Wheel alignment

[dfcpac]

Has anyone checked the wheel alignment on a sonex? If you have a issue that has to be taken care of how would you straighten the wheels?

I did check mine they are very close

Thank you
Dan carley

[kmacht]

My alignment was off and I didn't realize it until I was almost done with the plane. I had the toe in/out reversed. Fixing it was pretty simple. I oversized the hole in the gear legs, adjusted the alignment and then welded washers the same diameter as the bolt onto the outside of the oversized hole.

Keith
#554

[LarryEWaiex121]

Keith,

Unfortunately, many of us have had the same experience.
Now with closer to reality alignment on my axles, my tire life is around 125 hrs per side. I tend to swap them out before they show any bald spots.
The springy gear design of the Sonex creates some unique tracking issues on the ground. Often times folks have experienced the ground shimmy syndrome and I find that taxing at about 20 mph with just the right load condition can induce such a shimmy. Its also a brake drag matter also. Many variables.
The whole matter is a moving target because every parameter gives a different outcome.
Since taking a considerable amount of toe-in, out of my plane, it tracks much better and the tire wear is considerably reduced.
I used a method I found worked better for me than the spacers from Sonex. I used "bare" wheels mounted on the axles with a 12' straight edge to "project" toe-in about 20' in front of the plane; measured off the centerline, also extended way out in front of the plane.
It ended up getting me way closer and balanced toe-in than I could ever seem to accomplish with the spacer routine.
At approx. 600 hrs now, I'm quite happy with tracking, wear, etc. I fixed my original alignment at about 150 hrs after burning through 2 sets of the cheapy 2 ply rated tires. Ever since I've used the higher rated 4 ply tires with success. Never a flat, even on rough and rocky runways. Standard wheels and tires with Sonex hydraulic brakes since about 350 hrs.

Larry
Waiex121YX, Camit 3300, Skyview

[drPete]

I used a method I found worked better for me than the spacers from Sonex. I used "bare" wheels mounted on the axles with a 12' straight edge to "project" toe-in about 20' in front of the plane; measured off the centerline, also extended way out in front of the plane.

Larry,

I too am looking for alternate methods of setting my toe-in, as the use of Tracey O'Brien axles does not permit using the factory spacers to set the angle due to the interference of the TOB anti-rotation flange with a straight edge. If I understand the method you describe correctly, and using my XenosB dimensions with a wheel track of 64.5 inches, the plans call for a toe-in angle of 0.7 degrees. Setting up a right triangle using half the wheel track (34.25 inches) for the base leg, a 20' 'convergence distance' (240 inches) along the height, the toe-in angle is given by the inverse tangent of 34.25/240, or 8.1 degrees.

The 'convergence distance' needs to be a bit farther in front of the plane to match the 0.7 degree toe-in. Projecting the distance from the wheel to the airframe centerline in front of the plane using a base leg of half the wheel track of 34.25 inches, while setting a 0.7 degree toe-in, the intercept distance along the height, call it x, (out in front of the plane), is given by tan 0.7 = 34.25/x, 1/(34.25 * tan 0.7) = x, x = 2,640 inches or 220 feet.

This calculator http://www.carbidedepot.com/formulas-trigright.asp is helpful for checking the trig.

**Update: Half the wheel track should be, for my XenosB, 34.25 inches. Corrections to original post in blue.

[daleandee]

I too am looking for alternate methods of setting my toe-in, as the use of Tracey O'Brien axles does not permit using the factory spacers to set the angle due to the interference of the TOB anti-rotation flange with a straight edge.

Here's how I did mine with the Tracy O'Brien axles:

http://websites.expercraft.com/daleande ... g_id=56609

166 hours and still on the original tires.

Dunno If this helps ...

Dale Williams
N319WF @ 6J2
Myunn - "daughter of Cleanex"
120 HP - 3.0 Corvair
Tail Wheel - Center Stick
Signature Finish 2200 Paint Job
166.7 hours / Status - Flying
Member # 109 - Florida Sonex Association

[Area 51%]

I also have the Tracy O'Brian gear legs, wheels, and brakes. Very, very nice units. Was pain-free drilling through the legs. Used a couple of black-oxide bits turning very slowly.

For the alignment, I took the bolt out and reversed the axles so they pointed in, then used the Sonex spacers for the toe-in. Just make sure you get your head wrapped around where the spacers need to be to create a toe-in and not toe-out.

[drPete]

@ Area51. Clever, I'll give that a try.

[racaldwell]

I tried the Sonex method using TOB axles and that required a 0.015" shim at the axle tip for the straight edge to rest against. The trig said I would have the 0.7 deg. So I double checked that set up with long straight edges on the wheels and the centerline layed out on the floor. This method measured out as 2.4 deg. So that method was a waste of time for me. I readjusted the gear legs to give me the 0.7 deg and in round numbers, at about 70" out, the wheel alignment was about 7/8" in closer to centerline than the back of the wheel. This was fast and easy way to get both wheels exactly the same.

Rick Caldwell
Xenos 0057