Back in the shop today, my B190 Brooks saddle keeps rotating pitch wise going nose up at every bump in the road of late. Standard hardware, view stock photo.
https://www.brooksengland.com/en_us/b190.html
The seat post clamp and angle adjustment is inside the 6mm frame wires and on the outside are just1mm washers and 8x1 nuts. The torsion exerted on those puny 1mm washers overcomes the retention force of the stamped serrated adjuster bits of the seat post clamp.
I tried thicker 4140 washers with the same results.
So something has to change, Brooks has had this problem for some time. How long I do not know as I am going on anecdotal evidence, but mine is empirical.
The outside frame washers cannot take the strain put upon them.
This is my first attempt. Material, 7075-T6 aluminum. Dimensions per piece, .5x1.26x1.89. Two needed, one for each side. After squaring my block, I used a .062" slitting saw to separate the two pieces I needed conventional feed by hand. Using WD40 for lube. Two parts parted off.