severe vibration after t5 swap

Sorry about not giving you enough info about vibration, I would have to write a book about all that we used for this swap and the attempts to fix the vibration. This is my first time reaching out for help on this kind of forum, so I'm gonna screw things up, but I still appreciate your help. enough on that issue!
I've never heard about having to index the bell housing and adapter plate nor has anyone ever mentioned it while making the swap. Indexing seems to be very meticulous requiring specialized tools. I have taken the t5 back to the garage and ask the mechanic to leave tranny mounting bolts loose and start engine to test to see if that makes any difference in vibration, maybe off center is what I ask him to check for(crude form of checking for improper indexing )
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If you leave the bolts that mount the T5 to the adaptor plate loose you will most likely compound the problem and end up making things worse. The way to verify or rule this out is to index the bell housing / adapter plate. If your mechanic cannot do this then find one that can. In all honesty it just takes a dial indicator kit that you can get from Harbor Freight. If it is off then order the correct offset bell housing dowels and that will fix it.

As far as you having to write a book on what all you was used for the swap and what you have done in your attempts to mitigate the vibration I do understand. Think about how much we have gone back and fourth to get the information. Just saying that a little more work on your end would have saved a few of use some time narrowing down the focus of the source of the vibration. I am not saying that indexing it will solve the issue but we could have hit on this a lot earlier.

Also, you still need to check the end play on the input shaft of the T5 as that is a very common source of vibration. I chased it on my Tremec TKO for a couple of years only to find that $30 worth of parts solved all my frustration.
Each time i've reinstalled my T-5 back in my car, i check the runout just in case I need to index it. It's always been spot on, but i'm doing a factory setup without any adapter plate. I still check.

If oyu are using an adapter plate (not sure if you said you were), i would really index it. Just requires a drop indicator with a magnetic base to do it.
Again, I'm at a loss as to how input shaft could be turning and causing severe vibration when clutch disc is not touching flywheel. As is I understand, input shaft is spinning at same rate as flywheel when clutch engaged, conversely input shaft is not spinning at all if clutch not engaged. I suppose input shaft could be turning when clutch not engaged if end of input shaft is off center enough in pilot bushing. However, I don't know if this off center pressure on end of shaft inside pilot bearing could cause extreme vibration. I guess only way to find out is to remove tranny again, index everything and put back together. Lot of work. Mechanic said he didn't think it is off center since used original bellhousing, clutch disc, and pressure plate and factor adapter plate. I guess anything is possible
But you had to use a bell housing adapter to get the T5 to bolt up to it. This is where it could be off. If the factory one was off but barely in spec and then the adapter was installed a little off it could compound the issue.

Again, not saying this is the problem but it’s prudent to check and confirm what you have.
Again, I'm at a loss as to how input shaft could be turning and causing severe vibration when clutch disc is not touching flywheel.

Clutch drag would be the only way.

You can eliminate this as a possibility by sitting with the clutch in, and put the trans into gear. This will lock the input shaft and clutch disk in place.

You still have a vibration then?
The input shaft for the transmission is misaligned.

My illustration attempt:

The Red line is just a straight reference line.
The circles are a side view representation of the holes for the clutch, pressure plate, and input shaft bearing.
The blue represents a misalignment of the shaft due to the bell housing, adaptor plate, and trans case not being a straight line.

This is why the guys are insisting that that the adaptor plate must be indexed so that the shaft is straight from the face of the transmission all the way to the pilot bearing.
The input shaft for the transmission is misaligned.

My thinking is that if this is the case, the misalignment of the clutch disk and pressure plate can manifest as a vibration as the rotating pressure plate slightly makes contact in intervals due to the misalignment.

So not necessarily a vibration due to imbalance, but more due to intermittent drag
That would be roughly the same as a bent tailshaft or warped cluster shaft / mainshaft etc.
So, a micrometer on a mag base is your friend for a few checks
They make you check the alignment of the bellhousing and trans input when installing a scatter shield like a Lakewood
It causes your vibration trouble sometimes,
Factory bellhousings generally do not have that particular problem IMO
And it's very hard to check IMO
Tell me again, you coast that car down the mountain road doing 50-60, and it vibrates like crazy in neutral with the engine off? Right?
They used to tell us in NVH school that the driveline angle out of the trans needed to be the same as the driveline angle into the rear end
Mostly a lifted truck problem but worth checking
There are quite a few lifted red rock Moab trucks around here throwing drivelines on the freeway when not done correctly
Answer question end of post 42
Vibrates any time no matter what? That means engine off 50 miles an hour coast down a big hill?
Engine off coast? still vibrates?

Nicolaj: Did you try to loosen tranny mount and lift tranny slightly? and if so, did it make any difference on vibration?​

Yes i did that and the virbration goes away. Cant figure out if we have the same issue here. Still vibrates when u lift your transmission a bit? My problem is i dont know if the vibrations in my engine/transmission is normal and it just doesnt get damped enough. Or if my vibration is too much and the jack just takes the vibration when i lift the trans