You may or may not need to do this until you start aligning, but I’m a picky bastard and it can’t hurt. To do this, I start with rolling both mains on to a pair of grease plates. 99% of the hangar floors out there are not level, so it’s worthless to use that as a reference. The first thing you do is level the axles. With a little effort, you can get much closer than that. Cessna specifies 3” as the max difference between the left and right wing tips. Now that both gear legs are locked in place in the gear box, we can level the airframe. I’ve removed aluminum shims from a loose gear box and found them deformed and smashed, so I prefer steel. I’ve heard that the ones you buy from Cessna are aluminum, but I don’t know because I usually don’t buy what I can make in 5-10 minutes. I like to use 4130 since I usually have that around the hangar. The shims that you use with the wedge should be steel. Toe in leads to tire wear, toe out leads to insurance claims. Toe out is bad news and unexpected toe out is real bad news. The second reason I like to set it at the aft end is, if the gear moves, it will move forward and change the alignment to more toe in. If the gear is already as far aft as it can go, these forces won’t move it. The first is the majority of the loads the gear sees will be up (landing) or aft (hitting bumps and braking). I like to set it at the aft end for 2 reasons. One of the most reputable shops in the rebuild business usually sets the gear at the front limit of the travel. The gear leg probably has some room to pivot fore and aft in the slot of the outer bracket. I use my smallest ball peen and a brass punch with medium tap taps. You don’t pound the wedge in with a 2 lb. Once it is seated, I tighten the bolt to the appropriate torque spec. I usually put the bolt in place just to maintain alignment of the wedge/shim while I tap the wedge into place on either side of the bolt. DO NOT use the bolts to draw the wedge in to place, they are there just to hold the wedge once it is installed. The installation should have the shim(s) pushed inboard as far as possible and then the wedged tapped in to where it gets tight. If it gets this far, take it apart and add a thicker or second shim. You don’t want the shim riding up into the radius of the bend in the wedge. You can only push the wedges in so far before a thicker or additional shim is needed. This is done by tapping the wedges in a touch further or adding shims. Once the gear leg is dangling in the breeze, you can tighten it up. I suppose you could use the float lifting rings if you have them as well. The other easy way is a screwjack/stiffleg under the wing just outside of the strut. You can use a cherry picker and lift on one side of the engine mount where it meets the firewall, don’t use a chain, you’ll screw up your engine mount and who knows what else. To tighten the gear leg in the bracket, you need to lift that side of the airplane somewhere besides the gear leg since you need the gear leg dangling in the breeze. If you see light coming through between the gear leg and the outer bracket, it’s not tight enough. You take a mirror and look UNDER the gearleg from inside the gearbox. The way to check for a loose gear leg is to have your helper shine a light from outside UNDER the gear leg into the gear box. Sometimes you can hear it after lift off with an unbalanced tire/wheel shaking the gear leg as they slow down. You'll notice them being loose when your taxiing around and you hear a clunking noise coming from the gearbox. These 2 wedges are loose on about 20-25% of the airplanes that I work on. This is done with a pair of shim/wedge assemblies on top of the gear at the outer gear leg bracket. The first thing I do when leveling an airplane is lock the gear leg in the gear box. I sat down to write this so hopefully more folks can keep from wrinkling up their airplane and their ego. Second and third, just so you don't have to ask are tailwheel steering and rudder rigging, but that's for another day. Whenever I fly one that is like this, I look 3 places, the first of which is the main gear alignment. Any of us who have flown multiple 170s, 180s, or 185s have experienced different ground handling characteristics between seemingly identical aircraft. I've been working on these airplanes for a long time and one thing that I believe causes more ground loops than anything else (besides pilots) is bad wheel alignment. Here are the best instructions I've ever seen on alignment of Cessna tail draggers.
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