Adventures in alignment or wanderer no more
I got a new class C about 2 months ago from a dealer about 500 miles away. I was coming from a bumper pull toy hauler pulled by a silverado 2500hd that towed solid as a rock. I had a nice long drive home to get to know my first motorhome. It only took a few miles and I was really starting to wonder what I had gotten myself into. This thing was really a chore to drive, any irregularity in the road and it would take off in random directions. It was really taking some concentration to keep this thing on the road. I figured they must not all be like that or nobody would have one. I have driven race cars, heavy equipment, towed large trailers, driven in snow, off road, dirt bikes, motorcycles, pretty much anything with wheels. I don't shake easily behind the wheel of a vehicle and if it was bothering me then it must not be normal.
When I got it home I started researching how to fix this thing. I started with the sticky FAQ on this page. There was not real agreement on what to do. Many said take it to an alignment shop, some advocated, shocks, steering stabilizers, 17.5 inch wheels and real truck tires, sway bars, track bars, air bags, etc....
Many said that the best first step was to take it to an alignment shop. So I started to focus on that. I wanted to find what were the proper specs for motorhome handling. I came across a number of posts by the member on here that goes by Harvard on this board. He had handling problems that seemed similar to mine and he had increased his caster from approx 3.5 degrees to 5.5 degrees. He said this had helped tremendously. I went out and checked my caster and it was also about 3.5 degrees. My camber was around a positive .25-.5 degrees and I didn't really measure toe but visually it appeared to have a slight toe in (which is good).
I looked up the ford alignment specs and found.
Camber +0.5 +/- 0.5
Toe +0.06 +/- 0.25
Caster Min 2.0 Max 7.5
Whoa, look how wide that caster spec is. I knew that my camber was lose enough, the toe looked good, but I was at the low end of the caster range.
The only way to adjust caster and camber is with new bushings so I went and bought myself some 4 degree adjustable caster camber bushings and got to work. I adjusted the bushings to add 3 degrees of positive caster from stock settings and set it neutral on camber which in effect was -0.25 from stock since the stock alignment had a +0.25 bushing for camber.
So now I am at about 6.5 degrees of positive caster, around 0 degrees of camber, and a slight toe in. As best as my research can tell these are some decent specs for stability. Everything seems to indicate that within reason there is no down side to positive caster other than increased steering effort. I also upped the air bag pressure from 30 to 80.
I take it out for a test drive and it is night and day better. Yes the steering effort is more difficult but it is now easy to drive and while still not a corvette it now handles as normal as a 32 ft box on wheels can.
I just wrote this to help people know exactly what alignment parameters are what improves the handling. If I had taken it to an alignment shop they very easily could have told me that it didn't need an alignment because everything was within ford specs. However the caster spec is so wide that depending on where in that broad range you are is a large difference in handling.
When you guys go to the alignment shop make sure you have a discussion first about what specs are right for the handling you are wanting.
I would want MY class C around this:
Caster 5.5-6.5 degrees positive
Camber Neutral
Toe 1/8" toe in
When I got it home I started researching how to fix this thing. I started with the sticky FAQ on this page. There was not real agreement on what to do. Many said take it to an alignment shop, some advocated, shocks, steering stabilizers, 17.5 inch wheels and real truck tires, sway bars, track bars, air bags, etc....
Many said that the best first step was to take it to an alignment shop. So I started to focus on that. I wanted to find what were the proper specs for motorhome handling. I came across a number of posts by the member on here that goes by Harvard on this board. He had handling problems that seemed similar to mine and he had increased his caster from approx 3.5 degrees to 5.5 degrees. He said this had helped tremendously. I went out and checked my caster and it was also about 3.5 degrees. My camber was around a positive .25-.5 degrees and I didn't really measure toe but visually it appeared to have a slight toe in (which is good).
I looked up the ford alignment specs and found.
Camber +0.5 +/- 0.5
Toe +0.06 +/- 0.25
Caster Min 2.0 Max 7.5
Whoa, look how wide that caster spec is. I knew that my camber was lose enough, the toe looked good, but I was at the low end of the caster range.
The only way to adjust caster and camber is with new bushings so I went and bought myself some 4 degree adjustable caster camber bushings and got to work. I adjusted the bushings to add 3 degrees of positive caster from stock settings and set it neutral on camber which in effect was -0.25 from stock since the stock alignment had a +0.25 bushing for camber.
So now I am at about 6.5 degrees of positive caster, around 0 degrees of camber, and a slight toe in. As best as my research can tell these are some decent specs for stability. Everything seems to indicate that within reason there is no down side to positive caster other than increased steering effort. I also upped the air bag pressure from 30 to 80.
I take it out for a test drive and it is night and day better. Yes the steering effort is more difficult but it is now easy to drive and while still not a corvette it now handles as normal as a 32 ft box on wheels can.
I just wrote this to help people know exactly what alignment parameters are what improves the handling. If I had taken it to an alignment shop they very easily could have told me that it didn't need an alignment because everything was within ford specs. However the caster spec is so wide that depending on where in that broad range you are is a large difference in handling.
When you guys go to the alignment shop make sure you have a discussion first about what specs are right for the handling you are wanting.
I would want MY class C around this:
Caster 5.5-6.5 degrees positive
Camber Neutral
Toe 1/8" toe in
