We have a 2000 SH type and tonight it started making a very loud knocking or clunking noise. It is not a noise from the motor. It is worse when you depress the clutch. I drove it a very short distance and thought I would find an axle broken or a suspension part that was hanging down hitting axle or wheel. I did not see any broken suspension components and axles appear to be fine. We jacked the car up started it put it in gear and it does not make the noise when the wheels are off the ground.

Does anyone have any idea what this loud clunk could be?

 

Sounds elementary but check your lug nuts. I had that happen with my integra and I couldnt figure it out thought it was an axel. Turns out my left rear wheel was lose. Broke a stud, lost 2 lug nuts and the other two where only a few thread from falling off

 

wow, i had this exact same problem, freaking out i thought it was the hub bearing, and jacked the car up to troubleshoot and found 3 lugs nuts barely on. I have rims and chrome lugs and i had recently taken the wheel off to replace inner tie rod, i didnt have an impact so i obvisoly didnt secure the wheel properly. wow scary!

 

Could be radius rod where it mounts to the front subframe. If the lockut is loose you will need to buy another one and tighten it up. The rod will be under tension with car in air, won't be able to diagnose it up. Does it do it more when you switch from forward to reverse, or vice versa?
GL
Mike