Broken Driveline???

[Enter Hummer]

Hello everyone, this is concerning my front driveline.

I replaced both the standard u-joint and 6 ball joint on it and it still has a ton of movement. I took the truck to GM and a reputable shop (without telling them it was the driveline) and they both told me that the driveline has too much play and it needs replaced. Is there something else on the driveline that needs replaced/could break? I’m no engineer, but it only looks like a pipe with 2 joints on it. Ideas?

I am pretty sure it is the driveline because I have replaced the T-case with a new one and had the front diff rebuilt. When I take the driveline out I have a very pleasent ride with no clunk/jolt.

I understand some slack is normal, but this clunk/jolt is much louder and harder than it should be.

 

[4speedfunk]

H3 t-cases have a bunch of slop compared to most other models. If it’s new, then that’s probably not the problem. The shaft is exactly what you describe...a pipe with two joints. If that’s new, it’s probably not the problem either.

This leaves the front axle. Check the front crossmember first...very common issue. Have someone cycle from drive to reverse several times while you are underneath looking at the front diff. It should move slightly but if the mounting bushing is bad...it can allow the diff to lift up and slam back down when you drive.

Lastly, grab the yoke on the front diff. It should not have any “shake” to it (especially if I was just rebuilt). The backlash should be .010” or less. Your diff guy should be able to check this.