Awesome, what good answers!
I think the replier is right about the clunk. I think the van is somehow delaying the signal to BRAKE. I know the van has that crazy option to flash the brake light up high in the middle of the back.
I bet a mixture of that and the fact that it's a Minivan with NO prewire harness available means that they spliced into the signal out of the outboard braking computer and it's somehow delayed enough that the trailer CHUNKS.
It's strange because it happens at the EXACT same spot in the braking process EVERY time. There's about 1 inch of brake you can VERY lightly apply, but ANYTHING over that and BAM, HARD CLUNK.
It does sound like it's the trailer running into the ball on the van. because it jerks the van forward then back quickly.
It's ALWAYS worse when the brakes are very hot too. Like after being on the highway for a long time. You don't use them out there, but when you're back in town, ohh mama you have to be SO careful.
