slide volume without sliding clips

Are you editing the automation while it's over the clip or in a separate automation lane?  Wait, I don't remember when automation lanes came into effect.

Is the automation in the clip or on the track?

Clip envelopes by their very nature are locked to clip position - move the clip, automation moves with it
 
The only thing you can do is create a track envelope, then in Track View, under Options, remove the tick mark which says "Select Track Envelopes with Clips"

Base 57
The clip gain envelope Can be moved without moving the clip.
 
With track edit filter set to "Clip Automation-Gain", select the clip. That will select all of the envelope nodes in the clip. Hold down the Cntrl key and click on the nodes at each end of the clip to un-select them. Then while still holding down the Cntrl key, you can move the envelope forward or backward to the boundary of the clip. Note that if there are nodes at the boundary, they will move no farther.

Couldn't figure out what you suggested. What I did do was slight the MIDI clip, which dragged the volume envelope along with it. Then I de-selected "select track envelopes with clips," and slid the MIDI clip back. Actually for some reason the slide wouldn't go backwards, so had to do it manually.

 

Bristol_Jonesey

Base 57
The clip gain envelope Can be moved without moving the clip.
 
With track edit filter set to "Clip Automation-Gain", select the clip. That will select all of the envelope nodes in the clip. Hold down the Cntrl key and click on the nodes at each end of the clip to un-select them. Then while still holding down the Cntrl key, you can move the envelope forward or backward to the boundary of the clip. Note that if there are nodes at the boundary, they will move no farther.

Which is more or less what I said. The restriction still applies - you cannot move a clip to somewhere else in the project and leave the clip envelope behind. 

Yes. I should clarify. The clip envelope can be moved forward and backward within the boundary of the clip. And also within the boundary of unselected nodes. And it cannot be copied without the content of the clip.
 
The above applies to midi clips as well as audio. However I had forgotten that the OP had specified X3. I have not had a chance to check how it works in that.
 
 

If you are talking about volume automation, you can just lasso the volume nodes with the select tool, then hold down shift or control when you click (one allows horizontal sliding the other will allow vertical or horizontal depending on which action you do first) You can then slide all of your automation data over while keeping the movements intact.

For Clip Automation it's the same steps (except you have to hold Control). So use the Select tool, Lasso all of the Clip Automation Nodes, then hold Control down, if moving to the right click and drag the node farthest left so they will travel as far as you need to the right, if moving automation to the left, click and drag the node farthest to the right. Doing it this way will allow the nodes to keep going when they hit the end of the clip if needed. Hope that helps.

Read it and added my 2 cents. ✌😄