U joint. How do i know if it needs to be replaced?

Basically, i cut the floor and d-shaft tunnel to rise them, and before i weld the new steel in place i thought it would be ace to replace the u-joint if needed.
Question is, how do i know it needs replaced?

I have a new one in the shelf, thats why im askin, but i dont just wanna swap it. i mean if the one on the driveshaft is ok why bother?

 

If you feel bad about it then its good insurance to change it. Pull the cups off, Quite often if its badley worn you will see chatter marks on the cross peice where the cups with the needle rollers run, if thats the case definatly give it the ol heave ho.

 

Actually, if you just grab the shaft and give it a good push/pull sideways and find play, its obviously on the way out.

 

x2 on what banjo said. Hold onto the yoke in front of the drive shaft with one hand. With the other, try and spin the drive shaft. If there is any movement, replace it.
Do this in neutral with the wheels chocked or lifted off the ground. You don't want the weight of the car to hold the drive shaft from spinning if it is worn.

 

All of the above, plus any indication of rust is a sure sign it needs to be replaced.

If you use the old one, Murphy's Law dictates that it will break 50 miles from home and the first thing you'll think about is the nice new one in the box on the shelf at home.

Bob

 

ahah, true that, and i will also think how easy i would have had it changin it from the inside of the car rather than crawilin under it w/ no lift.

Anyways, THANX guys.
This afternoon i'll look into this and maybe grab some pics to show ya.
I can do most things, but im master at none, so i better seek advice first.

 

This info will not tell you if you have a dried up joint that will turn the needles into powder.The correct way to check a U-joint in my opinion is to remove the shaft and rotate both joints to feel a nice smooth and linear feel.And at that point give them both a good shot of grease.

 

X2. If you feel any tight spots or binding in the movement of the u-joint, it is time to replace it. You cannot do this with the driveshaft insalled on the car.

 

i see, i really dont feel like removin the shaft.
Do i needspecial tools to remove the u-joint? lookin at it it seems like a few clips and some "prying" should get it out.
I think at this point it would be a good thing to change it anyway.
If i find the otherone to be good in the future it can still be a spare in case of damage.

 

I usually use a pliers, hammer and a block of wood on the floor to replace them. Nothing special. Sometimes a vice is a help but be careful installing them with the vice as they need to be perfectly parallel.

 

Found this. i think i will remove the whole driveshaft after all. seems easy really, but one of those things that are tedious the 1st time around.

http://www.automedia.com/U_Joints_-_Installing_New_Universal_Joints/res20010201uj/1

 

You have to remove the shaft to replace the U-joint anyway... always worth checking out.