I saw a thread on the VAF WWW forums awhile ago about a clearance problem between wheel pants and brake calipers. I put an item on my To Do list to check this. I've been working on the final wheel pant tweaking lately, so yesterday I finally screwed up the courage to take a look at this on the left wheel pant. Sure enough, the back bottom corner of the brake caliper was hitting the wheel pant. This would push the floating caliper towards the brake disk, causing a dragging brake. At best, this would only lead to excessive brake wear. At worst it could lead to overheating brakes and a brake fire, or a control problem on the ground.

Some guys said they fixed the problem by putting a bulge in the wheel pant in this area. That would certainly work, but the thought of even more fibreglas work turned my stomach. Some other people reported that they fixed the problem by bending the wheel pant attachment bracket to push the bottom part of the wheel pant inboard, away from the brake caliper. I decided to try this.

I spent two hours tonight bending the bracket a bit, then putting the wheel pants on (one hard to get at bolt on the axle, plus a whole bunch of screws), using a flashlight and mirror to check the clearance, only to see that the wheel pant still hit the caliper, taking the wheel pant off, and then repeating the process. I finally got just the right bend on the bracket so I have about 0.050 inch clearance (as judged by a finally calibrated eyeball).

My back is very tired after two hours on my knees, bent over that wheel pant, so I am having a very tasty beer.

Update - 22 Jun 06 - I checked the right wheel pant this evening, and it too was hitting the brake caliper. I tweaked the attachment bracket to solve the problem. It went a lot quicker than last night, as I had learned a few things.

The big lesson is to be careful to keep the same angle on the flat part of the bracket that the wheel pant mates up to. Last night, I started off only bending the bracket right where it comes off the landing gear leg. This moved the end of the bracket inboard, which is what I wanted, but it also changed the angle on the end of the bracket. Then, everything would look OK until I tightened the screws that held the wheel pant to the bracket. As soon as I tightened the screws, the wheel pant would deform and hit the brake caliper. I finally figured out that I needed to bend the bracket in two places - at the landing gear leg, and at the flat part where the wheel pant attaches. The bracket needs to be parallel to the wheel pant surface, so that the wheel pant doesn't deform when you tighten the screws.