How do I troubleshoot the brakes on my Audi 80?

I've been experiencing some issues with my Audi 80's brakes. Sometimes they feel a bit spongy and other times they make a grinding noise. What could be the problem and how can I fix it?

First, you should check the brake fluid level and top it up if needed. If that doesn't solve the issue, it could be an indication of air in the brake lines. Bleeding the brake system may resolve the sponginess. Also, check the brake pads, as they may be worn and causing the grinding noise.

Another possible cause of this issue could be a malfunctioning brake master cylinder. If the master cylinder is not properly pressurizing the brake system, it can lead to symptoms like spongy brakes and grinding noises. Have a mechanic check the master cylinder and replace if necessary.

It's also important to regularly check and maintain the brake calipers and rotors. If they are worn or damaged, they can cause issues with the brake system and should be replaced.