How does the lower steering shaft work?

I'm trying to figure out my clunking problem, and I was able to momentarily reproduce the issue while parked in the garage turning the wheels. This makes me think it's steering related.

Looking at diagrams of the steering shafts, it looks like the lower intermediate shaft connects the upper shaft (steering wheel end) to the steering rack, and it's got a long boot on it. What's under the boot?

I've read/seen suggestions that the shaft is actually 2 pieces and can extend/shorten. If that's the case, why would we need that on the steering shaft? I get why the rear driveshaft needs a slip yoke, but the steering rack and the steering wheel are fixed to the chassis and don't move with the suspension. Is it because the steering wheel telescopes?

 

Here: http://www.customtacos.com/tech.old...6toyrm/06toypdf/06rmsrc/rm2006ta/04400210.pdf

The Lower Shaft has nothing to do with the telescoping process...

 

Check this thread out.

https://www.tacomaworld.com/threads/steering-column-fix.88077/

 

The steering shaft is two pieces, what's under the boot is the joint of the two shafts, which are "D" shaped or have two flat sides so there is no movement in between the two. Why it's there is safety, it allows the steering shaft to collapse in a bad accident instead of driving the steering wheel into your chest.

If your getting a clunk in the steering it's either the "rag joint" which is the rubber disc under the intermediate shaft or the bushings on the rack where it attaches to the frame, but I doubt that's the case on a '14, so I'd be looking lower like the lower control arm bolts, which if not real tight would allow movement.

 

That was the diagram I've been looking over. I guess the telescoping happens in the "Steering Column Assembly". The rubber accordion boot made me think the shaft was meant to change length, but it didn't make sense to me when this change would occur. @sparkystaco's explanation makes sense though.

Thanks, planning on throwing a zip tie in there since I'll be digging around under the steering column anyway.

LCA cam bolts are tight. When I reproduced the clunk in the garage, it didn't take more than 30 degrees of turning the steering wheel back and forth over the problem "spot" to cause the clunking. The fact that I wasn't moving makes me think it's something steering related.

 

Check the tie rod ends yet? Kinda of early for a '14 but you never know. I had some clunking that went away with new inner and outer ends on the drivers side and new bushings for the sway bar where they connect to the body.

 

Put new outer TREs on. The inners feel fine, no play whatsoever. The outer on the driver's side was leaking. Don't think the steering column is the cause of my noise anymore. Here's the thread where I'm actually trying to figure out the source. I just wanted to know what was under the boot on the lower steering shaft. GMs have a notorious steering clunk and it's solved by pumping grease into the boot. I didn't wanna blindly do that for no reason.