Drive shaft vibration after 14 bolt SF swap with ujoint adapter.

[496truck]

I'll be quite honest. People get by with getting the u-joint angles good. What you don't hear about is in some applications they are running the joints at the high end (even outside) of their normal operating range. This causes premature wear and a higher breakage probability under load. Most street driven and mild trail use truck owners just live with replacing u-joints every 6 months or year. The pinion pointed up and a CV style shaft puts the u-joints within their operating range and the joints last longer and reduces the chance of breakage under load.

I can drive my truck on the highway at 65-70-80 mph and it's smooth as glass. So, on the cheap, get the angles right. If you want to do it the right way for the long term, get a CV shaft made.

 

[Blue85]

That joint shouldn't be binding until 15 degrees or more. It's possible this is a strange yoke or something that doesn't allow much angle. It might be worth looking at some other driveshafts to see if there is one with a different style on the end. A driveline shop could swap it fair a reasonable price before doing the balance. Honestly just taking it to a good driveline shop might be time well spent, as an experienced guy might figure it out in person.

Like I said before I had about that same driveline for a couple of years with almost 13* in both joints. It had enough vibe on the freeway that I knew it was there, but AFAIK it didn't bind even off-road. If you can get the angles down to 10* or less you probably wouldn't notice any vibe.

I would figure out why it binds and mess around with the angles because there might be a cheap way out. If there's a setting that's smooth enough, I would re-do the spring perches. If you end up wanting the CV, it usually works pretty well with a shackle flip and stock perches (at least on a common-lift K5 wheelbase).

 

[K85 Octane]

thoughts:

1) The 14b axles close the distance between yoke and T-case, swapping from a 1/2ton. So your driveshaft is now inside the T-case more. Maybe you have spline damage. Not likely though.

2) Maybe the driveshaft is unbalanced, then again you didn't have any problems before the swap.

3) Maybe there is something wrong with the 14b's gear set up or bearings and this is what you are feeling.

4) Your driveshaft angles are off, as reported already. You need to rotate your pinion down, but can't because it's rubbing. Really weird the angle would be that bad with such little lift (from what it looks like in your pictures) You shouldn't have to drop the T-case, that stuff is for big lifts. Here is mine with it's 2.5" lift. Even with the slip way out, 0-85 mph was smooth.

5) I would buy a CV slip yoke shaft before dropping the T-case. If it's in the budget anyway. Though, I don't think dropping it will benefit you enough. 1" wont lead to good enough angles, and dropping a T-case 1" with only 2-4" lift kills your belly clearance. Get the pinion down one degree from the driveshaft (or you might be able to leave it the way it is) and spring for the CV shaft.

 

[Blue85]

Can you get some pictures of the shiny spots where it was hitting? I'm wondering if you could have the wrong adapter joint and it is able to move around under load. The 1330 joint is basically as wide as the 1350 and could be put in the same yoke - or something similar to this. It should vibrate the worst under light loads/coasting, though. With the tranny in neutral is this joint super tight? I've also seen the yoke ears wear so that the joint isn't quite centered in the pinion yoke, which would also cause vibs.


Also, looking at your pics again, there isn't much slip yoke showing. You should make sure the bump stops will limit stuff so you can't shatter the T-case. Angling the pinion back down will help a little.

 

[Blue85]

Ocatane, that last pic is the front driveline.

 

[K85 Octane]

Ocatane, that last pic is the front driveline.

 

[Mav2u]

thoughts:

1) The 14b axles close the distance between yoke and T-case, swapping from a 1/2ton. So your driveshaft is now inside the T-case more. Maybe you have spline damage. Not likely though.

2) Maybe the driveshaft is unbalanced, then again you didn't have any problems before the swap.

3) Maybe there is something wrong with the 14b's gear set up or bearings and this is what you are feeling.

4) Your driveshaft angles are off, as reported already. You need to rotate your pinion down, but can't because it's rubbing. Really weird the angle would be that bad with such little lift (from what it looks like in your pictures) You shouldn't have to drop the T-case, that stuff is for big lifts. Here is mine with it's 2.5" lift. Even with the slip way out, 0-85 mph was smooth.

5) I would buy a CV slip yoke shaft before dropping the T-case. If it's in the budget anyway. Though, I don't think dropping it will benefit you enough. 1" wont lead to good enough angles, and dropping a T-case 1" with only 2-4" lift kills your belly clearance. Get the pinion down one degree from the driveshaft (or you might be able to leave it the way it is) and spring for the CV shaft.

I'm pretty much sure it ended up the way it did by the angle I welded the new spring perches on at. Otherwise I'd probably be in the zone right now. Lesson learned. Get those spring perches welded on exactly where they need to be. A couple degrees makes for problems later as you van see how mine turned out by being off 3 or so degrees.

I'll probably get a 2 degree shim an try that an see if that helps out an take out my 6 degree shim.