T50 roundhead bolt Mashed up how to extract?

s_b

Marktheshark wrote: »

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.

sorry too late on a long weekend for me that
i can only reiterate if thread on bolt gets dirt then dirt goes into thread so goes tighter
this is why on this type of bolt its either air gun and go for it
or airgun wind up down up down up down
this is assuming you cant get to exposed threads
dont even start me on renault rubbish

stator

Cut a slot in it and use a screwdriver.

Wig

Ok thanks to all.

I got it out, it is a floorpan seat belt mounting bolt, for some reason these are always as tight as f@#^ maybe it's the 1mm pitch thread on an M8 bolt. who knows,

From the beginning this is what happened, I managed to take it out about 8mm or so, really hard work 1/4 turn at a time with the occasional slip, using T50 bit and 1/2" bar. Then the Torx recess became unuseable and I could go no further, it was still very tight.

Then I posted on here.

Then I got back to it with my M8 Ribe bit, with this I managed another 1/2 turn, when I removed the bit to go back clockwise with the bar, half the remaining torx teeth came out of the bolt-head (the ribe bit was undamaged). This rendered the whole thing impossible to do with a bit. Had I tried a ribe earlier, I might have been ok.

Had I cut the head off the bolt, I would have been screwed as there would be nothing to turn the tight bolt thread out.

OK so what did I do next? I got a 20mm nut (fits a 32mm socket) lathed out the inside until it was a good fit over the head of the bolt, then arc welded the nut to the bolt-head. In the process, the bolt was heated up.
The trouble was the weld stuck to the bolt but not to the nut, wrong type of metal. I was all set to buy a nut of a different type of metal, angle grind the weld off the bolt and try again.... when I decided to try molegrips, as the weld, which was all over the (round) bolt-head would allow me to get a good grip, and it worked, tough at first 1/2 turn at a time but eventually it got lighter and easier and out it came.

There was no rust on the bolt thread or the hole, it is just that these bolts are really freekin tight for some reason. I will tap the thread out a bit before refitting a hex head bolt with some molygrease on it.


The bolt is right beside the petrol tank, which is plastic, I didn't think about explosions, luckily nothing exploded, but I will have to try to inspect under the car where this bolt was that it has not melted the plastic, filling neck leading to the tank. this will be tricky as the bolt sits up behind the filling neck and it can't be seen from below, but I will persevere.

Thanks for watching.

facade

Seatbelt bolts are threadlocked, heating it up likely destroyed the locking compound, so it was the right thing to do. Hopefully it wont have damaged anything.

Jakg

It was probably a Ribe and not a Torx head in the first place - the ones on my car can be undone with a T50 (I always do) but are actually a Ribe which is slightly different.

I had similar problems undoing the rear seatbelt bolts on my car - bolt goes right through the chassis, and the threads on the other side are exposed. Over time they corrode, which then makes undoing them very very difficult.

s_b

i once made the mistake of welding over a tank
the breather pipe i didnt know existed fortunately sealed itself with the heat
or i wouldnt be here now
ive had one bad fire using welding equipment on a car, the car burnt out i got lung fulls of very black smoke,theres no way i would put heat on that bolt without a helper underneath with a fairy liquid bottle of water and the carbon dioxide extinguisher next to it
just saying ,health and safety might sound silly but it could safe your life or if working at home your house as insurance would say no