Toe in ?

[Kitfox Pilot]

I have 1/4'' toe in on 26'' tires. Is this an OK number? I have read about tail wheel planes being squirrely if the wheel are not aligned and just wondering how much out of line is bad?

1/4'' toe in is standard on farm tractors but I don't know about tail draggers....

[Av8r3400]

IMO: A taildragger should have as close to zero toe as possible. If any it is acceptable to have a slight toe out. Never toe in.

My Logic:

Landing in a x-wind, one main at a time. Wind from the left and the left wheel touches first. Toed in will cause the plane to roll further to the left, beginning a yaw to the right, trig to turn the plane cross to the wind.

Same x-wind with a slight toe out will roll the plane to the right putting the other main on the ground cancelling any yaw or roll.

Just taxiing, toe in will make the plane very touchy taxiing. A Kitfox is short coupled to begin with, so making it touchy will make it a real bear.

[jiott]

Harlan, I would try to get it to less than 1/8", and a little toe-out is better than toe-in.

[PapuaPilot]

I would second trying to get the wheel alignment to zero. I have a friend that really scared himself in his Dakota Cub on the first landings.

I checked mine with it leveled (tail up) at the same time that I weighed the plane. Check each wheel in relation to the aircraft centerline, not each other. Check the alignment on the wheel hubs, not the tires because tires are not necessarily true.

Here is how we do it where I work:
- Roll the aircraft onto grease plates so that the wheels can slide to their natural position. Chock both wheels.
- Level the plane as best you can by putting something under the tailwheel. Mine was about 32" and I used a bar stool and pieces of plywood.
- Put a long straight bar (~8' steel, wood) that touches both tires equally on the the most forward part of the tires. We put the bar on top of boxes, etc. to hold it at the proper height.
- The bar gives you lateral square of the aircraft & landing gear. It needs to extend outboard beyond one tire so that you can use something like a carpenter's square for the next steps.
- Hold the carpenter's square against the bar with it pointing aft. It's okay if it touches the tire, but it must be square on the bar.
- Hold it level so it goes past the centerline of the axle. It's much easier with a helper to hold the squares so you can do the next step.
- Measure (using something like a 6" ruler) the distance from the square to the fore and aft edge of the hub
- Compare the two measurements
- Adjust the caster if needed and repeat the above steps.

[Kitfox Pilot]

Thanks everyone and Thanks Phil for the process to correct it. Where do I get shims to correct it?

[PapuaPilot]

Grove has shims on their website along with some helpful info to determine which ones you need. Are you sure you need shims? Have you rechecked the plane on grease plates? Most people with Grove gear legs find they don't need any shims.

https://www.groveaircraft.com/accessories.html

[Kitfox Pilot]

I only have grove axles and brakes. Landing gear is monster shock version, not sure who builds it.

[PapuaPilot]

If the alignment is off you need to talk to the the manufacturer of the monster shocks.

On planes like the Piper Cubs they use a long lever on the axles and cold bend the axle/leg until they are aligned.

[Kitfox Pilot]

Monster shocks are just the shock builders, I'm not sure if kfox builds the rest or another party.

[jiott]

Just FYI, Kitfox factory has an alignment check method they sent me which is the same idea as Phil's but somewhat different. It uses snapped chalk lines on the floor and more importantly a 4' straight edge aligned fore and aft with the wheel hub rim. The measurements are taken from the ends of the straight-edge in to the fuse center chalk line. This magnifies the alignment and makes it much easier to adjust compared to measuring across a 6" wheel hub. Many ways to skin a cat. My Grove landing gear needed no adjustment.