Without the U-channel and clips, you run the risk of the sink lip not being/staying sealed to the countertop and a leak developing.

@HU-178658043 - agreed running a risk. Considering these clips as an alternative to U-channel clips to secure...

https://www.directdiamondtools.com/sink-mounting-accessories/1378-lc-bracket.html

I replace sinks for a living and don't know what a "U-channel" is for mounting a sink. Are you talking about the clips? If you can't unscrew them, drive a stiff scraper between the stone bottom and the sink flange into them and they will fail. If they are Sinkits, tap them off the flange and they will lose their bind on the flange and fall out. Don't do this before you run a pipe clamp through a 2x4 mounted on the top and secured to the bottom of the sink though the drain hole. You don't want a cast iron sink falling on your plumbing.

Secure your new sink with a Hercules Universal Sink Harness or a Sink Strap or two, please. No push-'em-ups. Like clips, they leak.

@Joseph Corlett, LLC By "U-channel" I meant the metal channel used to hold the clips. I'm trying to replace a cast iron with stainless and these channels interfere with the hole I have in my cabinet so the question is - are these clips really necessary to tie down a stainless steel sink? Or could I grind these channels off and just do a good silicone (and maybe Sinkits or your other suggestions). Or is this just a bad idea? Will the stainless sink pop up at a later date?

Okay, you're talking about a top mount (drop-in) sink. Excuse me for thinking you were replacing an undermount with an undermount.

I've replaced top mounts where I couldn't get access to all the U-channel and clips. As long as the sink lies nice and flat and you get a good bead of silicone underneath, you should be fine. I've never gotten a callback.

If you've got a grinder, put in a diamond blade, put on your PPE, open your widows, and with your wife manning the spray bottle and/or shop vac, enlarge your sink cut out to accommodate the U-channel.

I agree a drop in sink will be fine without the clips.

Did you find a way to remove the U-channel? I have the same problem with the cutout being too small. Trying to decide whether to forego stainless and go with a granite sink that does not have this issue.

The consensus was not to do it - possible discoloration from heat from the Dremel. I wasn't too concerned about not having the tie-downs, I thought a good silicone bead with weighing it down to dry would be ok. I ended up with a nice single bowl porcelain from Kohler and couldn't be happier.

HU:

Don't remove the U-channel please. What is your top made of please? Enlarging a cutout isn't a big deal.

Wrote this once before signing up. Guess I have to start over....

So we got a new granite countertop (Monday morning) as our laminate one was falling apart. Planned to put our own sink back in to save on costs. We got it out the day before with much tribulation due to rusted clips and U channels. The countertop installers cut the hole for our old sink. But we had decided last night to replace that old sink. Found one the sane size and type at a good price to pickup Monday afternoon. So our new sink wasn't here for the installers. To our dismay, the new sink will not sit flush in the hole. The U channels must sit in a different place than on the old because they don't all fit in the hole. I didn't measure front to back but I did measure width. The hole is just under 32" wide and the outside of the U channels are just over 32" wide. So it doesn't fit. I figure, from reading the comments here, that we have 4 choices. 1) See if installers will come back out and enlarge the hole. 2) Figure out how to do it ourselves. (Granite?!) 3) Remove 2 U channels (I figure back and right side). 4) Return the new sink and reinstall the old one without clips.

Pay the installers a trip charge to rnlarge please.