Help... Exaust Stud Drilling

[JJ 911SC]

Just spent 5 hours drilling though the stud, 1 broken extractor and 2 broken drill bits... But I manage to save the threads

So what is next?

My last drill pass was with an A (.234") bit and the max size that go in a threaded hole is an E (.250") so there is not much left.

How do you get the rest out?

BTW I do not have a drill out jig.

Thanks

J.J.

[911Freak]

Hey JJ

How to get the remaining threads out, right? I think you use a fine pointed pick or wire to raise the end of the thread up then use a small long-nose plier to pull out the remaining thread... It should just un-coil as you twist and pull it out. Getting a good bite on the end of the thread is the most important part, then carefully twisting/unscrewing the remaining thread out...

As I'm sure you are aware of there are many excellent threads on exhaust stud removal, including photo specific detailed instructions on your specific inquiry. A quick search will give you exactly what you seek. If I was at home on my laptop I'd provide the links as I've booked marked them all for future reference

Good luck and post your progress

[JJ 911SC]

Originally Posted by 911Freak

... As I'm sure you are aware of there are many excellent threads on exhaust stud removal, including photo specific detailed instructions on your specific inquiry. A quick search will give you exactly what you seek. If I was at home on my laptop I'd provide the links as I've booked marked them all for future reference

Good luck and post your progress

I was in the garage hoping to keep going but I think I push my luck enough for today... When the extractor broke I start sweating bullet. But the Dremel like tool kit and a Titanium Dremel bit save the day.

Thanks

JJ

[porschenut]

Here's the grandaddy of all the exhaust drilling threads:

Does anyone sell a fixture for drilling broken exhaust studs

[billybek]

Once you are down and can see the thread and the remaining bolt, you will have to pick it out.
Been there, done that. Not fun. (not on the 911 though)
Good luck!

[wildcat077]

J.J.

I replaced the exaust studs on my F150 this Summer,had to drill 10 out of 16 ... and most were snapped flush or a little inside the heads !
Drilled them out carefully with a #30 then #10 then a .250 drill and cleaned out the remaining with an 8MM tap if i remember right.I think with .016 left you should be good to chase the rest with a tap.Just go by steps and blow out the metal shavings with a blow gun as you go along.

By the way,i made those two jack pads this week,just have to weld them up and get them cadmium plated.

Cheers !
Phil

[Flat Six]

Originally Posted by wildcat077

J.J.

By the way,i made those two jack pads this week,just have to weld them up and get them cadmium plated.

Cheers !
Phil

Oooooh . . . nice. Phil, please post a few pics when they're done?

[JJ 911SC]

Originally Posted by wildcat077

J.J.

I replaced the exaust studs on my F150 this Summer,had to drill 10 out of 16 ... and most were snapped flush or a little inside the heads !
Drilled them out carefully with a #30 then #10 then a .250 drill and cleaned out the remaining with an 8MM tap if i remember right.I think with .016 left you should be good to chase the rest with a tap.Just go by steps and blow out the metal shavings with a blow gun as you go along.

By the way,i made those two jack pads this week,just have to weld them up and get them cadmium plated.

Cheers !
Phil

Phil

They look great and probably cheaper than the shipping cost from ottawa to Montreal...

Actualy my day was not that bad. Drill one out without any jig and get another broken one out with a bolt out as it was too closed to the fins to put the stud extractor on it.

Here is the story of the 12 studs;

2 studs came out with the barrel nut
2 barrel nuts came out clean
2 barrell nuts snap right at the end of the nut

I cut out all the 6 nuts

Of the 10 Studs lefts;

7 come out using a stud extractor and a air gun starting at 30 pounds, increasing to 40 and they came out at 50.

1 broke but we (me and Alex) got it out.

It left the two out. We put the extrator to one and it broke but left the flat part, so we grab that and I swear it start it to turn but snap flush, that is the one that I drilled out.

After taking a long break trying to figure out how to get the broken one which was close to the cooling fin, I decide to try a bolt out. I got it on using a 1/4" wrench... and put the air gun to it. Sure enough, after the 30 and 40 pound racheting, it come out at 50".

You past experience confirm our next step, 8mm clean out tap.

Cheers

JJ

[James Brown]

J.J., check out my post on SSi install I did the same thing. Don't bother trying to pic out the threads, they don't come out and the aluminum is soft. Just run a tap (M8x1.25) in there and that will chase the remaining threads out

[JJ 911SC]

Originally Posted by James Brown

J.J., check out my post on SSi install I did the same thing. Don't bother trying to pic out the threads, they don't come out and the aluminum is soft. Just run a tap (M8x1.25) in there and that will chase the remaining threads out

James

Will do and locking forward for your comments on the plugs soon to be posted on the Spark plug help please? thread.

Cheers

J.J.

[James Brown]

Good job center drilling that, looks dead nuts on. The final drill size is 17/64th that's .265625 inch. but yours is probably close enough.

[gregwils]

I purchased an exhaust drilling guide and used a tap. They worked well, but I ended up installing a time-sert, because the tap cleaned the threads a little too well. I highly, highly recommend buying a set of reverse threaded drill bits. If you want, you can always heat the exhaust stud prior to hitting it with a reverse bit. There is a great probability that the studs will back themselves out as your drill bites..

[Traveller]

Originally Posted by James Brown

Just run a tap (M8x1.25) in there and that will chase the remaining threads out

That would work, but we need at least three full existing threads to get started, otherwise we might be cutting new threads instead of chasing out the remaining ones.

[James Brown]

The tap will find the threads and follow. Or it will cut new ones. the outcome is the same, new threads.

[Traveller]

Originally Posted by James Brown

The tap will find the threads and follow.

Not unless we start on threads that are already there. Thats why I want a few threads to initiate the tap.

Originally Posted by James Brown

Or it will cut new ones. the outcome is the same, new threads.

I'd like to save the existing threads. If things go wrong, we can always thread deeper; there is at least another 10 mm not tapped.

[Traveller]

Originally Posted by JJ 911SC

My last drill pass was with an A (.234") bit and the max size that go in a threaded hole is an E (.250") so there is not much left.

JJ, the drill size for an M8 x 1.25 thread is 6.8 mm.

An A drill = 0.234 in x 25.4 mm/in = 5.944 mm or about 0.86 mm too small...not an issue, better smaller than larger.

But it might be why the starter tap is having a tough time getting started.

[JJ 911SC]

Yes a bit tight.

James last drill pass was 17/64 (6.746875mm).

Well, could try to clean-up the next 2 thread (# 2 & 3) or run a larger bit...

James

Came across your new product "Tap Out" acid posting. Any feed back since.

[James Brown]

No but that stuff works good on ferris (steel) things. Guys, you are real close, a tap cuts a thread to 70% (meaning only 70% of the stud will contact the metal stud, normal) so I think your ok, just be carful when starting, like any tapping, and keep it perpendicular to the hole for the first few full threads. After that, it will follow the hole.

[brads911sc]

17/64 is the MAX size drill you can use unless you want to use a Time-Sert.

James, often, with a 17/64 bit, a 8M tap, the stud will no longer be tight. You will then need to time sert. The proper tool is a thread chaser (looks like a bolt with grooves cut into it)... not a tap.

I just replaced all of mine... (have thin flange SSI's)... 8 of 12 snapped off. Used the jig from Christian, 17/64 bit. Picked out 3 of them. Used a tap on 3. On 2 of the 3 that I used the tap on... i now have a time sert.

Use a tap at your own risk...

[James Brown]

I'm just referring to what I did on my SSI install. Re tapped mine (chased the threads) See my post.