The new seal kit and the replacement brake pistons arrived! I had spent some of last night cleaning the caliper as best I could.
I initially attacked it inside and out with WD-40 and a soft brass brush. This would be an awful idea if I had not followed that up with a wipe down and then a second cleaning pass with CRC Brakleen. The residue that WD-40 leaves behind is a good protective cover for things that are left in the open air, but it’s just another bad contaminant on the insides of a caliper. However, it’s cheap and does a really great job as a “first pass” for getting rust, grit, gunk, and grime broken up and out of the way. The Brakleen pass then gets rid of any leftovers contaminants, and removes the WD-40’s residual lubrication. The result is a pair of brake cylinders that are clean and dry and ready for their new seals and pistons.
On a side note, I use WD-40 on the chain of my TU250x in a similar fashion – as an initial cleaning pass. It’s inexpensive, readily available, and gets grime out of the way. I always follow that up with a wipe-down and an application of a proper Teflon-based chain lubricant though.
I installed the new seals, and took special care to ensure that the inner seal was right-side-up. There’s a very fine lip that needs to be towards the inside of the brake cylinder, else when under pressure the brake fluid will force its way out past the piston. The dust seal isn’t as finicky.
Then it was just a matter of wetting the new pistons in clean brake fluid and pressing them carefully into their cylinders, taking care not to damage the seals on the way in. I closed up the drain screws on the caliper, and attached the new brake line.
I’ll remove the existing controls from the drag bars and move them all over to the new EMGO bars in the near future, and from there I’ll be in position to fill the and bleed the brake line and see whether things have improved. I’m pretty darn certain that they will have.
It seems that we live in a new golden age for the hobbyist mechanic. YouTube has been invaluable in providing education regarding the function and repair of the brakes, and Amazon and eBay have been an extraordinary resource in obtaining replacement parts. A person need only be possessed of the appropriate will, some basic tools, and an internet connection, and they can repair a wide variety of mechanisms with confidence.