Two weeks ago, we attempted to make the URLs of ca. 12 pages more search-engine friendly. We changed three things.
1. Make URLs more SEF
from: /แอร์-ราคา/brandname.html (meaning: /aircon-price/daikin.html
We set up 301-redirects from the old to the new URLs. You can find an example and the link to our page here: http://bit.ly/XRoTOK There are no direct external links to the old URLs.
2. Added text to img-links from homepage to brand-pages
Before those changes, we only linked to those brands with a picture, so we added some text under the picture. You can see that here, in the left submenu: http://bit.ly/XRpfoF
3. Minor changes to Title, h1-Tags, Meta Description, etc.
Only minor changes, to better match the on-site optimization with targeted keywords. For example, before we used full brand names, after we used what was really searched for:
from: Mitsubishi Electric Mr. Slim
to: แอร์ Mitsubishi (means: Aircon Mitsubishi)
Three days after these changes, we noticed a heavy drop (80% loss in non-paid search traffic) in rankings and traffic for those pages, and also for all pages which are sub-categorized. Rankings for all keywords not affected by the changes stayed the same.
Any ideas, what happened, and how we can regain our old rankings? We have already submitted a new sitemap.