engine vibration

Slowly trying to dial I'm my car after restoring much of it. I have a new 4r70 tranny in with new converter. When I slowly accelerate in park I feel a vibration from say around 13k to 18k. It slowly gets worse upto say 15k then cleans up in higher rpms.

Any inputs would be appreciated !

Jim

I went through a similar situation. Turned out my new torque converter was out of balance after I tried everything else.

If you can unbolt it and it spins freely, push it back towards transmission, you should have a little space. Then start it and see.

If your converter has studs, you won't be able to do this.

Did you install the new transmission on an engine that you had run previously without any problems?

Chasing the cause of a vibration can be time consuming and frustrating. There are so many things it can be, especially after making a lot of modifications. As Dave suggested it may be the torque converter. It would help if you provided more details, like if the vibration occurs with the car sitting or while driving and all of the changes you have made since the last time you ran the engine or drove the car.

Vibrations are a fairly common occurrence. If you type in vibration in the search box in the upper right you will find a lot of posts about vibrations and what can be done or what was done to solve them.

Did you install the new transmission on an engine that you had run previously without any problems?

Chasing the cause of a vibration can be time consuming and frustrating. There are so many things it can be, especially after making a lot of modifications. As Dave suggested it may be the torque converter. It would help if you provided more details, like if the vibration occurs with the car sitting or while driving and all of the changes you have made since the last time you ran the engine or drove the car.

Vibrations are a fairly common occurrence. If you type in vibration in the search box in the upper right you will find a lot of posts about vibrations and what can be done or what was done to solve them.

Click to expand...

Don

I didn't drive it. Just in park. As I Rev it up you start to feel it getting worse then if you sit at 1.5k or so it peeks and stays there. I don't have a history on the engine so I'm not sure there. The flex plat came from my old fmx, bought a new convert. The Tranny shouldn't come into play. The harmonic balancer look ok. Not sure how you know If they are bad. I read the other posts but non seem to have the same symptoms. I will call converter guys tomorrow and see if I can slip the converter back. I seen to remember it had studs so I might not be able to slide it back.

Jim

you should drive it and see what you have before you start getting into it. there might be a vibration that changes under load with the transmission engaged.

there are many things that can be suspect. the balancer, flywheel, torque converter, driveshaft, yoke.

and the 3rd member yoke.

easy things you can try.

first drive the car and see what you have with the current setup.

if you find vibration you cannot live with.

1) mark the position of the driveshaft on the yoke and the 3rd member.

flip the driveshaft on the 3rd member yoke 180.

retest the car see if something changed for the better, if not you can flip the transmission yoke 180 and reinstall. retest the car again.

there are 4 possible combinations with the driveshaft that can reduce or eliminate vibration.

if nothing worked then you go deeper, flywheel, torque converter, balancer, you can have the drive shaft and yoke checked for balance as well.

sometimes driving the car for a while loosens everything up and a vibration can reduce or go away.

Start with the easiest, remove the belts to make sure it's not the water pump, fan, etc.

If the harmonic balancer is the problem it's because the outer ring has slipped around. You can try to move it, however, the best way is to turn the engine to top-dead-center on the number 1 cylinder (requires an adjustable piston stop that is screwed into the spark plug hole) and see if the timing pointer points to TDC (0°).

Make sure all of the nuts are on the flex plate/torque converter.