so for about a couple days now theres been a loud warping noise coming from the rear of the car. it gets loud when im cruising on the freeway about 80mph on fifth gear.

 

I haven't any idea what a "loud warping noise" sounds like but now all I can think of is Star Trek.

Which isn't really helping.

 

Are you sure it's not 88mph?


But seriously is it a knocking, whining, drone.....is it intermittent? Or all the time? Do bumps make Difference?


What year and model are we even talking about?

 

no i noticed today it does it when I get close to 80 and louder as I speed up from there. I had a friend check out my car and he said it could probably the caliper warped the rotor. cause ive been doing some heavy breaking around corners and ripping the e brake. but who knows im still open to suggestions.

 

It should go away once you hit 88 mph......if not check your muffler bearings.

 

If you warped the rotors you'd feel it every time you stepped on the brake, as the pedal will oscillate against your foot if any rotor is warped.

Are you sure its not wind noise from a bad taillight gasket or hatch seal?

Any noises coming from the rear of the car are generally not good, though it may also be, but not limited to: Rear half shafts, bad tire wear (or new tires that have an odd tread pattern that causes more road noise), the sound of your rear differential deciding it no longer wishes to be your best friend, or a fuel pump that's getting noisy.

More information is required if you please.

 

80 is a little late to be hearing/feeling tire imperfections. Usually the last thing you'd notice is a flat spot in the tire from sitting too long, and that makes itself known around 65.

Safe assumption, if he's going that fast, that we can rule out anything else RPM/load related, since it'd probably also be heard briefly at lower speed.

My money would be on the half shafts, diff, or wheel bearings, but more info is definitely needed.

Another thought- does the noise change depending on throttle input, or is it consistent at speed? IE, if you take your foot off the gas completely at 80, what do you hear? (This is a not-nice hard test of the rear end fail points.)

 

Good Q's here^

At first i thought maybe bad U-Joints but that's more of a terrifying vibration.......

 

In my experience at that speed, u-joints are at their worst when you let off the gas completely, and half shafts are at their worst when you're off the gas, then stomp it.

 

Have you checked your tires to see if there are any defects ?

 

Its probably the diff? Does it make noise in all gears?

 

alright well after reading everyones post I decided to look at my tires and rear end everything looks good cause I did just recently changed my drive shaft and diff mounts tires are solid so IDK!

but the noise only gets louder after 80. and reaching 100 the "warping" noise gets louder and faster. I hear it more when I let my foot off the clutch going about 85. its a real bassy sound if that makes sense.

 

Is there a bad vibration associated with this? Or is it just more of a noise?

My first thought was U-joints, but you would be terrified to drive your car at 80 mph if the U-joints were that bad.

 

also check the struts, if one is leaking the tire may be bouncing merrily down the road.

 

What kind of diff mounts did you just put in?

 

Differential?

 

I respectfully disagree. Harmonics can manifest at any rpm.

 

Depending on the level of imbalance, yes. But the reading most shops will be willing to trade a tire for is 1.4-1.6, IIRC. So if these tires are failed, he's on his own, and unless he bought them from a race shop or their z rated, it wouldn't be a true failure on a street car. Consider the speeds we're discussing.

'Bassy' means large, to me. Considering the phrase 'warping' was used in the description, I'm calling differential bearings. I'd say preload, but I don't think it's likely.

 

ok well there is a crazy vibration sometimes on first and reverse after all day of driving it. the drive shaft is new from mazdatrix and also got there competition mounts from them.. didn't really think the vibration could probably be apart of it.. well right now seems like the car is falling apart problem after problem. dang old car but sticking threw till the end....

 

What shape are the subframe mounts in, or did you replace those too?

What's your fluid level in the diff and what kind? I know it seems like a stupid question, but.

 

if it's giving a vibration in first and reverse i would hazard a guess as to a faulty accessory or the transmission is about to implode.

 

Which, coincidentally, happens to be the very last thing that you want to hear right now

 

Eye balling your tires won't tell you if they are uneven try to run your hand around the treads of your tires to see if the grooves feel uneven /lumpy ,I've experienced with tires that apparently looked good but made noise at certain speeds .
Another thing to look at is the axles take a look at them to see if it has any wear or tear. Maybe even take them out and inspect .I had this problem on my s2k where one of my rear axles were cracked in half on the insert to the diff.(made noise at 45-to 50 and couldn't hear it at higher speeds due to convertible top ,but I'm sure it was there . Made a wopping sound ,wop wop wop wop wop and increased at higher speeds .. Just my 2 cents .hope you figure it out

 

yeah exactly! but ive heard from a couple people already that it might be my tranny...

 

yeah this is helps. sounds like my problem the "wop wop wop wop" gets loud at 80