Thread: engine/trans shake when burning out

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May want to check and see if any of the balance weights fell off the driveshaft. With a shaft alomst 6ft in length, you may have alot of whipping at RPM and if any balance weight has fallen off, that will lead to big time vibrations.

Seems to me that if you have no vibration at any rpm/speed with moderate throttle you've ruled out component balance from the list - it would be shaking somewhere in the rpm/speed range if it were a balance problem. What are your rear tires? Are you trying to crank some massive pro-stock meats? I like Hoss's idea about a wet burnout - what does it do on wet pavement? How stout is your driveshaft? Did you have it built for the HP & torque, or are you using an OEM or cut down OEM? I'm leaning towards a clutch/pressure plate/flywheel problem, or maybe the driveshaft wrapping up and going harmonic under maximum torque. Personally I don't like needle bearing pilots, but that's just me. Bronze provides known support, is rugged enough to withstand stabbing the tranny with minor mis-alignment of the clutch disc, and will wear before the input shaft regardless.

I switched the poly link mounts to heim joints because I thought I was getting flexing back and forth in those maybe, so now they are solid as a rock.
I had the driveshaft made custom, and there is no vibration even at 65 mph, which is the fastest I've ever turned it, so as spears said I def don't think there could be a balance issue.
I would hope the shaft is not wrapping, but I guess I can't be positive about that. The only thing is, I would think there would be less torque on the shaft after the tires cut loose than if I kept them planted, and there are no problems at all at full throttle in 1st gear as long as they don't slip.
I did try a burnout here at work, concrete plant, which is like wet conditions because there is a coating of dust on the pavement surface that makes them really slippery, and had the same results.
I wish I could mount a camera under the car to watch the trans when this happens.

You said it's a tri 4 link, is that a 4 link with the two top bars close together like a Chevelle or is it a tri link (1 upper bar)?
What's the IC of the rear suspension? Could be the 4 link / tri link geometry is off & only shows up under power. Bottom bars at the wrong angle? Just thinking out loud. Hard to tell without watching it and seeing what the set-up looks like. Could be the rear end is binding & unloading as the tires spin, Causing a clockwise/counterclockwise rotation of the rear end housing. That may not be noticed from outside the car. I don't know if I'm explaining what I mean right.

I think pro is on the right track if the rear is to tight it could be trying to go both ways at same time trying to remember where I read a post on just that topic. Might have been right here

it is a triangulated 4 link, so I have the two top bars angled inwards and the bottom bars are parrallel. I also added a panhard bar last month when I was attempting to solve the problem.
I'll find the pics I have when I get home of the rear before I put the bed on the truck so you can see it clearly, and I'll also post those video's if I can figure it out, but I've watched those things many times and I can't see any movement at all of the axle.