Can you post a picture of the broken off bolt? Which mount? And in my opinion the shop didn't know what they were doing.

Welding a nut to a broken off bolt is an old trick but it generally only works on bolts that the heads were rounded off by incompetents using the wrong tools to get the bolt out.

If the bolt is jammed far enough in there that the head snapped off when a high amount of torque was applied, then a welded on nut will just snap off when the same torque is applied.

If the bolt has really become part of the unibody then a torch can be used to cut it out, then weld in a replacement sheet metal patch, drill a hole in the right place, then weld on a nut. This is trivial for a good body shop to do.

 

i agree ^^^^^

 

 

drill and tap.

 

The shop tried to drill and tap. Apparently it broke a few of their drill bits.

 

find another shop with better drill bits.
I had an engine mount bolt break (the one into the timing cover). it wouldnt back out until i had drilled the whole length of it out. just take your time drilling, and use lots of fluid to lube and cool (cutting oil, WD40, water even)

 

My Procedure.

Remove the mount so you can work on the bolt removal. After MM removal, find a stainless steel washer that will go over the bolt post, or whats left of the it. Find a stainless steel nut that will fit tightly "over" the bolt post. Now here's where the magic comes in. Find a new dry 3/16'' stainless(316) welding rod. Take the rod and hold it at 12:00 o'clock and push the rod gently down and weld for a couple seconds. Be ready with a wrench that will fit over the stainless bolt. Have it READY! Slowly turn the bolt 15 degrees and then reverse. Keep going back and forth graduley increasing the turns. Works 95% for me, but don't feel defeated if the stainless nut pops off. Just set everything up agin and try again. When you weld the nut, you are putting a great deal of heat into the broken stud. That is why you need to be ready with the wrench. And be sure to use a stainless welding rod,and nothing else. Made my way through college doing these repairs. You can go to any reputable welding shop and tell them of your delimia. They will sell you a couple of rods pretty reasonable. Clean around the broken stud and do your homework. IT WILL BACK OUT! Good Luck and laugh at the broken stud when it comes out.

 

Addendum/ HEAT RANGE

That will be 75 amps on the AC/DC welder and start the weld at the center of the broken stud, gradually weld in circles untill you fill the top of the nut. And please don't use a wire gun on this job, as they aren't as successful as AC/DC generators. jmo.

 

That job right there shouldn't be that bad I mean drill that thing out of there and get a new stud in there.

 

just weld the mount to the top of the bolt with nice spot weld . An you ever have to take it out agin you'd have to grind ott th spot weld. Good luck on what ever u deside .

 

just weld the mount to the top of the bolt with nice spot weld . An you ever have to take it out agin you'd have to grind ott th spot weld.

that's not a bad idea. A 13-year old Focus ain't gonna outlive new motor mounts.

 

Well thank for all the advice I'd like to do this but I dont know how to weld nor do I have a welder yet. Which is why I took it to a shop.

 

That's precisely what left handed cobalt drill bits were made for.

The shop you to sounds like the lube monkeys got access to tools while nobody was looking.

Definitely remove the mount to get access, and so it isn't pushing on the remnant and helping hold it in place.

Absolute, worse case scenario:

Grind it flat, have a piece of flat bar stock welded to the mount to make it wider footprint, and it gets a new bolt hole and threadsert into the unibody/frame.

 

Drill will work, but you'll need to get things out of the way for access. Grinding the top flat will let you center punch & drill easier, as well as removing the surface that the welding attempts may have hardened.

It'll take time, but if you work up in sizes to avoid taking out the threads you'll eventually be able to pick out the last half moon shaped piece of bolt that's usually left because the drilling is seldom exactly centered.

If a tap isn't available, a spare bolt of the same size with slots cut lengthwise in the threads makes a good one use thread chaser to clean out the welded in nut.

To avoid rushing it & getting frustrated, remember what you said about this job being worth the whole car! Take breaks with your beverage of choice (grin) and it'll be done before you know it!

Luck!

P.S. - hah! we're all typing at once again...

 

interesting bit on the stainless welding.

Yeah I don't know how they keep breaking drill bits. You can drill the length of the bolt, and keep opening it up if all else fails. it should collapse in on itself.

 

that was the same bolt that i thought i broke when i did my engine mounts 2 weeks ago. scariest pop ever trying to get that off with a breaker bar. too bad i didn't put any anti seize on it before putting back in ahhah

 

I used to drill holes in a machine shop years ago.

You need the right drill bits and they need to be sharp, and they will get very dull very quick if you don't use cutting oil to lube the bit.

Carbite tip (colbalt will likely NOT work very well) and cutting oil (not motor oil, get cutting oil) and a slow speed to start followed by moderate speed, that will cut through it. Even if the top was hardened by welding. have an assistant continue to drip cutting oil on it while you drill.

 

One other hint - almost always when you drill these it's impossible to get the hole in dead center.

What you do is get the hole started then use a diamond tip bit on a Dremel to widen the hole in the direction it needs to go to center.

 

and why has no one mentioned pulling the fender liner to get at it from the bottom side.

 

That bolt is pretty easy to access with a drill and its just a weld nut on the body. I would get a quality drill (about 3/16 to start) and carefully center punch the bolt. Drill through the bolt and then drill out to the appropriate tap size and run a tap through it.

This is really not a that bad a job and a lot cheaper than a new car.

 

The weld may have heat treated the area to make bolt undrillable. Picking an expensive drill bit would prove that out. Regardless, I can think of 2-3 ways to fix that without using a welder at all. One could easily pick correct sheetmetal screws and drill holes for 4 of them surrounding old bolt and install, the 4 would be enough to hold that mount down.

Hard to believe someone thinks he may have to get another car over that...............