Removing old Frisone basin waste

[HairoftheDog1]

Hello
I am about to replace the basin waste in a bathroom. The old fitting is a Frisone pop up but I am unable to see how to remove it. All other basin wastes I have ever seen have a large 6 sided 'nut' that screws onto the fitting from under the basin and then tightens the whole thing in place. There is not one on either of the identical Frisone fittings that I have. There is simply the metal fitting (without any thread until the end 1/2" or so) that feeds through the plug hole which is covered with a rubbery washer tight to the bottom of the basin. Nothing to unscrew that I can see to enable removal.
Does anyone know how to remove the fitting?
Thanks

 

[Newboy]

If there's nothing holding it onto the underside of the basin then my guess would be that it's been bodged and glued in place with silicone or similar.

Edit - it's possible that a basin mate has been used but without the backnut - try unscrewing the big rubber washer

 

[needyahelp]

I know this thread is over 10 years old but ive just had a similar situation with my 20 year old bathroom basin plughole/rim. The plug in mine is Bensham but presents the same issue in that theres no backnut under the basin to unscrew from the plug rim, just a metal column under the basin that connects up to the plug rim. The column under the basin has an integrated rod and ball connected to it through a side tube to push the plug popup up and down, so you can grab this tube on the column when trying to twist it. The issue is the visible plug rim on top of the basin screws into the metal column that goes under the basin. Both pieces are metal and have corroded together so any normal force to twist the column just turns the plug rim as well. Ive seen posts suggesting sticking a screwdriver in through the topside plughole and into the overflow slots half way down the plughole and holding that fast whilst twisting the under column but this didnt work for me as the under colunm and plug hole rim were too corroded together and the screwdriver also chipped some of the ceramic that sits very close behind the overflow slots so beware. I eventually got it unscrewed by doing the following:
Removed the plunger rod and ball to make space under the basin.
Removed the popup plug
Removed the trap (i squirted some bleach down the plughole frst and gave it a while to work before flushing it through as removing the trap can be stinky!)
At this point you want to be sure the water supply to the taps has been stopped as theres no trap under there so you ( or more likely a member of your house absentmindedly turns on a tap!) could flood your bathroom if you accidentally turn them on.
Soaked the plughole with wd40 taking care to spray some through the overflow slots but between the ceramic and the metal as this goes down to the threads screwing the plug rim and metal column together, i also sprayed some around the plughole lip rim as this was a tiny bit loose with all the twisting so oil down there should also help uncease the threads.
Get a metal bar ( or something equally strong that wont snap when using it to twist the plughole) no more than 6-8 mm thick and only 1cm longer than the width of the plughole so that it can be placed resting across the overflow slots across the plughole (i cut a piece of threaded bar to size)
Get something that the small metal bar can be placed through and used to twist the metal bar when resting between the overflow slots. I used the end of a 12 inch adjustable wrench as it had a hole in the handle and the handle fitted down the plughole to where the overflow slots are.
With the wrench down the plughole and with the metal bar threaded through the wrench handle hole and sitting on the overflow slots i clamped the under basin column with water pump pliers and turned the under basin column one way and the adjustable wrench and plughole bar the other.
This actually didnt work as i had nowhere near enough strength or leverage to hold or even twist the wrench via the jaw end so i got a radiator spanner (looks like a massive allen key), clamped that in the jaws of the wrench and then slipped a length of metal tube (i used some scrap metal electric conduit tube about 2 or 3 feet long) over the radiator spanner to essentially create a long handle. This did the trick and plug rim and metal column ended their 20 year relationship and im now cleaning the basin up ready for a new plug and tap.

Hopefully the above gives some idea of what you can try if you have a similar problem.