Here are the two of the four threaded knobs holding the box onto the rack. The front two are 8mm bolts and the rear two are 6mm bolts. The only reason for the difference is this is what the hardware store had in stock. On this rack, all of the hardware is either stainless or aluminum to minimize rust. I mention this as removing the stock hardware was a hassle requiring generous doses of PB Blaster. I think rusty hardware is the norm for any Ural. About all that's left is covering the unused mounting holes. Instead of Gorilla tape, I may use the Eternabond roof repair tape. That stuff seems to stick to anything and never come off.
After the knobs are tightened, the box is really solid. And the positioning is just about right to lean against while riding. For the last couple of months, I was trying to figure out how to fabricate a rack with the stock bench seat and every solution I came up with would either put the top box too far back or too high. This seems like a good solution as the box is centered directly over the rear hub. I had considered getting a solo seat from Raceway or Ural of New England but they were way too pricey. Their seats are probably more comfortable since they have spring suspensions but we’ll see how this works. Some people complain about the Ural tractor seats but not everyone.
After the knobs are tightened, the box is really solid. And the positioning is just about right to lean against while riding. For the last couple of months, I was trying to figure out how to fabricate a rack with the stock bench seat and every solution I came up with would either put the top box too far back or too high. This seems like a good solution as the box is centered directly over the rear hub. I had considered getting a solo seat from Raceway or Ural of New England but they were way too pricey. Their seats are probably more comfortable since they have spring suspensions but we’ll see how this works. Some people complain about the Ural tractor seats but not everyone.
The lock on the top box is a generic key so I may replace it with something more secure such as the same key as the trailer compartment doors. I think that I may still have one left. And I will probably start riding again next week!