Thanks for all the info. A lot to consider. I took driveshaft and had it balanced. He said it was definitely out. I reinstalled and now it runs smooth tillabout60-70 mph then more vibration. Also getting the growling sound when clutch pedal released. Appears to only happen after warmup. One minute I think a pilot bushing, then I read about imput bearing, saw a video on clutches and was now thinking disc to light so springs making noise. Then I’m told drive angles. I guess I’ll have to pull the entire thing and examine. If I push clutch in the sound disappears. That tells me that would eliminate the pilot bushing and disc since the imput shaft is stationary. When pushed in, that would indicate the imput shaft bearing. I have two issues here. 1. Growling noise and 2. Vibration at higher spees(mph) revving in neutral does not give me vibration. I’m at a loss Thanks for letting me rant,

Might I suggest,


1. Look at where your throw out bearing is when your foot is not on the clutch pedal. If its misadjusted and riding on the clutch fingers, it will be spinning all the
time. Causing the noise when it warms up. There needs to be about 1/2" pedal play between the throw out bearing and the clutch fingers when your foot is off the pedal.
2. You mentioned earlier about checking the oil level. Do you ever to that? Because you never said you did. Since this is a new transmission, was it shipped dry? Although things do go south, even when new, I'm fearing the noises are from a lack of lubrication.
3. Someone made mention about the pilot bushing/bearing, Did one get installed when you installed the transmission? This would go in the back of the crank. This could be the reason for the front tranny bearing going out. I had a hard time trying to figure out if you did a tranny conversion, I'm guessing you did. Automatics don't require a pilot bearing, standard transmissions do. Might be the suspect for the vibration at high speed.


Just ideas to think about.
Chris

Does the car have aftermarket rear control arms or has anything been altered rear suspension wise? If so suspect drive line angles regarding the vibration.The faster you go the worse the vibration says it all...Dont ask me how I know.🤬The heat related noise is interesting...something is changing (expanding)with heat.The fact that it stops when you push the clutch in more or less indicates input bearing or perhaps an input shaft to output roller or anything else that ceases to rotate when the clutch is in.Manual transmission noises can be really dfficult to nail down..I once had a Warner ST10 that would howl like a wolf at the moon in 2nd gear ONLY turned out to be the output bearing was a little gritty....never understood that one.

Yep, was going to suggest checking the oil in the Muncie. They ship dry on a rebuild and if you didn't read that or check the level at any time previously, it might be the culprit..............

Stupid question but have you had the tires and wheels balanced ? Also brake drums ? One of my Wife's coworkers had an old Caddy that nobody could figure out a vibration and it turned out to be the brake drums. I balanced them on my crankshaft balancer and all was well.






That sounds like something in the trans. My S-10 does it but it has almost 300K miles on it. Was this a "New" transmission or a rebuilt one ? Do you have a lift or access to one ? Put it up in the air and have somebody listen to the trans with a stethoscope.

If you're rolling in gear with the clutch disengaged the clutch disc, input shaft and gear train is still spinning. If the noise goes away when you push the clutch in and the car is rolling it wouldn't totally rule out the transmission because such things behave differently under load/unloaded but I would concentrate on the throwout bearing and pilot bushing. Usually a bad pilot bushing will cause issues shifting as would a misaligned bellhousing.

I think Muncies only hold about a quart of oil so it would be cheap to experiment with a different oil.

As for vibration; the tires need to be balanced to rule out that variable.

Did you install a new pilot bushing before you installed the Muncie?