Any idea what could be causing a rough kind of grating vibe that happens at only about 20 mph, then disappears above that? I've had it looked at by a couple places, thinking it was tranny, but they said no, possibly u-joints. I grabbed the drive shaft and tried to see if there was play but seems pretty tight. Is there a way to check the u-joints, and are they in the middle of the driveshaft? Also, it makes the tranny do a little jerk or "hiccup" when I take my foot off the brake before giving it gas if I'm at a slow speed, and the shifter kicks a little. The driveshaft mount was just done, maybe I'm looking at the wrong place. I'm new to the forum and it's great. Looking forward to solving this issue and getting on with tinkiering with my truck. Thanks!

 

I would find a shop that specializes in drivetrain repair. They will put the truck up on a lift and listen to all the various drivetrain parts with a mechanics stethescope to narrow down the noise. Any good mechanic should be able to pick out a bad u-joint from miles away.

 

Thanks. That's what I'll do. Will follow up so it helps someone else. T

 

Id be willing to bet it is your pinion bearing.

I had the same issue and stethoscope suggested it was the pinion bearing.

 

Cool I will borrow a stethoscope over the weekend and give a listen. Would a bad pinion bearing make the vibration happen only at 20mph? I noticed that the center driveshaft support was a cheap aftermarket and all the rubber was cracked, and allowing a lot of up and down motion of the driveshaft so I got a new center support one from Toyota and was going to put it in over the weekend. If it doesn't eliiminate the vibration well at least it had to be done. At least it might improve the hiccup I get from the tranny when I take my foot off the brake to go. Keepn you posted. T