Transmission mount question

So after searching high and low I haven't found an answer to this question. I have a 2002 S-Runner, manual trans and want to know the purpose is of the vertical bolt on the transmission mount. Tightening the bolt puts a compression load on the rubber in the mount. It looks like it's there for some sort of preload on the rubber. Anyone know?

 

Maybe the bolt is only threaded so far and you can only tighten it till there are no more threads.

 

its to keep your trans in place if there is a catastrophic mount failure or if you are in an accident.

 

If the rubber around that rear bolt is torn and bolt can be turned and wiggled around, would that be a cause of what i think is a driveline viberation (even if the two rubber blocks appear to be intact)? I have already changed the center bearing, all u joints and had drive shaft balanced.

 

maybe??? but that bolt is supposed to be "free" as it isnt doing anything until the oh shit moment.

 

Ok. Thanks! Kinda thought that. Guess I'll have to look elsewhere for problem. Ever heard of the front (4wd) driveshaft free spining at or around 50 mph in 2wd and maybe that is vibrating due to u-joints needing replaced? Gunna check to see any movement in that shaft today.

 

Not sure if front driveshaft turns in 2WD or not on Tacomas, but I had a TJ Jeep vibration (at around 50 mph) that drove me nuts until I figured out I had a bent front (4WD) driveshaft and replaced it.

Maybe someone with more knowledge than me can answer whether or not it turns while in 2WD.