ThaGoat21

I have an 04 a4 gto, everytime I turn in reverse or make sharp turns in drive the is a rubbing or grinding sound in the rear. Has anyone else experienced this? If sp can you give me some insight as to what it might be. I took it to a local mechanic shop, and they told me it was the bushing that had gone bad so there was a lot of play on the rear, so I had them change them all and $1000 later I still have the problem. Any help would be much appreciated!

Rich-L79

Which bushings were replaced?

ThaGoat21

The bushings the differential sit on

Tim94gt

iTrader: (2)

What size wheels/tires? What other suspension mods do you have?

Where is the noise coming from? Left side, right side, middle?

2QWK4RU 06 GOAT

iTrader: (1)

You likely need friction modifier in your diff or a diff rebuild-I speak from experience and have built dozens of them.

The quick fix is a good quality 85w140 dino oil such as Castrol and the proper friction mod. Many have had good luck with the new GM stuff. Torco rgo is common in GTO circles but I have seen the least wear protection in diffs using that oil on a consistant level.

Driveshaft and exhaust should be checked too.

ThaGoat21

How much does a diff rebuild run?

2QWK4RU 06 GOAT

iTrader: (1)

Rebuilds vary depending on what your builder finds. I would say $500 to $2000 depending on if gears and/or lsd need replacing. Likely $600-900 would be the most common amount from what I see.

steamwalker

I had a grunting sound from the rear when I backed up. I replaced the gear oil and fm (Torco) and the sound went away.

2QWK4RU 06 GOAT

iTrader: (1)

I'm sure it did, it's thick and gunky and quiets our diffs very often. However, it doesn't do a great job at protecting the parts in it. I'd get it out and put something else in it.

Loudmouthls2

I had the same noise on my car. Came to find out my exhaust pipe was rubbing against my spinning driveshaft rubber connector when the car slightly squatted.. It was obnoxious

td1168

iTrader: (2)

"grinding and rubbing in the rear end!" Sounds like the title of a movie!

tofast4u-lsx

If the noise gets more pronounced as you drive longer distance, change diff fluid and add some extra friction modifier, worked for me, had clunking and grinding just as you explained.

SpiceRedLS2

Torco is good stuff just remember to get the type F friction modifier

ULTIMATEORANGESS

iTrader: (4)

i hope you didnt burn out your posi unit.

2QWK4RU 06 GOAT

iTrader: (1)

What experience do you have that makes it good? Based on my many years experience with it, I'd say otherwise.

GTObrake

The odd noise I was experiencing sounded like something in my trunk was shifting around and it turned out to be rubber failure in my multi piece drive shaft. BMR one piece and it is gone.

SpiceRedLS2

When i bought the car the previous owner had royal purple in it and after i had it around 3,000 miles i started to get low speed noises when turning like described. Switched to torco and have had no problems in 20,000 miles. What is your "expert" opion on what oil is best or should be used?