Vibraton at shut down

Have a Pro Mod with a 526 Hemi, 14/71 blower, etc. We now race 1/8 mile and I have a problem during shut down. Finish line out of throttle, with 160 speeds I do not need to pull chutes at finish line or I will not get off the track. As the car starts to slow down I get a bad vibration, like the motor is hydraulicing. Tried combinations of pulling chute, fuel shut off, killing MAG, etc., but cannot stop this vibration. Rod bearings do not show hydraulicing. The problem goes away at slower speeds (60?). Motor just gone thru, balanced, etc.

 

Silly question, can you/do you put it in neutral/push in the clutch?

 

Have Auto trans and tried putting neutral, did not work, at those speeds the trans drove thru and continued to drive engine

 

What transmission?

 

Drive shaft balanced? My strange driveshaft was said to be balanced. Took it to shop around the corner. Nope. Not even close to balanced. Now it's smooth as silk.

 

It's not the same type of car.....but just a reminder to check your drive shaft for straightness if you have a solid drive line (F/C - Altered).....chuck it up in a lathe and check run out....MW says they shoot for .005" or less....have had to send ours to MW to have straightened....but it's 28" long..

 

Trans is a Mikes Monster glide. Trans just freshen and torque converter looked at and checked for balance. Thinks, going to have driven shaft checked for balance and straight.

 

If you put it neutral at the stripe, there is no way it should be turning the engine..........

 

Just thowing something out their could your shut off might not be 100% shutting the motor off right when you push it or somthing like that. Or have you rebalenced your tires or tryed a diffrent set thinking outside of the box that you would never think to create a vibration. Or check all the wires are tight and not loose someware. just random things. hope this helps

 

Had drive line checked for balance and if bent. Came back was bent. Had straighten and balanced. Looked car over for any possible problems. Got the car down the track 3 times, but only one good run do to tire shake on other two. On the one good pass at finish line, backed off throttle, pulled chut, and hay no shake, and then it happened. Not as bad as before but still there. Winter season and I have a few months to get the car ready for next year. I will replace the drive shaft for good luck.
Thanks for all the input and help.

 

Bent rim?

 

Bent rim?? I'll have them looked at. Thanks

 

You can check that yourself on the stands with an indicator.