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Mysterious Bolt?

I am driving a newly acquired '98 Honda Civic HX. I was at a stop sign when I made a left turn. While making that turn, I heard a very lage clinging sound as if something fell off of the car. I pull over to find this very large bolt on the ground. It has a square head, 7/8" on each side while being 4 1/8" in length with a bolt diameter of 3/8". It is a gold-ish color and I have absolutely on idea what it comes from. Judging by the size, I’d say its fairly important but I haven’t a clue. Any help would be fantastic.

Sounds significant, you need a mechanic to look at it, avoid driving it until then, it could be from the suspension/steering. Of course, you might have run over the bolt, and it’s not from your car. No way to tell from here.

I’ve seen bolts that long on alternators and accessories. Some transmission to engine attachment bolts are that long. It also could have been in the road and you just ran it over. Exhaust manifold bolt?

This sounds like the type of bolt that would be used on an accessory (A/C compressor, alternator, etc.) based on the size description and the gold anodized color.

Years ago, there used to be a program on the radio called “Fibber McGee and Molly”. Molly was driving the car with a friend and they heard this tremendous clunk. Molly and her friend saw this big round disk laying in the road. They put the object in the car and drove it on home. “McGee will fix it”, Molly said. “He can fix anything”. Well, McGee goes to work on the car. He figures that the part is the flywheel. Molly isn’t so sure. “I haven’t seen any flies in the car, so the flywheel must be doing its job”, she suggested. At any rate, McGee has the car in pieces when a police officer arrives and orders McGee to give the city back its manhole cover.

Rather than me guessing as to what you found and you taking your car apart, have a mechanic look at the bolt and, if necessary, your car.

It has a square head, 7/8" …

If this is correct I would venture a guess and say this bolt was in the road and you ran over it therefore making the noise. I do not remember any bolt on a vehicle that has a square 4 point head.

Assuming the bolt wasn’t already just lying in the road, I’d check the alternator mounts. I know of a few cases where square head bolts were used for alternator mounts, so the bracket would hold the head and enable you to tighten/loosen the nut without the bolt spinning.