The topic inspired me to learn more on the subject - Internet and several alignment shops. I found several postings from "Harvard" in one of the forums regarding the caster settings. His recommendations about the caster settings are similar to the above. The gentleman published his own formula how to calculate them by applying some measurements.Bill Hemme wrote: Before buying steering stabilizers and larger diameter sway bars make sure first that you E350 or E450 chassis has a proper front end alignment. Two alignment adjustments that if set wrong can cause mild to severe steering wander. Those two items are toe in and caster. If toe in is actually set to toe out rather than in, your coach will wander. Toe in should be set to approximately 1/8". The other is caster. The Ford Spec for front end CASTER is:
LH +1.3 to +6.8 Degrees
RH +1.8 to +7.3 Degrees
It is best to have caster set to near the high end of this spec. Having the caster set to around 5 degrees will make a dramatic improvement in steering stability, sensitivity to cross winds and when meeting or passing large trucks.
The Ford E350 and E450 chassis are delivered from the factory with only the toe in adjustable. Camber and caster are fixed and the only way to adjust those two are either to bend the twin I-beam suspension arms or best to have your alignment shop install what are generally called adjustable camber/caster bushings to replace the factory fixed ones. Any light truck alignment shop worth its salt knows about and stocks these adjustable bushings. From my research on other RV forums one source of these bushings is the Ingalls Engineering P/N 59400 a photo of which is provided below.
Have the alignment tech set the toe-in to 1/8" and the caster set to around +5 degrees - about 0.5 degree higher on the right side vs the left side to compensate for the crown of the road.
Then see how your coach handles. The improvement may be rather startling and you may not need to buy a steering stabilizer or heavier duty sway bars.
Any alignment experts on this forum that have better information please post it.
Ingalls PN 59400 Bushing.jpg
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I visited several alignment shops (I am due to replace all tires) to evaluate their capabilities and learn more. All of them categorically claimed that adjustable bushings must be there for proper alignment. OK how many long time members of this forum know if they have adjustable bushing installed? And if somebody will be kind enough to publish a picture of an adjustable bushing so I can determine if I have them installed (I am not the original owner).
All shops claim that they comply with the Ford Specifications. I assume that the specification calls for:
- Toe Setting : TOE IN 1/8"
- Caster Settings:
LH +1.3 to +6.8 Degrees (I will specify +5.0 Degrees)
RH +1.8 to +7.3 Degrees (I will specify +5.5 Degrees)
- Camber Settings (Camber is the angle formed by the inward or outward tilt referenced to a vertical line)
Question: Is the PROPER ANGLE = 0 ?