let's play guess that sound

[LETZRIDE]

'I'm 100% stumped. If you remember right before I put the car away for winter I had a grinding sound coming from the car...was a faint metal on metal sound, like metal rubbing against another piece of metal while rotating...similar to that sound you get when you go over rumble strips, or when they've stripped that first layer of pavement from the road and you drive over it...but the sound is obviously quieter.


Anyways mechanic said rear sounded quiet...but the tail of the trans was grinding...fast forward to today, I've swapped trans and still have the exact same sound.

I thought the DS might be rubbing as there is marks on it...so I just put painters tape on the shaft where the marks are to see if it was infact the issue...tape is untouched.

Wheels don't look like they're near anything to rub, and I've swapped the rims/tires to eliminate that...still nothing.

I'm stumped...what the heck else could sound like it's grinding? Seems like you can hear the noise sometimes on accel, sometimes on decel...and the odd time if you put the car in neutral and rev it...all instances seems to occur with extreme light throttle, at higher throttle I'm sure its blended in with exhaust/motor noise.

Who has ideas?

I've pulled the belt and spun the pullies, most noise I hear is a squeaking
Alternator pulley.
Tires all turn freely, no marks on the rotors..I'm 100% out of ideas...I thought maybe even the timing chain, but my KR sensors pick up 0.1-0.5 degrees of knock at best and its random...and not usually when I can make out the grind/whine.

[LETZRIDE]

Re: let's play guess that sound

revisiting this, just got a new sphon tunnel mount torque arm. (thinking it may be the pinion angle being wrong, or the fact that the old tq arm was resting on the tunnel and transmitting noise)

my findings...new tq arm is set to -2 pinion angle, and the arm is not contacting anywhere.

I still have the noise, and an even louder vibration at approximately 80mph...infact, my floor sounds/feels as if it wants to tear off the floor the moment you hit 80mph, prior to that it is ok except for that light throttle grind/vibrationy sound.

I am now 100% out of any ideas at all.

[enzia35]

Re: let's play guess that sound

Where does it sound like the noise is coming from?

[LETZRIDE]

Re: let's play guess that sound

to be honest it's tough to say just when I think it might be coming from somewhere, it sounds like its coming from somewhere else.

Trying to break this down in my head a little further, when you apply light throttle, what is everything that moves or I guess I should say maybe torques itself or shifts position slightly?

also I should add, if any of you have let off the throttle before and had you're car dip to about 1000 rpm and then blip back to 1500rpm, that self blip also produces the sound, but when you're not on the throttle and it goes back to 1000rpm you can't hear anything anymore.

[MegaHertz]

Re: let's play guess that sound

Engine and tranny shift a bit - have you checked the mounts? Have you eliminated the rear end? Mine whines a little and that definitely changes as i get on and off the gas.

Found the post on ftv6 ;-) Also noticed you're running a ford rear end - double check that for noise.

[LETZRIDE]

Re: let's play guess that sound

stethscope to the rear end says it's quiet, the trans and motor mounts are poly, dont see how they would go bad...but I am considering changing the trans mount back to stock since the tq arm is no longer resting on the trans, and I have eliminated 2 bushings as a result.

[timthescarred]

Re: let's play guess that sound

Lets try to narrow it down, Do you get any noise sitting still or just driving?

[LETZRIDE]

Re: let's play guess that sound

just driving.

[LETZRIDE]

Re: let's play guess that sound

Do these marks look normal to anyone? like the whitish mark where it enters the transmission?

[flamingchicken]

Re: let's play guess that sound

Looks normal to me. Thats where the seal comes in contact as the DS shifts in and out of the trans due to the rear end moving up and down. All of the tactics I use to find noises you have done. Could it be harmonics of the engine, like a bad balancer or anything?

[transamtom1]

Re: let's play guess that sound

How about a bad pinion bearing or wheel bearing Mike?

[timthescarred]

Re: let's play guess that sound

Try jacking up the rear end and rotating the tires, get a friend to help and see if you hear the noise, if so, disconnect the drive shaft spin the tires and see if you still hear it, that will tell us whether its in the tranny DS or rear

[LETZRIDE]

Re: let's play guess that sound

How about a bad pinion bearing or wheel bearing Mike?

all are brand new with this rear end, as well as the front bearings were done 1-2 months before winter as well.

Try jacking up the rear end and rotating the tires, get a friend to help and see if you hear the noise, if so, disconnect the drive shaft spin the tires and see if you still hear it, that will tell us whether its in the tranny DS or rear

I am now battling 2 vibrations, the second one has come on since changing the tq arm to a tunnel mount one. I am convinced the pinion angle is off because I swear something feels like it wants to explode when I hit 80mph...similarily if you give it some throttle in reverse, I thought I blew the driveshaft out today.

Back to the first vibration (which is what this thread was about, as the 2nd one didnt exist at the time of this)

when I put the car up on jackstands and spin the wheels you don't hear the noise...same thing if you drive it and take it up to speed on the jackstands...no noise with the suspension unloaded. If you however jack up on the rear and run the car, you can get a faint sound from the car.

[timthescarred]

Re: let's play guess that sound

o.0 What kind of shape is the rear suspension in? Good bushings and shocks? Are your wheels balanced and your rotors true?

[LETZRIDE]

Re: let's play guess that sound

Shocks have about 80k on them, kyb adjustables...they're in good shape. Wheels are all balanced...rebalanced them to be sure before winter when we were originally trying to diagnose the issue. Rotors are brand new and went in with the rear end lol...this is why I'm going crazy