Re: Damaged Bolt Extraction

Paul Hovnanian P.E. wrote:
> I'm in the process of pulling the drive plate off a vehicle to replace
> the rear main seal. In the process of loosening the 10 bolts, I managed
> to bugger up the heads on two of them. The socket I was using slipped
> off and rounded off a couple of shoulders on the bold head.
> 
> When this happened, I stopped screwing with them in order to minimize
> further damage. There are several methods for removing such bolts. Prior
> to drilling and seriously messing around, I seem to recall some special
> damaged bolt sockets (with helical teeth in them). What are these
> called? Are they any good (the bolts are 14 mm, torque to 75 ft-lbs).
> Who would carry them in the Seattle area? Any tips when using these? Or
> other advice?
> 
>  
Wack the bolts straight on with a big steel drift and a good size hammer 
  before you try to loosen them again.