Is there an easy way to slow the tempo down to record something much faster than I can play?  I tried just changing the tempo box from 120 to 80 bpm, but it didn't slow the song down.  I'd rather not have to make a tempo track and all that.  Is there a simple way to just change the tempo of the whole song to record something simple, then change it back to the original tempo?

The tempo is for MIDI and the metronome. 
It does not change the audio. 
If your talking about slowing a tempo down to play and audio part, well I guess there is a way, But when you speed it up again it will contaminate the integrity of the audio quality. 
So you have to think about that,, it might be played more precisely but might sound terrible.
 
Better to just keep playing the part and make multiple takes then cut and paste the good parts together.
 
To record at a slower tempo better to open a new project to do this. Then import the track into the original faster version and use audio snap to make the clip follow the tempo. Short clips work best for this. 
 
 

Select all audio tracks, hit A to open the Audiosnap palette, and click the "power" button to enable Audiosnap on all clips. Make sure the option in the dropdown to the right of Clip Follows Project is set to Autostretch, and then click the button. Now when you change the initial tempo, all the clips will autostretch to follow it.
 
Once the recording is done, you can set the tempo back, and disable Audiosnap. But if the new recording is audio, you'll have to enable autostretch on that so it can follow the return to the original tempo, and then bounce it with the best offline stretching algorithm for the material (see options in the Audiosnap palette). The less you change the tempo the better, but speeding up audio is usually more transparent than slowing it down. If the new part is MIDI, it will follow the change automatically.
 

Hi,
I've been playing about with another aspect of this problem all morning.  i want to slightly increase a finished project (all audio, no midi) tempo from 68bpm to 75bpm before I mix it all down.  I have carried out the task as you describe above (and lots of other more complicated ways) but find that not all tracks/clips follow the change.  This results in a variety of track/clip speeds.   I have managed this with all the tracks bounced down, but I need the flexebility of not bouncing down at this stage.
I'm probably making a meal of it but I'm tempted to use a different DAW as this seems incredibly complicated just to stretch the project by a minor amount.
Anyone got any bright ideas?

You can use the 'Step Record ' option in sonar. It was built just for what you need to do
 
Cj

You might want to insure all of your clips are the same length and begin at the same place.
 
I think a project tempo change shifts the beginning points of clips (if they are not locked)
 
you could select all clips and bounce to clips, then drag the the beginning to the same point. Maybe do the same to the ends. Then try holding control and dragging the edge of the end of all the clips in towards the beginning to speed them up.  It very well may be Audiosnap will do a better job, but this way is easy. I don't know, I prefer to re record if I don't like a tempo. But if I didn't play the part well I do what I must do.
 
 

Thanks for all the feedback - all is now OK. It seems that I was expecting too much by not bouncing down the clips first.  When I thought about it, keeping most of the clips separate wasn't actually important.  So, I bounced all the clips down, selected all the tracks, opened audio snap, clicked on clips follow project and changed BPM from 68 to 72 and all the tracks became shorter instantly and now play back at 72bpm.  The tracks are all audio, a mix of vocals and instruments, and nothing sounds peculiar, I would imagine any large scale change in the tempo may result in the tracks sounding processed?
Thanks again all, much appreciated.
 
Bob

GuitarBob34
The tracks are all audio, a mix of vocals and instruments, and nothing sounds peculiar, I would imagine any large scale change in the tempo may result in the tracks sounding processed?
 

The greater the change, the greater the chance of artifacts. Generally you can get away with speeding up more easily than slowing down. Also note that if you want the "old school" tape varispeed effect where the pitch changes as well as tempo, you can do that too.