T50 roundhead bolt Mashed up how to extract?

Wig

This is a Corsa rear seat/seatbelt mounting bolt. It is a pan head screw (round head bolt) and has a T50 recess. It is so tight, that the T50 is now stripped out. Maybe an M8 thread. Looks like this here http://www.fairburyfastener.com/torx_sizing_guide.htm

By the way I reckon the T50 is too small for it, but the T55 was too big, and there are no other T51, T52 T52 T54 in Torx standards AFICS,
I am, however, looking on internet for 51 52 53, I think 54 would be too big.

The round head has a diameter of about 18-20mm

!!!!!! am I going to use to get this out? Maybe weld something to it but that's my last resort.

If I get it out I will be replacing it with a Hex head.

I dont think using pipe wrench will do anything it is so tight in there.
I would apply heat if I had an oxy acetylene torch, but I don't,

Rubidium

Assuming that you can gain access to the round head, grind some flats to enable the use of a spanner.

Wig

I got a Ribe set so I'm going to try a ribe bit, hammerring it in if necessary.

Trouble is my computer (internet access) is here, as are the ribe bits, and the car is 20 miles away.. So I'm going back soon with my ribe bits..

I do have good access, and grinding some flats on might be possible.

http://www.ebay.co.uk/itm/281819678294#ht_1265wt_974
Does not have a T50 size and seems to be a lightweight design with a drill.

ohreally

Wig wrote: »

!!!!!! am I going to use to get this out? Maybe weld something to it but that's my last resort.

This, job done.

Lomast

In this situation i usually resort to cutting a slot with 1mm cutting disc on the grinder and use a large flat head screwdriver and mole grips

atrixblue.-MFR-.

I would grind some flats in and try that, if that fails weld on a bolt and socket it off.

forgotmyname

Grind the flats add some glue and hammer an allen key into the hole also
with the glue and tight fit you should be able to remove it fairly easily.

I have a battery powered arc welder which is ideal for little tasks like these.

s_b

you dont say which bolt in rear belt
if its in the wheelarch then clean the exposed threads oil and weld a nut on the bolt head with a view to extraction whilst still warm whilst an accomplice makes sure heat doesnt affect fuel lines
if its a bolt on the floorpan and underside is covered by fuel tank that might be plastic depending on age then oxy or miggy is a no no as its too easy to cause an explosion
tank needs to come out

Marktheshark

last resort is to cut the head off, whats making it tight is then gone and you can spin it out with a screwdriver.

s_b

Marktheshark wrote: »

last resort is to cut the head off, whats making it tight is then gone and you can spin it out with a screwdriver.

how would that work?
if hes ruined the the head because the fastener has slipped then it still says its tight
as its probably a bolt exposed to the elements on the underside its probably picked up rust/ detritus and even a dead pigeon,even i would struggle here as bolts get tighter and tighter as they come out even if using air tools and proper sockets ribes or big hammers

Marktheshark

Depends if the base of the bolt has hit a dead stop, but it is the compression of the head of the bolt hitting the neck of the hole which creates the torque that stops it moving.
Place a nut over a bolt and twist it, you see that you can move either the bolt or the nut freely until it hits the nut and you apply some compression.
So by removing the head if the bolt is not rusted in you can simply spin out the thread.
If its a open thread you can spin it out as opposed to back up so its clean metal.