Crown Victoria Rear Shock Absorber Replacement Notes

The passenger rear shock absorber on this vehicle was severly worn. The casing of the shock was covered in oil indicating the seals had failed. And when the vehicle was driven on the road, the passenger rear side of the vehicle seemed to oscillate uncontrollably somewhere the natural frequency of the suspension spring. Replacing the deceased rear shock absorbers on this vehicle would have numerous safety and handling benefits. But this was much easier said than done due to corrosion and limited access to the top nut which retained the shock absorber to the vehicle's frame.

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First, the vehicle is raised and supported with a pair of jackstands under the frame and a jack placed under center of the rear axle assembly.



The top nut was hopelessly seized and wouldn't turn with a wrench.



So a different tool was used



With some really long blades



There's was still a little metal left retaining the top nut and washer to the shock to remove.



The shock absorber was still being stubborn and wouldn't come out after most of the material retaining the shock to the vehicle's frame has been removed. So the rearend was raised to it's upwards travel limit and then slammed down on each side by quickly releasing hydraulic pressure from the jack. The slide hammer effect of the spring finally broke the top of the shock free. And the vehicle did not fall off the jackstands, break the brake hoses, or have the springs fly out in the process either. Leaving one shock absorber connected between the rearend assembly and the frame at all times increased the safety of this procedure to some extent, but there was still a risk of the spring becoming unseated and causing personal injury or property damage.

The bottom nut of the shock was really easy to remove since personnel of the local sears service center had just had it off a few days ago.







Now that the old shocks were off, it was time to install the new ones. The gabriel ultras below were sourced from the local autozone for around fifty dollars a pair. Too bad a few hundred dollars worth of tools was required to install them.



The passenger rear shock was relatively straight forward to install onto this 1997 crown vic with a set of ratcheting flexhead gear wrenches. But maneuvering the gear wrench around the shock absorber stud on the drivers side which was located only a fraction of any inch from the fuel lines was difficult. Fortunetly, the 1998-2002 crown vics are easier to install the drivers shock on due to the fuel lines being relocated to the passenger side and taking a different route near the shock stud.



The drivers rear shock absorber required inserting the rubber insulator with a pair of needle nose pliers. Really long needle nose pliers likely would have more practical than the locking ones pictured.



That shinny new black tube is the shock absorber.

The yellowish glow on the rear brake rotor is from a 500 watt halogen work light. Even if you are working outside in bright sunlight during the daylight hours, it will still likely be useful to have an assistant illuminate the area in between the frame and body with such a light. It is really dark in there and accidentally cutting the fuel or brake lines will greatly complicate replacing the rear shocks.



Raising the rearend a little will preload the rubber bushing and hold the shock absorber center stud stationary so that the nut can be installed onto it.


Some points to consider here:

• The upper nut that retained the shock absorber to the vehicles frame was severly corroded, and would not turn. This was due in a large part to the fact that the vehicle had been driven through multiple "new england" winters. And many of the miles were "highway" in which the entire underside of the car was in contact with an aerosol mist of chloride salts used to clear the roads of snow and ice.
  
• Besides the top nut being corroded, the bottom casting of the shock absorber also exhibited deep pitting which indicated that it had been installed for a few years. The top dust tube was not corroded because it is constructed of plastic.
• The top studs and nuts on the rear shocks were less corroded than the front shocks likely due to them being in more protected enviroment and subject to less road splash than the front shocks. But access to the area where the studs and nuts for the rear shocks pass through the frame is very limited.
  
• At the factory, the rear shock absorbers on 1979-2002 crown vics are installed prior to placing the body on the frame.
• Some people have reported success jacking the vehicle's body off the frame in the rear a couple inches for shock absorber replacement. This solution may create other problems such as broken body mount bolts, broken body mount brackets, bent body panels and damaged wiring harnesses though.
• Some have also reported success cutting holes in the sheetmetal of their trunk floor. But locating where to cut the holes can be difficult. And one will also have to patch the holes after they are cut. There is also a possibility of damaging the fuel tank and other underchassis components.
• Instead of cutting the shock absorber nut off from in between the frame and the body, it is also possible to access the shock absorber stud from underneath the frame if the suspension spring is first removed. This method of removal is not covered here though.
• The top stud and nut of the shock is located only inches from the fuel tank. Use of an acetylene cutting torch near the fuel tank is extremely dangerous and is likely to result in severe personal injury or death.
• Use of an acetylene torch to cut the shock stud from underneath the frame is also very dangerous. Significant amounts of heat will be transfered to the area in between the frame and body of the car in the cutting process. And the rubber frame insulators may also catch fire.
  
• Many of automotive service centers in this area are already wise to the difficulty of removing the crown vic rear shocks and will have dozens of different bogus excuses to keep your car out of their shop.
• Many of the shops in this area that haven't dealt with these vehicles previously seem likely to get the car "up on the lift" and then not be able to get the top nut off the shock.
• It should be noted here that sometimes the top nut comes off by turning the dust tube and holding the top nut with a wrench, but sometimes it's hopelessly seized in place.
• A sawzall with a long 12" bimetal blade will cut through the stud and release the shock from the frame with some persistence. On the pre-1998 crown vics, the fuel lines are located on the drivers side of the vehicle and run extremely close to the top shock absorber nut. Be very careful not to damage them. On the 1998-2002 crown vics, the fuel lines are located on the passenger side.
• If the shock absorber is corroded, then the rest of the vehicle likely has some corrosion present too. The fuel lines on 95+ crown vics are constructed of high grade stainless steel that will not corrode like the steel ones used on 1994 and eariler vehicles. But fuel tank and other fuel system components are constructed of sheetmetal and will corrode rapidly if their protective coating has been damaged. There are also plastic and rubber seals in the fuel system that will fail with old age.
  
• An air chisel does not appear to be effective at cutting off the nut on the top of the frame. Nor does there appear to be sufficent space to fit a "nut cracker" in there.
  
• The rear end on the pre-1998 crown vics will drop really low after the shock absorbers are removed with the limiting factors being mainly the rear sway bar and the twisting action of the rubber bushings in the control arms. On the 1998 and later crown vics, the watts rear linkage appears to limit downwards travel to some extent. But one should always place a wide high capacity floor jack under the rear as a safety precaution.
• The stud and nuts which retain the shock absorber to the rear axle can also be stubborn, but impact tools will likely get these free. If they are really corroded, they may have to be "cut off" though.
• The small rotary tool pictured above is intended for light hobby use and appears to have been been irrepairably damaged by grinding off shock absorber studs. It's motor refused to spin shortly after this project was completed.
• Additionally, keep in mind that the high speed rotary tool will generate sparks which could ignite gasoline fumes. The risk with this tool is much lower than with an acetylene torch, but is still present. A high speed fan or outside wind will increase air circulation and decrease the risk of this complication.
  
• Metric flexhead gear wrenches were invaluable for this project due to the limited range of motion when tightening the top nut.
• 2003 and later crown vics have a slightly redesigned rear suspension with the shock absorbers located outside the frame rails. This makes rear shock replacement considerably easier on these vehicles.

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