71 Dart 727 w/suregrip having weird issue

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Belvedere66

Belvedere66

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Having a problem that started today. Don't know where to begin. When stopped at a light the rear of the car feels like it's grinding/humming. It goes away if I put it in neutral or start to move in gear. I can still hear/feel it while driving but not as bad. I didn't go over 35 mph back home to avoid damaging anything. Any ideas? Trans? Rear end? The car was running a little hot. Could warm fluid be causing these symptoms? I parked it at home and while sitting in the driveway I went through the gears and only felt the straining whirring sound in drive gears, not neutral or park.
 
Maybe something vibrating or rubbing, like exhaust or something? just a thought......
 
Well if you are not moving and still makes the noise it is NOT the rear because nothing is moving in there.....has to be trans
 
Stopped in gear, the only thing moving in the trans is the converter and pump. So if it doesn't do it in reverse then I wouldn't think it was the trans (u said only does it in drive gears, u didn't specify reverse). I'm guessing something in grounding out to the body. Check all ur clearances around your exhaust and engine.
 
Yes it was reverse as well. I think it was overheating, after letting the car sit in the garage for 2 hours I started it and moved the gears and it seemed normal. The old AC condenser was there so I removed it to maybe allow air to move more freely. I also may add a trans cooler or at least an electric fan on a switch. I never had this problem with any of my other cars......hot engines maybe but never hot transmissions so I was taken by surprise a bit there. If it ever stops raining I will take it on a loop around the highway and see if what I did helped any.
 
Belvedere66 said:
Having a problem that started today. Don't know where to begin. When stopped at a light the rear of the car feels like it's grinding/humming.This says it is ahead of output shaft. It goes away This says it is not from the TC forward if I put it in neutral This says it is in the tranny or start to move in gear.This says it is not after the output shaft. I can still hear/feel it while driving but not as bad.This again says it is in the tranny I didn't go over 35 mph back home to avoid damaging anything. Any ideas? Trans? Rear end? The car was running a little hot. Could warm fluid be causing these symptoms? I parked it at home and while sitting in the driveway I went through the gears and only felt the straining whirring sound in drive gears, not neutral or park.
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Ima gonna guess aerated fluid blowing out the pressure relief.It's a guess.So if it's gone,after sitting for an hour,it might be a good guess.If still there;not so good. If gone but returns with a short drive,could still be a good guess if tranny low on fluid.
 
Well i double checked the fluid level and condition, checked out good. I did finally get it up on a lift today and found one trans mount bolt loose and the other missing. I fixed that and it did get a bit better but not totally. A friend of mine who tinkers with race cars had me hold the brakes and give it gas and see if it gets worse and it acts normal, nothing weird happens. Shifts fine, drives fine...just weird vibrations. Also feel them slightly while coasting from around 40-50 mph. I have been told that exhaust vibrations can confuse people and sound like drive train problems? One more thing I did find was something I hadn't thought of before......my exhaust hits my driver side torsion bar, my passenger side rear frame rail, and my passenger rear spring shackle bolt. Could all of this weird pulsating while stopped be these things vibrating together?
 
Belvedere66 said:
Could all of this weird pulsating while stopped be these things vibrating together?
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Quite possible. I had a small vibration in my car, and it was the exhaust hitting the torsion bar. I could feel it in my feet when sitting in the car.
 
Belvedere66 said:
Well i double checked the fluid level and condition, checked out good. I did finally get it up on a lift today and found one trans mount bolt loose and the other missing. I fixed that and it did get a bit better but not totally. A friend of mine who tinkers with race cars had me hold the brakes and give it gas and see if it gets worse and it acts normal, nothing weird happens. Shifts fine, drives fine...just weird vibrations. Also feel them slightly while coasting from around 40-50 mph. I have been told that exhaust vibrations can confuse people and sound like drive train problems? One more thing I did find was something I hadn't thought of before......my exhaust hits my driver side torsion bar, my passenger side rear frame rail, and my passenger rear spring shackle bolt. Could all of this weird pulsating while stopped be these things vibrating together?
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Ummmmmm, did someone mention that in post #2??? Hope you get it sorted out...
 
I had the same problem and found the tailshaft housing was touching the upper crossmember.
 
I am going to be make my appointment today with my local exhaust shop, they said they would fix the rubbing for free since they are the ones who hung the exhaust initially. This is the thing causing the shaking while sitting still. Thinking of maybe just taking it to a better shop instead. But anyway....hopefully that helps. I was able to single out exactly when this other weird vibration/rumble is happening while driving. It was a combination of different issues and problems I think before, causing multiple symptoms but since some have been fixed since my last post, it is narrowing down. So after eliminating the low trans fluid and loose trans mount bolts (oops) the vibrations now only happen during specific speed increments.

Around 35-40 and 20-25 while holding consistent speed and also pretty bad while deceleration/coasting at the those same speeds (example if I am going 50 mph and I take my foot off the pedal and coast I don't feel it until the car reaches 40mph). I can only really feel it in my steering wheel. If I lay the hammer down from a stop I don't notice the problem. I have a bare floor right now so I tried placing my hand on the hump to see if I can feel it on the floor and I can't really notice any differences. Only in the wheel and obviously by sound as well. A passenger can hear it, just not feel it almost at all. It kind of sounded like a wheel bearing but the wheels don't have bearing play and new ones were installed this past winter when I did brakes all around and it also doesn't get more or less intense when shifting the car's weight side to side. My brain is getting tired, I am good with electrical stuff, trying to track down vibrations makes me crazy
 
Too much toe-in can cause a worn steering system to oscillate.As can a serious tire imbalance,or too much camber. If you feel it in the steering wheel, that's the first place to look;tires/wheels,tire balance,and alignment.
If the tires have lost an edge then they are worn conical, and they have to come off the front.They have to. There is nothing you can do after the alignment is proved,that will stop those tires from making trouble;short of putting a bazzillion pounds of air in them. They can be run off, on the rear, where you will hardly notice them;so long as they are balanced.
 
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Well due to reasons the fronts can't go on the rear haha. I'll have a buddy throw them on a balancer though.....last time I did it for the rears we found a bent wheel.
 
Wheels/tires are good. After toying with the car for a little bit, a couple of the techs there suggested maybe main bearings are wearing out? Since I can get it to vibrate while moving and while in park it has to be something that is still moving when the car is sitting still. IE engine/converter, etc. To test the converter they had me hold the brake and attempt to power brake it but without going as far as to let the wheels break loose. I guess they were looking for the car to vibrate badly under heavy load, which it did not. Which brings my brain back to the engine itself. Not giving up hope, the car hasn't broken me yet.

Also noted oil pressure readings at different intervals. While idle it sits around 25. WOT holds steady at 65ish, no loss of pressure. No knocking during cold startups either.
 
My son and I are gradually getting rid of vibrations and rattles on his '65 Cuda. The exhaust was hung from small rubber blocks wrapped in steel and bolted to the chassis. No much shock or vibration absorption there. We replaced the rear hangers and it is better, and will replace the ones in the axle tunnel soon. We're using old fashioned rubber strap hangers now. It got worse in left turns and at certain RPM's so that was a pretty good sign of exhaust vibrations. And uphill at 75 MPH, it phases in and out with a driveline or wheel vibrations.

So sometimes you just gotta keep changing things; one can mask another.
 
I had my exhaust fixed today, a lot less rattling around. I found one of my motor mounts with a hairline crack going through it and my tail shaft seal seeps onto my trans mount, softening it. Both are getting replaced next week along with a new seal. Little by little, just like you.
 
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