Spicer Driveline User Manual

DRIVELINE INSTALLATION

J3311-1-DSSP AUGUST 2008

Supersedes J3311-1-HVTSS, Dated February 2005

Safety Precautions

General Safety Information

To prevent injury to yourself and /or damage to the equipment:

• Read carefully all owners manuals, service manuals, and/or other instructions.

• Always follow proper procedures and use proper tools and safety equipment.

• Be sure to receive proper training.

WARNING: GUARDING AUXILIARY DRIVESHAFTS

We strongly recommend that a power take-off and a directly mounted pump be used to eliminate the auxiliary driveshaft whenever possible. If an auxiliary driveshaft is used and remains exposed after installation, it is the responsibility of the vehicle designer and PTO installer to install a guard.

• Never work alone while under a vehicle or while repairing or maintaining equipment.

• Always use proper components in applications for which they are approved.

• Be sure to assemble components properly.

• Never use worn-out or damaged components.

• Always block any raised or moving device that may injure a person working on or under a vehicle.

• Never operate the controls of the power take-off or other driven equipment from any position that could result in getting caught in the moving machinery.

WARNING: USING SET SCREWS

Auxiliary driveshafts may be installed with either recessed or protruding set screws. If you choose a square head set screw, you should be aware that it will protrude above the hub of the yoke and may be a point where clothes, skin, hair, hands, etc. could be snagged. A socket head set screw, which may not protrude above the hub of the yoke, does not permit the same amount of torquing as does a square head set screw. Also a square head set screw, if used with a lock wire, will prevent loosening of the screw caused by vibration. Regardless of the choice made with respect to a set screw, an exposed rotating auxiliary driveshaft must be guarded.

WARNING: THIS SYMBOL WARNS OF POSSIBLE PERSONAL INJURY.

WARNING: ROTATING DRIVESHAFTS

• Rotating auxiliary driveshafts are dangerous. You can snag clothes, skin, hair, hands, etc. This can cause serious injury or death.

• Do not go under the vehicle when the engine is running.

• Do not work on or near an exposed shaft when engine is running.

• Shut off engine before working on power take-off or driven equipment.

• Exposed rotating driveshafts must be guarded.

Table of Contents

Introduction .............................................................................................................................................................. 1

Driveshaft Torque ...................................................................................................................................................... 2

Common Causes of Vibrations .................................................................................................................................. 3

Universal Joint Operating Angles .............................................................................................................................. 5

Eliminating Compound Angle Induced Vibrations ..................................................................................................... 11

Multiple Shaft Installations ........................................................................................................................................ 13

Mounting a Midship-Mounted PTO, Pump, or Auxiliary Transmission ...................................................................... 16

Maximum Safe Operating Speed ............................................................................................................................... 18

Table of Contents

General Information

Introduction

This brochure is intended for:

• Installers who install Spicer driveshafts into an application where the transmission and axle are not in direct line with each other, causing the driveshaft universal joints to operate at an angle.

• Anyone experiencing vibration problems with their application or their vehicle that driveshaft assembly balancing will not correct.

• Truck Equipment Distributors who:

• Re-work a chassis to change the wheel base.

• Install a midship mounted power take-off or fire pump.

• Mount any other PTO-driven device such as a blower, hydraulic pump, or hydraulic motor.

Universal joint failures, as a rule, are of a progressive nature, which, when they occur, generally accelerate rapidly resulting in a mass of melted trunnions and bearings.

Some recognizable signs of universal joint deterioration are:

1. Vibrations - Driver should report to maintenance.

2. Universal joint looseness - End play across bearings.

3. Universal joint discoloration due to excessive heat build-up.

4. Inability to purge all four trunnion seals when re-lubing universal joint.

Items 2) thru 4) should be checked at re-lube cycle and, if detected, reported to the maintenance supervisor for investigation.

Experience with universal joint failures has shown that a significant majority are related to lubricating film breakdown. This may be caused by a lack of lubricant, inadequate lube quality for the application, inadequate initial lubrication, or failure to lubricate properly and often enough.

Failures which are not the result of lubrication film breakdown are associated with the installation, angles and speeds, and manufacturing discrepancies.

Driveshaft failures through torque, fatigue, and bending are associated with overload, excessively high universal joint angles, and drive shaft lengths excessive for operating speeds.

Installation Techniques

Driveshaft Torque

The following problems are usually a result of torque overloads:

Twisted driveshaft tube

Broken yoke shaft, slip yoke, tube yoke, flange yoke, end yoke

Broken journal cross

How much torque can be generated in your application?

Engine

Trans.

Axle

How to Calculate Torque:

LGT = T x TLGR x TE x SR x TCR x C

LGT = Maximum Driveshaft Low Gear Torque SR = Torque Converter Stall Ratio (if applicable)

T = Net Engine Torque or 95% of the Gross Engine Torque TCR = Transfer Case Ratio (if applicable)

TLGR = Transmission Low Gear Ratio (forward)* C = Transfer Case Efficiency (if applicable, 0.95)

TE = Transmission Efficiency (automatic = 0.8; manual = 0.85)

How to Calculate Wheel Slip:

WST = (.71 x W x RR) / (11.4 x AR)

WST = Wheel Slip Torque Applied to the Driveshaft RR = Tire Rolling Radius (in)

W = Axle Capacity (lbs) AR = Axle Ratio

For On Road Applications

Relate the lesser of above to Spicer universal joint ratings. If your torque exceeds the Spicer rating for the universal joint used in your application, switch to a size with a rating compatible to your calculation. However, the series selected cannot be more than one series below the series called for by the LGT calculation.

Driveshaft Torque

For Off Road or On-Off Road Applications

Use Low Gear Torque value only to verify or switch to a size with a rating compatible to your calculation.

Installation Techniques

Common Causes of Vibrations

The three most common causes of driveshaft vibration are: Driveshaft Imbalance, Critical Speed, and Universal Joint Operating Angles.

Driveshaft Imbalance

Eliminate the potential for balance problems before you undertake any other measures.

A driveshaft on a vehicle usually rotates at a higher rate of speed than the tire. For that reason, like tires, driveshafts should be balanced.

Any time you build or rework a driveshaft, make sure it is dynamically balanced at, 3000 RPM for Light Duty or 2500 RPM for Heavy Duty, to the following specifications:

Series Specification

1310, 1330 .375 oz-in total at each end of shaft *

1350, 1410 .500 oz-in total at each end of shaft *

1480 - 1880 1.00 oz-in for each ten pounds of driveshaft weight divided proportionally at each end of shaft

* Passenger Car, Light Truck, Van, and SUV only. Industrial, Mobile Off-Highway, PTO, etc. same as 1480 - 1880.

Critical Speed

Every driveshaft has a critical speed. Critical speed is the point at which a rotating driveshaft begins to bow off its normal rotating centerline.

Driveshafts begin to vibrate as they approach critical speed. If they are operated at near critical speed for an extended period, they often fail. This can damage the vehicle and possibly injure persons nearby.

As a driveshaft fabricator or installer, you are responsible for checking the safe operating speed of any driveshaft you fabricate or specify into an application. Make sure it will not operate at a speed higher than Spicer’s recommended safe operating speed. Use Spicer Calculator (P/N J 3253) to determine safe operating speed.

Checking for a Possible Critical Speed Problem

Here is what you must do to make sure you won’t have a critical speed problem:

• Determine the safe operating speed of the driveshaft you want to use in your application. Insert the tube diameter and center-to-center installed length of the shaft you want to use into a Spicer Safe Operating Speed Calculator (P/N. J3253). The calculator will tell you the safe operating speed of the shaft you have chosen.

• Determine the NORMAL and MAXIMUM POSSIBLE operating speed of the driveshaft. REMEMBER:

• On vehicles with a standard transmission that have a 1:1 direct drive high gear and no overdrive, MAXIMUM POS-

SIBLE driveshaft RPM is the same as the maximum possible ENGINE RPM.

• On vehicles that have an overdrive transmission, MAXIMUM POSSIBLE driveshaft RPM is higher than maximum

possible ENGINE RPM.

Installation Techniques

Maximum Possible Driveshaft RPM

To calculate the maximum possible driveshaft RPM in vehicles having an overdrive transmission, divide the maximum possible engine RPM by the overdrive ratio. (See examples below.)

Example 1:

Max. engine RPM: 2100

Overdrive ratio: .79

2100/.79 = 2658 maximum possible driveshaft RPM

Example 2:

Max. engine RPM 6000

Overdrive ratio: .66

6000/.66 - 9091 maximum possible driveshaft RPM

Compare the maximum possible driveshaft RPM with the safe operating speed determined from the Safe Operating Speed Calculator. If the maximum possible driveshaft RPM meets or exceeds the safe operating speed determined from the calculator, you must do whatever is required to raise the critical speed of the driveshaft you have chosen for the application.

Common Causes of

Sample Specification:

To specify a driveshaft for the application described in Example 1 above, compare the safe operating speed for the driveshaft selected with the maximum possible driveshaft RPM calculated (2658 RPM). Make sure the safe operating speed of the driveshaft is greater than 2658 RPM.

Changing the Safe Operating Speed of a Driveshaft

A driveshaft’s safe operating speed can be raised by increasing its tube diameter or by shortening the installed center-to-center length of the driveshaft. Changing the installed length of a driveshaft will require the use of multiple driveshafts with center bearings.

Important: The critical speed of an assembly can be affected by driveshaft imbalance, improper universal joint operating angles, or improperly phased driveshafts. (A properly phased driveshaft has the in-board yokes of the shaft in line with each other.) Each of the above items will tend to lower the true critical speed from the values shown on the calculator.

Since critical speed can ultimately cause driveshaft failure, it is extremely important to be very precise in all applications.

Vibration

Installation Techniques

Universal Joint Operating Angles

Every Universal Joint that Operates at an Angle Creates a Vibration

Universal joint operating angles are probably the most common causes of driveline vibration in vehicles that have been reworked, or in vehicles that have had auxiliary equipment installed.

Universal joint operating angles are a primary source of problems contributing to:

•Vibrations

• Reduced universal joint life

• Problems with other drivetrain components that may include:

- Transmission gear failures

- Synchronizer failures

- Differential problems

- Premature seal failures in axles, transmissions, pumps, or blowers

- Premature failure of gears, seals, and shafts in Power Take-Offs

When you rework a chassis or install a new driveshaft in a vehicle, make sure that you follow the basic rules that apply to universal joint operating angles:

RULE 1: UNIVERSAL JOINT OPERATING ANGLES AT EACH END OF A DRIVESHAFT SHOULD ALWAYS BE AT LEAST 1 DEGREE.

RULE 2: UNIVERSAL JOINT OPERATING ANGLES ON EACH END OF A DRIVESHAFT SHOULD ALWAYS BE EQUAL WITHIN 1 DE-

GREE OF EACH OTHER (ONE HALF DEGREE FOR MOTOR HOMES AND SHAFTS IN FRONT OF TRANSFER CASE OR AUXILIARY DEVICE).

RULE 3: FOR VIRTUAL VIBRATION FREE PERFORMANCE, UNIVERSAL JOINT OPERATING ANGLES SHOULD NOT BE LARGER THAN 3 DEGREES. IF THEY ARE, MAKE SURE THEY DO NOT EXCEED THE MAXIMUM RECOMMENDED ANGLES.

A universal joint operating angle is the angle that occurs at each end of a driveshaft when the output shaft of the transmission and driveshaft and the input shaft of the axle and driveshaft are not in line. (See Fig 1)

The connecting driveshaft operates with an angle at each universal joint. It is that angle that creates a vibration.

Engine

Trans.

Axle

Figure 1

per

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