I was driving on a short freeway type road in my hometown, cruising around 60 mph max, perfectly flat straight road with no bumps, in perfect sunny weather. There were no cars behind me, but a couple of everyday passenger cars ahead of me. Out of no where I hear an extremely loud popping noise from the rear of the vehicle, not sure where but definitely behind the seats. It honestly sounded like a gun shot, enough to make me jump out of my seat, almost like a window being shot out. I drove pulled over on a side road and checked everything over. No leaks anywhere, the oil filter was in tact, all of the windows work fine. I have a Mugen hardtop and it was in perfect condition, no marks on the exterior of the vehicle from flying debris.

My car is pretty much stock, it does not run rich or have any abnormal fuel tuning, so nothing to cause a back-fire to occur. I was simply in cruise mode, not accelerating and not decelerating. Check all four tires and the are fine. I don't carry a spare tire. Nothing in the trunk at the time that would cause any odd noise. Nothing being carried in the interior.

Later in the afternoon we got the car on a lift to install a wideband AFR kit, and we could not see anything under the vehicle that would be out of character.

I was wondering if differential mounts can explode, or rear shock absorbers leading to such an explosive noise ? I've got Bilstein PSS coilovers, had them about one year thus far. No signs of leaking on the shocks or diff mounts, or front engine mounts. After the incident I drove on the highway about 2 hours, then did a bunch of WOT runs to street tune my car after having a wideband AFR kit installed. The engine and suspension felt perfectly normal. Outside of the coilovers all other suspension parts are OEM. Brakes work fine. The sound could have been similar to a stressed suspension part breaking under load, I know people talk about bumpsteer arms doing that but I don't have any bumpsteer kits.

Located in small town Canada, hand guns are banned, No strange looking redneck vehicles anywhere near me

Thanks for reading, Any ideas or has anyone ever experienced something like this ?

 

Do both of your seat belt retractors still work? Don't they have explosive locks? Check the passenger side.

 

Thanks for the reply, I'll have a look, if I had to guess I'd say the noise was closer to the passenger side than the driver side.

 

Joey,any cowboys,in your neck of the woods???

 

Spare tire installed???
Maybe the plate/bolt was not installed perfect and it slipped into place.
Thought the same thing about the rear catchers for the hardtop

 

Not really, and it isn't deer hunting season either , lol

 

Thanks for the reply. I actually don't run a spare tire, so it was not in the vehicle. It sounded like a stressed item breaking or snapping into place, that kind of sound, but extremely loud. A gunshot is the best way to describe it, but the noise was in the rear part of the vehicle or cabin, not external to my car.

I poked around the rear underside with a bright flashlight, everything looks normal. There is a small bit of brown fluid on the driver side rear diff mount, nothing that would resemble an explosion, just enough fluid to mark up my finger when touched. All the lugs are in place, brake components, no broken suspension that I can see. The coilover springs are not cracked, no sagging of the suspension and tires are good, and lug nuts in place.

 

No handguns means the law abiding don't have handguns. That being said, it may be something as simple as a rock flying up and hitting something. Been there, heard that. Sounds like you rounded up the usual suspects.
Then again it may be some time before you find something and you get the "ah hah" moment.

 

Yes sadly that is true, the gang bangers in our country all have hand guns, the innocent law abiding citizens can't own hand guns. But that's another story.

Yeah at this point I have no idea, and I will keep an eye on things, it may show up later, or it may have been road debris as you noted

Still not sure if diff mounts or shock absorbers can make such a noise ?

 

Maybe you ran over something? Even like a plastic bottle, air explodes when you run over it. Maybe even blown under tire by wind, so no chance for you to see it coming, and if its clear plastic, and now flat, not much to see in rear view mirror...

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