Hot Rods Help...driveshaft binding on new build

The rear u-joint is binding in the shaft. That rear joint has to be able to rotate freely in the driveshaft.

If both clips are on the joint while its in the shaft, there most likely isn't anything wrong with the caps or the needle bearings in joint itself. What you need to do is seat both of the bearing caps on the driveshaft side of that rear u-joint, into the driveshaft. The process of installing the joint into the shaft often pinches the bearing caps tight against the end of the joint cross piece. Often you need to seat the bearing caps against the clips on the driveshaft to allow clearance for the joint cross. I do it every time I install a new u-joint.

With the shaft out of the car, and the clips still on the joint caps, you set the u-joint cups that connect to the rear axle on top of an open vice so the joint itself is between the vice jaws and smack down on the drive shaft end with a rubber mallet, then flip it 180 degrees over and do the same thing on the other side. That should allow the u-joint to be seated, and should allow the joint to rotate freely in the shaft.

While the driveshaft is out of the car, I would do the same thing with all 4 caps on the front joint as well.

I'm betting the bind goes away. Gene

 

I've done the same thing Gene suggested just about every time I installed a U joint. You want them to feel right before you put the driveshaft in the car or you take it back apart and figure out why it doesn't feel right. Even the most experienced of us can have a needle drop down in the cap too.

 

did they mask off the u joint bearing areas before powdercoating the shaft?

 

What about the old problem of one of the needles coming adrift in the cup on assembly and causing binding. Put up your hand who hasn't done that? I can't see any hands, I thought so.

 

Never been able to seat a Ujoint deep enough to put the clip on when a needle fell out of place.

 

In my younger and inexperienced days I just picked up a bigger hammer.

 

Just got to work for a 12 hour shift so I'm stuck all day to think about it. If I have time tonight I'll try setting the u joints.....just trying to picture exactly what you guys mean. Basically hitting the cross to push the cap slightly back out of the driveshaft or yolk? Since I got all the clips in I'm assuming I didn't have a needle fall out.....I used a press for install but don't remember having any major resistance issues.

As for powdercoat in the bore for the ujoint....they got some in there but I cleaned them back to bare metal with a dremel before installing .

Thanks for all the input so far.

 

I managed to chew up a number of u/j's in short order until, by complete fluke, I came to the realisation that I was purchasing the wrong joints! The caps that fit in the axle yoke need to be very snug fit in the saddles, indeed possibly requiring a slight tap with a soft mallet. There are other caps that feel like they fit and with the u bolts fitted must be good and tight, right? but I fact allow a slight rocking / rolling motion which allows displacement of the needles. I didn't make it around the block on one occasion before the banging started. I now have tens of thousands of miles on one, correct, joint (but carry a spare!).

Chris

 

If the joint is tight that is a problem regardless, you can buy different thickness snap rings to fix that. As mentioned about seating the caps by hitting the cross, what you want to do is push the cap out against the clip holding it in. One other thing is if the joint has a grease fitting and it is installed in the wrong direction it can hit the end of the pinion nut and cause what you describe.

 

I disagree with your angles being too far off. If I remember correctly, Mopar's Direct Connection themselves wanted the pinion 3 degree's down from what the output shaft was at in order to compensate for leaf spring wrap. Regardless of whether or not I am remembering correctly, if you are truly out just 1 degree, that is not the issue.

Since you've determined it isn't the incorrect fluid in a posi rear, the driveshaft isn't too long, the angles are fine (me speaking here), I am with the others who say ... "you have an issue with a U-joint".

 

I'm definitely going to at least try seating the ujoints whenever I get home tonight to see if it helps. If so I will probably just replace them out of an over abundance of caution. I'll report back late tonight. Thanks

 

Some Spicer brand joints come with three different thickness snap rings to adjust the clearance , also Dorman sells some that may be a different thickness also. The joint should never be tight when things are correct. But it can be a time consuming process to get it right.

 

I think the problem is in one of the U joints as well, but I agree with Budget 36 that I have never been able to get a circlip in place if a bearing is on the end of the cap. You could have overtightened a clamp when installing the driveshaft and made the cap out of round.
I would put the car back in the air if your jackstand setup is pretty steady......and try starting the car and putting it in low gear at idle.........and see if you get the noise when there is no weight on the suspension. Obviously you need two people to do it and no one under the edges of the vehicle. From a few feet away you may be able to see if there is uneven movement. Be safe if you do that.

Looks like you have done some nice work there.

 

I actually did this yesterday and it was barely noticeable. Just enough to see the tailshaft of the trans vibrating a bit. When I moved it on the ground 20' it was really pronounced though.

And thanks for the compliment...hopefully this one is good enough for a few magazines like my past builds.

 

How tight did you get the yoke u-bolts? There is a torque spec, which is fairly low. It's easy to overtighten if just going by feel, then the rollers brinell into the trunnion, causing the popping.

5/16" = 15 ft lbs

3/8" = 17-26 ft lbs

7/16" = 30-40 ft lbs

 

I had always installed U-joints by simply using a bench vice and never had a problem. Then my wife bought me a hydraulic press and I thought ... "why not use it for the U-joint I am doing now". Welp, as you can guess, one (or more) of the needles dropped in the cup and I actually WAS able to press the cup into position. It was impossible for me to tell how much force I (the press actually) was exerting. Once "in position" I installed the clips then realized I had a problem. Never say "it can't be done"

That was the first and last time I used that press for a U-joint

 

That is a very good point. Too tight could crush the cap enough to bind the needles.

 

I used a box wrench to tighten the u bolts so not a ton of force....same as I've always done.

I did however use my hydraulic press to install the caps.....in the past I've always used a vice

 

Smack the outside of yoke between the cap and the tube with a hammer. The shock should let yoke spread back out and free up the bind.
Learned that from the mechanic at the gas station where I hung out as a kid. Shame kids now-a-days don't have a such a place to pick up knowledge.

 

Ruh Roh .... welcome to the club

With a vice you can easily tell how much "oomph" you are applying, with a hydraulic press it ain't so easy.

 

I'm thinking that you would break the U bolt before you ever crushed the cap.

As far as using a bench vise, hydraulic press or the balljoint press that I use either still has to be better than driving the caps in with a hammer and hoping that you hold the cross tight enough with the other hand to keep the needles in place.

 

Give me a good hydraulic press and I can break almost anything!

 

Well ... unfortunately I am (once again) speaking from experience here it really isn't too hard to deform a cap simply by over-tightening the U-bolt ... been there, done that ... then left before the awards ceremony so I didn't get a shirt

For those wondering how one person can be so adept at stupidity ... look at my user name, it is also my given name

 

I'm going out on a limb to say if it's binding there's a problem. I go further out and say if it don't, it's not to say it's done right, just that it doesn't bind.

 

These are Neapco u joints without a grease fitting. I'll be home in about 2 more hours and have about an hour to mess with it tonight. I'll report back later.

 

I think about every thing else has been covered. had a problem once with pinion nut hitting the ujoint maybe a fat u joint or a long pinion nut or to much angle

 

The rear ujoint is definitely boogered up in the driveshaft. I tried several times to seat it with a deadblow and it didn't free up at all. I remember it being a bear to press in as well. Since I have to remove it to reinspect it I'll just grab a new one tomorrow hopefully and replace it.

 

Here is a Spicer chart for the different thickness snap rings. It may help someone. I like using a nice C clamp to install with. I look at a u joint like a engine bearing. It needs to fit just right.

 

That's the problem using a hydraulic press to install U-joints, you don't realize when the cap is not going in straight and it will just force it's way in possibly damaging the yoke!

 

After messing around on the 20 ton press and then the vice on a couple of 2 piece drive shafts that took way to long, I bought a cheap U Joint press.