Need advice: 06 Legacy GT 5MT center diff bearing noise. Service diff or swap trans?

[adwinistrator]

Backstory

 

Transmission was rebuilt at 86,000 miles 3 years ago (lost 5th gear). Sold to previous owner at 110,000 miles, I purchased at 125,000 miles 6 months ago.

 

I had the transmission fluid changed at the beginning on December.

 

Here's a picture of the fluid that came out.

 

A few weeks later, I heard some speed related scraping noises that went away after a few minutes. My first thought was wheel bearing.

 

On 12/26, I start hearing a whining noise, like a wheel bearing would make. It changes pitch and intensity as wheel speed increases, no changes on acceleration, deceleration, steering, gear change, or neutral. I was hoping it was a wheel bearing, but the fact that it didn't change when steering had me concerned.

 

[ame=www.youtube.com/watch?v=br9iXvEXRkk]Drivetrain noise[/ame]

 

In the following days, the noise would come back after about 10-15 minutes of driving.

 

Took the car into my shop on 12/31 and had them check it out, the sound is coming from the center differential. On the way there, the noise didn't seem to come back while I was on the thruway, but when I got on the side roads, I could hear it again. The range and pitch of the noise/speed seems to have changed.

 

 

Diagnosing

 

I'm not sure exactly what is causing this noise. My main guess is the rear bearing on the transfer driver gear (output shaft) of the center differential. A lot of the people with center diff noise say that the noise is only during acceleration or deceleration, but that's not what my problem is.

 

 

Decision Time

 

They recommended that I purchase a used transmission and swap it out. Their rationale is that it's highly unlikely that one bearing is the only issue with the transmission, and that doing the service might end up being a waste of money.

 

I've been doing a bit of research online, and this seems like a somewhat common issue. People are writing up DIY center differential bearing replacement guides.

 

LegacyGT.com guide

NASIOC thread

 

The only used transmission in the area would cost $1,400, free delivery, 30 day warranty (parts only), and has 114,000 miles. Labor would be about $650.

If it's just the center differential bearings, parts would be about $175, labor about $400.

If the differential's viscous coupling is damaged, the cost would end up around $1,100.

To just open the center differential and see what it looks like would be about $250.

 

I'm leaning towards having the shop open up the differential and proceed from there. If it looks like there are worse problems then just the bearings, I'll purchase the local transmission, or order one with less miles and pay shipping, then have them install it.

 

 

Questions

 

What would you do if you were in my shoes?

 

With the noise being consistent with the wheel speed, and not changing depending on other factors, would that lead you to believe that it's the differential bearings, or the differential's viscous coupling? I would think if there's noise on load, that it's the viscous coupling, whereas if the noise happens all the time, it's a bearing.

Thanks in advance for any advice you can give!

[Max Capacity]

Be prepared, IMO with the fluid looking like that, you have more issues. More bearings are bad or will be bad in the near future.

 

If you buy the junkyard tranny, you may install it, only to find out it has noise, or begins to make noise. 30 day's goes by quickly.

 

My junkyard 5mt was opened up and inspected before it was installed. After the test drive it still had a noisy input bearing. Tranny came out again. 5 month's later the clutch began to slip, it had 50,000 miles on it, tranny comes out again. 8 months later it began making more noise, the fluid was looking pretty gray. VC blew, and the metal bits contaminated the bearings. Shop said the snap ring on the VC broke.

 

I don't launch the car, I've put 21,000 miles on the junkyard tranny in 13 months.

 

The past month I've noticed the noise stopped as the car rolled to the stop sign when the speed dropped to about 15mph and I'd step on the brakes.

 

Hope to have the back from the tranny shop tomorrow.

[Rhitter]

^ looks like it's time for a 6spd swap Max.

[RX7LegacyGT]

Had the same noise on my 2005 gt wagon and just wanted to confirm what it was with the dealer before actually repairing it. And it was a bearing in the center diff that had went. Dealer said it wasn't worth replacing and to just buy a used trans cause a new one would count around 5400. I said thank you and went on my way. Did my research ordered the appropriate bearings and diff ( was getting a knocking noise also when steering wheel was fully turn) and went at it the job is soo simple only took around 3 hours and that's with me aND a buddy messing around.http://i77.photobucket.com/albums/j51/rotarydriver108/Mobile%20Uploads/20151206_110058_zpsoq9fgobp.jpghttp://i77.photobucket.com/albums/j51/rotarydriver108/Mobile%20Uploads/20151206_110105_zpsgc7u5elx.jpg

[RX7LegacyGT]

This man was a big help for me and made my job easier. Didn't go into it blindly. Helped me order the parts I needed. Only thing I didn't do was his gear oil mixture

[lucas623]

Hey guys, I am actually having what seems like the same problem on a 2005 gt I just bought. Here's a video with the sound. The noise seems to start becoming noticeable around 40 mph which is what it seemed like in your video, and then gets higher in pitch as wheel speed increases

 

https://vimeo.com/153722426

 

 

Sent from my iPhone using Tapatalk

[adwinistrator]

Hey guys, I am actually having what seems like the same problem on a 2005 gt I just bought. Here's a video with the sound. The noise seems to start becoming noticeable around 40 mph which is what it seemed like in your video, and then gets higher in pitch as wheel speed increases

 

https://vimeo.com/153722426

 

 

Sent from my iPhone using Tapatalk

 

It could just be a wheel bearing, I'd have a shop check them out, ask them to locate the sound (screw driver as stethoscope).

 

For me, the Center Diff's viscous coupling's snap ring broke, and got lodged in the center diff bearings. Replaced all the bearings and the VC.

 

I didn't have any of the normal VC failure symptoms, which is binding noises when turning at full lock.

 

Other issues could be driveshaft joints.

[chhrisd]

Hey guys, I am actually having what seems like the same problem on a 2005 gt I just bought. Here's a video with the sound. The noise seems to start becoming noticeable around 40 mph which is what it seemed like in your video, and then gets higher in pitch as wheel speed increases

 

https://vimeo.com/153722426

 

 

Sent from my iPhone using Tapatalk

 

Mine has this same "airplane" noise on acceleration with low RPM. Pretty convinced it's the center diff bearings, and maybe the center diff itself. I get some binding at full steering lock in reverse, which is also indicative of center diff problems.

 

I had the center diff snap ring break and take out the transfer gear in my 2010 WRX. That sounded like a card in the spokes of a bicycle wheel. Up until that happened, I got a whirring/grinding sound on deceleration.

[ssulb]

This happened to me in my 2001 Forester. I have the 4EAT transmission. The noise frequency and loudness did vary on how fast I was going. At first the noise sounded like a winning bearing, then it gotten worse. After, it sounded like metal grinding and metal knocking noises. I knew it was time for a new transmission. When I was driving one day home, the front differential finally gave out. Sounded really bad but I made it home since I was only a few miles away. I got home trying to drive the rear wheels only which the Foz did not like because it didn't want to engage them most of the time. Felt like I was in neutral but I was in drive.

 

Anyways I replaced the transmission for one with less miles and all is good. Except I think the noise is coming back when taking the car past 80MPH.

 

I think it would be less of a headache to get the entire transmission swapped rather than trying to fix it. Never know what else can go wrong or what else is bad.

 

 

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