Load Levelling Suspension Repair
by Jason Hochstein
I own a 1993 Chrysler New Yorker (Fifth Ave) that has load leveling suspension in the rear. Recently, these shocks went out and needed replacement, BAD. Well, I called around and was told that there are no aftermarket solutions for these shocks. I then called a few dealers and was told that the right and left shocks would cost about $490 and $280 respectively. The difference is because the right shock houses the sensor. I had bought my car for $3000 and wasn't about to spend 25% of the car's worth on two shocks. So I began to sort out my options.
1. I could fork out the dough for the Chrysler shocks. ($$$)
2. I could put on normal shocks. (Non load leveling so the car squats)
3. I could use air shocks and manually pump. (Inconvenient)
I decided I would use the air shocks but would attempt to make a sensor so I could still use the car's pump to automatically level the car. I've seen those cars on the road many times that look like they're almost bottomed out in the rear and I didn't want that. If I couldn't get my sensor to work, I figured I could always just pump them up with an air hose or even better, connect the airline to the car's pump and use a toggle switch under the dash to manually trigger the pump and release valve.
I made the sensor and so far it has run flawlessly for over 2000 miles:
IMPORTANT!!: PROCEED AT YOUR OWN RISK!!
You'll need to have some shop skills to do this. It entails cutting, drilling, and welding. Be sure to read through this and look at the illustrations before and during.
Step 1: Using a jack or the car's pump, bring the car to level and measure the ride height of the car from a reference point on the body to a reference point on the axle. Measure close to the passenger side of the car since that is where the sensor is. Remove the passenger shock. Be careful with the air hose coming from the pump. We will be reusing this hose.
Step 2: Extend the shock 2"-3" from fully compressed. Carefully cut off the bulge area of the shock where the sensor is contained. You're not going to use this shock again so make sure the cut is wide enough so as not to cut the sensor inside. There is a magnet inside that you don't want to damage as you cut around the bulge.
Step 3: Once you have removed the bulge with the reed switch, remove the magnet from the shock. Note its position and orientation to the reed switch. Now reconnect the electrical plug to the car and turn the key on. Move the magnet from the bottom of the switch to the top slowly and stop at the top. After the built in delay, (~18 sec) the pump should kick in. With the pump on slowly move the magnet down until the pump quits. Mark this position on the side of the reed switch. Move down in small increments, pausing each time for the built in delay, until you hear the relief solenoid click. Mark this position. Move back up in the same fashion and mark the switch again where the pump turns back on. Turn key off and disconnect the switch.
Step 4: Disassemble the electrical plug of the reed switch taking special note of the placement of each wire. Now you can remove the reed switch from the bulge by removing the nut that holds it in place.
Step 5: You can now remove the magnet's bracket so you don't have to manufacture that part later. To get it out without destroying it I ended up cutting the shock open more.
Step 6: Take a piece of 1.5" schedule 40 PVC pipe and cut to 8.25" long. Mark a straight line down its side to keep drilled holes in line. Mark the line 1.5" down from one end and drill a hole there just big enough for the reed switch's stud to go through. That end will be referred to as the top. Make 2 more marks at 6.25" and 7.75" from the top and drill .25" holes there.
Step 7: Take a piece of 1/8" thick flat iron, 1.25" wide and 4.75" long. Bend it into an 'L' shape (90 degrees) about 3" from one end. This bracket should fit snugly on the bottom of the cylinder with the long end going inside along the wall. Put 'L' bracket in place and mark the holes for mounting and for the ram. The ram should have a 29/64" hole in the other side of the 'L' positioned closer to the side of the cylinder opposing the line you drew and about 1/8" to 1/4" away from the inside wall. Using quarter-inch bolts, attach the 'L' bracket with the burrs on the outside. (You may opt to cut the bolts to length but beware of heat melting the pipe.)
Step 8: Take a piece of 7/16" rod (I used an electric fence post) and cut it to 14 1/2" long. This is the ram. Smooth it nicely all around (ends included) with sand paper or emery cloth so that it slides nicely and doesn't wear quickly. On one end, weld the bracket removed from the shock that held the magnet.
Step 9: Mount the reed switch inside the cylinder. You may have to put the nut on backwards to get enough threads to hold it good. I actually found a nut in the bolt bin that did the trick nicely. (You may opt to take the switch to a hardware store and get a new nut as well) Then slide the ram into the cylinder and mark the triggering positions that you marked on the reed switch on the ram where it comes out of the bottom of the 'L' bracket. Use a metal pen or permanent marker. These marks need to be visible and not easily smudged.
Step 10: Extend the ram out fully and weld 2 ears on the bottom for mounting to the chassis. The holes should be 3/8" diameter and about 1/2" away from the end of the rod to allow free movement. Make sure they are perpendicular to the magnet holder and that the holes are aligned. Cool the rod so as not to transfer heat from welding into the 'L' bracket and ultimately melt the cylinder. Mount the magnet.
Step 11: Drill a 3/8" hole in the pivoting arm about 4" ahead of the shocks mounting hole and just low enough to keep enough meat to hold the ram good. (I drilled mine at a slight angle so I didn't have to remove the hub. Be careful! You don't want a lot of play.)
Step 12: Using some more of that flat iron used in the 'L' bracket, make a low profile 'I' bracket. (See illustration below) Drill 1/4" holes in the corners for bolting to the fender wall. (Mine was about 6 3/4" long and 4" wide)
Step 13: Using 2 hose clamps, attach cylinder to 'I' bracket. Center it so as to allow for maximum adjustment. This will help with error when mounting bracket to body. The wire should come out towards the front of the car parallel to the 'I' bracket. You can reassemble the electrical plug at this time. (Hope you remembered your pinouts)
Step 14: Mount the new air shock with the air port to the back of the car. It needs to be in place to make sure that the sensor position doesn't interfere. (I used NAPA air shocks rated for my car for ~$99 a pair.)
Step 15: Using a couple of jacks, (One on the axle and one on the body) position car in relation to the axle to the height you want the car to level at. Slip the 3/8" bolt that connects the ram to the chassis in and double nut it so it can be tight without pinching the ears too tightly. (I used a few washers to keep it straight and remove any slop.) With the car in position, place the cylinder against the fender wall such that the ram is extended to the middle mark. Tilt the cylinder so that the ram slides up the opposing wall of the cylinder from the reed switch. (You don't want the ram to come up and hit the reed switch or break the magnet off.) Mark the holes on the body where the 'I' bracket will bolt. The cylinder will probably not sit flat against fender wall so pick the orientation that promotes straight ram movement when marking. When bolting on use large washers to space the bracket out from fender wall where it doesn't meet.
Step 16: Move the trunk liner and carefully drill the 1/4" holes in the fender. Don't let the bit wander and affect the overall position of the cylinder. (You may opt to drill pilot holes first using a much smaller drill bit. This may help the drill bit from wandering.)
Step 17: Now mount the cylinder to the fender using 1/4" bolts and appropriate washers to space it properly on the fender wall. Use large washers under the burrs too to ensure they hold to the fender wall securely and don't pull through. Check over everything to make sure it is tight and properly positioned. You may have to rotate the cylinder slightly so that the magnet is parallel to the switch. Place a 1 1/2" schedule 40 PVC cap on the top (You might opt to not glue it. 2000 miles and mine isn't glued) and plug the electrical connector in. Mind your wire routing to make sure it is secured and not in the way of any moving parts.
Step 18: Install the other shock and route air lines in accordance with the instruction provided with shocks. Avoid heat sources. (The valve stem 'T' that comes with the shocks is not necessary but I installed mine into the fender wall anyway. Now I can measure the pressure with a gauge or release and pump the shocks manually too.)
Step 19: Using a 'T', connect the air hoses from each shock and the car's pump together and fasten the 'T' to the fender wall. (I had different sized lines so I went to NAPA and got a brass 'T' with different sized compression fittings. ~$5) Mind your air line routing to avoid moving parts. Try to keep them as close to the fender wall as possible. If they stick out, any debris picked up by the tires will be more likely to catch them.
Step 20: Set the car down and test it. Hopefully the bladders inflate and lift the car to the desired position. (If something is wrong don't let it pump forever as it may burst the shocks.) Sit on the bumper and make it pump up some more. Then get off and make sure it deflates it back down to the desired height again. You can move the cylinder on the hose clamps for minor adjustments. Be careful how far you move it so the ram doesn't hit either end of the cylinder. That would just tear the whole assembly apart.
Step 21: Check over the air lines with some soap water to make sure you don't have any leaks. Use silicon or RTV gasket maker to fill edges around 'L' bracket and cylinder. (I used super weatherstrip adhesive.)
Now your height sensor is external and you can use any standard air shock rated for your car and all for about $100 in materials and a few hours of your time. If you've been driving a while without proper shocks, check your fuel lines back there to make sure the parking brake bracket didn't bounce up and rub a hole in them. (I took a big channel lock and bent mine down a bit so it wouldn't happen again.)
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