strange grind???

AlfaRomeo1750 · #1 (**permalink**) 04-16-2008, 08:13 AM

Hey Guys,

Last night driving home from work while backing into the drive way I heard a momentary grind coming from the back of my 164S. It sounded analogous to say scraping your tail pipe on a parking divider.

At first I thought it was simply me catching the driveway wrong ... I looked under the car for damage.. saw none and thought nothing of it..

Today backing out of a parking space on flat ground I heard the same noise and like before it lasted mere fractions of a second.

Again I looked under the car but couldn't see anything rubbing ... this only happens in reverse and its coming from the back of the car...

Any thoughts??

Cheers
Martin

ChazzyD · #2 (**permalink**) 04-16-2008, 08:43 AM

Do you have a rock stuck in a caliper bracket rubbing on the rotor, or between a backing plate and the rotor? You may have to remove the wheels and investigate.
Charles

AlfaRomeo1750 · #3 (**permalink**) 04-27-2008, 08:47 AM

Hey guys,

Charles .... thanks for the reply. However I could not find any signs of a stone... and the noise has gotten more pronounced.

The grind only occurs when the car is in reverse at low speed and appears to originate from the RT rear wheel. My question is... what is back there that could cause such a noise?

It doesn't occur in a forward direction... only reverse...so what could it be... its becoming very frustrating..

Cheers
Martin

Alfisto Steve · #4 (**permalink**) 04-27-2008, 09:41 AM

Quote:

Originally Posted by AlfaRomeo1750

Hey guys,

Charles .... thanks for the reply. However I could not find any signs of a stone... and the noise has gotten more pronounced.

The grind only occurs when the car is in reverse at low speed and appears to originate from the RT rear wheel. My question is... what is back there that could cause such a noise?

It doesn't occur in a forward direction... only reverse...so what could it be... its becoming very frustrating..

Cheers
Martin

AlfaRomeo1750 · #5 (**permalink**) 04-27-2008, 10:08 AM

Steve

Thanks for the reply. I did jack up the car but can't reproduce the noise and I can't seem to locate a source. The noise is intermittant... so I am wondering if there are possibly bearings or other moving parts back there to look at?

I couldn't find evidence of a stone jammed in the brakes which was my first incling...so I don't know what else could be back there to scrape.. and why ONLY in reverse??

Cheers
Martin

Alfisto Steve · #6 (**permalink**) 04-27-2008, 02:10 PM

Quote:

Originally Posted by AlfaRomeo1750

Steve

Thanks for the reply. I did jack up the car but can't reproduce the noise and I can't seem to locate a source. The noise is intermittant... so I am wondering if there are possibly bearings or other moving parts back there to look at?

I couldn't find evidence of a stone jammed in the brakes which was my first incling...so I don't know what else could be back there to scrape.. and why ONLY in reverse??

Cheers
Martin

**Alfissimo Int.** · #7 (**permalink**) 04-27-2008, 03:51 PM

Quote:

Originally Posted by AlfaRomeo1750

Hey Guys,

Last night driving home from work while backing into the drive way I heard a momentary grind coming from the back of my 164S. It sounded analogous to say scraping your tail pipe on a parking divider.

At first I thought it was simply me catching the driveway wrong ... I looked under the car for damage.. saw none and thought nothing of it..

Today backing out of a parking space on flat ground I heard the same noise and like before it lasted mere fractions of a second.

Again I looked under the car but couldn't see anything rubbing ... this only happens in reverse and its coming from the back of the car...

Any thoughts??

Cheers
Martin

AlfaRomeo1750 · #8 (**permalink**) 04-27-2008, 04:32 PM

Jason,

Yeah it is a strange one... The noise is frustratingly intermittent and it only occurs while backing up with no brake pressure applied. I have tried jacking up the car and seeing if I could reproduce the sound by turning the wheel, however my efforts were unsuccessful.

I tried putting the car in a hard reverse while applying the brakes to see if the sound stopped before the car did... however again I was unsuccessful as the car stopped about the same time as the noise.

Why it doesnt occur in the forward direction is also a mystery... I would think that anything that could affect the system would occur no matter what direction the wheel was turning.

The brake calipers and rear set up are only a year old.. and the stopping power is great with a nice solid feel and good emergency brake. Out of curiosity how would the dust shield get bent, and why would it only scrape in reverse?

Does any one have photos of the rear wheel taken apart to give me an idea of what to look for when I pull it apart? Also it seems like the noise is getting louder...

Thanks for the advice guys... If I cant figure this out it will have to go to the mechanic... and that trip I was saving for bigger fish that need to be fried.

Cheers
Martin.

jontg428 · #9 (**permalink**) 04-27-2008, 05:36 PM

Hmmm, this sounds like a challenge. My one thought is that upon reversing, the rear suspension lifts up slightly, exposing the noise, which could be caused by loose strut mounting bolts between the chasis and strut, or maybe the pads between the spring and upper mount are worn. It may not do this upon jacking the car up because the slight life is slow, not quick like when you are backing up. This is just a guess, but maybe worth looking into, hope it helps,
Jon

ChazzyD · #10 (**permalink**) 04-27-2008, 05:55 PM

You checked the muffler, right?

It's not dragging on the ground?

Sure sounds like a backing plate rubbing the rotor the way you describe the sound, but doesn't make any sense happening only in reverse.

Charles

**Alfissimo Int.** · #11 (**permalink**) 04-27-2008, 06:47 PM

Quote:

Originally Posted by AlfaRomeo1750

Jason,

Yeah it is a strange one... The noise is frustratingly intermittent and it only occurs while backing up with no brake pressure applied. I have tried jacking up the car and seeing if I could reproduce the sound by turning the wheel, however my efforts were unsuccessful.

I tried putting the car in a hard reverse while applying the brakes to see if the sound stopped before the car did... however again I was unsuccessful as the car stopped about the same time as the noise.

Why it doesnt occur in the forward direction is also a mystery... I would think that anything that could affect the system would occur no matter what direction the wheel was turning.

The brake calipers and rear set up are only a year old.. and the stopping power is great with a nice solid feel and good emergency brake. Out of curiosity how would the dust shield get bent, and why would it only scrape in reverse?

Does any one have photos of the rear wheel taken apart to give me an idea of what to look for when I pull it apart? Also it seems like the noise is getting louder...

Thanks for the advice guys... If I cant figure this out it will have to go to the mechanic... and that trip I was saving for bigger fish that need to be fried.

Cheers
Martin.

jontg428 · #12 (**permalink**) 04-27-2008, 07:16 PM

I hear you Jason, the only thing I could come up with is the suspension rapidly rising, probably not the cause, but worth a shot!

dennism · #13 (**permalink**) 04-27-2008, 07:23 PM

Are the front wheels turned? Front tire rubbing at full lock?

**Alfissimo Int.** · #14 (**permalink**) 04-27-2008, 07:28 PM

Quote:

Originally Posted by dennism

Are the front wheels turned? Front tire rubbing at full lock?

AR4me · #15 (**permalink**) 04-27-2008, 08:54 PM

Warn wheel bearing resulting in enough play for ring gear to grind on ABS sensor (just about 1 mm of clearance)? Perhaps in reverse the load is right to move it towards the sensor, while going forward it moves it away from sensor - just another whacky thought... Check for play in wheel and see if ABS sensor has grind marks.
Jes