vibration

[jschreiner]

Hey all, my 69 lwb has a vibration from about 45-55, under or over that is smooth. Going to a 3.50 gear moved it up, so I took my shafts to the shop and they balanced the short shaft and made a new long shaft. The same. I can turn the rear shaft 90 or 180 and make it worse. Any thoughts? Jay

[fordman]

line up the ujoints on each shaft to equal out the vibes. that is the stock way. other than bad mouthing someones possible work i would not know what else to say.

[theskytoucher]

When was the last time you had your tires balanced??

[jschreiner]

The tires are have been ruled out.

[AlleyCat]

Is your truck a 4x4?

[jschreiner]

Allycat, no, 2wd

[AlleyCat]

You said you have eliminated the tires as a cause.Did you have them balanced or swap them out with others? The reason I ask is your vibration may be a bent wheel or axle shaft.If a bent wheel were on the front it would likely shake the steering wheel out of your hands on the rear though it wouldn't be as noticable.A bent axle can cause the same problem.

[jschreiner]

Allycat, I took the steel wheels off and put on center lines a while back, and the rear housing and axles have been changed, with no change in vibration. The only change was when I changed from 3.00 to 3.50 gears. The mph changed when it comes in.

[fordman]

are the ujoints new? is the carrier bearing new?

[wt4speed#2]

When you drive out of it will it come back at a higher speed? I still wouldn't rule out tire balance especially if you are experiencing at a 10 mph increments.

[craftsman]

What trans do you have? If you have a manual trans, it could be a bad pilot bushing that can cause some vibration. I had one do this to me. When i push the clutch in at the vibrating speed it would go away. Just a thought.

[James72]

If it changed with the gearing, You have to remember that the drivetrain is still traveling at the same RPM even thuogh your speed is now higher, look at your trans output shaft bearing and pinoin bearing. Also leaks in those areas usually mean a bad bearing or bent component. I'm not sure of the set up procedure of your pinion, but I do know if the bearing is too loose you'll get what you're describing. FYI, you'll normally find that shaft seals won't leak unless something else is wrong too.