High Speed Driveline Vibration

[michibronc]

Hi All,

My '96 (stock height) has always had a vibration at highway speeds of 65 mph or over. It starts getting noticeable at about 67 mph, gets worse till about 73 mph, then starts becoming less and less noticeable at higher speeds. It has done this through new springs being installed, new tires, several wheel balancings, and a rear driveshaft rear U joint replacement.

It seems to be getting worse. I just took the truck about 500 miles this weekend and it's to the point where it's driving me nuts. The vibration comes and goes (but it's there 90% of the time). It seems a touch worse (but not much) if I'm accelerating or trying to maintain speed up a hill. Letting off the gas and coasting doesn't seem to lessen the vibration much if any.

Although I can feel it in the steering wheel, it's very faint there. The seat and the body panels vibrate much more than the steering wheel does.

I've searched in the how to's and I've googled also. I'm at a loss. I looked at my driveshaft and it doesn't look like it's lost a weight or anything but it is rusty as ****. I don't know how to check the U joint setup at the front of the rear driveshaft, but I guess that could be the problem. I've heard that there's a spring and something to keep the double cardan centered but I don't really know how to tell if mine's bad or not.

Any ideas on how to proceed before I turn this one over to the shop?

 

[BroncoJoe19]

I'm not the expert here.

It sounds to me like you are looking in the right place.

If you feel the vibration more when accellerating then it is a little more likely a worn U joint, otherwise it is just as likely a slightly out of balance or bowed (bent) drive shaft.

Sometimes when U joints start to go, they get squeeky, and the noise is much more noticable under load.

When I road tested a motor home a few years back it had a vibration, but at lower speeds than what you are talking about, and I told the dealer to have it checked... It felt like it had a bad universal. HE looked at me like I was a jack-a**, but had his mechanics check it none-the-less. It ended up that it had a bowed drive shaft. As it was being driven from the factory, the driver ran over re-treads that were strewn on the road. Aparrently they swung up and hit the drive shaft with enough force to bend it a bit.

I guess if you are so inclined, you can pull the rear drive shaft and road test it in front wheel drive, but since the transfer case oil pump gets its power from the rear drive shaft I don't know how far you can travel at 65 mph before you cause troubles for it.

 

[muddinlate86]

you also might want to check your wheel bearings. they might be loose or worn my truck does the same and i know my bearings are a little loose good luck

 

[aqua_wonder]

Check the U-joint, driveshaft, yoke and hardware at the transfer-case on the rear shaft. I had a real bad vibration. Going down the road about 55-65 the doors, floor and seats all vibrated, but stopped somewhat when I took my foot of the gas. It ended up being loose bolts holding the driveshaft to the yoke on the transfer case. Another time I had a bad u-joint with half the roller bearings gone in the joint on the transfer-case.

 

[michibronc]

And the prognosis is....

Front wheel bearings were a bit loose. Re-pack and re-tighten seems to have fixed the shimmy. Thanks for the help! My money would have been on drive shaft, but I was wrong (yet again).

 

[Billy Toppless]

Hi All,
My '96 (stock height) has always had a vibration at highway speeds of 65 mph or over. It starts getting noticeable at about 67 mph, gets worse till about 73 mph, then starts becoming less and less noticeable at higher speeds. It has done this through new springs being installed, new tires, several wheel balancings, and a rear driveshaft rear U joint replacement.

It seems to be getting worse. I just took the truck about 500 miles this weekend and it's to the point where it's driving me nuts. The vibration comes and goes (but it's there 90% of the time). It seems a touch worse (but not much) if I'm accelerating or trying to maintain speed up a hill. Letting off the gas and coasting doesn't seem to lessen the vibration much if any.

Although I can feel it in the steering wheel, it's very faint there. The seat and the body panels vibrate much more than the steering wheel does.

I've searched in the how to's and I've googled also. I'm at a loss. I looked at my driveshaft and it doesn't look like it's lost a weight or anything but it is rusty as ****. I don't know how to check the U joint setup at the front of the rear driveshaft, but I guess that could be the problem. I've heard that there's a spring and something to keep the double cardan centered but I don't really know how to tell if mine's bad or not.

Any ideas on how to proceed before I turn this one over to the shop?

how often do u go mudding or off road?

may sound dumb but...

mine had the same problem and i took a hose to my entire undercarriage, behide the wheels and i even took off the beauty rings and it seemed to make it do it less

i also replaced both the front and rear U-Joints

and an other thing could be

do you have it 4x2?

 

[shift1313]

i know its fixed but i wanted to add something in here for anyone who searches.

driveshafts are balanced. if you take them out to replace ujoints mark where they mounted to the diff and tcase. when testing ujoints you can just climb under the truck and just grab the drive shaft and rotate it by hand. the only thing this wont check is the needle bearings in the end caps. if the truck sits or gets deep in water the bearings can start to rust causing vibration issues. this is more noticable under accel because the pinion angle changes.

another big issue is front end alignment. i know i had one of my trucks aligned and the shop said they could only get the front end within 1degree. well its got a little more toe in than i like which affects ride quality.