Can someone please help me? I'm a little lost now. My 95 dakota (that only has 66,000 orig. miles) has a low pitched humming noise/vibration i can feel at my feet ONLY between 65 and 70 mph. Usually when vibrations occur at specific speeds, it means a balancing issue, right? So I have replaced and rebalanced my tires, replaced my u joints, replaced my lower ball joints and pitman arm, and had the car aligned. What else could it be? I don't wanna spend any more money chasing phantom and ghosts...

 

try replacing the u joints

 

Check the Service manual in the FAQ in this section. In the wheel section, there is a great diagnostic chart for vibration issues. Even one chart for speed related vibrations.

 

I'm fighting the same thing - brand new tires, good balance, good wheel bearings, new u-joints, etc... I have noticed when coasting from the 65-70 mph mark, it also occurs, but not while braking, only coating, like when releasing the gas breifly while going down-hill, etc... to maintain speed...

I too am at a loss - however, my dad and I are going to check the trans x-member, and tranny mount - last option we could think of is the drive shaft being out of balance...

I have gone thru the diag chart in the 95 guide in the FAQ, and after elimating all the other options, these are all that we found left...

 

if you give it gas or on flat road and it does not vibrate but downhill or let off the gas it does it's the u-joints. the driveshaft tightens under load and does not shake, when there is no load (downhill) it flops around giving a vibration and shake. when you replaced the u-joints did you check for easy movement, if not they may be too tight and bind up. if they are easy to rotate (a good thing). then i would look at wear on the splines. grab the driveshaft and try to rotate it back and forth, if it slops around check for wear on the rear axle pinion, output shaft on the tranny and the yokes on the driveshaft.

couldn't find anything in the haynes manual about a driveshaft support bearing for long wheel bases (had a short wheelbase sport) but if it has one that could be a problem.

 

Take a look at you breaks too the pucks could be bouncing around on the rotor this starts to happen when the get towards the end of there lives and break piston retreats in the cylinder. My buddies Chev. Venture did this. Then at the same time check you front wheel bearings worn bearings can also cause a vibration.

 

My 93 dakota does the same thing around 70mph and I replaced my 4 ball joints, tie rods, brakes, ujoints, and had my driveshaft rebuilt. So it can't be any of those parts and my best guess is the hub/bearings assembly.


Mine are shot to hell and your bearings might be too.

 

I'd say u-joints or carrier bearing. I would take it to a good drivetrain shop and have them do it all. I had a similar vibration and they replaced all 3 ujoints, the carrier bearing, and had to replace one of the yokes that had cracked and balanced the shaft. Never a vibration now.