So I had Best Buy install a system a few months ago(September?) on my 85 4000s. Nothing spectacular just a pair of 70 watts speakers in the dash and 100's in the rear with a 360watt 4-channel amp(in case i wanted to go bigger{LOL}) and 1 farad capacitor.

Ran great for a while until the OEM alternator bearings wore out and scream until i finally had to replace it. I thought that since this was a new alternator I could run my system. I was mistaken and at the first sign of bearing wear I stopped using my stereo but it persisted in degrading and I am close to the point where i have to get a new one. AGAIN. I would really be happy to find out why it's destroying alternators and how to fix it. ANY help is greatly appreciated.

 

It sounds like you need a bigger alternator to power everything. I don't know if one is available that fits the 4000, but that's where I would start. Since its already going bad, try and find one that is higher performance or rated for more amps when you replace it.

 

Yeah, you might want to upgrade the amps rating a bit.
If your bearings are screaming, and are wearing out prematurely,it's most likely your belt is too tight, and causing excessive tension on the pulley...this will kill a bearing qick.
If your belt is screaming, you need another belt, your alt.pulley isn't in-line with the drive pulley(s) on the engine,or the belt is too loose.

When you usually nuke an altenator, due to an over loaded scenario,your brushes will get shot, and cause problems regulating the voltage output.

 

I second that. Tight belt worn out bearings. Overloaded system worn out brushes.

 

Based on that I would say it's too tight cuz i stopped using my stereo and it kept going downhill but I'll check it all out anyways.

As far as getting an alternator with a higher Amp rating could I just fab a mount and stick a better one in without any other compatibility issues? Other than that, have any suggestions as to what amperage or a specific alternator i should use?

 

A heavier grade alt. will fit in the originals alts space with no modifications.
Check with blauparts, or any on-line Audi parts place for prices, and applications.
Ususally you don't have a ton of choices. Usually there's a heavy duty rated alt, and this shoud be a perfect upgrade for you.

 

Thanks for all the help, I'll look into that.