Technical Roof stud snapped - help!

[brom]

Hi,
My 2009 Doblo MPV has three pairs of roof mountings for bars/rack. It's a long time since I have fitted bars, but I need to transport a canoe, so I found the bars, and remove the roof studs from the car, in order to fit the bars.
I was very gentle, as I know how flimsy these studs can be...
Three came out easily. The fourth, as always, didn't. Little initial resistance; the shaft just snapped, level with the roof, just below the head.
These studs are very thin.
Any ideas on how to remove the broken stud, without destroying the thread in the roof? If not, that b.....s up using roof bars on this car, forever.
Any suggestions most gratefully received.

 

[the green vanper]

Use penetrant oil (I'm using cyclo break away, works miracles), leave for a day or two, you can reapply in the meantime, then weld a thin bolt and unscrew.

 

[brom]

Thanks. I've just sprayed some GT85 on it. Doesn't help that it keeps raining! But when (if!) it ever stops, I'll reapply. I'll have to get my trusty local garage to do the welding, though, as I don't have the kit or the expertise.

 

[brom]

Update - turns out those flimsy roof studs are made of PLASTIC! Therefore, it's easy to drill them out, and once that's done, you can screw in the roof bar bolts. Had the broken stud been steel, it might have been a very different story...

 

[the green vanper]

WOW. In fact I haven't thought about such possibility, even though I used the same method in my daily to protect the mounting holes for my bike rack

Next time before placing them lubricate them thoroughly to prevent similar problems in the future.