Generic white and brass faucet cartridges, O-rings, grease, pliers, wrench and hex keys laid out on slate

Faucet & shower cartridges

Kohler shower cartridge (Rite-Temp) parts

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Quick answer

Kohler's common Rite-Temp pressure-balancing valve (K-304) doesn't take one Moen- or Delta-style cartridge. It has two service parts: a mixer cap and a pressure-balancing unit (Kohler also calls it the PBU or regulator).

Rite-Temp K-304 service parts (Kohler)

Part	What it is
GP77759	Mixer cap (Rite-Temp pressure-balancing mixer cap)
GP500520	Pressure-balancing unit (PBU)
GP76851	Mixer cap and PBU kit

Kohler's GP77759 page says the mixer cap works with many Kohler trim collections, naming Memoirs, Fairfax, Rite-Temp, Revival, Bancroft, Stillness, Forte, Purist and Coralais.

Where to buy: genuine part from Kohler.

Kohler GP77759 on kohler.com

Kohler's install cautions

Shut off the water before you start.
Before removing anything, note where the cap's tab or the word "UP" points.
Pull the PBU with pliers. Clean any debris or brass burrs out of the valve body. Kohler suggests 50/50 white vinegar and water, and a Scotch-Brite pad for burrs, without scratching the surfaces the seals sit on.
Put new small O-rings on the back of the PBU, with silicone lubricant to hold them in place.
Line up the tab inside the body with the notch on the PBU, and press the PBU in straight. Kohler warns that tilting and rotating it moves the small O-rings and makes the valve leak.
Line up "COLD" on the regulator with the cold inlet.
Fit the black cap assembly first, with its tab at 12 o'clock, then the metal collar and screws. Never put the collar on before the cap.

Not sure it's a K-304?

Kohler publishes an interactive "Identifying Single-Control Shower Valves" guide (linked in Sources) that walks through its valve families. Use it before ordering. Kohler has made several single-control valves, and we have only covered the Rite-Temp K-304 here because it's the one we could document from Kohler's own pages.

Questions people ask

How do I adjust the temperature on a Kohler Rite-Temp valve?

Kohler's steps for K-304 valves: remove the handle and trim, then take the black O-ring, caution tag and red collar off the brass stem (older valves have a black collar). Turn the stem clockwise to run the water and check it with a thermometer. At the maximum you want, refit the collar, turn the water off and reassemble. Kohler says never to set it above 120 °F.

What's the difference between the GP77759 and the PBU?

They are two separate service parts in the same Rite-Temp K-304 valve. GP77759 is the mixer cap. GP500520 is the pressure-balancing unit (PBU), which Kohler also calls the regulator. Kohler sells both together as the GP76851 kit. Note where the cap's tab or the word "UP" points before you take anything apart.

Why does my Rite-Temp leak after I replaced the PBU?

Kohler's most likely cause is that the PBU went in crooked. Press it in straight with its notch on the tab inside the body. Kohler warns that tilting and rotating it moves the small O-rings on the back and makes the valve leak. Also line up "COLD" on the regulator with the cold inlet, and fit the black cap before the metal collar.

Sources

Fetched and checked 2026-10-21. Part numbers change; confirm against your own valve and the maker before buying.