How long can we expect our U Joints to last when put behind the PSD? Mine wasnt used to tow or haul much of anything before I bought it but I tow quite often and generally pretty good loads, most between 8000-15000 trailer weight. I get a nice little clunk when I let off throttle at interstate speeds, and have a vibration at interstate speeds (intermittently) that has not been fixed by new tires, new ball joints, alignment, and front end inspection, etc. My guess is the U Joint is on its way and in the process probably destroying the carrier bearing with it. My question is, how much do they cost and what is the procedure for replacing them? Never done one, but can't be that hard. I dont feel like waiting 4 days for the local guy to do it then charge me 50 bucks an hour for labor if it is something I can do myself--I am pretty handy on mechanical stuff but this is one thing I have yet to tackle!

Thanks guys,

Matt

 

Try doing a search on "Drive Line Clunk" or "Rear End Clunk"

I think this has been a topic in here for quite some time.

YMMV

Your Resident Foneguy

 

Check your carrier bearing, especially if you've added a bit of lift. All of these symptoms are similar to what I experienced with as little as 1/2" of shim needed, the clunk was more from a standing start but I could 'feel' it while driving.

 

Yeah my dually sits pretty high, the 99 factory lift block is 3", and I have air bags on top of that front and rear, so it probably has thrown the angles a little off kilter. I will check the bearing--what do you mean exactly by the "shim"? I don't have a clunk from a standing start, only notice it if you get back on the pedal after coasting, and when you let of the pedal to coats, especially at higher speeds. Just seems like there is some slop somewhere but can't quite point it out. If I had more time I would probably do all U Joints, replace carrier then grease the spline at the slip joint. Maybe next weekend? Kind of wanted to do it before I haul about 10,000 lbs this weekend to Lincoln NE but don't think that is going to happen...

 

If you crawl underneath the truck and look at the carrier bearing in the middle of the rear axle you will notice it is bolted directly to a crossmember.

When you lift the suspension it puts this bearing in a slight bind, generally on the output side toward the rear axle. In order to correct for the angle, you put a block (shim) between the crossmember and the bearing - effectively droppping the whole driveshaft to maintain alignment through the bearing with a minimal increase in u-joint angle at the transfer case. Mine is basically a 1/2 inch block of steel with holes drilled in it for longer bolts - nothing real sophisticated.

Its simple enough to do, and I'd bet with the suspension mods you mentioned this will solve the problem.

 

I was just changing my oil and was crawling around under there--can't even budge drive shaft and U Joints look fine to me. The only play in anything down there is the carrier bearing, and I can push it up towards the crossmember about 1/2 inch or so. I think I may try the shim idea and see how that works. I see what you are saying now, makes a lot of sense. It does bind it up a bit at that angle. So yours is 1/2 thick? How big area wise is it and won't the foctory bolts reach the extra 1/2 inch? I got gobs of bolts here, sure I can rig something up...

 

If you were "pretty handy" you wouldn't be asking us how to replace U joints or how to check them.

 

Dude! That's just wrong.

 

I didn't mean I know everything there is to know--what I am saying is, if I have some sort of idea, I can usually tackle it. This is something I had never done before so I wanted to make sure I did it right. Growing up on a farm you generally have a pretty good knack for fixing things that break down, so I have mechanical know how and knowledge. By having some background info it would make the task a lot easier for me. Does making smartass comments on a forum make you feel superior because you don't have to say it to someone's face for fear they would beat you like you most likely deserve?

 

Thanks Cookie. My experience has been very positive on this forum, but of course like everywhere else there has to be the flamer with low self esteem who makes himself feel better by picking on others.

Should I ever have a question about what women's clothes best fit a man, I will know who to ask, mschultz.

 

Ok pup. Here is what you do. Sounds to be like 1BADF350_4XCREW7.3 knows what he is talking about. I'd follow his advice on the shim if your lift is the same. Your U Joints should be sound as long as the truck has not been beaten on. The OE part spec'ed by Ford has been pretty good in our experience. Look for telltale signs of rust at the points where the joint contacts the yoke. You can also check for driveline slack but you need one end of the shaft to be free- Try neutral with your emergency brake engaged. Block the tires just in case 'cause they still need you on the farm. Then with pressure on the driveline released, check for slack. The carrier bearing is not usually an issue. Last, if/when you pull the driveline, mark each U-Joint/Yoke connection with chalk or paint. It should go back together exactly the same way or you may cause even more vibration than you sought to fix. Once the drive shaft is out you will figure out how to pull the U joints by looking at the new part- it is just like a PTO shaft on your farm equipment. Take the whole works to your local blacksmith/machine shop if you have any questions. In my experience, they will do a better job than the dealer if you do not have a good vice handy. If you operate in a lot of mud or water, you might consider a serviceable U joint w/ a grease zert- But be careful, a little synthetic grease will really mess up a nice skirt.
-Mike

 

You da man! If the carrier bearing is usually not an issue though, why bother shimming it? Or are you referring to the fact that the bearing itself is probably okay and it just needs adjustment? Yeah the U Joint procedure isn't difficult, I have everything I need. I guess I was more worried about shaft alignment and that kind of thing than actually putting the new parts in and whatnot. Thanks for the info.

Hope I don't break a nail...

 

Hey-

I meant the carrier bearing should not be shot this early. But now that I think about it, the change in driveline angle may have placed different stresses on the entire driveline that it was not engineered to take. The change in driveline angle may diminish the service life of your U joints as well- I'd adjust the angle with a shim just as the other post suggested- Maybe check with the people who made your lift kit and see what they suggest for your driveline so you get the right height/wheelbase shim adjustment. I don't know anything about lift kits other than we keep them away from our work trucks. (11 1,500lb bales on 6,000lb goosenecks is not a load you want to pull with a buggy) Good luck with the u joints- I'd recommend a replacement brand but I have had different luck with the same parts on identical trucks.

good luck

Mike

 

Did you mean the rubber sleeve around the bearing will compress 1/2", or that there is that much play in the shaft?

Been thinking about the vibration being "intermittant", does it come and go acording to how much pressure is in the airbags? When the truck is loaded/unloaded?

I think a carrier bearing shim likely is the answer for you, but since you probably don't keep the airbags at max psi, the angle will be constantly changing. Might try a smaller shim (1/8", 1/4", etc) and try to find a happy medium.

 

My, My, look at all the fun I missed while reviewing Paris Hilton's video....

The shim on my truck is a block about 3/4 inch thick and is the same dimensions (W x L ) as the base of the carrier bearing clamp - roughly 1 inch by about 6 from the looks of it. I don't know what added height you got from the airbags, but my driveshaft is in a straight line through the bearing - maybe make up a couple of 1/2 or 1/4" pieces of stock and trial and error to find the right thickness before making a final shim. I have seen people talk about 'shim kits' but don't know anything about them.

Good luck, let me know what happens. Can I go back to my **** forum now, or am I gonna miss out on more fun???