Kinda Stumped

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straightlinespeed

straightlinespeed

Sometimes I pretend to be normal
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This may be vague and I'll try to explain the best I can. Driving my 71 Scamp with a 360/727 TTI's, stock rubber engine/trans mount and larger 1.03 torsion bars, I get a odd noise/vibration coming from the brake and gas pedal area under the car.

When I am at a stop light and go to take off slowly I will get what sounds like the headers or something in the transmission making a odd noise/vibration. The issue stays until I get moving at least above 10mph. I took it to the track and I foot braked the car, loaded the drive line before letting off the brake, and the noise is very noticeable. Once I let off the brake and hammered the throttle, it went away. If I let off the gas and roll very easily into the throttle, there is no sound. It only seems to be there under standard acceleration and loading of the drive line.

I can tell you this. My TTI's are only about a 1/8" max from the torsion bars, but before I changed to the larger bars I still had this sound but not as noticeable as now. I did install a torque strap to help with the engine twist, but it still seems like I have some movement.

Last thing... I will be pulling out my engine and trans soon. The trans probably only has around 2500 miles on it and was opened up and checked prior to install by a transmission mechanic who is a member on here. He did find some issue with it (TCI) and corrected them. So Im leery its in the trans, but unsure. I tried to get a sound recording of it, but you cant hear it with the engine noise. You can feel it, in your feet more than hear it. With all that being said, what do you guys think I should look into?
 
Had a similar issue. Turned out to be the drivers side collector tapping against the bottom of the floor board. 1/8" is not much clearance. Under load, you will get more flex than that even with the straps.
FWIW, take a look under the car and I bet you find some marks from the impacts.
 
Something from the motor is "grounding",, transmitting engine vibration to the chassis..

If you have any adjustment in that torque strap,, cinch the motor down,, this should reduce/eliminate vibration,, then go find what it is,, and make adjustments as nec. Remember the motor not only twists, it also tries to lift on the drivers side..

Sometimes it's as easy as an airfilter, tailpipe,, somtimes inside a soft mount itself,, or just something really close, like that torsion bar...

cheers..
 
Just a guess, but I agree with a mechanical vibration of some sort. Headers, other exhaust, linkage, etc, touching at some point.
 
Thank you everyone for the suggestions. I was just dreading tearing open the trans. I'll take a look and see what all is rubbing or close to rubbing. Such as the headers on the torsion bars..

I was thinking of swapping out the stock biscuit mounts to poly locks and throwing a poly trans bushing in just to help stiffen up all that.
 
Your crankshaft is fixin to break into five pieces..
 
straightlinespeed said:
I can tell you this. My TTI's are only about a 1/8" max from the torsion bars, but before I changed to the larger bars I still had this sound but not as noticeable as now.
Click to expand...

You may be headed in the right direction right there Ramie. Larger bar made the vibration more noticeable.

Here's what I would do. Find a piece of rubber type material and stuff it in between the header and the TB.

If the vibration is gone or lessened substantially , you've found your problem. :D
 
Cut a piece of radiator hose lengthwise and slip it over the torsion bar and take it for a ride, I'll bet it's the culprit! I have a variety of these sounds coming from the exhaust rubbing things on my GTX! It sounds like a main bearing is gone sometimes because the tailpipe rubs the pinch weld along the gas tank, there is a loud knock at the door under my feet when I nail it because the drivers side headpipe hits the crossmember cutout! The exhaust is at least 15 years old, but still in really good shape so I tend not to notice! I think it's from doing so many burnouts over the last 15 or so years has gotten the whole system twisted out of shape!!

My money is on the exhaust system!!
 
This sounds like a noise I had in my Dart. Drove me NUTS for a long time. I checked header clearance, converter bolts, motor mount bolts, anything I could think of. It turned out to be the trans mount. When I took it apart it wasn't broke but the rubber had shifted, causing the metal inside to chatter against the crossmember. I could see it was shinny where it was hitting. Good luck!
 
Thank you all once again for the advice.

340doc, I was thinking the same thing earlier this summer. I checked out my trans mount and sure thing. The rubber was tore and not really supported. I thought it would had taken care of my issue but its still there. So I found one thing that was a problem but not the culprit.
 
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