MH Handles Worse After Wheel Alignment

dhind · 08-08-2009, 07:06 PM

Our 36 foot motor home on a W22 handles worst after a wheel alignment. It basically wanders down the road. Last Year I installed a Super Steer rear stabilizing bar and that helped a lot. This year, I thought a wheel alignment and rotating the tires might be a good idea. (I know I did it in the wrong order). After the wheel alignment, the MH is handling similar to before the S.S. Stabilizer was installed.

I have attached the results from the wheel alignment for review and comments.

Thanks in advance.

Dave.

Full-Timers · 08-08-2009, 08:55 PM

By looking at your before and after specs it looks like you toe was changed quite a bit. Actually I think that is the only thing adjustable on these chassis. That might account for your current problem. I had a bad toe in problem on my motorhome that badly wore the outside of my tires. Before the alignment I could let go of the wheel and the motorhome would continue straight down the road forever. After they straightened the wheels it has a tendency to wander. It makes sense since toe in would tend to make it snow plow and hold it straight.

BellaBo · 08-09-2009, 08:11 AM

Caster is adjustable. Your caster is 2.5 and 2.7. Mine was 2.5 and 2.3. Mine wandered so bad it scared me. Workhorse approved a caster adjustment and the final was 5.1 and 5.1. It handles very good now.

DriVer · 08-09-2009, 08:26 AM

Caster set to 5.0° has exhibited remarkable results for a great number of these types of issues.

You would basically have to bend an axle to do a caster adjustment however what they will do is add a set of caster shims. A caster shim looks like a small wedge and it's inserted from the front. Once torqued down and set on an alignment machine the caster angle will show a value close to the ~5.0° +/- a couple of tenths of a degree. You are just about going to double what you are currently showing.

We have seen testimony here in the past from W24 owners that this adjustment made a BIG difference in their ownership experience. W22 owners can also realize benefit if this is a problem on their rigs.

dieselclacker · 08-09-2009, 09:01 AM

Add a 5 degree caster shims, and give it 1/8 inch total toe in, adjust your front tire pressure, and you will be amazed at how well it goes down the road.

Dieselclacker

DriVer · 08-09-2009, 09:22 AM

Quote:

Originally Posted by dieselclacker

Add a 5 degree caster shims, and give it 1/8 inch total toe in.

Dieselclacker, I believe what you are saying is to add caster shims that will total 5.0°!

1/8" of toe total would be .125" divide that by 2 = .060" which would be too much toe angle.

The toe on these things is .02 to .04 and the closer to .02 the better.

Currently dhind's toe is w/i spec, but I'd probably like to see the value as close to .02" as possible.

I do have to agree strongly with you that air pressures depending on weight and a small fudge factor upward (5 PSI) works great.

1 other thing that might help would be to "zero out" the box. When the spokes on the steering wheel aren't straight some drivers might tend to over-steer if only in perception.

There is also another dimension that we rarely talk about and that's folks driving their rigs with their eyes focused in too close to the immediate front of the vehicle. Looking forward 100 or more feet and focusing on that viewpoint sometimes makes a difference.

dieselclacker · 08-09-2009, 03:38 PM

DriVer 1/8 inch total toe in works really well with this axle set up, and will not wear tires. Works really well with the added shims to increase caster to make these chassis go straight down the road. I have been running these specs for quite a while, and am quite happy with the way it holds the road without the tendencey to wander.

Dieselclacker

DriVer · 08-09-2009, 09:49 PM

Quote:

Originally Posted by dieselclacker

.... and am quite happy with the way it holds the road without the tendency to wander.

Dieselclacker, If that's working for you then so much the better! I ain't gonna suggest you fix something' that ain't broke!

Gitting to where you need to be at the end of the day with some spare wind in your sails makes for an easy day. Struggling all day long will exhaust anyone so a good setup is essential.

dieselclacker · 08-10-2009, 06:31 AM

[quote=DriVer;

Gitting to where you need to be at the end of the day with some spare wind in your sails makes for an easy day. Struggling all day long will exhaust anyone so a good setup is essential.[/quote]

DriVer, exactly!!

Dieselclacker

dhind · 08-12-2009, 09:25 PM

I always remember getting our first RV, a 97 Ford Explorer V8 and a 22 foot hard body trailer. The unit was so badly setup by the dealer, it was barely manageable, but of course, I didn't have any experience to know this. After the first couple trips of terror, on recommendations from Standens in Calgary, I installed a Reese Dual Cam hitch system and changed the rear tires on the truck. What a difference, after that it was a breeze to drive. The unit was close to it tow limit, but all the problems were solved and we thoroughly enjoyed the combination for the next 10 years. I always remember when we would get home, my wife would say "thank you for all the safe driving". (She's a pretty nervous passenger...even in a car).

Hopefully one day I will feel the same about the motor home.

We have driven 15,000 km over 3 years with it. It can be managed on the highway, but conditions need to be near perfect of go 60 mph. Typically we travel 5-8 mph below the posted speed limit up to 55 mph. Then hold at 55 mph because of the feel of the unit. Add some curves and the speed drops further from the posted limit. I expect this is not right, but I don't have the experience to be able to tell. I am not looking for sedan handling, and am well aware of the effects of wind, traffic, loading, tire pressure and road conditions, but, sure wish I could drive 1/4 mile with one hand on the wheel for a change or my wife would not say, "you only scared me few times this trip".

Hopefully I can convince Standens to change the camber and toe in settings and we will see if that solves the problem, assuming there is a problem to fix.

Proper individual tire pressure helped, adding a SS rear track bar helped significantly (even my wife noticed the difference from the passenger seat), traveling with an empty fresh water tank helped (water tank is mounted well behind the rear wheels), but the wheel alignment was a significant step backwards.

Thanks for the help and advice.

Dave.

dieselclacker · 08-13-2009, 07:41 AM

Dave, the camber on your motorhome is not easily changed, as it requires the bending of the front axle. The caster, however, is adjustable by the addition of a wedge shaped shim that is installed between the front spring and the axle. Installation of the proper shim to achieve around 5 degrees positive caster seems to work really well. As stated above, in my own rig I find that additional toe in on the front wheels from the factory specs also helps it go in a straight line. From looking at your before and after specs on the chart supplied by Standens, looks like they removed some of the toe in, this could be why it handles worse after your alignment.

Dieselclacker