Acceleration vibrations?

I've been getting some pretty rough vibrations when accelerating. It started a few months ago as a small, almost unnoticeable shudder when I hit the gas. Now the truck shakes like an earthquake when the needle climbs through 10-35mph, and you can still feel it at higher speeds.

I thought it was a bad cv axle at first, and lo and behold, the driver side axle was leaking grease out of a loose boot clamp for god knows how long. I replaced the bad axle and made sure the passenger axle was still good. The vibration has been cut in half, but it's still there.

I have an automatic transmission, the fluid that leaked out when I popped out the old cv axle was almost pitch black. I assume that's real, real bad.

My check engine light hasn't come on since any of this started, but I'm going to check for codes tomorrow anyway, as well as change the transmission fluid and filter.

Any extra advice is super appreciated.

 

Check the driveline U-Joints.

 

In addition to that, check the driveshaft carrier bearing. It should have a slight amount of play ~1/8th of an inch but no more. Mine was shot at 120000 miles. Not too bad of a fix either.

 

Will do, as soon as I can get it back on ramps.

I forgot to mention that the vibration will cut out completely after I take my foot off the accelerator for 2-3 seconds. I'm not sure of the significance of that, if any. I can be going 60 on the highway, vibrating, then suddenly take my foot off the gas, still vibrating for 2-3 seconds of coasting, then the vibration suddenly cuts off, and I'll smoothly coast until I drop down to 15-10 mph, where the vibrations will quickly return, slower in frequency and more intense.

 

Usually when the vibration is under load it's because of U-joints. Sometimes (not often) when the double cardan joints are bad when on the pickup they will not show any sign of problems. I doubt that's your issue but could be if you've replaced the end joints on the rear driveline.

 

Torque convertor. Just a guess.

 

My u joint just back from carrier bearing needed replacing, 60k miles.
Same situation as you, no vibrations after replacement

 

Really sounds like a u joint issue. Vibs under load then u let off creating a situation of no load on the system then as she starts to further slow down more strain is put back on the joints thus feeling the vibs again...

 

Check carrier bearing and tranny mount while your under the truck to.

 

Well guys, when you're right, you're right. The rear u-joint snapped and it looks like the yoke has been rubbing itself to bits because of it. I'll be replacing all parts involved as soon as possible, and then the other u-joints as well. Thanks for the help everyone.

 

Probably wouldn't hurt to replace your needle bearing with the east coast gear supply bushing. Just search it, there's plenty of info on here about it.