[Maintenance log] Razor-sharp edge? White GSX750S Katana! Precision rear caliper overhaul eliminates brake drag

It looks like rain is on the way for the next few days.
Are you prepared for it? Well, most people probably aren’t…

For those living in semi-basement apartments or garages in urban areas, during heavy downpours
you really should think ahead about “where to move your bike or car if things get bad.” It’s too late to figure it out once you realize it might be a problem.
If you’re renting a semi-basement garage in the city…
“definitely go for the second floor.”
Maybe second-floor garages will become more in demand going forward.

So today we’re doing a full rear caliper and master cylinder overhaul.

Limited-edition inspection certificate holders on sale for our one-year Chiba relocation anniversary (*´ω｀*)

Detailed request details

I looked up the WP suspension specs.

I set up the regulator with spare wiring just like the current setup.

I proposed and sourced a chain and sprocket.

Now let’s head to the main event (*´ω｀*)

The paint looks pretty tired.
Let’s quickly remove it and check.

Removed it quickly. I was impressed by how simple old bikes are!

The slide pin action is very poor.
The seal groove is in about what you’d expect (*´ω｀*)

The master cylinder is in pretty rough shape.
It’s the usual Nissin 1/2 size, but the later M6 fixed type.
I’m wondering if it would be cheaper to buy the assembly… that’s the moment you really think about it.

For now I want to strip the paint and then decide.

It looks like it’ll work, so we’re going for reuse and revival.

If it had been messier, we would have replaced it, but after stripping it was in good condition so we finished it.

It looks worse than it is inside, so I’m relieved.

The body is a bit worn but still good.
Tokico… if you could anodize it… not with wind-blown paint…

I also finished the axle area parts with Gun-Kote coating as requested.

Inspecting parts before assembly really boosts your confidence (‘◇’)ゞ

Single-piston caliper boots are really important—you should replace them every 2 to 4 years.
I just go ahead and replace them aggressively.
Unless you clean the slide pins until they move really smoothly, a single-piston caliper won’t work right.
Cleaning up the small plate parts too makes a huge difference in the finish.

This is the one that works.
By the way, even with 1/2 there are length differences, so be careful.
If you’re not sure what something is for and don’t have confidence, it’s safer to just replace the assembly.

By the way…
to be precise, the reservoir tank must show the fluid level or it fails inspection.
I do it on my own Inazuma 1200 too, but…
the front is easier to spot than the rear, so be careful.

I haven’t met an inspector that picky yet, but…
there are lots of aftermarket parts sold that don’t pass inspection, so watch out.

Mystery solid object in the shop

For the past few days, mysterious black chunks have been rolling around the shop.
Jet black like a lump of carbon, completely crumbly and mysterious.

Finally today I figured out what it was.

It’s you (*´ω｀*) I mean… a hub damper gets like this? It’s completely destroyed.
It’s unbelievable.


I scraped it off and cleaned it up.
The customer also requested bearing replacement with their own bearing, but the part number is different so it won’t work.
When the wheel was swapped, a different one was installed. I sourced the same size.

I installed a new damper temporarily and figured out what the mystery powder was…
Life doesn’t always go smoothly ( ；∀；)

To be continued