Customs Grinding Sound part throttle

Actually, Happydaze, that's worth looking into, one way to test is to get the car up to speed, put the trans in neutral, then shut off engine to see if grinding noise goes away.

 

I tried to read carefully, but maybe I missed it. Have you checked the fit of the yoke in the transmission? Seems to me there was a similar thread somewhere, and the trans bushing was worn and overlooked because the seal wasn’t leaking. On a bagged vehicle there can be a lot of variance depending on how the PO drove it.

 

Does it only grind when moving now? That would basically rule out every internal thing forward of the transmission, including the flexplate.

 

Not going to be the planetaries at 70 MPH.They're not working...just along for the ride.

 

I would put the car up on 4 jack stands. Go out when it gets pitch dark, lay on a creeper and look everywhere under the car with a flash light. You may see traces of ground up metal somewhere.

 

SO my coil took a crap on me so couldnt try things out but got that changed and went on another ride yesterday. then traffic started getting abd on the highway and couldnt continue. will try again today but leaving to go out of town.

drove buddy in it yesterday to let him hear it and he was baffled too. definetly a rotating issue since its speed related.

 

Bolts too long through cross member into trans mount? I know it's not rotation related but I've seen cases of this where the bolts are contacting the upper metal plate of the mount effectively making the mount solid.

 

I feel your pain Whitey.
I had a Porsche years ago that had a RR wheel bearing go and it was a deep howling/grinding sound only over a certain speed. And it sounded like it came from everywhere, not just the right rear.
I had an MII that had a worn tailshaft housing bushing and it vibrated, but only at certain speeds. No whine or howl from that one.
Years ago I borrowed my bro's 62 F-100 with a mild 460 in front of the "2 spider" 9 inch and it came apart on me. That one made crazy clunking and clanging sounds before it disintegrated. I limped it home and it had massive shrapnel in there. That was my first diff rebuild, many more followed.
Doesn't probably fit the diff gear whine, but just to be sure, please go to 24:36 of youtu.be/rB2f1zq4CIU and listen to the very pronounced gear whine that only happens at a certain speed. I've set up several diffs and one gear set just howled like a mofo and it sounded exactly like Vaughn Gittin's.
Good luck brother.

 

ok sorry i was late but here is my noise. its 8 minutes long but you get the idea.

 

You mentioned it made noise at very little throttle as well as at 70+ mph, have you checked the end play of the crankshaft? Any forward movement of the car will load the torque converter, which in turn pushes the crankshaft forward. They can make a lot of noise rubbing the dust covers or pulleys up front. I had 440 Mopar which ballooned the converter and shoved the crank forward about 1/4".

 

Sounds like something like an inner fender brace that reacts to shitty alignment.

 

Sounds like brake drum contacting backing plate. Any end float in rear axles?

 

Sounds to me like there is a lot of difference between the car being loaded (under acceleration) and unloaded.

That brings it back to 3 possibilities. Motor mount/trans mount letting the motor shift enough one way or the other so that something attached to the motor may be making contact with something. The sound would indicate that contact would be metal on metal, but it could be metal on a hard surface, or even something as simple as a trans cooler line vibrating against a mounting bracket. I don't think the contact is a hard contact, it sounds more like a light touching. A fix might be as easy as a zip tie pulling something more tightly together.

Possibility 2 is your rear suspension mounting. Something like a slightly loose bolt, or a little slop in a bushing to bolt, or a bushing to the trailing arm movement. It probably isn't much, and may only show up a fine metal filings between the two contact points. Unfortunately, your going to have to really inspect every end of each piece, its probably only one end joint.

There was one more thought. The Mopar 8 1/4 has "C" clips holding the axles in place. I've seen warn "C" clips and worn "C" clip grooves that allow the axle to shift side to side more then it should. This would allow the brake drum (or drums) to make occasional contact with the backing plates. That contact point could be one spot on either the inside of the grove in the end of the drum, or it could be the full diameter of the drum or the edge of the lip on the backing plate. The contact point would be more shiny then the rest of the drum, or the lip on the backing plate. You may have to give the grove on the drums, and the lip on the backing a light coating of paint then test drive, and pull the wheels and have another look. You might get by with a light grinding of the offending spot, or you may end up replacing the "C" clip, or an axle.

 

I'm not hearing a grinding noise in your video (but it only watched the first half). I hear rattling noise, and I'd guess it's the exhaust hitting something. Again, I think if you stick your head under there you will find it.

Take the car to a car wash and clean the hell out of the underside as best you can. Then drive it a little. Then put it on a hoist and look everywhere under there for fresh paint or rust scrapes where anything touches something else.

 

since car sets so low could be a cracked tranny housing u cant see or cracked starter housing, something is flexing under acceleration that is rubbing, could be starter to flywheel , tranny or in rear end ,look for metal shavings, good luck ,let us know what u find, Dempsey

 

Any of the accessories could do this too. Ck them all, even the starter. Gen/ Alt, waterpump, A/C compressor. And the front "U" joint it could be rubbing in the back of the trans tailshaft under load. Also, consider changing the engine and trans they're kind of cheap for a new crate engine and trans.
Check the ebrake pull cable under the car, when you release it the cable droops and might rub the driveshaft under load.

 

Sounds kind of tinny like a loose heat shield or something hitting a heat shield. Could be e-brake cables even. I also noticed a pretty significant vibration on what seems like deceleration. Drive shaft or u joint issue. Possibly bad driveshaft angle or worn tail shaft bushing. It’s probably something cheap or easy to find.