Broken screws

[Jonlloydfoster]

Having some trouble getting these bolts out.

when taking off the suspension arm the bolts broke off.

they are now partly left inside the chassis.

I have tried using reverse screws to get them out but they won’t grip at all.
Any suggestions?

 

[Barron]

You'll probably have to drill and re-tap I'm afraid

 

[t-tony]

Is that both bolts and both sides? Jeez that is bad luck, first time I’ve heard of those breaking on any BMW. I agree that drilling is the way to go.

Tony.

 

[IainP]

Common up at the salty end of the UK.
Get yourself to Toolstation, set of cobalt drills for about £8 ish I think, don’t bother with HSS on those bolts, you’ll be there all day, I speak from experience.
M10 tap, plenty of oil.
Lots of patience, don’t try and rush it, start with the smallest drill in the set then slowly work up. Do use cutting fluid if you have any. Horrible job because of the angle, but it is recoverable.
Since you have screw extractors, you may find by the time you get to7mm the heat will have helped to loosen them. I have some left hand drills now for exactly that reason, sometimes they back it out as they cut.

iain

 

[jaguartvr]

If the bolt has snapped the thread is seized so there is a good chance the screw extractor will snap as well, if it does it will not be possible to drill it out as they are hardened. Drilling out with a cobalt drill set as suggested above is the way to go.

 

[Jonlloydfoster]

Tried doing the cobalt drill bits from toolstation but they literally won’t drill into the metal they just dig a small crater and either snap off or polish the screws

 

[t-tony]

What speed were you running the bits at? Too fast by the sound of it. What size bit did you start with?

Tony.

 

[Jonlloydfoster]

Started smallest but even those weren’t cutting into the screw I’ll give it one more go before giving up