Last year when I got her on the road, I noticed a driveline vibration @ about 45 miles per hour and between 1500-2500 rpm in park. Having time this winter to chase it, I found that the flexplate is wobeling(SP?) a little bit. Everything is tight. Will this cause damage? Do I need to pull the engine to replace it? Or is there a simpler way to change the flexplate. TH400.
Thanks

 

You don't have to pull the engine or the transmission. First take the starter off. Next take out the tq conv bolts than push it all the way back. Then you can take a long wrench take out the bolts. Then you can remove the flexplate. You'll need some one to help with keeping the engine from rotating. My second choice would be to drop the transmission then use an impact to remove the bolts from the flexplate.

 

My torque converter only moves back about 1/4" or so. Is that enough?
Thanks

 

Try turning the conv. clockwise and pushing on it. 1/4 of inch wouldn't be enough.

 

I will check again, but it was close when I just reinstalled my trans after changing the converter, pump, clutches, 34 element sprag and drum, 4l80 band, and transgo kit etc.

 

If this is a new flexplate, make sure it was balanced.

Some are internally balanced, and others are externally balanced.
If you got one that wasn't balanced, that's your problem.

I ALMOST pulled the trigger on a cheap flywheel off Ebay for my T56 conversion
til someone pointed that part out to me. I just assumed all were balanced.
I was wrong.......saved me a headache.

 

If the flexplate is wobbling, it is bent. Replace it. I have never been able to swap the flexplate without first moving the trans. I have been able to leave the crossmember in place and simply slide the trans rearward while on the jack, however. You will need to remove the rubber trans mount to do this.

 

Well, it only moves back MAYBE 1/4". I guess I'll just have to try sliding the trans back. To do this, I'll have to unhook the trans lines to the radiator. In doing this, will alot of fluid come out of these holes?? My flexplate has an external balance plate welded to it. How does the internal plate vary?? I see ATI has both offered for the Olds.

 

There's only one factory flexplate for RWD cars for the 1968 to 1990 model years. The weight is normal. As for the fluid, it will continue to drip so long as you are under the car, usually waiting until your hair is directly below the drip.