Can toto ultimate upgrade to ultramx via fill vavles replacement?

[justthinking]

I got a couple of the toto g-max fill vavles kits from the flea market the other day.
I used one to fix my leaking toto ultramax, and I was wondering will this g-max fill valve fit onto a toto ultimate?
If I do the swap, will that be all the work required or do I also have to change the flush valve too?

[jadnashua]

The fill valves are likely interchangable, not sure about the flapper valve. On many of the Toto's one uses a blue one and the g-max uses the red one. Using the red one will DECREASE the amount of water that gets used in the flush, so it might make the flush worse. The red ones are designed to close faster (because of the hole you can see in the lower part) than the blue ones.

[SamC]

We need Terry's expert input here. To the best of my knowledge, the Ultimate and Ultramax are the same pottery, but the parts inside are different. As you said, the fill valve is different. The flush valve in the Ultramax is the red G-max flapper with the hole in the side of the cup for earlier closing. The reason the flapper can close earlier and still pass 1.6 gallons is that the water is higher in the tank of the Ultramax, raising the head pressure. This would also mean the overflow tube is taller in the Ultramax. So it MAY be possible to turn an Ultimate into an Ultramax by changing all the tank parts. Terry?

[Reader Review]

If you raise the water level, by changing the flush valve, the G-Max has a higher overflow tube, and comes with the quicker closing Red Flapper, and raise the fill valve setting, then the increased head pressure will be like that of the G-Max Ultramax.

I had the Ultimate installed for over a year in one home, and it worked fine though.