I've had a vibration since I put my TH350 in. It's a wavey oscillation. Seems to be more load sensative, definitely speed sensative though.

B&M Install kit 30299

Driveline is a 4th gen LS1 Aluminum. Balanced at 3 different places(3 different times to be sure), new U joints. Seems as though it should engage another 3/4 inch, but no way to change that.

New Tailhousing Bushing.

Checked the pinion angle and figured the rear to be upward 4º
(I think, I will check it again on my next day off)

All wheels are in balance.

New ring/pinion/carrier.
LCAR brackets (on the lowest hole, had vibration on the top hole too)

Haven't checked axle straightness, Not exactly sure how.

Is 4º or the semi lack of yoke engagement going to cause this? At say 80mph+ and coasting down from the track it shakes the whole car like some seriously rough road?!

Any way to tell if it's the transmission itself or the torque converter?

Also on my next day off, I'm going to check and see if the vibration goes away when coasting down in neutral. Forgot if it does or not.

Any problems with this B&M kit?

It's aggrivating! The freeway speedlimits here are 70 and it makes for a really annoying drive at 3300rpm to begin with! (FWIW vibration was there before gear swap from 3.23 to 3.73.)

 

Stupid answer (but you never know).... Have you tried unbolting the rear u/j, hten refitting the propshaft after turning it half a turn?

I don't exactly know if this is relevant because of your balanced Aluminium shaft, so please don't flame me (much!)

Mark.

 

Rechecked angles.... Output shaft angle was 0º and the pinion was -4º.

I relocated the front torque arm mount down 3", which in mathematical terms yeilds about a 3ºdrop in the pinion angle. Putting the total +1º higher than the outputshaft angle.

The vibration got better, starts later, not as violent, and the cruise oscillation is slower.

But it's close to factory angles, why so much vibration still?

How much flex is in the torque arm at 4000RPM (driveline too), 72mph, 26" tires, and 3.73 gears?!