Hey, I was just now thinking... I have several sites, and one of them has a 4 PR rank on google. its niche is a free tests/exercise for learning how to drive a car. so my question is, if i'll add a second niche to the same site, lets say on a subdomain, for example bla.domain.com, will it get high ranked on google even if the niche is absoloutly different then the main niche of the website? Will it help/harm me somehow? or should I drop this idea? Thanks for your thoughts.
The subdomain would be treated as a separate website. You will not get high rankings immediately. This new subdomain would be starting fresh. I don't think it would harm your site at all though.
I'd start afresh with a new domain and new site all together. It will probably be easier to manage and administrate in the long run too - you can keep all accounts/links etc separate.
Hello, Using a subdomain is just like using a new domain, or even worse. It's like saying, even if this is a different niche, it's a sub-niche of the main domain (which is false in your case). Different niche subdomains make sense only if you have some sort of directory, or if your website is on a free hosting server (which is also like a directory). If you would add a directory, the PR of the domain might influence the new directory (if you link it ofc), but only for PR purposes, not for ranking purposes as the topic is different. Like suggested above, just get a new domain and start fresh for the new niche.