rumble-grumble-vibe

This weekend my 01 XJ started making a weird flapping-popping noise (would only "pop" once) if I backed up in reverse then moved forward. Definately metallic sounding. Never made the sound from a dead stop. At the same time, I noticed a slight vibration in the steering wheel but shrugged it off due to the highly maintained and well kept county road I was on. /sarcasm

Today coming home from work, the jeep was "grumbling / vibrating" which caused a very loud annoying ambient sound much like mud swampers at 65mph. I've had death wobble before and it definately wasn't DW. The vibrations caused my coin tray, glovebox, dash, and anything else plastic attached to the body to rattle. Under throttle, it felt almost like a miss or a plug wasn't firing. Engine revs butter smooth though. Worst vibes are 25-35 mph.

Only changes in the recent past was new tires which are only about two months old. Anywhere I should start? The only remaining parts up front that have yet to be replaced are ball joints and ujoints. Did a quick inspetion when I got home, everything is nice and tight. Haven't checked ujoints for play though.

my rig was just doing the same thing from reverse to forward. turned out to be the lower control arm bushing. check it out. might be your pop

Check your trans mount and ujoints. Bad trans mount could but a wierd bind in the driveline.

Shouldn't be the lowers, I put them in just a few years back. Uppers maybe? I just don't know. I have 150k+ miles on the jeep, original ujoints on the axle shafts and original ball joints. I'm guessing maybe one of those. Tranny mount looks fine, driveshafts are Tom Woods with heavy duty ujoints so I doub't it is either of those.

Found the problem. Took the rear driveshaft off and when I did, one of the caps from the pinion end remained in the yoke. It was devoid of all needle bearings and grease. The other caps on that ujoint were fine which was weird. I regularly grease all my joints so I guess it was plugged. Anyways the rest of the shaft is a bit suspect. It's a Tom Woods CV shaft I bought a few years back and only has about 50k on it. Anyways, I replaced the u-joint after much swearing and hard work. Soon as I buy a hydraulic press, I'm replace the other two ujoints.