Failure to wear safety glasses can result in personal injury and/or partial or complete vision loss.
2. NEVER go under a vehicle while the engine is running. Be sure the vehicle’s engine is off, and keys are removed from ignition.
3. NEVER go under or work on a vehicle that is not on a level or flat surface.
4. NEVER work on a driveshaft without blocking the vehicle’s wheels and releasing all parking brakes.
5. NEVER lift a vehicle without the appropriate weight-rated, vehicle-support equipment.
6. NEVER REMOVE a driveshaft from the vehicle without keeping the vehicle’s transmission in neutral.
7. CAUTION – Driveshaft assemblies can be very heavy. Be sure to use proper lifting techniques when handling driveshafts. More than one person may be needed when handling driveshaft assemblies.
8. ALWAYS use support straps to prevent the driveshaft from falling out of vehicle during the removal and installation process.
9. NEVER heat components or use sledgehammers or floor jacks to remove the driveshaft from vehicle.

Note – For driveshaft applications that have pillow blocks, dampers, parking brakes or retarders, refer to these component manufacturers’ or the original equipment vehicle manufacturers’ service manuals for proper procedures.

Inspection

Note – The following procedures are to be performed prior to any lubrication of universal joints or slip members.
The addition of lubricant can mask the looseness in a component that is beginning to show wear and may be in need of replacement.

Note - The following pics are taken from Spicer's Heavy Duty Driveshaft manual (trucks over 30,000lbs) so the driveshafts themselves will appear huge, compared to what we 4x4 users are used to.

To properly inspect the driveshaft, you need to block the vehicles wheels, set the parking brake, put the transmission in Neutral (N), and the transfer case in 2wd. If you have a selectable locker or lockout manual hubs, unlock them. This is all important because you want to make sure that there is no drag or pressure or bind on the driveshaft that can mask wear and sloppiness during your inspection.

INSPECTING END FITTINGS

Visually inspect all input and output end-fitting (yoke) retaining nuts, clips, or bolts for any gaps between mating surfaces. If gaps are present, consult transmission, axle or transfer case original equipment manufacturers’ service and maintenance manuals for proper fastener specifications.

INSPECTING UNIVERSAL JOINTS

Visually inspect all universal joint kits in the driveshaft assembly. Make a careful inspection of the caps of the U-joints where they are held captive in the end fittings (yokes). Look to see if the caps are polished or shiny. If they are, it indicates that the cap is spinning in the bore, and the U-joint and attachment hardware will have to be replaced.

There are 3 types of U-joints used in driveshafts:

1. Relubable style
2. Permanently Lubricated Plug Style
3. Permanently Lubricated Net-Formed Style

Each requires slightly different inspection procedures

INSPECTING SLIP MEMBERS

INSPECTING TUBING

Check the driveshaft for bent or dented tubing, cracks, or failed welds. If any of these situations is evident, replacement of the complete driveshaft assembly or tube is necessary.

INSPECTING CENTER BEARINGS

Lubrication

Why?

Lack of proper lubrication is one of the most common causes of universal joint and slip member problems. In all of my experience, (and Jess will back me up on this too) the U-joints most likely to fail are the re greasable kind that haven't been properly lubricated frequently enough.

Proper re lubrication flushes the universal joints, thus removing abrasive contaminants from the bearings. Relubable slip members must also be adequately re lubricated to prevent slip member failure.

When?

First, on installation, regardless of if the joint is re lubable or not. Replacement universal joint kits contain only enough grease to provide needle roller bearing protection during storage. It is therefore necessary to completely lubricate each replacement kit prior to assembly into the yokes.

After initial installation, you can follow either your vehicle manufacturer's recommended intervals, Jess's recommendations, or follow my recommendations, which are:

Severe use (wet, muddy, or high-torque carrying use, extreme low gears (80:1 and lower), large tires(35" and over)) After every off-road trip, 3000 miles, 2 months, or 250 Hrs, whichever comes first

Moderate use (dry conditions, on and off road use) 5000 miles, 3 months, 500 Hrs, whichever comes first

Mild use (mostly street duty - some off-road) 8000 miles, 6 months, whichever comes first

How?

For the Universal Joints:

Note: If your shaft uses permanently sealed (non re lubable U-joints - don't attempt to disassemble them to re-lube them, and DO NOT attempt to use any of those sharp needle attachments designed for piercing seals to inject grease. You will only make things worse, and hasten their demise, as you will ruin the seals. Just leave them in there, and replace the whole thing when it wears out. If you find yourself dissatisfied with their life-span, consider trying the re lubable kind in future.

For the Slip Member:

For the CV assembly (if applicable).

THIS is critical. This is probably the single most neglected grease fitting on a 4x4. Long, smooth driveshaft operation demands proper and frequent lubrication. You wouldn't be too lazy to change the oil in your engine for 50 000 miles, so don't abuse your driveshaft that way either.

Important Note: High Angle Driveline is the ONLY company to offer a true HIGH ANGLE 1350 CV assembly that is re lubable for smooth operation and long-life. the others say it couldn't be done.......but they were WRONG! Jess has worked his magic - and it works, and it still brutally strong - anyone claiming otherwise is fooling themselves. This is reason enough to go to Jess for your driveshafts. Having that CV head assembly wear out prematurely because of improper service and ingress of contaminants (and if you use your 4x4 like I do, you WILL get water and mud and grit and dust in EVERYTHING!) would be a huge pain, and expensive to repair/replace!

With What?

Spicer recommends that the following requirements be met for any lubricant that will be used to service most vehicular, industrial and all auxiliary driveshaft applications.
• Use a good quality E. P. (extreme pressure) grease
• Timkin Test Load - 50 Lbs./23 Kg. minimum
• Meeting N.L.G.I.,* E. P., Grade 2 specifications
• Grease must have an operating range of
+325°F to -10°F (+163°C to -23°C)

*National Lubricating Grease Institute

GREASE COMPATIBILITY*
When greases made from different thickeners are mixed, the mixture may result in lower service performance or physical properties than either of the original component products.
This reduction in lubricant performance is called incompatibility. It may show up in any of several areas, such as:
1. Lower heat resistance;
2. Change in consistency, usually softening; or
3. Decrease in shear stability.
Mixtures which show none of these changes are considered compatible. Incompatibility is not always caused by the thickener, since each of the greases in the mixture is a complete package – thickener, fluid, and additives. Sometimes the thickener of one grease is incompatible with the fluid or the additives present in the second grease. If the mixture proves to be significantly softer, less shear stable, or less heat resistant than the original grease, the mixture shall be deemed incompatible. Incompatibility is best determined in service or in service related tests; it is not predictable. Certain thickener combinations often have been found unsatisfactory and are generally so recognized. These would include lithium and sodium greases and organo-clay and most soap greases. Contact your local lubricant supplier for grease compatibility information. To help reduce the effects of incompatible greases, make sure to thoroughly purge all four bearing seals on each universal joint with the new grease. Purge seals until the fresh grease is visible on the outside of all four bearing seals. It is recommended that all purged grease be wiped clean to prevent discharge into the general environment.

Did I do it right?

Ever wonder if you HAVE to get grease purging from all 4 bearing caps in a U-joint when lubricating it? Ever wonder why? The answer is "yes, you do, because otherwise you cannot be sure all bearings are fully lubricated and all foreign material and water is evacuated due to unequal seal pressures due to tolerance stack up in components." What the heck does that mean? It means, grease the joint until all 4 sealed purge! And if all 4 will not purge - relieve the pressure on the bearing caps that will not, and try again. The procedure is outlined below. If the joint still will not purge from all 4 seals - it must be replaced. See the Spicer Video on Proper U-joint Lubrication for the complete story.

Procedure for releasing universal joint bearing seal tension

Bearing strap / U-bolt style.

After all four bearings purge fresh grease, re-tighten c-clamp to squeeze out excess grease and wipe clean. This will ease installation of universal joint kit back into yoke. Install universal joint in the yoke using new hardware and torque bolts or nuts to the required specifications.

If the bearings still will not purge, complete removal and replacement of the universal joint is required.

Driveshaft Removal

Support the driveshaft with a support strap, if required, at the appropriate location, Attach support straps to frame rails or some structural part of the vehicle.

Remove the bearing retainer bolts and bearing retainers or stamped straps or remove nuts and U-bolts. Stamped straps and stamped strap bolts or bearing retainer bolts CANNOT be reused. Loosening or removing bearing retainer bolts or U-bolts requires replacement of used bolts with new. Do not substitute other hardware – Spicer driveshaft hardware is made from correct alloys and is specially heat treated.

Replacing universal joints in the driveshaft.

Remove driveshaft from vehicle as described above, and set on work bench

Remove joints from shaft

Install new joints in shaft

Note – Spicer Life replacement universal joint kit bearing assemblies contain only enough grease to provide needle roller bearing protection during storage. It is therefore necessary to completely lubricate each bearing assembly. It is also necessary to fully lubricate the universal joint kit after it is installed in the vehicle.

Driveshaft Installation:

Place the driveshaft in place in the vehicle, use supporting straps if required.

Install the bearing retainers or new stamped straps and new bolts Torque the bolts down evenly and to required specifications.

Check to make sure the bearing cup assemblies are fully seated in the yoke ears. Repeat for the axle pinion yoke.

It may be necessary to extend or collapse the slip member assembly to allow clearance to install driveshaft into the axle pinion yoke.

Completely re lubricate all the universal joints and the slip member assembly (if slip member assembly is re lubable) as described in the lubrication section

Part 4 - U-joint tech

Choosing U-joints

When it comes to universal joints of a given size or series, there are 2 decisions to make - which brand to choose, and which style (permanently sealed or re lubable)

The first decision is simple in my opinion. Spicer Life Series no question. I believe they are simply the best. Why? I'll let them explain it (below):

Why should you use Spicer U-joints?

According to Spicer:

Spicer has been the leader in cardan universal joint technology since 1904, when Clarence Spicer patented the first practical application of a universal joint to replace the chain drives of his day. Since that time, we have refined our universal joints with improved forging technology, metallurgical studies, hardening processes and sealing capabilities to ensure greater durability and low maintenance.

Spicer engineers research and implement advanced hot and cold metal forming processes for journal crosses, heat treating methods for case hardening bearing cups, finite element analysis and three-dimensional modeling to understand and control stress points, and perform myriad laboratory and application tests to validate joint performance. We sweat the details so all of our cardan joints provide you with longer, trouble-free service.

There are 2 different models to choose from - the Spicer Time-Tempered™ and the Spicer Life™. Both are described below. As you will see, the only choice for us is the Spicer Life™ series.

Spicer Time-Tempered™ Replacement Cardan Universal Joints*

This OE-acceptable replacement U-joint kit has a hot-forged steel journal cross that is heat treated and through drilled for grease channels. It is equipped with a grease fitting for ease of re lubrication. Journal cross trunnions are hardened for long life, and the faces are grooved to ensure consistent lubrication of the needle roller bearings.

Features include:

Cold-Formed Journal Cross
Cold-formed for increased strength, the journal cross is not through drilled with grease channels, but rather partially drilled to increase strength and retain the appropriate amount of premium, lithium-based grease for maintenance-free operation.
Thermo-Plastic Seal Guard
Helps prevent contamination in the bearing assembly and secures the bearing onto the trunnion of the journal cross.

To lube or not to lube

So the only remaining question is - do I use permanently sealed U-joints or re lubable U-joints (assuming there is a choice in the size/series you are using)

This is not so simple to answer, and has long been the topic of many fierce debates. It may well come down to personal preference, but there are some points to consider.

Most importantly - relubable U-joints MUST BE re lubed. It sounds obvious, but the one thing you do not want to do, is to kid yourself that you will do regular routine maintenance on your driveshaft and U-joints, and the not. And yet, this is exactly what a HUGE number of people do. Avoid it. Be honest with yourself. If you aren;t going to re lube them - use the "permanently" sealed kind, if not, you will experience premature failure.

So, we have to be brutally honest with ourselves, fine. But what if we are the kind that actually would re lube the joints EACH and EVERY time they require it, properly, completely (see Part 3), and without fail (am I making a point here? There aren;t many people who fit into this category). Is there then any reason to prefer on kind over the other? You have to decide for yourself, but some advantages and disadvantages to consider are:

Re-lubable

• (-) They have to be religiously re-lubed, a PITA
• (-) They generally are not as strong, due to the grease channels in the cross
• (-) If you lose or break a grease zerk (not uncommon) the joint is useless (you could just replace it, but it it's been out for a while, way more contaminant will have ingressed into the joint than can even be flushed out by proper lubrication
• (-) Slightly more of a pin to install, as you have to get the grease zerks in the right place and all lined up
• (+) They are generally cheaper
• (+) Depending on environment, they may last longer (if conditions are wet and muddy, the ability to purge the joint and relubricate it, may well extend the life of the joint beyond that of a joint that cannot be relubricated. However, in dry condition, this will likely be much less of a factor.

Sealed

• (-) Depending on environment, may have a reduced service life than a relubable, since nothing is ever really 100% sealed, so that if contaminants do get in, there is no way to flush them out
• (-) More expensive
• (-) A bit more of a PITA to install, as you have to make sure you have sufficient lubricant in the caps before you install the joint, since you cannot add any afterwards.
• (+) Stronger, due to absence of through-cross grease channels
• (+) Less to worry about - don't require any maintenance.

Personally, I choose to run Spicer Life Series permanently sealed (NON-relubable) U-joints in my 1350 CV driveshaft, for the following reason: With my type of rig and the wheeling it does, the fact that it's a trailer queen, sees very little high speed use, sees very little total mileage in a year, and yet must be as strong and reliable as possible - I need to squeak every little bit of strength I can from every component, and things are much more likely to break catastrophically way before their time, rather than wear to due to a lack of lube.

Spicer Life Series Universal Joint Cross-Over Index:

Causes, Analysis, and remedies for Driveshaft failure

Causes and remedies of driveshaft vibration include:

• Improper universal joint operating angles / improper driveshaft geometry
  • Measure and set proper geometry (see Part 2)
• Too extreme universal joint operating angles
  • Switch to higher angle capable U-joint series or CV joint
  • Reduce operating angles (usual. by reducing suspension height)
• Poor balance of driveshaft assembly
  • Have driveshaft professionally balanced
• Driveshaft balance weights damaged or missing
  • Have driveshaft professionally balanced
• Worn-out / improperly lubricated U-joints
  • Inspect, lubricate, replace U-joints as required
• Worn tail-cone / slip yoke or slip member
  • Inspect and replace worn components as required
• Bent, dented, fractured tubing
  • Inspect and repair/replace as required

Driveshaft Failure analysis Guide

Yokes
Universal Joints
Tubing