Kohler Class 5 3″ Toilet Flapper

The Kohler Class 5 flapper fixes a leaking toilet with a part specifically engineered for Kohler’s high-efficiency Class 5 flushing system. This 3.25-inch (3-1/4”) flapper is designed for 3-inch flush valves, and that quarter-inch difference matters. Standard 3” flappers often do not fit because the Kohler Class 5 requires an exact 3-1/4” seal diameter.

Worth it for contractors who service Kohler toilets regularly. The snap-on installation makes for quick DIY replacement, and users praise the ease of installation and the fact that it immediately stops leaks. Skip it if you’re looking for the longest warranty — Korky alternatives offer a 5-year warranty versus Kohler’s standard 1-year limited warranty for service parts.

The 3-1/4 Inch Requirement

Here’s what catches contractors: Kohler Class 5 toilets don’t use standard 3-inch flappers. They need exactly 3.25 inches. That’s not a suggestion — it’s an engineering requirement. The oversized seal provides superior coverage of 3” flush valves, and without that extra quarter-inch, you’ll chase phantom leaks all afternoon.

Kohler Class 5 (Class Five) toilets only use this specific size. Compatible models include Cimarron, Memoirs, Bancroft, and Devonshire. Write those model names down. Customers rarely know their toilet model, but they’ll recognize these names from the tank casting.

Specification	Value
Flapper diameter	3.25 inches (3-1/4”)
Flush valve size	3 inches
Material	Chlorine-resistant red rubber or corrosion-resistant plastic
Chain	Stainless steel
Weight	2.4 oz

That red color isn’t decorative. Red color provides easy identification as a Class 5 component. Kohler color-codes their parts, and experienced plumbers know red means Class 5.

OEM Numbers and Aftermarket Options

Kohler uses multiple part numbers for essentially the same flapper: GP1078441, GP1039444, GP1067183, 1016546, 1042313, GP1078440. Don’t let that confuse you — they’re all 3-1/4 inch Class 5 flappers. The different numbers reflect manufacturing runs and packaging variations.

The Korky alternative deserves consideration. Korky 3010, Korky 3010BP, and Korky 3010CM work as direct replacements. The Korky 3010 is a common ‘made in USA’ alternative with a 5-year warranty, often preferred over the standard 1-year OEM warranty. Five years versus one year — that’s a real difference when you’re standing behind your work.

Montana’s hard water beats up toilet parts faster than manufacturers expect. The materials resist chlorine and hard water treatment chemicals, which matters in communities treating aggressive mineral content. Some users note durability concerns in extremely hard water, reinforcing why that 5-year Korky warranty looks attractive.

Installation Reality

Installation follows standard flapper replacement: shut off water and drain tank, remove old flapper from overflow tube ears, snap new flapper onto the ears, then attach and adjust chain to the flush lever. Takes five minutes if everything goes right.

Some users note that the chain may need slight adjustment. That’s normal. Every Kohler tank has slightly different geometry between the flush lever and flapper. Too much slack and the toilet won’t flush completely. Too tight and it’ll run constantly. Find the sweet spot with about half an inch of play when closed.

Included items: Flapper, Stainless steel chain, Hook. Everything needed for a complete repair comes in the package.

The verdict? This flapper does exactly what it’s supposed to do — seal a Kohler Class 5 flush valve. Reviews average 4.6/5 stars, with users praising easy installation, perfect fit, and effective seal. Just remember that quarter-inch difference. Standard 3-inch flappers won’t cut it, no matter how much silicone grease you use.

Frequently Asked Questions

Q: Will a standard 3-inch flapper work in my Kohler Class 5 toilet? A: No. Standard 3” flappers often do not fit because the Kohler Class 5 requires an exact 3-1/4” seal diameter. Using the wrong size flapper leads to slow leaks and phantom fills.

Q: What’s the actual difference between the Kohler OEM flapper and the Korky 3010? A: Warranty coverage. The Korky 3010 is a common ‘made in USA’ alternative with a 5-year warranty, often preferred over the standard 1-year OEM warranty. Both seal effectively, but Korky backs their product five times longer.

Q: How do I know if my Kohler toilet needs the Class 5 flapper? A: Compatible models include Cimarron, Memoirs, Bancroft, and Devonshire. Look for the model name cast into the inside back wall of your tank. If you see one of these names, you need the 3-1/4 inch flapper.

Q: Why is the Kohler flapper red instead of black like most flappers? A: Red color provides easy identification as a Class 5 component. Kohler uses color coding across their parts line — red means Class 5 flushing system.

Q: Can hard water damage this flapper faster than normal? A: Yes. Users report durability concerns in extremely hard water, even though the material resists chlorine and hard water treatment chemicals. Consider the Korky alternative with its 5-year warranty if your water tests above 10 grains hardness.