U joints

I haven't seen any posts on what to look for and how to replace them so I thought I would start one. Soooooo....
What are the signs of a bad u joint and how easy(or difficult) is it to replace??

First, and primary, sign of a bad u-joint is too much play in the when you grab it and give it a pull.
Another sign is the joint heats up - check after driving for a little while - and you can feel it when you crawl underneath and feel the joint.

Another sign is a squeaking noise, mostly at low speeds. It tells you the joint is dry. You may hear it while going through a drive-thru window. The sound will bounce back to you off the building.

Just did my first u-joint job a week ago. Did it on my 97LS lasted until 135K. Noticed it was loose. Had a budy remind me to heat the chevy u-joints from the factory. He was right they have a wax or rubber ring in there. Heat the U-joint and you'll see the rubber blow out. Then pound them out. It was pretty easy. Saved myself a 100 bones.

I haven't seen any posts on what to look for and how to replace them so I thought I would start one. Soooooo....
What are the signs of a bad u joint and how easy(or difficult) is it to replace??

As said play, heating up ,strange noises,clunking when put in gear and viberation are all good signs .
And if you ignore all of that and head down the highway about 70 MPH and something sounds like the truck got hit by a freight train.
Time to replace the u joint and drive shaft and transmission and whatever else it done to it. :grinyes: :lol:
And if a 2 piece drive shaft do not forget to time the joints or it may do it again.
MT

I thought mine was a wheel bearing based on the sound it made.

Sounds strange but, after checking the wheel bearings I decided to try to reproduce the noise standing still.

Sure enough it was a U-joint. Replaced the ones on the rear and checked the fronts. They were good but I took them apart and regreased anyways.

As far as heating them to get em off, I had to use acetylene. Propane wasnt hot enough.

On this U-joint thing do you have to heat them up to get them off? I know it sounds stupid but this will be my first and I don't know what to do. Today while driving I noticed a new noise coming from my blazer didn't sound good so I went to the only shop in town I trust. They took it for drive and came back in said it sounded like U-joint, they put it on the lift and played with the rear wheel, came back said it was the U-joint and asked I wanted them to fix it, I didn't have the $80.00 they wanted so I said no for now. I want to do it myself cause after checking the price of this it is much cheaper for me to do, but I don't know what I will be doing or even where it is, so can someone please let me know thank you.

On this U-joint thing do you have to heat them up to get them off? I know it sounds stupid but this will be my first and I don't know what to do. Today while driving I noticed a new noise coming from my blazer didn't sound good so I went to the only shop in town I trust. They took it for drive and came back in said it sounded like U-joint, they put it on the lift and played with the rear wheel, came back said it was the U-joint and asked I wanted them to fix it, I didn't have the $80.00 they wanted so I said no for now. I want to do it myself cause after checking the price of this it is much cheaper for me to do, but I don't know what I will be doing or even where it is, so can someone please let me know thank you.

The old heat them up was more for the U joints that have the plastic sealer holding the U joints i the shaft.
Some OEM joints and shafts do and some just use clips to hold the joints in the shaft.
But if you are not set up or know how to replace or check the drive shaft joints.
The proper way to change a u joint is The joints should be pressed out and in.
Some people drive them in and out or they can be changed in a emergency that way.
But just driving them out in or out can damage the drive shaft and U joint
Your best bet would be to remove he drive shaft and take it to a automotive machine and get them to check and press the joints out and in for you.
MT

Heating them up is a bad idea, you could weaken or distort the flange and cause an even worse vibration and premature joint failure. It's best to use a U-joint press. If you don't have one go to a local autozone and get the ball joint press from their loan-a-tool program.

Before removing the drive shaft make sure that you mark the way that everything goes, so that you don't cause the working angles to change (which could also cause a vibration and premature failure).

One quick way to get around heating the U-Joints up is IF you have access to a press, you can press them out. I used a 20-ton press and "popped" them out... When the caps pop out, they sound like someone just fired a .45 so wear eye and ear protection to be safe...

If you don't have access to a press, check out Harbor Frieght... If you plan to be a regular "do-it-yourselfer" it would be worth investing in. Good luck!

It cost me less than a 100 bucks to have my rear one replaced.

That way it was done right. The rear one is the one that goes bad most often. Get a Moog replacement, it has a lifetime warranty and grease it until grease comes out of all four caps every 6 months regardless of miles.

Blazee,

what the/who the heck is that spiffy new avatar ?





Heating them up is a bad idea, you could weaken or distort the flange and cause an even worse vibration and premature joint failure. It's best to use a U-joint press. If you don't have one go to a local autozone and get the ball joint press from their loan-a-tool program.

Before removing the drive shaft make sure that you mark the way that everything goes, so that you don't cause the working angles to change (which could also cause a vibration and premature failure).

Blazee,

what the/who the heck is that spiffy new avatar ?

Lt. Col. William Kilgore from the movie "Apocalypse Now".......

"I love the smell of napalm in the morning."

Great movie, the Redux is insane, you need digital surround sound to really enjoy it.

When replacing u-joints due to the vibration problems with most 2nd gen 4wd Blazers, I always get the drive shaft balanced at the same time - requires a machine shop that can spin it up and tack weighs on. If you take the shaft to them about $95 for both u-joints installed and a balance - well worth it!

I agree with muddog - take out the shaft and bring it to a shop. They can replace both joints and balance the shaft - it will cut out any vibration due to inconsistencies in the shaft. Very well worth it.

I'll tell ya I didn't have to put much heat to mine at all. Touched it with the torch and that crap blew right out the little weep hole I guess its called and the thing tapped right out. got out of the whole job for less than 20 bucks.

jkdon