Tlaloc75

Last night I was putting my subframe back on the car and ran into a major problem. I tightened the main bolts (at the bushings) to 120nm and then went to work tightening all the other bolts that hold the subframe to the car. A couple of the bolt holes weren't properly aligned so I realized the fittings at the bushings must have a little play available and so I'd need to loosen, shift the subframe slightly and then retighten.

One of the bushing bolts came out no problem. The other one had a hard time budging and as I tried to work it free the bolt broke with most of the threaded portion of the bolt left up in the frame of the car.

I was, and am, devastated and trying to work my way out of this mess that I've created.

I talked with some mechanics in town and after consultation I started to drill the stuck bolt out and have applied pressure with an easy-out style bolt extractor several times in an effort to budget it free.

I started drilling with 1/8, then moved to 1/4 and then to 3/8. I used a guide to start the pilot hole so its close to the center but not 100% exact.

Picture of what it looks like now:



My drill bits are dulled out so I am going to get some more 1/4 and 3/8 along with a #4 easy out to complement the #5 that I'm using. I have an M12x1.5 tap to clean up the threads once the bolt is pulled.

I woke up in a cold sweat last night thinking about all the things that could go wrong:
- Bolt or part of the bolt could be stuck forever
- Drilled hole is slightly off center so I could ruin the threads of the hole the bolt goes into
- Somehow I mess up the surface that the bushing presses into, so that the bushing no longer lays flat

I'm looking for your thoughts, advice, support and any help you can give me to help this come out right.

I've never had to extract a bolt before, this is a first for me, so the whole thing is very scary given the importance of the fitting that I'm working on.

Since the bolt was stuck hard enough to break, I think its going to be really hard to get out with an easy-out, I think I probably need to keep drilling until the bolt weakens enough that it collapses out...

What would you do in my place? Am I on the right track? Are there other ways to mess this up that I should be aware of and be sure to avoid?

trophy

Sorry to hear about you issues... Couple of things.

1. Go SLOW, take your time, you dont want to drill so much out that you can break the bol away (Almost impossible to do) you need to keep as far away from the threads in the body as possible.
2. You want to use the smallest easy out you can, so your drilling reduces the chance of damaging the threads, a #4 is the recommended size for a 12mm bolt.
3. Don't use a tap to clean out the threads when you are done you can remove material from the threads and the bolts can become loose. Get your self an old M12x1.5 bolt and cut 4 slots along the threads of the bolt (Dremel is good) and use that to clean out the threads, with some PB Blaster as a lube as you do it, this will clean out any debri and not damage the threads.
4 GO SLOW.....

Good luck.

trophy

Here is what I was referring to as a thread chase, I prefer more slots.

Tlaloc75

Ok, so I think I should stop with the 3/8 drilling and stick with 1/4. You can see that where the 3/8 has drilled in it is getting pretty thin and close to the threads on one side (right side of the picture).

So I think I'll drill with 1/4 till I get through the end of the bolt and then apply force with a #4 easy out.

Here's my concern though - how will it be possible for me to budge this with an easy out, when the level of force that caused it to get stuck broke the original bolt? I really, really don't want to break the easy out as that will compound my problems dramatically.

trophy

The other thing I forgot to mention,

Do you have a punch, that is less than 1/4" in size) If you do, you should use that in the drilled hoe and give it a few good wacks with a hammer.

the #4 easy out is designed for a 12mm to 14mm bolt should be plenty strong enough.

Just go SLOW, did i mention to go SLOW?

Ivan J

This is a real concern given the torque that is required. I tried extracting a broken bolt that was previously installed with the lower strength lock tite The extractor broke off inside the bolt. Once that happens, you have a bigger problem.

I would try to get a professional to take care of this.

Tlaloc75

How much force did you exert before it broke? I'm sticking with nothing larger than a 1/2" driver and the amount of force I can exert on that. No breaker bars or anything, that's what got me into this mess...

How did you ultimately get it out?

I'm considering a professional. It would require me to bolt subframe together (minus this bolt). Get the shock and control arms back together, get the car on its wheels and then roll into a flatbed to carry it to a shop. That may end up being what I have to do, but it's not a small thing - so I'd like to try to break this free on my own if I can do it and do it in a way that doesn't cause any damage.

Ivan J

Perhaps a slightly smaller high strength bolt can be welded to what remains of the broken one, so you could get a wrench on it?

Maybe a laser could be used to vaporize what remains of the broken bolt, such that a threaded insert can be installed into the frame?

Ivan J

I didn't. My situation did not involve something like a car frame. It was a motorcycle part, which I took to a machine shop. I don't know how they managed it, I came back two days later to pick it up and all was well.

Tlaloc75

Its recessed in the frame. Are you thinking a bolt could be welded on, inside the recess and then a socket fit to that in order to pull it out? Given the drilling I've done (see the picture) there isn't a flat surface to weld to, even if that was feasible.

Hadn't thought about a laser... if it gets hot enough to vaporize the bolt, wouldn't it destroy the hole as well? That definitely be a job for a pro. I'd probably shoot a laser through my car and out the roof of my garage.

Ivan J

If you continue on your own, I would go in the direction of trying to drill the entire thing out, knowing that you might need a threaded insert installed. At least, this is what I thought I should have done when I had my bad experience.

Don't listen to me, I'm an idiot about these things...

OverBoosted28

Maybe cut a small notch, which you can get a chisel/flat head screwdriver, and then small strikes, slowly trying to "crack" it loose? Without the head on bolt applying pressure, it should be possible. Hopefully the bolt wasn't too long, buried end of shank into end of hole. With the solid panel bushings, you need shorter bolts. Good luck

OverBoosted28

I am no expert on thread inserts, but believe they are not designed for such loads?

user 723923490

Can you get at the back side of the bolt?
Is this bolt Loctited from the factory?
Best way to neutralize Loctite is with heat. If you can get at the other side you can get stuff (like wiring etc.) that can get destroyed by heat.
Trophy mentioned using a punch. I would add that you should use a small center punch and make sure your center mark is perfectly on the broken end of the bolt.
Use HIGH quality drill bitts, maybe cobalt but not standard HSS. Talk to a machine shop if necessary.
Another option is to rent a magnetic drill.
A last option may be to find someone to come out to your place to do the repair.
Don't panic! A well thought out plan can fix this.
Where are you located?

Ivan J

You are probably correct. Like I said, I'm an idiot about these sort of things