Thanks in advance for any help. This is a weird one. I am working on my neighbors 08 Dakota. It has the 3.7 in it and around 70k miles. He is a bit older and I do a lot of mechanical work so he asked if I could help him out. His description of the problem is if he is going down the highway at around 40 he starts to get a shake. If he lets off the gas and gets back on it he accelerates fine with no vibes. He says it does it around 60 as well. I went to take a look at it and when I went to k turn in my yard for a test drive it started vibrating hard when I had it in reverse at full stop with the steering. It felt like the abs had kicked on in the brake pedal. But not normal abs, like extra abs. If I came off stop with the wheel it would stop vibrating. If I wasn't in reverse, I couldn't get it to vibrate. It had to be under load with the wheel at stop (worse to the left than right) and as soon as you let up on the brake slightly it started vibrating. I had him hold it in that position while I checked the brake module, the brake calipers and thee steering rack. I could feel the vibration in the passenger tire but cant find the source. He had his rack replaced recently so I looked that over and they reused his old bushings. I figure replacing them is a start but it doesn't explain the vibrations while not in motion. Is this a failing pump? From his original explanation on the phone I was expecting a bad u joint or control arm bushings something to that effect. However once we replicated the vibes at stop it became more confusing. He is good on all fluids and the ps pump only has a very light whine at stop. I hope someone can point me to an answer because I am now officially confused.

 

So if i read it correct, the vibration will occur with the transmission in reverse or drive, but not in neutral or park?

If the rack or steering pump is not bad, it could be the motor mounts.