Bad Shaft OR U-Joint ?

[NissanFairladyZ32]

Sounds like its coming from the rear, I need to get this addressed its annoying.

[Strider]

that is a weird noise. It's not shocks or anything? If you drive along side a fence the sound should be lauder from bouncing off the fence. Maybe try that to see if you can figure it out?

[boisking]

When i reverse, The squeak increases as my speed increases with the sound of the car.

With the car not in gear, (Neutral) the car will never make the squeak. Only when rolling in gear it will, most noticeable when taking off from 1st &, reversing.

Engine revs do not have a direct effect on the squeak. Wheel speed does have a direct effect on the squeak.

Place the vehicle on jack stands, engine off, in neutral. Assuming you have a torsen, open, or viscous diff, spin one wheel at a time by hand (all 4 wheels). Listen for noise. Remove the wheels and try to see if the backing plate for the brakes is rubbing the disk (common). Next, double and triple check that all of the retainer and alignment clips on the brake pads and calipers are seated and installed properly (common). Next check all the brake hoses for wear resulting from rubbing (less common, less noisy, bigger consequences). Look at the inside of your wheels to see if anything has been polished from rubbing (more common for wide aftermarket wheels). Look at the brake rotors to see if anything has been polishing them that wasn't a brake pad (both sides of the rotor).

It has been a while since I was inside a Miata brake. Remind me: do the pads have those little v-shaped springs that help return the pads to a resting open position? If so, check for the proper installation of those things (common).

Do your brakes ever squeal under light-moderate braking? Did you use OEM, Aftermarket OE equivalent, or high performance pads when you replaced?

[NissanFairladyZ32]

Engine revs do not have a direct effect on the squeak. Wheel speed does have a direct effect on the squeak.

Place the vehicle on jack stands, engine off, in neutral. Assuming you have a torsen, open, or viscous diff, spin one wheel at a time by hand (all 4 wheels). Listen for noise. Remove the wheels and try to see if the backing plate for the brakes is rubbing the disk (common). Next, double and triple check that all of the retainer and alignment clips on the brake pads and calipers are seated and installed properly (common). Next check all the brake hoses for wear resulting from rubbing (less common, less noisy, bigger consequences). Look at the inside of your wheels to see if anything has been polished from rubbing (more common for wide aftermarket wheels). Look at the brake rotors to see if anything has been polishing them that wasn't a brake pad (both sides of the rotor).

It has been a while since I was inside a Miata brake. Remind me: do the pads have those little v-shaped springs that help return the pads to a resting open position? If so, check for the proper installation of those things (common).

Do your brakes ever squeal under light-moderate braking? Did you use OEM, Aftermarket OE equivalent, or high performance pads when you replaced?

I used pads from the local oreilly's, brakes do not squeal under any kind of braking, i will put the car on stands tomorrow and check it out

[jakepkoe]

Your description sounds like a u-joint or, less likely, a CV joint. When you're in reverse you're applying pressure to the "back" side of the u-joints, same as when you're engine braking. Could be some other rear end bearing, but it sounds like it needs to be something that's loaded differently when in reverse than when in a forward gear. When you check it on jack stands you may have to load the parking brake a bit to get the noise to show itself. Listening to the video it sounds like a dry u-joint - the frequency sounds too great to be a CV.

[NissanFairladyZ32]

Your description sounds like a u-joint or, less likely, a CV joint. When you're in reverse you're applying pressure to the "back" side of the u-joints, same as when you're engine braking. Could be some other rear end bearing, but it sounds like it needs to be something that's loaded differently when in reverse than when in a forward gear. When you check it on jack stands you may have to load the parking brake a bit to get the noise to show itself. Listening to the video it sounds like a dry u-joint - the frequency sounds too great to be a CV.

Yeah i had it up on jack stands today and could not replicate the noise, turning the back wheels forward or reverse didn't give me a peep.

Im sure your correct about the sound being "loaded" because i could coast in neutral all day long with out a sound, but if i run the RPMs up and let off the gas quick enough for the car to shake back and forth it will squeek and upon reversing and taking off in 1st and 2nd, less noticeable in 3rd.