No motor mount chassis nut

[thescifiguy]

The driver's side motor mount crossmember nut that is achored, blind, in the chassis on my GT snagged and broke loose inside the inaccessable chassis member. The other two bolts on that side just achor to flimsy wheel well metal, which, on this car, has been replaced and is even flimsier.

With no way to support the engine on that side I had to drill a hole straight down through the top of that 6"-8" chassis "box", drill out the remainder of the nut and install an 1/2" x 8" bolt and nut to hold the engine in on that side. The "top of the box" I'm talking about is directly under brake booster support rail that our coil and voltage regulator mount to. The bolt hole I drilled is directly next to the motor mount. The sheet metal is much thinner there than at the bottom where the nut was and there's not much room to put washers to spread out the force. I'm afraid that over time the chassis will crush in that area or the bolt head will rip down and through.

What better fixes for this are there?

The car doesn't run yet, so it's inconvenient to get it to a body shop or welder.
Should I be patient and wait till she's running, then take her to have something welded in?
Is there some sort anchor nut concept that expands or spreads out like a drywall anchor?
Or is the bolt and nut I'm using good enough?

[namba209]

That blind nut isn't totally inaccesible. I had the bolt get cross threaded and was able to get a tap through it for a heli-coil, and could just barely get a finger on the nut to remove the excess heli-coil threads. IIRC, this has happened before, and some members have cut out that section and welded a new piece in its place with a new nut welded in. You may want to check the availability of a mobile welder in your area. A good welder can make the area better than original with good penetration in the repair. HTH.

[Johnvan]

I would cut out the section and if weak fabricate a new section and weld in a new nut as suggested.It sounds like you have other rust issues in the area and you may want to consider repairing all of them at the same time.If rust is severe in the uni-body rails and other anchor points it may be easier to support the engine and take out the crossmember for access or remove the engine and transmission as an assembly and repair all rusted areas on both sides.Sometimes ease of access makes a less visible and higher quality repair and is faster in the long run. This site offers a lot of advice on engine removal.
You could consider purchasing a small 110 volt mig and do the work yourself and save some money.Mig welding is not difficult to learn and has also been discussed on this site.
This is a common area of damage on Opels and may include the footwells and front jacking points.I realize your car may not have severe damage but it is worth looking carefully to know the extent of damage and the best cheapest way to repair it. Let me know if I can help in any way. John

[thescifiguy]

Certainly my East Coast car has it's rust issues, but the unibody rails are reasonably sound. It's just that the nut binded and spun itself loose from the chassis. After my drilling, there's now a nice clean 5/8" hole through decent metal.

Nutserts are a system for mounting nuts to sheet metal. Is there something like that I could use?