U-Joint help

[Dr.Doug]

So, I have this vibration, at speeds over 65 mph, in the rear driveline when ONLY coasting. Could it be the U-Joints? This is a '91 four door 4x4 automatic with 100K miles.

I go to PBY and purchase H.D. U-Joints and for $25.00 and get to work. I lower the drive shaft and everything feels tight. The drive shaft is a two piece unit attached in the center with a slip sleeve, sealed with a boot. That too, appears to be OK.

The front companion flange, where the drive shaft attaches at the transfer case, appears to be slightly loose. Hmmm, could this be the problem? Worn bearings in the transfer case?

Well, the drive shaft is down. I decide to replace the original U-joints any way. My Haynes repair book claims that the U-joints can be pressed out using a large vise or an Arbor press.

I place the joint in my "large" vise, using sockets to extend into the joint for proper clearances, and nothing happens. I spray penetrating metal lubricant on the joints and still no movement. This time I use a breaker bar and I bend the Vise handle. NOT GOOD. I decide to call it quits for the night after applying extra penetrating oil for an overnight soak.

Has anyone ever removed these U-Joints from the drive shaft? If so, short of renting an arbor press, how did you do it?

In addition, has anyone experienced problems with the bearings in the transfer case? If so, did this cause vibrations when coasting over 65 mph?

Sorry this message is so long. I felt the need to have all of the facts on the table.

Thank you in advance.

Doug.


[This message has been edited by Dr.Doug (edited 02-04-2000).]

 

[indianajohn]

Doug-
Regarding the high speed vibration, it could be a few things (including a bad transfer case, but I'm not too familiar with those)... a friend of mine had a similar problem and we found out he had a slightly bent (actually twisted) driveshaft. This will throw the shaft out of balance causing vibration at higher speeds. I'd also check the rear wheel bearings, the U-bolts holding the leafs to the axle, the rear wheel lugnuts, and check the rear differential for metal in the oil (the differential oil could probably use changing anyway).

As for disassembling the U-joint, it shouldn't be as much trouble as you seem to be having (although your U-joint may be possessed or just downright nasty). This may sound elementary, but did you remove the C-clips from the U-joint? With those things in, it's not goin' anywhere. (I figured this out the hard way once).

Also, make sure that when you're pressing the yoke out of the driveshaft, the socket only presses on the YOKE on one side... if you place sockets that press on both sides of the yoke itself, you're essentially just squeezing the yoke, and it's not going to budge. So on one side of the U-joint the socket should be pressing against the YOKE ONLY(not on the driveshaft itself), and on the other side of the U-joint, a larger socket should be pressing against the DRIVESHAFT ONLY and NOT the yoke (this socket should be large enough to allow room for the yoke to be pressed out through the socket). I hope this doesn't sound too confusing... it's just hard to explain in text. But hopefully it will help anyway. Good luck.
-jm

 

[Dr.Doug]

John

The drive shaft appears not to be bent or damaged. The weights appear to be intact with no clean marks of where one may have been thrown. The rear wheel bearings have NOT been checked. The U-bolts to the springs appear to be tight and solid. The rear wheel lugnuts are torqued to 100 pounds. I have not checked the rear differential for metal in the oil. I will change this fluid in a few weeks.

Yes, all eight C-clips were removed from the U-joint. Finally, I am using the proper sized sockets, one larger and one smaller, to avoid squeezing the yoke with no effect.

May be tomorrow, after the penetrating oil has worked in, I can press these things out with my DAMAGED vise.

Keep in mind that this vibration is only made when free coasting above 65 mph in drive or neutral. (No torque applied to the drive shaft in the form of accelerating or decelerating.)

Thanks for your advise.

Doug

 

[stcroix949]

Doug
Open the jaws on your vise about 2 inches, rest the horizontal yoke on the jaws and give the vertical yoke a couple blows with a good sized ball peen hammer. Be sure to pound right next to the u-joint, don't hit the drive shaft itself. They will slide right out.
It's much easier to handle the drive shaft if you pull it apart and while you're at it smear a little synthetic grease on the teflon sleeve on the spline.
The hammer technique for removing u-joints is the way the mechanics do it Quik and easy. Then use your vise and sockets to push the new cups into the yoke. Hope this helps.
Brad

 

[Dr.Doug]

Brad,

Thank you very much. The hammer worked perfect!!! I am not sure if I did a bad thing but I had to use a hammer and socket to place the new cups back into the yoke.

The U-joints have needle bearings on the outside. I don't think that hitting the cups had an effect on the bearings. Time will tell. At any rate, they have a life time warranty.

Well, here is the deal. I replaced both U-Joints and noticed that the rear output flange, on the transfer case, was slightly loose. According to my Haynes book, the rear output flange nut should be torqued at 150-180 ft pds tight. I placed my 30mm socket on the nut and could easily move it. Hmmmm, not good. I torqued it to 150 ft pds and waalaa, no lateral movement!!! I replaced the driveshaft and the vibration was gone!!! PERFECT!!!

Not only did this fix the vibration, the speedometer no longer jumps. In addition, as a result of the speedometer not jumping, the cruise control now holds steady at the selected speed!!! Three fixes for one loose nut.

Now I am thinking, just how long has the nut been loose? 100K miles? Are the needle bearings and ball bearings, as a result of the lateral movement, now worn inside of the transfer case? Only time will tell. The previous owner, whom I know and trust very much, claims he had never had driveline work done. Obviously, the nut was not torqued from the factory. Gotta love FORD.


Take care all.

Doug




[This message has been edited by Dr.Doug (edited 02-05-2000).]