Yes, like all tightened bolts, the bolt is under tension, elastically stretched, because it is torqued up, that locks it into the threads and the surface it is pulling down on. Take the head off , bolt springs back to resting length, and loses its grip on the thread, and the surface it is pulling down on. Unless its a stainless steel bolt which was so clean, it has cold welded itself ... (e.g. see NASA trying to undo two stainless bolts in a clean room, recovering samples from an asteroid )
Thanks for that, another mechanic stood next to him was shaking his head…all the other bolts eventually came out and the threads were clean with no sign of rust.
Well, an Easy out didn’t work….,may speak to an engineering company…. doubt a drill bit off EBay would do the job and would probably need to go up to the 18mm size of bolt head in a couple of goes.
How clean is the fractured bolt head where the easy out has been? They are renown for being unsuccessful as they chew everything up. If its clean enough, try drilling it down far enough to tap it with a left hand thread. Get a threaded bolt wound in and try persuading it out that way?
I'm not even clear which bolt this is so I'm keeping quiet. But, no, go through the head to the thread size only, the head will fall off. If you now snapped off a rock hard easy-out in there, go luck drilling that!
It’s one of the bolts that holds the drive plate ( auto equivalent of flywheel). Just messed up the bolt, which was a socket head recessed bolt. Sent from my iPhone using Tapatalk
Unfortunately, my mate, who whilst is a proficient mechanic has mainly worked with go carts for the last 40+ years. As a result he will always find the easiest (for him) and the most expensive for his clients. This approach is fine in racing, but not for our old busses.
Too late now but I might have tried tightening all the other ones to the torque setting in the book or a little more then trying that one. I hate socket head screws, so easy to damage. Did he snap an easy out in there then? Maybe a mig weld is the way forward at this point - just the heat can work wonders.
Nothing snapped it, just the remains of the socket head screw. Was tempted to look the other way and fasten the others up and leave it, but the seal is leaking and it just leaves a job for my son, at some point in the future.
I’d weld a nut on what’s left of the bolt head. Don’t drill it to 18mm or you’ll probably knacker the flex plate, the thread is 12mm so no need to go larger before the head drops off. The bolts are p/n 021105305A M12x1.5x19. I have a set you can have but getting then to you would be a pain in the arris since Brexit.
You could go out and buy a set of Torx driver bits and hammer one in the round hole if drilling seems worrying. I would drill and then use something like Engineer brand locking screw removal pliers on the remains of the bolt. https://www.engineertools-jp.com/pz65
Couldn’t believe how expensive the flex plate is ….over £ 300 and out of stock. Not a route I want to go down. I must ask, where do you obtain all these bolt dimensions from…I presume the Samba …. or is it just your “specialist subject “ for when you go on Mastermind. Was pondering this whilst lying in bed after you provided the size for the tap to clean up the head bolt hole. Memo to self …… must get a life.
I’m hoping not to break it….daft question, but what is there to break….it just looks like a solid piece of metal from what I can see?
Whilst these look a clever bit of kit, if a well fitting Allen key and a breaker bar failed to turn it, I’m not sure how a modified mole wrench would work…or am I missing something?
It's often the case that leverage applied steadily chews things up that a short, shark shock will get moving. I know this hindsight isn't helping. Sorry.
Think I’ve got it, the mole wrench is used on the remaining part of the bolt after the plate is removed……yes?
The samba is good and if you look the bolt size is probably there, but that’s not where the info came from. I just use the parts book. Incidentally, the bolts are not Allen socket screws, Google the part number you’ll see what they should be.
