A new strut or shock is only as good as the parts attached to it. These "required" components (notice I did not say add-ons) should be sold as part of any shock or strut replacement.
Upper Bearing Plate
One mistake to avoid when replacing struts is reusing the original bearing plates. It’s like rebuilding an engine with a new crankshaft and reusing the old bearings. Replace the old bearing plates with new ones, or install preassembled struts that come with new bearing plates. The preassembled struts are faster and easier to install than bare struts, and they reduce the risk of comebacks.
Struts may also need to be replaced if the upper strut bearing plate has been hammered to death. The bearing plate serves as both the upper spring support and the steering pivot. The bearings in the plate are sealed assemblies and cannot be lubricated. So if the bearing plate is rusted, loose, worn, noisy, binding or damaged, it has to be replaced.
The symptoms of a bad bearing plate include:
Steering noise such as snapping, popping, creaking or groaning sounds when turning;
Suspension noise such as clunking, rattling or popping on rough roads;
Increased steering effort (most noticeable with manual steering) brought on by binding in the bearing plate;
Steering snap back after turning caused by a frozen upper strut bearing assembly and spring wind up; and
“Memory steer” or poor steering return where the car doesn’t want to go straight after turning due to binding in the upper mount.
Bump stops that fit on the rod of a strut should always be transferred from the old assembly or replaced with new parts. This is cheap insurance against damaging the new unit if it bottoms out. Even if the old strut does not have one, check the parts catalog for a replacement.
If a strut or shock bottoms out, it can damage the valves in the piston or at the bottom of the bore.
The boot on a shock or strut is critical to the outside and inside of the unit. When a stone hits the chrome shaft of a shock or strut, it will first cause a pit or scratch. This might cause damage to the seal, which might cause a loss of fluid. If the damaged area starts to corrode, it could cause the shaft to lose even more chrome.
The seal at the top of the body is the barrier between the harsh environment outside and the fluid and gas within the unit. The seal can not be effective if the surface of the shaft is pitted or damaged. Poor sealing surfaces can cause the unit to leak. If the pitting or lost chrome plating is large enough, it can damage the seal. This can lead to water and debris getting into the unit and damaging the valves and piston seal. To protect the seal, it is essential to replace the boots. If any of these items are missing, it could cause the premature failure of the new unit.
When a strut is removed, now is the time to replace and cam bolts to adjust the camber angle. Failure to sell these up front could lead to a second phone call to the customer to get approval. It could also tie up the alignment bay while you are waiting for the parts and the time it takes to install them.
An air compressor that is not operating correctly could have leaky or obstructed air lines, faulty compressor or spring solenoids. Diagnosis is made via the self-test and visual inspection. A bad compressor or solenoid must be replaced, but damaged air lines can be repaired by splicing.
One of the leading causes of compressor failure is air leaks (usually in the air springs or lines). If the compressor is constantly running, it’s going to work itself to an early death.
It is very important to ensure that the source of air for the compressor is clean and as dry as possible. When air is compressed, the water vapor contained in the air is condensed into a liquid. If there is no means of removing the water from the system, it will find its way to all parts of the system, causing corrosion damage or freezing.
Most systems have a dryer that is connected to the compressor outlet to absorb the water entering the system. The dryer contains a moisture-absorbing desiccant such as silica gel. The desiccant can hold a given amount of water and once it is saturated, it will allow water to pass into the system.
The dryers that are installed on most systems do not have an indicator that will show when it is saturated and no longer able to absorb water. An additional dryer with a moisture indicator can be added to the original equipment dryer. It can be installed in the supply line and placed in a position where a periodic check can be made.
Toyota Camry 2001-2011
If you are replacing the rear struts, pay special attention to the upper strut mounts and replace the spring insulators. If you do not take care to insulate the upper strut mount from the body, the customer may come back complaining of a ticking noise in the rear. The solution recommended by Toyota is to apply foam tape to the three surfaces of the strut mount.
Ford Escape 2001-2010
If you are installing front struts on a Escape, you might want to add the cost of camber adjusting bolts into the estimate. Ford has a limited amount of adjustment built into the upper strut mounts. The upper strut mount has three different positions that can change the camber and caster by ±.39º from the baseline.
If just a camber correction is necessary, it is easier to replace the upper strut-to-knuckle mounting bolts with cam bolts. These bolts can change camber by ±1.75º without altering the caster.
Jeep Patriot 2007-2011
The Jeep Patriot is a net-build vehicle. If you replace the struts, it may alter the camber and caster angles. Front camber and caster settings on this vehicle are determined at the time the vehicle is designed by the location of the vehicle’s suspension cradle. The result is no adjustment of camber and caster after the vehicle is built or when servicing the suspension components.
Chrysler recommends shifting the cradle to adjust the camber and caster. Camber is adjustable with a lower bolt kit for the strut. The kit will only give ±1º of camber. Aftermarket camber adjustment bolts are also available from various manufacturers. The camber adjustment bolt package contains new bolts and nuts for attaching the strut clevis bracket to the steering knuckle. The bolts contained in the package are slightly undersized allowing for movement between the strut clevis bracket and the steering knuckle.
Honda Pilot 2003-2008
The independent rear suspension on the Pilot will gain significant camber and toe if it is overloaded. These altered angles can lead to tire wear on the inside edge. Even loads like batting equipment for a little league baseball team can cause some sagging. One option is to replace the springs when the shocks are replaced.
Aftermarket rear spring airbag kits are available for the rear springs that can increase load-carrying capabilities between 500-750 lbs while improving rear tire wear. Prices for the airbags start around $100 and can go up from there depending on how the bags are inflated.