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Quick answer from a licensed plumber: The gasket is brand- and size-specific. American Standard names a kit per tank: 7381163-200.0070A for the Champion 4 Max, 738756-0070AP for the Champion two-piece, 7381147-200.0070A for every toilet on the 4000 tank, 7381426-100.0070A for VorMax. Kohler installs its GP51487 tank gasket on most two-piece toilets, and GP51487 is also its encapsulated bolt kit for the three-bolt tank connection. The universal makers exclude Kohler from their bolt kits and 3-inch gaskets (Fluidmaster 6102, Korky 480BP/481BP) and Fluidmaster excludes Gerber from its standard 2-inch gaskets. For everything else with a 2-inch flush valve, a Fluidmaster 6100/6102/6106 or Korky 2-inch gasket fits; 3-inch flush valves take the Korky 480BP/481BP or Fluidmaster 6110.
Most common fix: Fluidmaster 6100 universal 2-inch tank-to-bowl gasket for a standard two-bolt tank (Amazon-sold on September 25, 2026); American Standard and Kohler owners, use the brand kits in the table.
Step 1: Confirm It Is the Gasket
American Standard’s troubleshooting page puts the gasket first: “A toilet leaking between the tank and the bowl is usually due to a faulty tank-to-bowl connection.” Its most likely cause is “a worn-out rubber gasket. This gasket acts as a seal between the tank and bowl. Over time, it can deteriorate, crack, or become dislodged, causing leaks.” Second is loose or corroded bolts: “Gently try to rock the toilet tank. If you notice movement, the bolts need tightening. Be careful not to overtighten, as this could damage the porcelain.” Third, and rarer, is a crack in the china, which “usually require replacing the damaged component, or in some cases, the entire toilet.”
The kit you buy depends on the flush valve size and the brand, and American Standard says so: “To ensure the correct fit, please identify your toilet model before purchasing a replacement kit.” A 2-inch flush valve takes a standard 2-inch gasket; a 3-inch flush valve needs the larger gasket; and Kohler and Gerber tanks use their own gaskets, which the universal makers call out by name.
Step 2: Match the Gasket to the Brand
| Toilet | Part the maker names | What is in it (maker) | Notes |
|---|---|---|---|
| American Standard Champion 4 Max (2586 / 231AA) | 7381163-200.0070A EZ Install Tank To Bowl Kit | “the tank-to-bowl gasket, tank grommets, and the easy-install handle kit with washers and nuts” | FAQ 168 keywords add tank 4215A |
| American Standard Champion 2-piece | 738756-0070AP Tank to Bowl Coupling Kit | “one gasket, two hex nuts with washers, two coupling bolts, and two tank grommets” | Install steps in FAQ 707 |
| American Standard tank 4000 (Cadet, Studio, Estate, Touchless) | 7381147-200.0070A Activate Tank to Bowl Coupling Kit | “Despite the various versions of toilets such as the Cadet, Studio, Estate, and Touchless toilets, the toilet tank model 4000 uses the Activate Tank to Bowl Coupling Kit” | Amazon titles it the Cadet 3 concealed trapway repair kit |
| American Standard VorMax two-piece | 7381426-100.0070A VorMax Tank-to-Bowl Gasket Kit | “the tool, two washers, two nuts, and two gaskets” | Not found as an American Standard listing on Amazon on September 25, 2026 |
| American Standard Yorkville pressure assist (tank 4098) | 047218-0070A | Pressure Assist Toilet Gasket for Flushmate | FAQ 844; the 4142 EverClean pressure-assist tank uses the 730599-0070A close coupling washer |
| Kohler two-piece (most) | GP51487 tank gasket / encapsulated bolt kit | Kohler’s video installs “the tank gasket (GP51487) and toilet tank on most KOHLER two-piece toilets”; “The encapsulated bolt kit part number is GP51487.” | For the “triangular three bolt tank to bowl connection” |
| Kohler (other) | K-1070291 Gasket Kit | Kohler’s part page lists no toilets by name | Confirm on Kohler’s parts diagram for your model |
| Any 2-inch flush valve, standard tank | Fluidmaster 6100 gasket, 6102 gasket + 2 bolts, 6106 gasket + 3 bolts; Korky 2-inch | 6100: “fits most close-coupled 2” flush valve models”; 6102: “Not for use in Gerber and Kohler toilets” | 6100: “Not for use in Gerber toilets, hardware sold separately” |
| Kohler or Gerber 2-inch, universal route | Fluidmaster 2602G-008 Universal Tank-To-Bowl Gasket System | “Use just the red gasket for most standard 2″ flush valve toilets, use the black gasket for Kohler specific 2″ flush valve model toilet, and combine both to fit Gerber specific 2″ flush valve model toilets.” | No buy box on Amazon on September 25, 2026; not linked |
| 3-inch flush valve (not Kohler) | Korky 480BP gasket / 481BP kit; Fluidmaster 6110 (Cadet 3) | Korky: “FITS MOST 3-inch, 2-piece toilet tanks (excluding Kohler)” | Fluidmaster lists the 6110 as “3 In. Tank-To-Bowl Gasket For American Standard Cadet 3 Toilets” |
The American Standard numbers matter because the same brand uses different kits by tank. Its FAQ answers are model-specific: the Champion 4 Max gets the 7381163-200.0070A, a Champion two-piece the 738756-0070AP, and every toilet on the 4000 tank the 7381147-200.0070A. Find the four-digit tank number inside the tank (our American Standard fill valve guide covers where it is stamped) before ordering.
I send an occasional note when a new guide goes up — repairs worth doing yourself, and the parts that actually last. No spam, no course funnel; written by a licensed Georgia plumber.
Step 3: Universal Gaskets, and Who They Exclude
Fluidmaster is specific about fit. The 6100 is “a universally designed toilet bowl gasket that fits most close-coupled 2” flush valve models,” with a “Universal fit for close-coupled toilets with round, or hex shaped flush valve nuts,” but “Not for use in Gerber toilets, hardware sold separately.” The 6102 adds hardware (“Stainless steel bolts to resist rust and corrosion (5/16” x 2 3/4” length)”) and is “Not for use in Gerber and Kohler toilets.” The 2602G-008 is the one that covers those two brands, with two gaskets in the box: red for standard, black for Kohler, both together for Gerber. Korky draws the same line on its 3-inch parts, which “Does NOT Fit Kohler.”
Universal parts, all Amazon-sold on September 25, 2026 (the Fluidmaster 6102 showed only a few left and the 2602G-008 had no buy box, so neither is linked):
- Fluidmaster 6100 universal tank-to-bowl gasket, 2-inch — gasket only.
- Fluidmaster 6106 2-inch tank-to-bowl gasket with 3 bolts and hardware — for three-bolt tanks.
- Fluidmaster 6101 tank-to-bowl bolt kit — bolts alone, 2 3/4-inch.
- Korky standard 2-inch tank-to-bowl gasket.
- Korky 481BP large 3-inch tank-to-bowl gasket and hardware kit or the Korky 480BP 3-inch gasket alone — both say they do not fit Kohler.
Step 4: Install It the Way the Makers Say
American Standard’s Champion sequence works for most two-bolt tanks: “Insert Grommets: Push the two black grommets into the holes located on the bottom of the tank. Insert Coupling Bolts: Insert the coupling bolts down through the installed grommets. Position Gasket: Place the large gasket onto the large flush valve nut. Mount Tank: Carefully position and install the tank onto the toilet bowl.” Then the nuts: “Tighten the nuts alternately to ensure even pressure and a secure fit between the tank and bowl,” and the check: “The tank should be flush against the bowl with no gap. Check for stability by gently wiggling the tank; there should be no movement.”
The one thing that ruins a new gasket is turning the bolt instead of the nut. American Standard: “Tank bolts should be held in place from the top, and the nut should be tightened from under the tank. Turning the bolt inside the rubber grommet can damage the grommet, resulting in a leak at the tank bolts.” Its tightening procedure: hand-tighten first, then “Using a deep-well socket or wrench, tighten the nut on the right side a little (e.g., a quarter-turn). Then, tighten the nut on the left side by the same amount. Continue alternating between the bolts. This ensures even pressure on the gasket and prevents the tank from tilting.”
Kohler’s Three-Bolt Tanks
Many Kohler two-piece toilets hang the tank on three bolts in a triangle, and the universal makers name Kohler as an exception to their standard kits. Kohler redesigned that hardware: “The bolts for the triangular three bolt tank to bowl connection were redesigned,” and its note says “The encapsulated bolt kit part number is GP51487.” That is the same number Kohler’s installation video uses for “the tank gasket (GP51487),” so on a three-bolt Kohler, one kit is the gasket and the bolts. If your Kohler parts diagram shows the K-1070291 gasket kit instead, buy that; Kohler’s page for it names no models, so the diagram for your toilet is the authority.
FAQ
What tank-to-bowl gasket does an American Standard Champion use?
The Champion 4 Max (2586 / 231AA) uses the 7381163-200.0070A EZ Install Tank to Bowl Kit, and the Champion two-piece uses the 738756-0070AP coupling kit, per American Standard’s FAQ. Toilets on the 4000 tank (Cadet, Studio, Estate, Touchless) use the 7381147-200.0070A instead.
What tank-to-bowl gasket does a Kohler toilet use?
Kohler’s installation video installs the GP51487 tank gasket on most Kohler two-piece toilets, and Kohler says GP51487 is also the encapsulated bolt kit for its triangular three-bolt connection. Universal makers exclude Kohler: Fluidmaster says the 6102 is not for Kohler and Korky says its 3-inch parts do not fit Kohler; Fluidmaster’s 2602G-008 includes a black Kohler gasket.
Do 2-inch and 3-inch toilets use the same tank-to-bowl gasket?
No. Fluidmaster’s 6100 and 6102 are for 2-inch flush valve toilets; Korky’s 480BP and 481BP and Fluidmaster’s 6110 are 3-inch gaskets. Look at the flush valve opening in the tank before buying.
Why does my toilet still leak between the tank and bowl after a new gasket?
American Standard names loose bolts or damaged bolt grommets as the second cause, and warns that turning the bolt inside the grommet damages it. Hold the bolt from the top, tighten the nut from below, alternate sides a quarter-turn at a time, and if the china is cracked at a bolt hole, American Standard says the cracked piece, or in some cases the whole toilet, needs replacing.
How tight should toilet tank bolts be?
Hand-tight, then a little at a time alternating sides until the tank is flush against the bowl with no gap and does not move when wiggled, per American Standard. Do not overtighten; it can damage the porcelain.
Why Trust Plumbing Picks
Plumbing Picks is written by a licensed Georgia journeyman plumber. Every part number, model list, size, setting and fit on this page comes from the manufacturer pages and documents listed below, which we opened and read; product details come from those makers and from the Amazon listings, not from hands-on testing. Each linked product was shipped or sold by Amazon, new and in stock, when we checked on September 25, 2026. Where a link goes to Amazon we may earn a commission at no extra cost to you. Nobody pays to be included here. More on who writes this and how we pick.
Sources
- American Standard: What causes a toilet to leak between the tank and bowl? (FAQ 230)
- American Standard: Champion 4 Max Tank to Bowl kit part number (FAQ 168)
- American Standard: Installing the Champion tank-to-bowl kit 738756-0070AP (FAQ 707)
- American Standard: Tank-to-Bowl kit for toilet tank 4000 models (FAQ 205)
- American Standard: VorMax Toilet Tank to Bowl Kit part number (FAQ 169)
- American Standard: Tank-to-bowl gasket for the Yorkville pressure assist tank 4098 (FAQ 844)
- Kohler Assist: Two-Piece Toilet Tank and Gasket Installation (video, GP51487)
- Kohler Assist: Encapsulated Bolts for Three Bolt Tank to Bowl Connection
- Kohler: Gasket Kit K-1070291
- Fluidmaster: 6100 Tank-To-Bowl Gasket, 2″ Flush
- Fluidmaster: 6102 Tank-To-Bowl Gasket & 2 Bolts, 2 3/4″
- Fluidmaster: 2602G-008 Universal Tank-To-Bowl Gasket System
Bottom Line
Rock the tank, then look at the flush valve size and the brand. American Standard: kit by tank number. Kohler: GP51487, three bolts. Everyone else: a 2-inch universal gasket, or a 3-inch Korky for 3-inch flush valves. Hold the bolt, turn the nut, alternate sides, stop when the tank sits flush and does not move.