Maybe you've noticed this. You have a car, or truck, or some vehicle that you use every day. You've been using it for years and you realize it's getting a little worn. It's developed a few little quirks, but it still gets you where you want to go, so you keep driving it until one day a wheel falls off and you say "oh, poop", or something similar and you finally break down and spend some money to get it fixed. And now after it's been repaired you realize just how badly broken it was because your car drives like brand new now and you can't believe how much smoother it is and you wonder why you didn't get it fixed earlier.
Twin I-Beam Front Suspension. Time went by and he finally started making some money so he went down to the tire store and bought two brand new tires for the front wheels of his truck. Boy, oh boy! New tires! Are we downtown or what!
He's driving his truck home on the freeway going and he hits a bump. It was a pretty bad bump, like one slab of concrete had sunk a couple of (three? four? six?) inches relative to the next one, so there was a lip clear across his lane. He hits that lip and both of the brand new front tires blow out. Needless to say he was a little ticked off. Had the truck towed back to the tire shop where they discover that the frame is sitting on the axles. The springs have completely collapsed, there is no movement in the suspension at all. The big question is why the old tires hadn't blown out. All I figure is tha he knew they were old and worn and so he had been driving it very slowly and carefully and not on the freeway. When he got the new tires he thought he was in good shape, shoot, we can drive on the freeway now!