This tutorial is for a heavy-duty weight distribution hitch. For the light-duty tutorial, or to find out which one you need, go to this article.
STEP BY STEP (see photo gallery)
01 To establish what kind of WDH is needed, first establish the nose weight of the caravan. Then select the WDH that will accommodate that load range. For an accurate assessment, weigh the van laden.
02 It’s essential to set the height of the towball to suit the van. Some offroad vans have a high chassis while some road vans are comparatively low. Back up close, but do not connect yet.
03 The bolts in the receiver hitch can be undone and the ball height selected from the series of holes in the assembly. The large hexagonal washer is a cam that adjusts the angle of the ball mount.
04 Before coupling van to tow vehicle, measure the distance between a fixed point at the front of the car (such as the peak of the front wheel arch) and the ground. Also measure the distance between the rear wheel arch and the ground.
05 Connect the ball coupling and clip the ball handle down. Remove the jockey wheel. Clamp the load brackets to the A-frame in a position that will have the chain vertical when the bars are in place.
06 Insert the T end of the spring arm into the hitch by having it at right angles to the car and laying it into the lower hole. Note that the chain and U-bolt will be on the opposite side to the part of the T going into the hole in the hitch.
07 Turn the T vertically and locate the upper section of the T into the recess in the hitch, then swing the spring arm to reach along the A-frame.
08 With the hinged part of the load bracket lowered, select a link of the chain to connect onto the hook of the load bracket.
09 Using a section of tubing to assist with leverage, tension the chain and pull the load bracket over-centre above the A-frame.
10 Align the holes in the hinged and fixed parts of the load bracket, and then slip in the rectangular locking pin to keep the chain tensioned. Set up both sides of the WDH.
11 Re-measure the height of both wheel arches (or other nominated points). If the distances that the vehicle has settled front and rear are similar, the WDH is very close to being correctly adjusted. Some suggest a short run up and down the road to let the suspension settle before making your measurement. If the measured distance is greater than 5-10mm at the front than when unhitched, then an adjustment is needed, as this indicates that the front wheels will lose braking and steering performance.
12 To adjust the tension and thus alter the height of the car body, undo the hinged section of the load bracket, select a different link, re-tension the device and check until the difference in drop between front and rear of the vehicle is almost zero.
13 When the measurements are even, the rig will sit evenly and the ride will be safer.
Source: Caravan World Aug 2010