New sound under front end
Two weeks ago we went on a big ride and I had a new clank show up half way through the ride. When climbing hills in 1st gear and in 4lo, I usually creep up them with no problem and no clank. On hills with more difficulty, when the I got into situations where the front tires started to spin a bit and the engine/ axle and all components were under a lot of stress, I heard a loud clank or pop come from up under the front end. I was unsure if it came from the differential end of the front driveshaft or the transfer case end. It seemed to clank once about every two or three turns the front driveshaft made. If I backed off the throttle and eased the tension, the tires would stop spinning and it would not make the sound anymore.
I climbed up under and felt of the U joints but they did not feel any looser than they ever have. I have had all the fluids changed in differentials/ transmission/ transfer case in the last 3 months and everything internally looked fine.
Also note that this sound never happens when driving daily and on pavement, only when under great stress, climbing hills.
Can someone give me some ideas on different components to check? Thanks for any input.
1998 TJ Sport, 4.0 I6, 4.88's, super 35, Auburn lockers f/r, 7" RK, 36 Iroks, 15X10 ProComp series 51, K&N, swaybar disconnects, Ramsey 8500lb winch