flountown
flountown Reader
12/29/17 3:37 p.m.

So I have a 95 4Runner, 4WD V6 and have had an issue of ridiculous vibration while above 30-40 mph and coming off the gas.  All my research has lead me to think it's U-Joints on the drive shaft that are the problem.

In all the videos I have watched, there is enough slop/play on the damaged joints they are replacing to rattle the shaft back and forth.  When I get under my truck, I am unable to wiggle or rattle the shaft in any direction.  Could this mean the U-Joints are not the problem?

If so, what other type of problem can cause hard vibration when lifting off the accellerator.  There is a known issue with the EGR sensor that I am working on fixing as well as a few other engine issues, but I wouldn't think they could cause this type of vibration.

Thanks in advance,

Andrew

APEowner
APEowner HalfDork
12/29/17 4:08 p.m.

Seized ujoints will also cause vibrations and you can't feel that without pulling the shaft.  

wannacruise
wannacruise New Reader
12/29/17 4:25 p.m.

If you would like to view some video on proper U-joint analysis then go to Weber Auto / u-joints on You tube.  This guy is very thourgh.  In short, U-joints will cause vibration if they are not balanced.  Meaning even newly installed u-joints will contribute to vibration because they are not centered well upon installation. As said in previous post, tight U-joints are as bad as loose u-joints.  Here is a pic of a u-joint I took apart on a Mid-year Corvette that looked fine from the outside.  I took it apart just because I was changing all the others. But also, if yours appear to be taking grease well then I would not suspect them.  

 

pjbgravely
pjbgravely Reader
12/29/17 5:14 p.m.

Even a slight roughness can cause a vibration. Pull the shaft and check for smoothness.

 

If you have to change the U-joints mark the shaft and ends to make sure you put it back together with the same  alignment.

 

dean1484
dean1484 MegaDork
12/29/17 8:42 p.m.

The short answer is if they are original replace them. I have looked at many u joints in vehicles that I could not see slack but out of the vehicle you could see they needed replacement. 

dropstep
dropstep SuperDork
12/29/17 8:45 p.m.

The one in my wagon i replaced last year had an issue with grease not getting to all four. It locked in place and shook like crazy. Zero slop moving it by hand.

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