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Installing Ladder Bars

Note: I have not had this car since March of 2005 and it's been much longer than that since I last worked on it.

DISCLAIMER: This document does not cover all of the operations needed to completely install ladder bars. It is an outline of the major steps needed to perform the swap on a 1966 Rambler Classic or Rebel 2 door. The process on other vehicles may require additional modifications not mentioned in this document. This process exposes the installer to significant bodily harm due to the weight of the components and the tools involved. Additionally, this procedure requires extensive modification to and/or replacement of the manufactures original design. The author assumes no responsibility for the outcome of this operation.

Here's what you will need to convert from a torque-tube rear suspension to a ladder bar rear suspension and keep your original springs:

• A framing square
• A plumb bob (or a nut on a string)
• Chalk
• A tape measure
• A piece of chalk
• Masking tape
• A piece of poster board or light cardboard about 2 feet wide square
• Heavy cardboard for bracket mockup.
• Springs in good condition - replace bad springs before you start this process
• 3/16" steel plate
• 1/4" steel plate
• Steel bar stock 1.5" O.D.
• Several feet of mild steel tubing 3/4" O.D., .120 wall thickness
• A replacement rear end from the manufacturer of your choice (I used a Ford 9") that is the same length to the original rear end
• Ladder bars from the manufacturer of your choice
• Panhard rod from the manufacturer of your choice - OR - you can cut the brackets off of the original rear end and use the factory rod.
• Shocks of suitable length
• Cutting and welding equipment
• A book on chassis fabrication. Hot Rod Chassis by Boyd is a great book to start with.
• A floor jack, a screw or bottle jack, and eight jack stands
• Materials to shim the car
• A level
• An angle finder

Step 1 - Preparation

Before you even loosen a lug nut, read the chassis fabrication book. It will have all sorts of information on setting up a chassis properly. Clean the area you will be working in. A clean floor will be easier to see the alignment marks on plus, you and your tools will stay cleaner. Check the condition and operation of the jacks and other tools. A trip to the store is easier now than when your in the middle of the job. Measure from two fixed points on one side of the car to the ground. You will need this measurement to make sure the car has the proper rake when it is on jack stands.

Step 2 - Out with the old...

Jack the car up as high as you can and place it on jack stands. Put one on each corner of the car and a pair under the rear axle. Make sure the axle is at ride height (put the jack under the center of the axle, jack up until the car just starts to lift, place jack stands under the axle and let the car back down -- you want the weight of the car on the jack stands under the body).  Level the car from side to side. Using the measurements taken before, make sure the rake on the car is the same. Shim as needed. Note: from this point on, do not move the car. If you move it, you will lose your reference points.

Remove the rear tires (you may need to lower the axle to do this). Measure between the center of the old axle and the ground on BOTH sides. Use the plumb bob to make a mark on the floor marking the center of the rear axle. There is a dimple in each axle that marks the center, make sure the string passes through it -- this establishes the side to side location of the axle. Measure from the center of the spindle on the front wheel to the center of the rear axle -- this is the cars wheel base. It should be similar on each side if the steering is straight. If it is different, just make sure you don't move the steering. Use the plumb bob to make a mark on the ground showing the edge of the car. Make sure to indicate where on the body you had the plumb bob -- this establishes any axle offset the car may have had. Measure the compressed height of the springs.

Drain and remove the gas tank. Drain and remove the rear axle according to your service manual. Note: Treat coil springs with respect. If you let one fly out while it is compressed, it could go through the car or anyone near by. If you will be using the factory panhard rod (the link that goes between the axle and the body), remove the bracket from the old axle. Remove the shocks from the car.

Step 3 - Mockup...

Once the new axle is prepared, place it on jack stands underneath the car in the approximate location of the old one. Using the measurement you took before, set the wheel base. Use the framing square, line up the marks you made indicating the center of the axle. Set the center of the axle to the height you recorded before. Check all of the other measurements. You should be within 1/16" of what you recorded. Put the screw jack under the pinion carrier (the area that the driveshaft bolts to) of the rear end and set the pinion angle according to the instructions that came with the ladder bars.

Assemble the ladder bars to the rear end. Depending on the bracket design, you may need an extra pair of hands for this part. Make sure the bottom tube on the ladder bar is parallel to the ground and place it on the jack stand at that height.  Tack weld the bracket to the rear end. Double check that the rear end is in the same spot as before. Use some heavy cardboard to make a bracket to connect the front of the ladder bar to the body and make the bracket. You will need to do each side separately. They may be variations in the structure of the car from side to side. Once the brackets are made, tack weld them in place and install the front bolts for the ladder bars. Once everything is tacked together, recheck the position of the rear end and the pinion angle. Once everything is where it belongs, check the ladder bars for freedom of movement. The whole assemble should be able to touch the suspension stops and drop about 12 inches without hitting any part of the car.

Re-center the rear end and install the panhard rod The panhard rod should be parallel to the ground and as long as possible. Recheck for any binding and correct as needed. You will probably notice a slight side to side motion as you raise and lower the suspension. This is normal.

Cut the light cardboard to the spring height you measured before and wrap it around the rubber spring isolators. Install the "spring" in the upper spring seat. Make sure the "spring" is plumb. Use the heavy cardboard to make a template for the spring seats. Again, you will need to do this for each side. After the seats are made, tack weld them in place.

Install the real springs and wheels. Carefully set the car back down on the ground. Check to make sure the car is sitting properly and the tires are in an equal amount on each side. Put the car back on jack stands and correct any problems you found.

Tack weld the lower mounts to the rear end. Fabricate an upper shock mount from the mild steel tubing. Install the shocks as recommended by the manufacturer and position the upper mount. Tack weld the upper mount and any shock brackets in place.

Step 4 - The home stretch...

Final weld everything in place. Put gussets on the front ladder bar brackets. Hook up the brakes and bleed them. Check for proper operation. Install the driveshaft yolk in the transmission. Make sure it is bottomed out and then pull it back 1 inch. Measure the distance between the center of the front and rear u-joints. Use this measurement to have a driveshaft made. Reinstall the gas tank and put a few gallons of gas in it.

Once you have a driveshaft in the car, put it back on the ground and take it for a short drive. Check the rear suspension for any cracked or broken welds. Fix any problems you find and then take the car to a race track and really hammer it. Check everything again afterwards.

Last Updated 08/17/08 04:02:49 PM