Thanks Doug, but its not that easy with the forum software, compared to a standard website.
It really should be. Vbulletin is just a PHP web app. And considering Vbulletin is working already with https how does redirecting http clients to https at the web server level cause issues? The only way it could is if your current Vbulletin setup is messed up with a mixture of https and http (maybe for some addons you have?).
Now I understand that you may have customizations and addons that may need special consideration. But changing over is just the below (and I bet you've already done it). So what is still http that needs to remain http?
I HAVE MY CERTIFICATE INSTALLED - WHAT NEXT?
The next step is quite simple. Log into your vBulletin AdminCP, and then follow the appropriate instructions below for your version.
vBulletin 3
Go to vBulletin Options > vBulletin Options > Site Name / URL / Contact Details.
Edit 'Forum URL' and add the 's' into the URL.
For example, if your URL is
http://www.contoso.com/forum, change it to
https://www.contoso.com/forum
Then go to Settings > vBulletin Options > vBulletin Options > Server Settings & Optimization Options > Use Remote YUI
Set this to Google.
vBulletin 4
Go to Settings > Options > Site Name / URL / Contact Details.
Edit 'Forum URL' and add the 's' into the URL.
For example, if your URL is
http://www.contoso.com/forum, change it to
https://www.contoso.com/forum
Then go to Settings > Options > Server Settings & Optimization Options > Use Remote YUI
Set this to Google.
vBulletin 5
Go to vBulletin Options > vBulletin Options > Site Name / URL / Contact Details.
Edit these three settings: 'vBulletin URL'; 'Login URL'; 'Core URL' and add the 's' into the URL.
For example, if your URL is
http://www.contoso.com/forum, change it to
https://www.contoso.com/forum
NOTE: Do not remove the word 'core' at the end of the core URL. You will break your site!
Then go to Settings > Options > Server Settings & Optimization Options > Use Remote jQuery
Set this to Google.
The key to all three vBulletin versions is that all you do in the URL settings is change http to https. Do not alter any other part of the URL.
Once you have changed these settings, go to AdminCP > Maintenance > General Update Tools, and rebuild the styles. (In vB3 this is AdminCP > Maintenance > Update Counters). Leave the default settings and just run this update tool.