Front Drive Shaft Binding (I think)

[dhuser]

I will start by stating the obvious. I KNOW NOTHING.. I am not to bad at turning a wrench but I lack in the diagnostic skills. I just locked the hubs on my newly purchased 74 Bronco for the first time. Even before engaging the 4x4, there was a VERY HEAVY vibration. Almost like I was driving on Octogon shaped front tires. Even at slow speeds. It seemed to way to heavy of a vibration to be an out of balance drive shaft (I think). That leaves me with U joints or a binding front drive shaft. I am leaning towards the latter. My Bronco has a 4.5" lift. Does anyone know how I can diagnose the problem, and how I can resolve it.

Thanks in advance for any help.

Doug

 

[Revelation]

Hey Doug, First I am sure it will get moved to the Tech section when a mod see's this, The help and test section are for computer related issues, Bronco Chat is general Bronco talk, and Tech is for things such as this, Off topic lounge is just that Off Topic.

As for your issue, first step is to put it in 2 wheel drive, with the hubs unlocked, crawl under and turn the front drive shaft, if the shaft is the issue you will feel/see the problem while spinning it by hand.

 

[dhuser]

I was able to spin the front driveshaft by hand with no binding. It did get very close, but seemed to have clearance all the way around.

 

[TBS-POPS]

dont just spin it, push and pull it up and down and sideways, I bet the u-joints in the cv are bad. there should be no sideways movement in the joints! use a screwdriver if you have to, to make sure.

 

[bax]

Sounds more like the center pin of the c/v joint is wore out. They can be rebuilt.

 

[ol gray mare]

A couple of other things I've seen cause serious vibration from a driveshaft are excessive wear in the slip yoke, and a bent tube. They can let the shaft go around much like a jump rope.

 

[Broncobowsher]

IF you want to make sure it is in the shaft, take the shaft out, lock in the hubs, go for a drive.

If the vibration is gone, it is in the driveshaft
If the vibration is still there, you have other problems in the front axle (but does not rule out the driveshaft also having problems).

If the U-joints feel good, head to a driveshaft shop and ask them for advise. A good one will look at it and talk to you about it.

There is another possibility now that I re-read and saw the 4½" of lift. IF the caster has been heavily corrected then the U-joint fromt eh driveshaft tot he front diff may be at such a steep angle that it will not rotate smooth. Do you know what has been done to the front suspension? Drop brackets, radius arms and C-bushings are what I am mostly interested in hearing about.

 

[KennyB]

U Joints are Cheap.... You'll need help the first time you do a CV Joint. Now that this Bronco is "Yours" and you are going to want to check through All of it, go with BroncoBowsher's advice, think about Fresh U Joints. A lot of guys overlook Greasing U Joints.....

 

[DirtDonk]

I suppose another possibility (there are so many, aren't there!) might be a worn out front output bearing in the transfer case. Or even a loose yoke?
I'd do what they all said first, especially the trip without the driveshaft, but these are at least a couple more things to keep in mind when you're testing.

I do know though, from experience, that when a double-cardan (CV) joint's centering ball goes bad, you can sure get some strange (and inconsistent from one vehicle to the next) vibrations.

Just for giggles you might even try un-locking the hubs and then shifting the t-case in 4wd to see if the vibration changes.

Paul