Weird Engagement Vibration (Clutch/Driveline)

[JCorbo25]

Background: My clutch was slipping and I knew I didn't have much time left so I babied it a couple thousand miles. One morning, it just started vibrating on engagement. The vibration feels rotational, like half the clutch is gripping or wheel hop. This happens when just doing a slow engagement in 1st/reverse, but I got pretty good at slipping it in at 1,500rpms with little to no vibration.

When I replaced my clutch, half the friction material was missing on the pressure plate side. That made sense given my vibrations... so I rebuilt the transmission, replaced the clutch (ACT2100, new TOB, new ball, new fork), clutch slave has 2,000 miles on it, SS clutch line, both front axles (torn CVs) and tossed it back together.

SAME EXACT VIBRATION. /ubbthreads/images/graemlins/banghead.gif I'm at a loss now. Could it be driveshaft? rear diff dying? half shaft bearing? Maybe my transmission is flexing on clutch engagement? (I installed all the bolts listed in the vfaq, including the 'rear' bolt) Crank walk?

So Vibration:
Slow engagement 1st (no gas): feels like half the clutch is gripping, very rotational, engine bucks
Slow engagement 1st (mild gas): car jerks forward on the rotation grip (grip, loose, grip, loose)
Slip in 1st at 1,500; sometimes a minor clunk, but engages smooth

No issues on 2nd/3rd/4th/5th.

Still on my list to work on:
Rebuild clutch pedal assembly
Rear Axles

I also have a 2WD-4WD center diff (stock GVR4 tranny)

 

[transparentdsm]

what in the transmission was rebuilt? did you rebuild it or a shop?

 

[JCorbo25]

FFTEC in Hayward (Dave) rebuilt the transmission. He's a pro.

 

[EHmotorsports]

Did you install the bolt that attaches the trans on the back side of the block? I find people leave this bolt out a fair amount.

 

[JCorbo25]

Yes, I followed the VFAQ and made sure to install all those bolts (including the back side of block bolt).

 

[transparentdsm]

hmm, maybe transfer-case? i had a trans that vibrated, but it had a cracked tab and bad bearings on the 1-2 gear cluster ends.

 

[JCorbo25]

It happens in first/reverse, so I doubt it's an internal tranny issue.

What happens when the half-shaft bearing has issues? Maybe the driveshaft needs a rebuild?

Could be transfer-case, fluid looked in decent shape when i drained it. Pull it out and turn it by hand?

 

[Fish]

Was the flywheel surfaced or replaced, maybe it's warped and causing a vibration on engagement.

 

[JCorbo25]

flywheel was resurfaced and stepped to spec. Didn't have any signs of cracks or damage when pulled out.

 

[JCorbo25]

Ok, I've been noticing that the issue goes away when it's very cold out. I just got it smogged last week and the alternator died on the way home, so I swapped that last night. This morning, almost no engagement vibration and felt like it was running like a top.

Could this just be fluid thickening up? Just baffles me right now.