Measuring toe angles ( toe in or out)

[tectweaker]

Can somebody suggest a simple and practical way to measure the toe angle on the landing gear?

I have seen fairly complex ways to do it. I am just trying to see if I need to make a correction.

[gasman]

Just a guess here....... If you have an RV4, there is no adjustment.

[tectweaker]

I have a rv3 - I am assuming that it would be the same way? Built in 80s.

[HFS]

If you have a -3 or -4, the toe in/out is fixed at the time of assembly by the original builder, at least during the early days. The plans called for a neutral set up, but some of the Bakersfield Bunch used to tell us to build in around 1/2 degree toe in. That was done by adding a 16Ga. spacer to the outboard side of the jigging arrangement at the axle location prior to drilling the gear legs to the motor mount sockets. That's the way I did my -4, way back when, and it didn't seem to hurt anything - usually got around 400 hrs. per set of tires.

If you do check the toe condition - try to use the face of the wheels as a datum instead of the sides of the tires. They may be biased for one reason or another and not give accurate results.

YMMV

David Howe

[vfrazier]

A relatively easy way to check the toe is to obtain two pieces of angle aluminum about 6 feet long.

Remove the wheel pants and clamp one angle to each brake disc. Clamp it in the middle of the angle so it balances. Make them level horizontally.

Drop a plumb line off of the tip of the spinner. then snap a chalk line from the center of the tailwheel to the center of the spinner. (Yes, I know that the engines may be offset.)

You should be able to obtain 4 numbers now, i.e. the distances from the angle ends to the centerline. Then measure another 2 places, from the front of each left and right angle and the back of each left and right angle... to see if the angles are parallel to each other.

Compare the numbers to see if you have toe in or toe out. Google the trig formulas if you want to determine the actual angles.

The angles should be parallel if your toe is zero. They may be slightly un-parallel to the centerline you dropped, due to engine offset or other building differences. Your numbers should give you an idea of what's up.

NOTE: this will give you a ROUGH estimate. Wheel friction when you move the plane forward or backward WILL affect the toe that you see. Put the plane on greased plates if you want a truer number.

Grease plates can be made from four 1' square, 1/4" thick aluminum plates. Put a thick blob of wheel bearing grease between 2 of the plates. Make 2 sets. Put one set under each tire. The plates will allow the tire to find its natural alignment, giving you a truer toe reading.

Store the gooey, greasy plates in a plastic bag or two. You'll use them again. Or your buddy will. Or give them to your local EAA chapter as a very useful tool.

Easy.

[Don Patrick]

http://www.mykitlog.com/users/displa...173552&row=292

[vfrazier]

Don's technique is great for RV-8s during construction.

I don't think it will work very well with Wittman type gear. Be sure to follow the plans for those.