After researching the site, I believe thatthe noise coming from my sister-in-laws 2001 A4 Quattro is a failing wheel bearing. The symptoms are that the noise/sounds starts low and gets louder with speed. Turning to the right increases the sound (IE loading the left rear) so I think its the left rear bearing? Please confirm if you think my diagnosis is correct and answer these questions

1) Is it best to only change the suspect one or both?
2) Cost for DYI vs mechanic? In other words is it extremely hard, special tools or can a decent mechanic who has the motivation succeed?
2) Best place to buy the parts?She is on a budget, but I don't want to do this again because of crappy parts!
3) How to do it? Any tips, suggestions, do's dont's and does anyone have a step by step or photos?
4) Any other common sense, must do items while changing a bearing etc.

Thanks a million, you guys are always great!...Max

 

I just had mine replaced in my 01 quattro, cost my 120 for the bearing and 50 to have it installed. The wheel seemed like it got really lound but the mechanic said i had another couple months yet. From the start of hearing the sound, i would say you probably have 3-4 months to get it fixed.

 

Interesting... I just had to replace my rear wheel bearing last week. I've seen the parts online for as little as 49.95 with the axle bolt (it needs to be replaced each time it's removed). I was worried that mine wouldn't last until one came in the mail so I picked it up locally for just over $60 + $6 for the bolt. I was quote about $250 to replace it from an Audi mechanic (not dealership either)... I couldn't afford that so I took the whole knuckle off myself and took it to someone to have the bearing pressed off/on (cost me an additionl $20) and took me about 45 minutes each way to take it off and put it on. If you do decide to do this yourself and take the knuckle off make sure you mark the lower bolt position, may help avoid having to have the alignment done. I took pics of the whole proceedure but never posted them anywhere. It's pretty straight forward though.

 

try this lift up the side you think is the bad bearing, and shake the wheel if it has play its bad. ive replaced boith my rears, hopefully th fronts dont go out. from what i hear its pretty common for these to fail. go to blauparts.com they have very good bearing for about $55. you can take it to a shop and have it doen for 100-200 or take off the upright yourself and have someone press on a new one.

 

I paid $250 for an independent mechanic to replace a rear wheel bearing.
It needs to be pressed in.

 

I just did mine last weekend. The cost was 66 dollars for the wheel bearing from audi at cost. Then I took everything apart and ran the hub to a shop where they pressed the old bearing out and the new one in for nothing, I did give them some money though. Then I put everything back together and drove it. It took about 3 hours because i had to run back and forth to the shop. I would just have a shop do it if you have no mechanical experience.

 

Here is a nice step by step DIY with pictures.
http://www.audiworld.com/tech/wheel33.shtml