Terrifying rear-end collision, shrimp-bent GPZ900R repair. Swingarm overhaul, wheel bearing replacement, rear master overhaul, seat rail replacement

Now that Golden Week is over, logistics are finally getting back to normal.
Everyone, how’s the May slump treating you???

We can’t move forward until this GPZ is running smoothly.
Everyone, please bear with us!!!

I’ll keep hammering this point home “Closed Mondays and Tuesdays”

Used parts sourcing specialist (*´ω｀*)

Discontinued parts have to be sourced used.
I keep model years and condition specs locked in my head “Yahoo Auctions → Up Garage → Mercari”
endless loop.

In every case, “I wish they’d list things a bit more professionally.” That said,
I actually don’t hate listings from people who haven’t done much research and offer reasonable prices.

What I sourced were “seat rail/rear wheel/right step plate” three items.
The key is “treating it like it’s your own and checking it thoroughly”
That way you have fewer regrets.

I don’t do proxy purchases like this every time, you know.

The wheel turned out to be in absolutely pristine condition!

Once you remove the tire, everything becomes clear.
This was clearly maintained with great care.

No runout, minimal corrosion, paint is still vibrant—very good condition.

We also coat the inside of the wheel during tire replacement.
This Hyper Resin is the latest ultra-powerful shine chemical.

The painted surfaces become super glossy and look great even after wet blasting.

We swap the air valve to TR412.
Checking the wheel’s balance point alone often means you’ll need less balance weight.

We replace all the wheel bearings too.
The play in the wheel is pretty significant…

The distance collar probably won’t fall off completely,
but someone who hammered the axle definitely shifted it way off.
It’s a pain to do, so I didn’t bother with the distance collar adjustment—just mechanic’s rambling, don’t worry about it.

The oil seal looks good.
Similar to Honda’s design.
Single-lip, no spring, color doesn’t fall out, minimal sealing function.

Suzuki uses double-lip seals with springs on wheels sometimes.
I’m guessing those are actually engine oil seals?
You need to give it some initial break-in “or the iron wheel collar will wear down.”
Just rambling, don’t mind me (*´ω｀*)

Usually I use C3 for non-contact.
Wheel bearing replacement rarely produces dramatic changes unless things are really bad…

Rear wheel complete!

Now let’s overhaul the rear brake master

A lot of people have never overhauled their rear brake master—that’s actually pretty risky.
Since it’s Japanese-made, major problems are rare, but you want to keep your brakes in top shape.

This one wasn’t leaking, but about 80% of them have gunk inside the boots.
Plus, corrosion often builds up around the return port.

If it clogs, pressure won’t release and you get dragging and other issues, so watch out.

The cup umbrella shape is totally different.
The umbrella sits closed inside the master, so it naturally stays closed.

When pressure is applied, the umbrella opens—that’s the mechanism, so it resists leaking and seeping.
Basically, when it wears out and stays closed, you get initial softness in brake feel.
If the brake feels soft at first, that’s a red flag.

The rear master body got wet blasted
and the rod assembly was gun coated. *We disassembled, painted, and reassembled.

That looks amazing (*´ω｀*)
Better than new.

Overhaul the swingarm and linkage, then reassemble

Quickly wet blasted it to clean it up.

The step plate assembly also got wet blasted.
Really tightens up the look.

This bushing is also discontinued, which is a bit annoying.
But everything was in good enough condition to reuse, so I polished it and put it back to work.

The early model has reinforcement on the swingarm.

Interesting—didn’t know that.
We sourced a painted replacement and refreshed the bearings too.

Just having the rear on makes it look way more like a bike.
Since it’s a big component, there’s a real sense of progress… but honestly,
the fine details take way more time than expected.

At least now it can roll, and we’ve cleared out a lot of clutter.

By the way, Kawasaki really puts effort into this GPZ

You might not notice at first glance, but there are some tricky details.

From the front it looks like just a square tube.
But from the back, there’s a groove for the fender to fit into.
How did they even make that…? I was genuinely impressed (*´ω｀*)

There’s some debris, so I’ll cut it out. To be continued.