The product, once installed, is good compared to other flapper systems I've repaired in the past. I am not a plumber, but I do all my home repairs if at all possible, and I would say that I am as experienced with repairing and installing toilets, faucets, shower fixtures, water heaters, etc., as most DIYer's. I had no hesitation whatsoever in attempting to replace the Kohler flush valve kit on a Santa Rosa model toilet. The old kit came out with no problem. The new kit had me frustrated and cursing. I followed the tip of lubricating the gasket with cooking oil, and while I'm sure that is helpful, the problem I had was not related to friction; rather the gasket could not be compressed enough to allow the plastic tabs that hold the unit in place to get below the thickness of the tank. It could be that this particular model has a different thickness than some of the others that have been reviewed here. To figure out exactly what I was up against, I used a digital caliper to make some measurements. The thickness of the tank at the opening is 9/16". The thickness of the gasket is the same: 9/16". The distance from the bottom of the flush valve (the part that sits on top of the gasket) to the top of the tabs that go under the tank opening to hold to unit in place is 13/16". In order to be able to be able to install it, the gasket has to be compressed from 9/16" to less than 1/4" thick. I contacted Kohler support, armed with this information, and talked to someone who was not familiar at all with the issue. After putting me on hold for a few minutes, she came back with the recommendation to soak the gasket in hot water for 5 minutes (the complete opposite of the freezer tip read elsewhere in these reviews). It made sense to me though, and I thanked her and promised to call back if I was still having trouble. It did not work. I first used hot tap water, and that didn't make a difference in the pliability of the gasket. Then I heated water on the stove to 180 deg F, and that didn't work either. I did another web search and pulled up a review where the gasket was first compressed, then put in the freezer. That also made sense to me. So I went down to my workshop and cut two pieces of plywood just big enough to put the gasket between, protected by some butcher paper, and clamped it into my bench vise. I was really surprised at how much pressure I had to apply in order to squeeze it down to less than 1/4". The gasket really didn't want to stay compressed and in order to keep it uniformly compressed, I had to use hand clamps at each corner. I put that entire assembly into the freezer overnight (it just worked out that way), and was able to finally get it installed with about as much difficulty as the average reviewer has expressed. I lubed up the plastic part where the gasket would make contact and put the frozen gasket in place. It began thawing out and decompressing shortly after I had the tabs hooked under the tank, but not fully rotated into position, so it was still somewhat of a struggle to get it completely rotated. By the time I did, the gasket was noticeably decompressed and I was able to hook everything up and fill the tank, thankful that there were no leaks. Thanks for reading through this. I'd be interested to know if anyone else has taken a measurement of the tank bottom at the opening. Please let me know if yours measures differently than 9/16".
