I am in the process of rebuilding a 72 MGB. It was a race car from new until about 1980. In it's last state of competition, it was a highly modified autoXer. The fenders were pie cut, pulled out to make a flare, a strip of steel was welded to hold the shape, and then they were covered with fiberglass and bondo. By the time I got the car, there was major rust. I was captivated by the shape and history of the car. I probably should not have, but I started a slow resto on the car. I installed all new seem welded floors, and rockers. Removed the bolt in cage and welded in a new roll bar. I wanted to keep the Sebring look to the car, so I made new bolt on front fiberglass fenders with flares. I cut away most of the rear fenders, and all of the outer clamshell for the inner fender. I made thick fiberglass fenders for the rear that are both riveted and bonded to the remains of the rear fenders. They are strong. You can lift on the fender lip enough to pick up the rear of the car. My intention is to someday turn this car into a street car that looks more like a race car. It will also see some time trial/track days. I was wondering if anybody out there has a similar set up. In particular the bonded on rear fenders. Has anyone experienced cracking from body flex? I have a BMW 2002 race car that has bonded on fenders. They have cracks. I did not build that car, and that car has more body flex than the stiffened up MGB. I will be dissapointed if they crack after all of this work. That is why I made them thick. For reference, those rear tires are 235's mounted on 14X8 rims.