Specifications

8-bolt wheels (9/16 bolts) get 140 ft. lbs.
5-bolt front wheels and 10-bolt rear wheels get 180 ft. lbs.
We're still not quite ready for that alignment.
There are two more items to check. Ride height and frame angle. Both affect the caster that will
be set during the alignment. Without these numbers, you CANNOT come up with a valid
CASTER setting.
Ride Height
Ride height is checked at four points. Tolerance for manufacture of the springs is ± ½ inch. If
the side-to-side measurements are not equal, within the tolerance, some work needs to be done.
Also, the front-to-rear ratio for each side should be close to the same. However, there are steps
that can be taken to fix or correct these measurements quite a bit.
Ride height measurement points are specified by the manufacturer. On some vehicles, it is from
the frame to the ground, a specific point on the underside of the body to ground, or between
components as specified by the manufacturer.
The measurement for the P Chassis is taken as illustrated in the next diagrams. The best
circumstance is to disconnect one end of each shock absorber before making this check (good
time to check the shocks too) and the motorhome must be on an absolutely level surface. If the
surface is not perfectly level, you can shim to level by placing squares of plywood under each
wheel until the tops of the plywood at each corner are at the same level height. Another option
is to take the measurements, mark the position of each corner tire and turn the motorhome
around 180 degrees, park in the same marks facing the opposite direction and check the four
points again. An average of each reading should bring you close to actual. Of course, you need
to start this with an almost-level location. This won't work very well if you do it on the side of a
hill.
REAR:
The reason the rear ride height is important to us is because it can affect the handling. Basically,
the measurements should be the same side-to-side, just as the front. Before doing anything,
check the rubber bushings on the springs and shackles. Look for broken spring leaves –
evidence of a crack in the side of a leaf may be the only visible evidence without complete
disassembly of the springs. Also make sure there are no obvious broken mounts. The U-bolts
should be tight and not broken. Take a close look at the welds where the shackles are attached
to the frame and the shackles themselves. If one of these is broken or loose, you will have
handling problems. (You already checked the shocks and their mounts and bushings, right?)
http://users.sisna.com/cebula/P-Chassis-AlignmentProcess.pdf 14 Version 0.7 –Sep 14, 2005