DS vibe help: I don't feel it, but I hear it.

I recently lifted the rear of my '99 XJ (auto, 231 tcase, 8.25 rear) from 16.5 inches to 20 inches. I did a road test today and didn't feel any vibrations, but it makes a loud hum around 34 mph. I'm guessing this is the DS vibrating? I'm hoping it settles to 19 inches and may try putting a couple hundred pounds of sand in the rear to drop it down. Does that sound like a good idea?

20 inches.....over stock??

I think he means the center of wheel to bottom of fender. Stock is ~17", now he has 20"

That could be - but we're assuming without the original poster's input.

Wheel-center to bottom of stock flare is 17.5" front, 17.0" rear...

TMXONR said:

I think he means the center of wheel to bottom of fender. Stock is ~17", now he has 20"

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Yes, TMXONR is correct. The measurements are from the center of the axle to the bottom of the fender. Before the lift, it sat low at 16.5" and now it's sits at 20" so I lifted it about 3.5 inches.

Can you hear, rather than feel a DS vibe? Around 34 mph it sounds like I've got Boggers on, but I don't. It's got a very mild Firestone on it. My front is an HP30, so I'm guessing the noise is the rear DS. Does that sound correct? How much weight could I put in the rear (safely) to try and sag it down?