The Lotus Grand Tourers

You mean it's a single threaded tube running to the bolt for the passenger side catch? I wonder why it has seized then!

Yes. They seize because the tube is often poorly sealed against water ingress between the body and transmission tunnel.

Pete

well I have a broken drill bit in the broken bolt.. and the bolt on the other side has broken! I am however close to getting the drill out using an 8mm diamond coated hole saw.. however progress is slow

Just think how good it will feel when you get them out!!

Pete

Well the bast%&d drill is out.. and I have run drills to 9mm through, and I’m not seeing any threads yet.. question is what would the next size drill be to use.. or is it worth trying a tap (with the attendant risk of it snapping!)

I also have a broken bold on the passenger side, but I may try putting plus gas the now open end and sealing the hole and hope that frees it off and it can be wound out…

Well technically the minor diameter of a 7/16" UNF female thread is 9.74mm, so I'd go to 9.5mm and assuming you're not drilling in the absolute centre you should start seeing some evidence of threads. Hopefully you'll then be able to dig the rest of the bolt out.

Keep going!!

Pete

My eye must be good.. 9.5mm and still no sign of the thread.. except a short bit I pulled out with pliers, however examination with a USB borescope still shows no threads inside the hole.. anyway.. 25/64ths next..