Smoother Roads Ahead

| August 02, 2001

When ride and handling start to suffer on your truck, chances are good that the problem can be traced to the suspension. Without routine maintenance, the long, hard miles take their toll on suspension parts. Nuts loosen and back off, spring components develop cracks and break, and friction causes excessive wear on unlubricated moving parts.

Suspension problems are the second most common defects cited by roadside inspectors after brakes. Signs of misaligned, shifted, cracked or missing springs; loose or missing shackles and bolts; spring hangers unsecured at the frame; and cracked or loose U-bolts can put your truck out of service in an inspection.

First rule of suspension maintenance: Keep the nuts tight. Clamps, brackets and U-bolts holding the suspension together stretch over time, allowing the nuts to loosen. On new equipment, fasteners should be retightened within the first 1,000 miles. They should be checked again at 10,000- to 15,000-mile intervals and retorqued to the manufacturer’s specifications every 100,000 miles.

Don’t rely on a roadside inspector’s report to learn about the condition of your truck’s suspension. It’s better to get underneath yourself on a regular basis to inspect the springs, shackles, U-bolts, shock absorbers, torque rods, air bags and other parts that wear and fail over time. While you’re at it, take a grease gun and torque wrench with you. A little effort can save you lots of trouble.

Suspension manufacturers have reduced the amount of maintenance required on their products over the years, but the basic types remain the same: multi-leaf or parabolic taper leaf springs on the front and four-spring, walking beam, multi-spring and air-ride on the rears. Air suspension, the most popular, requires little maintenance except when air lines and air bags develop leaks through punctures or chafing against other parts.

Importance of Lube Job
Keep metal suspension components well lubed to prolong their life and help ensure that your suspension operates at peak performance. Hit every zerk fitting with a grease gun as well as other parts that wear against each other according to the manufacturer’s guidelines. Bronze bushings should be lubricated, but rubber bushings should not, since lubricants can damage them. Keep lubricants away from rubber blocks and other rubber suspension components, too.

Pins and bushings that secure front springs are especially critical and should be lubricated roughly every 15,000 miles for over-the-road equipment. Proper lubrication minimizes friction that can wear out bushings prematurely and damage springs. When replacing bushings, they must be torqued to the manufacturer’s specifications to avoid crushing them by over-torquing. Under-torquing is no good, either. That allows the bushings to move and wear faster than normal.

Hendrickson Truck Suspension Systems offers extended-wear Laser Lube front spring eye bushings. They are designed to solve the three major problems with front bushings: lack of lubrication, contamination by dirt and moisture, and distortion of the bushing’s shape. The bushings are impregnated with graphite for continuous lubrication. Urethane seals at each end prevent contaminants from entering, and a laser-welded seam provides improved dimensional stability.

Horton’s Roller Bushings are designed to provide a smoother ride and improved handling for heavy-duty front suspensions. Dozens of tiny needle bearings create unique grease grooves for maximum lubrication and minimum maintenance, the company says. A ribbed surface makes installing the bushing easier. Horton sells a heavy-duty pin-and-bushing tool for removing and installing Roller Bushings. It also works with standard pins and bushings.

Bronze bushings, used mainly for extra heavy-duty service, have a single zerk fitting. Ball indented bushings in the spring eyes of the Hendrickson RT2 Series have lubrication channels. To properly lube them, the rear of the vehicle should be lifted to relieve the load on the bushings; then, grease should be forced into the channels until it comes out the other end. Severe service applications require more frequent lubrication.

On walking beam suspensions with spring packs, a pair of zerk fittings on the hangers at the spring pins facilitate the job of lubing. The hangers should be closely checked for cracks and excessive rust, signs that they should be replaced. As a general rule, when working on suspensions, do not reuse U-bolts, bolts and huckbolts after removing them. New fasteners – Grade 8 nuts and Grade C U-bolts – should be used.

Hendrickson advises that springs with one or more leaves broken below the No. 2 leaf should be replaced with a new spring assembly of the same part number. The number is stamped on the spring clips. Springs on both sides should be replaced at the same time for even spring deflection.

Smoother Roads Ahead

| August 02, 2001

When ride and handling start to suffer on your truck, chances are good that the problem can be traced to the suspension. Without routine maintenance, the long, hard miles take their toll on suspension parts. Nuts loosen and back off, spring components develop cracks and break, and friction causes excessive wear on unlubricated moving parts.

Suspension problems are the second most common defects cited by roadside inspectors after brakes. Signs of misaligned, shifted, cracked or missing springs; loose or missing shackles and bolts; spring hangers unsecured at the frame; and cracked or loose U-bolts can put your truck out of service in an inspection.

First rule of suspension maintenance: Keep the nuts tight. Clamps, brackets and U-bolts holding the suspension together stretch over time, allowing the nuts to loosen. On new equipment, fasteners should be retightened within the first 1,000 miles. They should be checked again at 10,000- to 15,000-mile intervals and retorqued to the manufacturer’s specifications every 100,000 miles.

Don’t rely on a roadside inspector’s report to learn about the condition of your truck’s suspension. It’s better to get underneath yourself on a regular basis to inspect the springs, shackles, U-bolts, shock absorbers, torque rods, air bags and other parts that wear and fail over time. While you’re at it, take a grease gun and torque wrench with you. A little effort can save you lots of trouble.

Suspension manufacturers have reduced the amount of maintenance required on their products over the years, but the basic types remain the same: multi-leaf or parabolic taper leaf springs on the front and four-spring, walking beam, multi-spring and air-ride on the rears. Air suspension, the most popular, requires little maintenance except when air lines and air bags develop leaks through punctures or chafing against other parts.

Importance of Lube Job
Keep metal suspension components well lubed to prolong their life and help ensure that your suspension operates at peak performance. Hit every zerk fitting with a grease gun as well as other parts that wear against each other according to the manufacturer’s guidelines. Bronze bushings should be lubricated, but rubber bushings should not, since lubricants can damage them. Keep lubricants away from rubber blocks and other rubber suspension components, too.

Pins and bushings that secure front springs are especially critical and should be lubricated roughly every 15,000 miles for over-the-road equipment. Proper lubrication minimizes friction that can wear out bushings prematurely and damage springs. When replacing bushings, they must be torqued to the manufacturer’s specifications to avoid crushing them by over-torquing. Under-torquing is no good, either. That allows the bushings to move and wear faster than normal.

Hendrickson Truck Suspension Systems offers extended-wear Laser Lube front spring eye bushings. They are designed to solve the three major problems with front bushings: lack of lubrication, contamination by dirt and moisture, and distortion of the bushing’s shape. The bushings are impregnated with graphite for continuous lubrication. Urethane seals at each end prevent contaminants from entering, and a laser-welded seam provides improved dimensional stability.

Horton’s Roller Bushings are designed to provide a smoother ride and improved handling for heavy-duty front suspensions. Dozens of tiny needle bearings create unique grease grooves for maximum lubrication and minimum maintenance, the company says. A ribbed surface makes installing the bushing easier. Horton sells a heavy-duty pin-and-bushing tool for removing and installing Roller Bushings. It also works with standard pins and bushings.

Bronze bushings, used mainly for extra heavy-duty service, have a single zerk fitting. Ball indented bushings in the spring eyes of the Hendrickson RT2 Series have lubrication channels. To properly lube them, the rear of the vehicle should be lifted to relieve the load on the bushings; then, grease should be forced into the channels until it comes out the other end. Severe service applications require more frequent lubrication.

On walking beam suspensions with spring packs, a pair of zerk fittings on the hangers at the spring pins facilitate the job of lubing. The hangers should be closely checked for cracks and excessive rust, signs that they should be replaced. As a general rule, when working on suspensions, do not reuse U-bolts, bolts and huckbolts after removing them. New fasteners – Grade 8 nuts and Grade C U-bolts – should be used.

Hendrickson advises that springs with one or more leaves broken below the No. 2 leaf should be replaced with a new spring assembly of the same part number. The number is stamped on the spring clips. Springs on both sides should be replaced at the same time for even spring deflection.

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