I recently did one with an ratech spacer, I wasn't impressed. It came with a shim pack, which I also wasn't very impressed with. I had to reduce the size of the spacer also. I used a lapping table and just ran it in a figure 8 pattern by hand, which took a noticeable amount off quickly. I don't think that this would collapse easy at all, but I also wasn't impressed with the instructions which told me to tighten the pinion nut to 125 ft lbs, which seemed too low to me.