Replacing a link with an automatic redirect from secondary site?

Good idea, or bad idea?

[Shoestring]

We have just completed a nice revision to our main site and seem to have held most of our Google ranks fairly well, overall.

We also have a secondary domain which we placed a static link on pointing to the main about 18 months ago.

Would it be a mistake to change this to an automatic redirect?

We would like to do this (it is a more memorable URL, frankly) but are concerned about tripping up ranks or a penalty filter in the process.

Anyone have experience with this, good, bad or otherwise?

[punitseo]

Place 301 permanent server side redirect to instruct search engine spiders about the new location of the URL it will not harm main website.