Went out in the garage earlier to change the stat tower on my waterrail over with the new one from Raceline. It is held on with two allen bolts...one came out after a bit of a struggle, the other one has sheared off. Tried heat and putting a slot into it with no effect. Next I ran a 8mm HSS drill into it and got 7-8mm down into the hole and can't go any further, new HSS-Con bit is just polishing it.

I'm racing tomorrow so I'm screwed if I can drill this out.

Any ideas?

I don't have a welder.

[Edited on 19/9/15 by jeffw]

[Edited on 19/9/15 by jeffw]

Is it a blind hole? Cant remember what mine looked like but not sure if its blind or on a sticky out flange?

Not blind, it goes all the way through. I wonder if my mains powered electric drill is too fast for the drill bit....

How about drilling into the sheared off stud with a 5mm drill and tapping it 6mm to get you through tomorrow?

I've drilled about 8mm down into the bolt with an 8mm drill. The idea was to drill through and nut/bolt it. Now the three new HSS bits I have just seem to polish it.

You need to drill it out in stages 3mm first then a 4mm and so on drill it slowly and spray wd40 to cool it then your get through it.

I managed to drill out a stud in my rv8 head that sheared off. Went through with a 6, then a seven and got the rest of the treads out with a small pick.

Ran a tap down to clear it and it bottomed out a nd snapped! Waht a bummer.

Managed to get that out by using a carbide bit and a hammer to smash it to bits. The ali thread even survived that!

As above,work your way up from a small drill bit using wd40 etc to keep it cutting,drill should be on a low speed too.

How about a cobalt bit? Worked for me

How about a cobalt bit? Worked for me

Also try drilling in sized stages from the reverse side if you can get access, that'll be easier if you've hardened the bolt on the top side

James

if it is two flanges, could you put an external 'G clamp' on it?

Bit late now but left hand drill bits often work when drilling out broken bolts but a welder works so much better

Cobalt bits haven't touched it, going to have to go to Carbide I think.

Is it a stainless bolt? Very easy to work harden it when drilling. If so best bet is start again from the other side. Slow drill and plenty of cutting oil, work up the sizes.

Don't think it is stainless as it has rusted in place.

As you drilled a large hole already, how about one of the better quality 'eayout' left hand thread type devices, with lube and heat it might do it.

Thanks for all the replies

Carbide bits and cutting compound allowed us to drill this out in a couple of minutes. Car is running again....