# Tool list / Procedure needed for checking and adjusting backlash on an '04-'06 GTO



## Robk46 (Jul 23, 2010)

Guys, been lurking for a while, and have a couple questions. I recently bought an '05 A4 GTO with 65k miles on it. I knew the rears on these cars had issues, so I bought this car knowing the rear end whine it had was common. I have the typical 40-50mph whine, with it getting progressively quieter the faster I go. Can't hear it at 100+! I would like to know how to check the backlash, and what tools I need to check and possibly adjust it with, and how. Thanks!:cheers


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## jpalamar (Jul 22, 2008)

Don't know the procedure but I think the whine has nothing to do with the blacklash part.


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## Robk46 (Jul 23, 2010)

Hmmm. I've read in a few posts where people have thought whine was caused by improperly set backlash from the factory. I know on different diffs, if the gears are set with too little or too much backlash, you get whine and clunking.


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## jpalamar (Jul 22, 2008)

When was the last time you changes your diff fluid and what did you use?


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## Robk46 (Jul 23, 2010)

2k miles ago. Torco RGO 85w140 with 2 ounces F type modifier.


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## GM4life (Mar 18, 2007)

I replied to your PM.

This some things that I didn't put in the PM that I just thought of:
Backlash is adjusted by side adjusters. You can buy the tool from Speed inc. its about $100 or if you have the srap metal to make one yourself. You may need the non-click type torque wrench to adjust them too.


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## Robk46 (Jul 23, 2010)

Here's a link to the tool. http://www.speedinc.com/cont.cfm?cid=C0000719

I'll probably tackle this in a couple weeks. I'm just going to check the pinion and make sure it's close to spec, check the backlash, and make sure all the ring gear bolts are tight.


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## pctek (Jul 18, 2010)

Robk46 said:


> Here's a link to the tool. Speed Inc - Pure Power
> 
> I'll probably tackle this in a couple weeks. I'm just going to check the pinion and make sure it's close to spec, check the backlash, and make sure all the ring gear bolts are tight.


Can someone please explain how to use this tool to quiet the common whine of the diiff I dont get it yet? Thanks

I have a slight but not loud whine from the common speed of around 40-55 mph while the gas is aplied, but gets quiet when let go of gas. I can live with it it doesnt bother but if this tool can fix it then, can someone tell me how.


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## Robk46 (Jul 23, 2010)

Probably won't fix it. It's just a tool to use to adjust the side adjusters, which are used to change the backlash of the pinion gear. From what I've been able to gather, the backlash on these differentials was not set correctly from the factory and cause a whine. The pinion not set up correctly can cause this also. I thought I'd spend a few bucks and buy the tools to adjust it if my dial indicator says the backlash is out of whack or I find that my pinion nut is loose when I check it out.


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## pctek (Jul 18, 2010)

Robk46 said:


> Probably won't fix it. It's just a tool to use to adjust the side adjusters, which are used to change the backlash of the pinion gear. From what I've been able to gather, the backlash on these differentials was not set correctly from the factory and cause a whine. The pinion not set up correctly can cause this also. I thought I'd spend a few bucks and buy the tools to adjust it if my dial indicator says the backlash is out of whack or I find that my pinion nut is loose when I check it out.


OK now is this all adjusted wiithout draining the gear oil or does this involve draining and opening up the diff?

So the side adjusters change the clearance between the pinion gear and ring right? So the bigger the clearance then you get whine and backslash/clunking? Am I right?

So with the tool are you jsut guessing how much clearance to give it and jsut test the car by driving it to see if its quiter?


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## GM4life (Mar 18, 2007)

pctek said:


> Can someone please explain how to use this tool to quiet the common whine of the diiff I dont get it yet? Thanks
> 
> I have a slight but not loud whine from the common speed of around 40-55 mph while the gas is aplied, but gets quiet when let go of gas. I can live with it it doesnt bother but if this tool can fix it then, can someone tell me how.


Backlash is adjusted with preload. Just slaping on that tool and going to town is not going to do anything for you unless you do the correct preload. Once the gears start howling its too late they are allready worn beyond repair. Incorrect back lash will cause the gear noise and if you have a howl during accel most likely its the gears. Howl during decel is going to be pinion bearing.

That tool fits into the side adjusters of the diff housing where the CV's go into.


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## GM4life (Mar 18, 2007)

Here is my thread, you can see the side adjusters in these pictures.

http://www.gtoforum.com/f39/inside-dana-26971/


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## pctek (Jul 18, 2010)

GM4life said:


> Backlash is adjusted with preload. Just slaping on that tool and going to town is not going to do anything for you unless you do the correct preload. Once the gears start howling its too late they are allready worn beyond repair. Incorrect back lash will cause the gear noise and if you have a howl during accel most likely its the gears. Howl during decel is going to be pinion bearing.
> 
> That tool fits into the side adjusters of the diff housing where the CV's go into.


Ok so I dont want to waste time and money so you already tried fixing the whine with the diiff side ring tool we are talking about in this thread right? And when you say howl you mean whine right? Thanks


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## Robk46 (Jul 23, 2010)

You need a dial indicator attached to a base. You measure backlash and set the adjusters until it's at the desired spec. There's a sticky with the specs in this forum. The diff has to be opened to do this. I have been told that if you're careful and adjust both the left and right side adjusters the same amount, you won't lose your existing pre-load. I have also read a few threads were folks far more experienced with diffs have opened them up and adjusted the backlash to a tighter spec like .005-.007" and have gotten rid of some of the whine, if not all.


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## GM4life (Mar 18, 2007)

pctek said:


> Ok so I dont want to waste time and money so you already tried fixing the whine with the diiff side ring tool we are talking about in this thread right? And when you say howl you mean whine right? Thanks


Nope, I did some reasearch by talking to a local guy about the diff trying to weigh my options on letting someone fool with it, or doing it myself. Thats after I popped the cover off and didn't see any obvious defects. The gears will cost $600+ and it looks to be around $300 to install vs. getting a mag base for my dial indicator, side adjustment tool, dial indicator torque wrench, bearings, and whatever else, might total about the same in labor. Yeah I do my own work on my car and it looks like the only gain I will get is the experiance. I'm just dealing with the howl now.


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## Robk46 (Jul 23, 2010)

Keep in mind most people just get the diff rebuilt, buy a new one, or just live with the maddening whine. I just thought I'd give it a try.


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## GM4life (Mar 18, 2007)

Robk46 said:


> I just thought I'd give it a try.


Nothing wrong with that. If you have time please post pics w/instructions, I'll make it a sticky. I may just give it a try anyway. Still in the air for me.


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