Drivetrain Vibration

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the picture is a 904 but I can't tell you if those are specific to one or the other. I think both housings have the squared off bit with two mounting holes. These don't all come in the same outside shape however. I measured my hump (tunnel?) and found one that wouldn't touch at any point and still allowed for a little motion. Maybe a longer housing beyond the tranny support might allow for a longer movement radius (???)
 
The guy who made my crank gave me this. It‘s german but maybe you find out something.

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If I would decide to go back to stock, (crank and rods) would it cause vibrations again when oversized pistons are used?
 
jakuzzie said:
If I would decide to go back to stock, (crank and rods) would it cause vibrations again when oversized pistons are used?
Click to expand...
jakuzzie said:
If I would decide to go back to stock, (crank and rods) would it cause vibrations again when oversized pistons are used?
Click to expand...
Should not if you have the rotating assembly rebalanced.
Balancing the rotating assembly includes the weight of the pistons, piston pins and rings.
 
Numbers are numbers and just what is on the paper that crank is junk. Stop this video at the end and compare the numbers. The crank my son spun was a external balanced crank. It is now internal balanced. 1.36 grams and 0.21 grams, He screwed that crank up bad. He should be liable

from what I see . He has it at 138 grams and 186 grams. Comparing the two It is 138 minus 1.36 is 136.74 grams out of balance on one side. 3 grams and less is good. 136.74 Not good at all. He forgot to look at the decimal point there is none.

A woman would love to sit in the seat and rev that thing. That's better then a sex toy.

 
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So I finally I did a test drive.
Same like before.
Nothing changed.

Do not know what to do now..
 
Oldmanmopar said:
Did the same shop balance the crank. Those are awfully big balance holes.
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No, different shop. Hey build drag cars. I think he knew what he is doing.

I got I Beam rods. Those are really light. Maybe that causes those big holes.
 
I am checking the tranny mount next.
Got a mount from energy suspension installed.
Feel the vibration coming from the floor.

Before installing the mount my transmission did not line up correctly.
The rubber always did come out of the mount.
 
Those energy suspension mounts are supposed to cause some vibration. They are supposed to be rubber.
How is the vibration now in park?
I just went through a vibration problem. I had a bent flexplate.
I would get a dial indicator with a magnetic base. Check the shaft for runout.
Also, download the Tremec app.
It makes checking angles simple. The number on the app will turn green when you are good.
I looked at the pictures you posted of the angles, and I think the rear should only be 2 degrees less than the trans. Yours was 6.
 
furyus2 said:
Those energy suspension mounts are supposed to cause some vibration. They are supposed to be rubber.
How is the vibration now in park?
I just went through a vibration problem. I had a bent flexplate.
I would get a dial indicator with a magnetic base. Check the shaft for runout.
Also, download the Tremec app.
It makes checking angles simple. The number on the app will turn green when you are good.
I looked at the pictures you posted of the angles, and I think the rear should only be 2 degrees less than the trans. Yours was 6.
Click to expand...
The vibration change with speed.
The faster you go the stronger it get, but not faster.
At deceleration it get faster.
The engine runs smooth af now with the crankshaft rebalanced.
Can feel the vibration coming straight from the floor. It’s the area where the tranny mount is mounted.
Still got the old.
 
Changed the transmission mount back to stock style.

VIBRATIONS 90% GONE!

After all those years chasing the vibrations I almost gave up.

Cause of the vibrations:
  1. Wrong balanced crankshaft
  2. Energy suspension transmission mount
  3. Driveshaft out of balance
 
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