Are the consequences to renaming a thread if it has a lot of back links?

[Kiss Of Death]

I know if you rename a thread and someone clicks on the old link vb seo will redirect them to the correct page, but does it affect your serps if you have a lot of back links to the original url?

For example i have a thread with 4500 back links to it, my vbseo is setup so the thread name is included in the url, if i changed the name of the thread to include the keywords i was targeting would i lose the power of the 4500 backlinks

[Brian Cummiskey]

Threads are auto-301'ed to the final url. The back link would still function, but it would return a 301 before a 200. If it already has 4500 back links, it obviously already ranks well Why change what isn't broken?