Migrating to a new CMS - things to be careful about?

[pavlovapete]

We are considering a migration to a new CMS (let's call it widgetpress).

I am paranoid that Google will punish me. I know this is foolish but the fear is there nonetheless.

I think that I can keep most of our URLs the same but a handful will definitely change.

The source code ordering will also probably change as I bid goodbye to my robust but antiquated nested table design.

Can I expect some changes in the volume of traffic Google sends our way as a result of a CMS change?

Given that this particular CMS is the blackhat's CMS of choice is there anything I need to do to ensure I don't inadvertently trip any signal wires?

Thanks

[tedster]

I think you can do well if you preserve titles as they are. Also, leave the content areas essentially untouched, at least for a while. Just change the templates, in other words, and see how just that much goes.

[pavlovapete]

Thankyou sir. I could not ask for more than advice from one who has done this and survived.

Cheers

[tangor]

I did this about a year back for a widgettalk site and had a drop for about three months then came back gangbusters... the revamp offered many improvements. YMMV

[pavlovapete]

Thanks for your comment tangor. I don't know if my heart could cope with a 3 month drop.

OK at the risk of pushing my luck - what about changing the structure of the URLs. We are looking at a complete overhaul of the information architecture. Currently our CMS dictates a 3 level hierarchy and I have:
example.com/toplevel-folders/secondlevel-folders/pageurl.html

What will happen if I change the names of toplevel-folders and secondlevel-folders? I'm pretty handy with my 301 tool so I feel comfortable about redirecting. Explaining to the team that a folder name change will probably kill our traffic for 3 months is a conversation I'd hope to avoid.

Cheers

[pavlovapete]

leave the content areas essentially untouched

tedster,

It will be a new CMS - Joomla to Wordpress. I can probably get the Wordpress theme coded in such a way that it will mimic the Joomla source ordering.

The fact that you included this in your reply makes me think this is a fairly important variable to control.

[BradleyT]

We did this in April 2008. All site URLs changed. We had 4-6 weeks of lower search engine traffic. Since then search engine traffic has gone up every single month.

We're doing it again in April 2010 with our main site.

Lots of 301's and checking webmaster tools for errors.

[pavlovapete]

Thank you BradleyT for your comment.

So it looks like 2 months of low traffic is inevitable.

May I ask what percentage drop did you see? When did you recover April 2008 traffic levels?

I guess if you are doing it with your main site next month then you are fairly confident you know what the outcome will be.

Cheers

[tedster]

So it looks like 2 months of low traffic is inevitable.

No, not inevitable. It seems to depend on these factors: the technical accuracy of all your changes and redirects, plus the frequency and depth of spidering that your site gets from Google. I know of sites that made very complex changes but it did not result in more than couple days traffic disruption.

Still, if there is a critical cash flow dependency on search traffic, I often recommend a small "war chest" fund that you can kick in for some key PPC ads, just in case. And Bradley's advice to watch your WMT account intensely is excellent. Catch trouble fast and fix it fast! Watch your own server logs to monitor your googlebot interactions, too.