Richard and Rhonda
05-26-2009, 02:52 AM
You will be convinced that I have lost it :-)
After much tweaking of the caster settings on my coach, the rig still has a very slight pull to the right. I had made some crude measurements a couple of months ago, and both the drive and the tag seemed to be in decent alignment. Although I do remember the right tag being a little odd. I dismissed it, but the continuing pull had me wondering.
So, I went to a huge flat parking lot and used some of my homemade alignment tools that basically consist of a laser level mounted to straight piece of wood that spans the rim. Using some basic trig, tangent of the angle equals the rise over run, you can calculate the angle of any wheel if you take two measurements of the laser beam a suitable distance apart. I found the drive axle has a vector of 0.0006 degrees to the right. Hmmmm, that is well withing the accuracy of the tools I was using. However, I found the right tag was toed in 0.04 degrees, and the left tag toed in 0.02 degrees. Two hours of searching and I finally found some Prevost specs that say the tags should be at 0.02 degrees or less.
That's not a lot, but I began to wonder if that could be the culprit. I searched for hours trying to find the answer to the question. If the tag is pointed to the left, which way will the coach pull? What do you think?
I wasn't about to go through the trouble of adjusting the suspension without some evidence that would cure anything. I could postulate two different scenarios. One, the tag pointed to the left, pulls the coach to the left, inducing a left pull. I know if the drive axle were canted to the left that's what would happen. Scenario two, much harder to get my head around, was that the tag pointed to the left would actually use the drive wheels as a fulcrum and make the coach pull to the right.
Quite a mental exercise today trying to figure this out.
So, I started making my second Newell as you can see in the pictures. Just kidding. I made a scale model using wheels and axles I robbed from Pinewood Derby cars in the trophy case. You ex scouters will recognize the wheels. I mounted them on separate wooden blocks so I could adjust each axle separately relative to the body to see the impact. The pieces of paper on the bottom are shims I used to get all six wheels to make even contact. I used the granite countertop in the house as my test track because it should be flat and smooth.
And the answer is...............if the tag axle is pointed to the left the little wooden chassis will veer to the right. One of my tags is pointed to the left too much, and the coach pulls to the right.
After much tweaking of the caster settings on my coach, the rig still has a very slight pull to the right. I had made some crude measurements a couple of months ago, and both the drive and the tag seemed to be in decent alignment. Although I do remember the right tag being a little odd. I dismissed it, but the continuing pull had me wondering.
So, I went to a huge flat parking lot and used some of my homemade alignment tools that basically consist of a laser level mounted to straight piece of wood that spans the rim. Using some basic trig, tangent of the angle equals the rise over run, you can calculate the angle of any wheel if you take two measurements of the laser beam a suitable distance apart. I found the drive axle has a vector of 0.0006 degrees to the right. Hmmmm, that is well withing the accuracy of the tools I was using. However, I found the right tag was toed in 0.04 degrees, and the left tag toed in 0.02 degrees. Two hours of searching and I finally found some Prevost specs that say the tags should be at 0.02 degrees or less.
That's not a lot, but I began to wonder if that could be the culprit. I searched for hours trying to find the answer to the question. If the tag is pointed to the left, which way will the coach pull? What do you think?
I wasn't about to go through the trouble of adjusting the suspension without some evidence that would cure anything. I could postulate two different scenarios. One, the tag pointed to the left, pulls the coach to the left, inducing a left pull. I know if the drive axle were canted to the left that's what would happen. Scenario two, much harder to get my head around, was that the tag pointed to the left would actually use the drive wheels as a fulcrum and make the coach pull to the right.
Quite a mental exercise today trying to figure this out.
So, I started making my second Newell as you can see in the pictures. Just kidding. I made a scale model using wheels and axles I robbed from Pinewood Derby cars in the trophy case. You ex scouters will recognize the wheels. I mounted them on separate wooden blocks so I could adjust each axle separately relative to the body to see the impact. The pieces of paper on the bottom are shims I used to get all six wheels to make even contact. I used the granite countertop in the house as my test track because it should be flat and smooth.
And the answer is...............if the tag axle is pointed to the left the little wooden chassis will veer to the right. One of my tags is pointed to the left too much, and the coach pulls to the right.