constant noise

[123redtail]

my backdraft has constant noise behind cockpit .sounds like leaves blowing down the street. does anyone know if its sand off of tires hitting fiberglass inner fender? Or possible road noise coming up thru roll bars? its not too loud ,but its always there while driving. hard to tell what and where it coming from.

[patrickt]

Is the noise the same when driving with the top up?

[123redtail]

no top, full convertible . I have 2 rollbars . sounds like leaves blowing on the street. backdraft has 1450 miles .I can cruise and not hear the exhaust but hear the light continuese noise .only stops when the car stops.

[spdbrake]

If you can.
Jack it (use jack stands preferably) and let it idle in second or third and see if it L -R side half shaft CV joints or wheel bearing and the Diff possibly.
The CV typ have a ticking or crackling sound, wheel bearing a dry drone (sharpening stone) Diff have more a howl which goes to a higher pitch (tone) with speed.

These type of checks should always be done with someone at the controls. The person listening should not wear any loose fitting or long sleeved shirts.
A spinning tire will come-here-you terrifyingly fast.

Hopefully you just have a plastic grocery bag wrapped up on the axle.

[6t8stang]

Is your significant other in the passenger seat when you hear this noise? LOL

I was going to suggest the same as spdbrake...maybe try spinning the tires in the air by hand while under the car before running the car. Does the noise change based on the type of road you're on (asphalt, concrete, etc)? Does it change with speed?

[1795]

I would also take a look at the tires for signs of wear and possible a stone or some other object that is stuck in the tread. A stone that is at the level of the tread will make a humming noise as it makes contact with the pavement. Aso, wiggle the tires side to side while you have it up; they should be solid. If there is any play it could be sign of a bad wheel bearing.

[MOTORHEAD]

Some tread patterns will make more noise than others, jacked-up pickup with mudders as an extreme example. Run your hand lightly over the tread, does it want to catch on raised edges ? If so, that indicates scuffing due to mis-alignment. Had many rear alignment problems when I was working for local dealer some years ago. Don't know if inprovements have been made since then.


Ted

[patrickt]

Originally Posted by 123redtail

no top, full convertible . I have 2 rollbars . sounds like leaves blowing on the street.

OK, the easiest, and most harmless, would be air noise, maybe in combination with the backs of your seats, carpeting, etc. You don't get that though until you get up around 30mph or so. When I do a "noise diagnosis" on my Cobra, I get it up to about 45mph, on a smooth road, then put it in neutral and kill the engine. The only thing I hear is the air noise which, on my car, sounds like just like a good leak in a tire. I can still remember the first time I did that I thought, for an instant, "oh my gosh my fire extinguisher must be leaking." But, the sound of leaves, is just plain different. And, of course, if you can hear the sound at very low speeds, then it can't be air noise at all.

So, take it up to about 45mph, on a smooth road, kill the engine, and then listen as carefully as you can, then, ever so lightly, put your foot on the brakes and see if you can change the sound as you increase the pressure. If you can't, then that pretty much eliminates the brake pads and rotors. Then, pump your tires up to 40psi and repeat the test to see if the sound has changed (then put your tires back down to regular pressure). That will point you to tires. If you still haven't found the sound, then you're going to have to jack the car up and look for (if you are really lucky) something, like a plastic bag, stuck under your car and hitting the drive shaft, inner wheel, etc. Then use a mechanic's stethoscope to listen to all the moving parts as one of your kids spins the rear wheels by hand, as fast as he can, with the car in neutral. Put the stethoscope on everything from the transmission, to the rear differential, to the hub area of the bearings. Then have him spin the front wheels while you do the same thing. There's only so many things that it can be, and you will eventually find it (especially if you discover that one wheel sounds significantly different than its mate on the other side of the car).

[Ozzie Goat]

Since you are a blown coyote, I assume it's a newer car.

My car has the baffle style side pipes, and on decel I can hear a rustling leaves noise.
However, you should have the glass pack style side pipes; therefore different noises.

[Bill Bulmer]

I also have a newer cobra and get the same sound, it used to drive me crazy. I have found it to be the quality of the road surface;almost anything other then newly paved blacktop kicks up sand, gravel, leaves and any other debris and it resonates loudly through the rear fender wells into the car.

I first realized this when doing a small burnout on an aged paved road, and I thought someone was shooting bullets at me for doing it. I think a rubberized undercoating in the fender wells would go a long way in solving this problem, although I haven't done it yet myself.

[jimbo01]

I hear the same noise. Coming from the tires and the glass body. The tires pick up sand on my local street. I agree that a good coating on the wheel wells would likely fix the problem but I don;t like the rubber coating. Just live with it.

[carmine]

Cut and glue 1/4 inch thick black foam sheet to inside of wheel well openings.