I had an encounter with some road ‘debris’ that looked like a car AC compressor laying in the middle of the highway that I couldn’t avoid and broke the middle tunnel brace and fortunately not much else besides a small dent on the exhaust piping.



After removing the broken brace I noticed the threads on the drivers side are missing and I think I can see 2 nuts loose inside the cavity.



Does anyone know if these nuts are accessible from inside the cabin if I remove the carpet?

Even if I’m able to reposition the nut somehow I have a feeling the threads are trashed from the impact.

Here’s the other side..

 

nope... that sucks. those are not accessible from inside. i had to cut a slit on the side of that pedestal and fish the broken one out and put a new nut in there. its a tremendous hassle. not at all worth the effort. i'll bet the earth, sun and moon that there will be no difference in driving without that cast aluminum brace and its 4 12mm bolts. dont worry about it and leave it off.

 

If you have a welder or know someone that does it looks like it could be cleaned up and replacement nuts welded back in.

 

All good advice. Those were nuts welded onto the back side of the sheet metal at the factory and they've pulled out of the metal. You can't get to the back side of that, it's in between the layers of steel that makes up the chassis.

I'd probably leave the brace off, as stated I'd doubt you would notice a difference. Long term you'd need to get that sheet metal repaired and fasteners fixed. Since that brace is for adding to structural rigidity it has to be VERY sturdy how it's mounted. Nuts and bolts probably won't cut it, the package would just slip on the sheet metal.

Dale

 

If it were my car I would fill in the stretched out holes with mig wire at very low voltage, grind the weld flat, re-drill the hole and use an m8 (pretty sure those are m8's) rivnut. You could alternatively grind off the tacks that hold that mount to the body sheet metal to get to the back of it, then weld a few new nuts to the back side, re-weld it to the body. I can't imagine that's going to be significantly more sturdy of a repair, and you're going to have to strip off the under coating all around the mount, but that would be the most OEM style repair.

 

I broke the same brace the same way...on one of those folded up baby strollers of all things, that fell off a truck. Fortunately it didn’t pull those captive nuts out.
Rivnuts should work.
Along the same lines I’d probably just drill the holes out to just larger than the proper size steel nuts. Insert those steel nuts in the hole with a long bolt. Hold them flush with a magnet and mig them in. Remove bolt, grind smooth, reinsert bolt and spritz some undercoating. Remove bolt and reinstall the replacement brace.

I agree you probably wouldn’t notice anything, but it’d drive me crazy not to fix that.

 

Thanks for the replies. All great info and saved me from pulling the interior.

Those Rivnuts are interesting.

I wonder if I could use a larger Rivnut that will fit the existing hole and then use larger bolts to match..maybe a M10.

M10 rivet nut hole size is 12.1mm
M12 is 16.1mm

I also like the idea of welding a nut back in place but I don’t have a welder although I’ve been wanting one..might be a good excuse to buy one!

 

I've fixed a bunch of cars with damage like that. Slit the sheet metal and peel it back to gain access. Clean the area and hit it with weld through primer and tack weld in new nuts. Then weld the flap you bent back. No big deal.

 

its just a tremendous effort for something so insignificant. also a huge expense if youre having to pay someone.

 

No technical background but in tension and compression I think those braces work together and with the PPF to limit chassis twist. And what I described shouldn’t take more than a hour or so on a lift with the tools...and welder of course. Personally I would not cut anything.
Depending on the OP’s deductible his comp might cover the costs to have it done if need be. Just a thought.

 

to limit chassis twist under street driven conditions or high performance track driving conditions? its obviously up to the op but i seriously do not see a point in spending the time or money to have this fixed. i fixed mine out of necessity since i needed the mount points for my diff brace.... no ppf due to something other than a rotary powering the car.

unless he has the equipment to do it himself, i cant see someone charging less than 200 do have it done correctly.

 

how do you prevent internal rust in a repair like that?

 

I’d probably just liberally rattle-can zinc chromate in thru the holes. Once dry if you still needed peace of mind I suppose you could follow-up with some Fluid Film. But I don’t really think rust would be a huge concern.

 

I live near the beach so rust is always a concern. Although my car hasn't needed repairs, just sitting in storage things start to rust.

 

Wouldn't expect much in the way of stiffening effect. Even though it's usually hard to get past the ppf, normally these bits are for catastrophic driveline failure.

Should still be a vid out there somewhere, of a rotary blowing the tail off the box and pirouetting skywards after contact between that thing connected to the diff and terra firma.

 

Fixed as I described that chassis protrusion would probably outlast the rest of the car.
Fixing it would also be practically invisible and help maintain chassis stiffness and the car’s value.
Leaving it as it is would be the larger risk IMO. And it would just bug me.

 

One of my brace mounts was broken in a very similar way. Local rotary shop was able to fix it without much effort. It did involve some welding though.

I don't remember how much it added to my overall bill, but in the range of 200-300 bucks I think. I just had it fixed to satisfy my OCD and also to prevent any weird rusting from stuff getting in there.