Kohler GP1078441
Score: 85/100
Kohler 1138648
Score: 75/100Rankings
The Kohler GP1078441 is a genuine OEM replacement flapper designed specifically for Kohler two-piece toilets featuring Class Five flushing technology. Its key strength is the precise 3.25-inch rubber seal that effectively prevents phantom flushes and maintains high-efficiency performance. However, it is incompatible with non-Kohler models and may degrade faster in hard water environments.
The Kohler Genuine Part 1138648 Flapper Assembly is an OEM replacement component designed for Kohler toilets, specifically compatible with two-piece models manufactured prior to 2004 that utilize a 2-inch flapper design. It controls water flow from the tank to the bowl and is constructed from durable, chemical-resistant materials to ensure optimal performance and warranty protection. This part is essential for routine maintenance and DIY repairs on compatible units like the San Raphael K-3722.
| Attribute | | |
|---|---|---|
3.25 inchesbest | 2 inches | |
1 countbest | 1 countbest |
Click an attribute name to sort · Green = best, red = worst (relative to this comparison)
| Attribute | | |
|---|---|---|
Material & Durability(2) | ||
Material | Rubber | Chemical-resistant |
Seal Type | Rubber | null |
Design & Features(3) | ||
Chain Material | Standard | null |
Installation Type | Direct Replacement | Direct replacement |
Flapper Type | Standard Flapper | Flapper Assembly |
Packaging & Support(1) | ||
Warranty Period | 1 Year Limited | null |
Compatibility & Fit(5) | ||
Flush Valve Compatibility | Kohler Class Five | null |
Flapper Diameter (inches) | 3.25 inches | 2 inches |
Toilet Type Compatibility | Two-Piece | Two-piece |
GPF Compatibility | 1.28 | null |
Flush Valve Size | 3.25 inch | 2 |
Products in the top-left offer the best value (high score, low price).
Plumbing experts and editors from sites like Ferguson and CPE Supply highly recommend this part as the definitive OEM replacement for Class Five systems. They highlight its precise 3.25-inch seal as critical for preventing phantom flushes and its durable rubber construction for resisting corrosion.
Everyday consumers generally report high satisfaction, with many noting that the flapper perfectly fits their Kohler models and restores the toilet to like-new flushing performance. Common praise includes the ease of installation and the elimination of running toilet noises.
“Perfect fit for my Kohler Cimarron-flush like new!”
“No more running toilet; lasted 2 years in hard water”
“Installed in 2 minutes, chain included.”
No independent professional reviews, editorials, or expert analyses from recognized plumbing authorities or consumer reports are available in the source data. Retailers and Kohler's service pages describe the part positively as an essential component for reliable flushing and meticulously designed for performance, emphasizing its OEM quality.
There is a complete absence of consumer reviews, ratings, or testimonials in the available data. One listing explicitly notes zero customer reviews, making it impossible to identify common praise, complaints, or recurring themes from everyday users.
