Wheel alignment...a photo tutorial

[t j]

Tools needed:
Carpenter's level
Plumb bob
Carpenter's square
Tape measure
Chalk
Chalk line

Due to camber, wheels further apart at the top than the bottom, tail wheel airplanes need to be in the tail up attitude to check wheel alignment. After aligning my kitfox wheels to straight ahead with 1/4 inch of camber in the tail up attitued, it has about 1/4 inch toe in on each wheel with the tail down. This alignment took all the squirrelyness out of it and makes it a very nice and easy to handle airplane on the ground.

1. Jack up each wheel. Make a chalk line around the tire near the center of the tire tread by spinning the wheel and holding a piece of chalk on it. Make a cross mark on this line at both the front and rear of each tire at 1/2 the tire height.

2. Level the fuselage both ways.

3. Drop a plumb bob from the center of the tail spring and one from the center of the spinner. Mark these on the floor.

4. Snap a chalk line from these marks on the floor to mark the center line of the airplane.

5. Measure the distance from the front and rear chalk marks on each tire to a carpenter square held on the center line. Grooved tires make this easy. if you have smooth tires you'll need a helper to hold the tape. Use these measurements to determine amount of toe in or out of each wheel.

6. Measure from the square held against the outside of the tire to the top and bottom of the wheel rim. Use these measurements to determine amount of camber.

On my kitfox the right wheel was parallel to the center line and had 1/4 inch of camber. The left wheel had about 3/4 inch toe in and 3/8 inch of camber. I took the axel out and bent it cold in a vise with a sledge hammer. It took several trial and errors to get it the same as the right wheel.


Some people have chained the tail down and used a six foot cheater to bend the gear in place on the airplane. I tried that but stopped when it seemed I was going to damage something and nothing had bent yet.

[HansLab]

Very clear story here! Tx for the photographs - they will help when i'm this far.

[oldfox]

Thanks Tom this is a big help and picture are great !!! thanks again Chris

[chefwarthog]

Thanks to have taken the time to make pictures like those, thise few minutes you take will save hours to those who will see this tutorial



I Just throw an idea, why not do a Sub Discussion, in the Features : Tutorial (Photo or Video) so it could be easyer to search for instruction how to do a specific job on our plane

[Paul Z]

How often should you inspect the alignment?

[t j]

Probably just once. I think you would have to hit something pretty hard to knock it out of alignment.

Wheel alignment issues seem to be just a tube gear problem due to weld warp or something. The grove gear uses tapered shims to align so is easy to set correctly during construction.

[PapuaPilot]

I want to add a few more tips on wheel alignment. You really want to do this before your first flight. I've heard some scary stories about planes that dart off the side.

1. Wheel alignment changes with the airplane's weight. It is best to do the alignment at gross weight or at your average flying weight. If you fly by yourself 90% of the time then you might consider doing it with the plane loaded to simulate of you, full fuel plus the weight of any extra stuff you normally carry.

2. The wheels need to go to their normal, relaxed position during alignment. To do this you can put grease plates under the wheels so they slide to that position. Use 4 sheets of aluminum (about 16" x 16" each), make 2 sets of sandwiches with grease in the middle of 2 sheets. Lay the greased sets on the floor and roll your main wheels on top of them. Now your main gear will go to its true position. Sometimes you need to jiggle the plane to get the gear to settle into this position.

Going back to the first point. If you add the ballast to simulate your body weight while on the grease plates you will notice the gear will spread. The camber (the angle/tipping from top to bottom) has changed and the tow may have changed too.

3. You don't need to draw a chalk line on the the tires. What if your tires aren't true on the hubs? There is a more accurate way. You really want to align the hubs, not the tire. Just like the picture of checking the camber you can check the tow similarly with a carpenters square. Place a straight beam or board on some blocks so that it spans and touches the front of both tires half way up. Now use the carpenter's square. Put one side of it on the beam outboard of your wheel. You want to see if your hubs are parallel to the square. Measure the distance from the square to the front and back of the hub half way up (don't measure to the sidewalls of the tire). If you want zero tow out then the distance needs to be the same. If you are setting some toe in then it will require some calculation or the use of a protractor.

4. Set your alignment per the manufacture's recommendation. If they don't give you any data then set them to zero camber/zero tow at the weight you chose in step one. Kitfox sells angled shims for adjusting this. Put the shims between the gear leg and axle. If you can't get the tow right on then I would favor a little tow in.

[jiott]

I don't understand why you would bother checking caster; there is nothing you can do to adjust it on the main gear. On a nosewheel or tailwheel it is important.

Also I believe the line around the tire method as in the tutorial is just as accurate and maybe more so than your method. The tire line is put on (and I would use something like a ballpoint pen rather than a fat chalk line) by rotating the tire 360 degrees against a fixed marker pen, which gives you a true circle of rotation with respect to the AXLE. This is what you want rather than the hub rims which could themselves be out of true.

[PapuaPilot]

My bad in saying caster, I meant tow. I edited them all to say "tow".

[kitfoxnick]

My alignment story. A friend bought a model 4 sight unseen and him not having a tailwheel endorsement asked if I would help him bring it home. After checking out the plane real good, everything looked good. I told my buddy somethings wrong with this plane because no one owns a plane for 4 years and only flys it 7 hrs. On take off as soon as I lifted the tailwheel off the ground I immediately knew why this guy didn't fly this plane much. It was everything I could do to keep it on the runway, and this was on takeoff. When I got to our destination I full stalled it on a piece of grass next to the runway. I instructed the new owner to not even bother taxing this plane until we could get it aligned. Well he let a mechanic friend take to give it a tune up. This guy is a competent tailwheel pilot with a lot of pitts time and he managed to run it off the runway at his destination airport. When he brought it back he ran it off the runway again and slow looped it in the grass. When I helped align it, using greese plates and line lasers we found it was 5deg towed out on the right side and 2 deg to in on the left side. Using shims we were able to get the Grove gear aligned correctly. The plane has no bad habits now, and the fellow was able to get his tailwheel endorsement, and fly happily ever after.

All that said, this is the only Grove gear I have seen with an alignment issue. If your getting ready to do your first flight. It is certainly worth it to check the alignment first, and stack the deck in your favor.

[Av8r3400]

I wonder if the gear was misaligned that badly to begin with or by the "test" flying and multiple ground loops?

Checking the alignment is a great idea. However, IMO, if a new set of Grove gear is out that far, it should be sent back to Robby Grove for reworking on his dime.

[kitfoxnick]

This friend was the fourth owner so hard to know what happened. I've never had to adjust a new set of grove gear.

[Esser]

Just did my gear alignment. It’s bang on straight. Is this ok or do I need to add some toe in or out?

[PapuaPilot]

Mine was the same as yours and I didn't do anything. I have been happy with how it handles.

[jrevens]

Did you guys check yours in the 3-point attitude, or level? Level, mine was straight also. Rotating down to the 3-point I had 1 deg. of toe-in due to the camber in the Grove gear. Toe-in with a taildragger is de-stabilizing, and causes more tire wear than neutral alignment of course. I figured that 99% of the ground miles would be in the 3-point attitude, so I shimmed neutral for that, and now when rotating to level it's close to 1 deg. toe-out (which is actually stabilizing with a taildragger). The airplane is just a little better handling now... it's a subtle perception, but a fact in my case. I used a 1/2 deg. shim on each wheel. FWIW.

[Esser]

Interesting John, I had done it in the level position. Tomorrow I'll go back to the hangar and see what it says in three point

[rosslr]

I also aded shims and noticed a significant difference is stability on landing particularly.

r

[Esser]

Toe out Ross? Was it straight before you added shims?

[rosslr]

No Josh - it was for camber. It used to sit with the bottom of the tire closer to centre line than the top ( I forget if this is neg. or positive !?) and the outside of the tires wore more than the rest (26" Airstreaks). Now they wear evenly and it feels more stable on landing.

I did the alignment for toe in/out before first flight and it didnt need any adjustments for that.

Getting close now Josh - and it looks a monster!

Best of luck.

ross

[i800711]

Thanks for posting this tutorial T J. After a few landings in my recently purchased model 2 with my instructor we knew something was bad wrong. It would make some un-commanded turns to the right and rudder was ineffective at keeping it running down the runway in a straight line. I performed the alignment, had a 3/8" toe in on left main and a 3/8" negative camber. I bent the axle until I had both at 0". I also learned the Maule tailwheel was unlocking with full left rudder so I replaced the tail wheel with a new Matco 8" pneumatic wide tailwheel. My tail spring was also bent so I replaced with the new 3 spring version which after installation, I realized the spring was canted to the right. We built a shim to correct the spring and installed it on top of spring. All 3 things, alignment, tailwheel and spring mounting was causing the aircraft to turn right. Now that all of that has been corrected, it is WAY easier to control. I solo'd shortly after correcting these issues.

[Nickfox]

I’ve just purchased a s7 with grove gear I’ve taken a measurement and my left wheel has a 5degree negative camber and a 3 degree negative on the right I’ve found the shims for sale but how do you know if you need the 500+5 or the 600+6 shims
sorry if it’s a stupid question I’m new to all of this
cheers nick

[efwd]

Click on the Grove banner above ( sponsors ). Find the Axel tab and click. You will find a pic of the shim. Look below that and you will find the link to the shim bolt pattern document. Sorry, if I were more savy than I am, I could have attached it.....

[jrevens]

The 2 basic Grove landing gears for Kitfox Models 3 & 4 and Series 5,6 & 7 have a type 1 axle bolt hole pattern, which is the square pattern (opposed to the type 2 pattern, which is rectangular).