Topic

Nothing there to argue with & much to applaud. I like the left handed drill stunt, but most of us would need to break out the battery drill.

The drill bits I use are Sutton, highest quality made here in Melbourne, they’re M35 high speed steel with 5% cobalt. I find the M42 drills 7% cobalt a bit too brittle for the job of back winding the bolt.
The trick to this is TAKE YOUR TIME, if something doesn’t look right STOP! If you think you haven’t got it right, redo it until it is right.
That’s where the die grinder comes in handy.
Another point about the die grinder is the vibrations it generates help loosen the bolt… I’ve even had the bolt come loose by. The die grinder alone.
Even when punching the centre, I start with a small centre punch, if I’m happy that it’s left it’s mark dead centre then I punch it again with a big bugger and a 4lb hammer (I rarely use piddly little flower arrangers or hair dresser’s hammers, I let the hammer do the work instead of taking wild inaccurate swings with a small hammer, I find it much easier to be precise using a big bastard gently)
The point of using a small punch first is that it leaves a shallow impact depression, so if it’s not quite right it’s less work to grind away and start again.

Next time I should do a video, mind you I don’t often have someone handy to be the camera operator, and generally the job is a breakdown and the client is in a mad rush to get production back up and running. So to have me piss farting about, doing multiple takes and lengthy explanations would probably be somewhat frowned upon!
So it might be sometime before the planets align to allow this.

Yep I'm all for the left-handed drill and cobalt it's a job you could well do without but trust me it can turn into a disaster when even the thoughts of a cold beer at the end seem light years away. I have used a door hinge drill if the bolt has broken off down in the mating point. It helps with finding the centre of the bolt you're trying to remove.

I've made centring sleeves where a bolt has failed at the bottom of a hole & other such devices. However it's all well & good if you have the gear to make stuff like that but for the majority the hinge drill is a great idea.

Thanks for all the advice. The left handed drill bits have now arrived so i'l start to tackle this later today after work, weather permitting. I dont have a die grinder but i do have a Dremel with a variety of different small grinding wheels that should help to flatten and level the broken end, albeit slowly. I picked up some screw extractors, is it worth trying one on the off chance it might work but with the expectation I will probably still have to drill out and use a tap ?

Admire the engineering that went into making the extractor & get on with drilling the bolt out.

Yeah, I have never had much luck with extractors, more time than not they break, and then it's an even bigger job that you started with. Just take it steady with the drills, keep them as central as possible, and you will be OK.

You were right about it being a painstaking process. I drilled and retapped them, broke one tap in the process but thankfully it was easy to remove plus I had a spare.

It should now be already to assemble this morning and get the front of the car back on its wheels except..
I followed the How To on here about broken subframe bolts when i was ordering the various bits I needed and didnt realise there was a difference in bolt size between the front and rear mounts. Consequently i now have 2 nicely retapped 8mm threads -but all the other bolts on the front subframe rear mounts are 10mm.
Arrgh. The How To didn't mention different front and rear mounts had different sized bolts and it didnt occur to me.

So; the question is can I get away with these 2x being 8mm ? The original F was designed to use only 3x 10mm bolts each side. The 4th was only introduced to hold the X cross brace on the TF. So is it safe to assume that 2x 8mm and 2x 10mm bolts should be as adequate as the 3x 10mm bolts of the original design ?

Or do I order some larger drills and taps, sacrifice more time and take them out to 10mm ?

Can I quote from a post on here a while ago when we were discussing a suspension problem & the need to drill out a bolt “Don’t break a drill, their really hard, even grotty ones.I broke a tap in part of a locomotive I was building & had to take the frames to another town to have the broken bit spark eroded, you can’t do that if you brake a drill in a mounting point. And there’s always tomorrow”.[/quote]
Firstly how far is the tap in, the more thread in there the greater the likelihood of failure as the torque resistance increases with the square of the depth (I think that’s correct, it’s a loooong time since I had cause to remember things like that).
I hate to question your choice of tools but was it a tap from a well known manufacturer or an offering from the Far East.
There was no YouTube when I was building the loco & so no useful advice from that source but now I’d be looking on there for guidance. I recall pages of advice some credible others less so, a high percentage of these were contributions from America The Americans have been remarkably successful in most of there endeavours; going up seems to be a speciality, going down, we’ll I’ll have to make your own mind up.
Unless you have used a spiral fluted tap you might be able to knock some thin rod (a pop rivet mandrill ?) down the flutes & by gripping those work the tap out. Or you might just be getting more junk into the mix.
See if anyone in your area does spark erosion, they might have some portable kit.
M

Airportable wrote:

Can I quote from a post on here a while ago when we were discussing a suspension problem & the need to drill out a bolt “Don’t break a drill, their really hard, even grotty ones.I broke a tap in part of a locomotive I was building & had to take the frames to another town to have the broken bit spark eroded, you can’t do that if you brake a drill in a mounting point. And there’s always tomorrow”.

Firstly how far is the tap in, the more thread in there the greater the likelihood of failure as the torque resistance increases with the square of the depth (I think that’s correct, it’s a loooong time since I had cause to remember things like that).
I hate to question your choice of tools but was it a tap from a well known manufacturer or an offering from the Far East.
There was no YouTube when I was building the loco & so no useful advice from that source but now I’d be looking on there for guidance. I recall pages of advice some credible others less so, a high percentage of these were contributions from America The Americans have been remarkably successful in most of there endeavours; going up seems to be a speciality, going down, we’ll I’ll have to make your own mind up.
Unless you have used a spiral fluted tap you might be able to knock some thin rod (a pop rivet mandrill ?) down the flutes & by gripping those work the tap out. Or you might just be getting more junk into the mix.
See if anyone in your area does spark erosion, they might have some portable kit.
M[/quote]