The Cessna 120-140 Association Forum

I am getting excessive wear on the inside of the left tire. I presume that this means I have too much toe out. I will be measuring it today. My question for the group is, where do I find the proper shims to adjust this? Looking at the parts manual it seems these are very specific angled shims. I also am uncertain as to whether going from a 1deg to 2deg increases the toe in or the toe out.

Any help would be appreciated. I am putting new tires and tubes (larger sized) and don’t want this left tire to wear as crazy fast as my last one.

You can install the shims either way. If you put the thin side forward it will increase tow in, and if you put the thick side forward it will increase tow out, or reduce toe in.

It is unusual to have wear on the inside of only one tire. The toe measurement is between the two main wheels and tends to affect both equally. Do you find the plane constantly pulls to one side or "crab"? Does it pull to the right? Either way, you need to also look at the camber (tilt of the tire in or out at the top.) Uneven camber will cause the mains to want to steer to one side or the other and also wear the tread unevenly. The Cessna shims are also tapered up and down and can be used to adjust camber, but if the camber is off significantly you may want to look for a weak gear leg spring or gear box issue. Make sure when the plane sits on level ground that the gear box top is level.

You can also get shims from Grove, but I don't know if they have the dual taper or not.

Thank you. I found that I have 1/8 toe out on one wheel (the bad one) and 3/32 on the other. Interestingly enough, this seems to be due to the shims. I am going to try removing or reversing them. Camber is great, gear boxes are level, and everything else looks ok. But the left one is more toe out and much more wear on inside of tire.

When i first got my plane I found it would wear the tires (evenly) on the inside edge. I checked the alignment and found one wheel toed out and the other "correct". When I went to correct the bad one I found I could get it right by flipping the shims. My guess is someone else flipped them inadvertently at some time in the past.

The plane will tend to crab enough to split the difference, and the tires wear pretty evenly unless you're constantly correcting the crab.

I went flying yesterday with all of this in mind and, paying close attention, realized I am constantly correcting a very minor crab. I am replacing the tires and correcting the shims during my annual in august so hopefully this will sort itself out. I am not sure what amount the shims are adding but I will try removing and then reversing if that seems necessary.