O.K, ever since I did my 4l80e swap Ive got a vibration. I didn't think much of it at the time because I had two sets of tires. One set was balanced the others where just for burning out in town. Guess which set was all was on all the time. lol
So I finally start tracking down the vibration, starting with tires. All four balanced with sticky weights on the inside. Next had pinion angles checked, I just spend 150 bucks to rebalance my speed engineering drive shaft.
Tonight I just swapped out my wife’s tires that I know don't vibrate with mine. (God I love it when she takes her car to work and not the truck)

Still have the vibration.

So At 80 mph in OD it vibrates through the floor pretty bad in kind of a pulsating pattern. It will go away after it clears 90+mph. It also vibrates worse if it is in third, which leads me to believe it is in the drivetran and not the drivelines or tires. Throw the truck in neural and the vibration goes away even if I rev the eng up to the rpm it would be if in gear. So that leads me to the trans. I'm thinking converter?????

Does this sound possible? Has any one ever run across something like this? The drivetran shop said it may be caused by the steel drive shaft, he said he would make a aluminum shaft for me to try, but I'm a bit worried about the drive shaft being aluminum. I'm far from done with this tuck as far as power is concerned

 

Read this article, sounds like it might be the torque converter, but I am no expert by any means. Even thou the article is about 700R4 and 4L60E, i think it still applies.

Torque Converter

 

Dusty I've been suffering this EXACT scenario since I blew my first driveshaft (9/2004)(4l60e). Since then I have done all the things you have AND, went through aluminum DS', the 80e, balancing shafts, shimming, blah blah. Hell I even got rid of my one piece and put a 2 piece in. I finally killed mine with a front driveshaft balance. Hasn't repeated that same vibration since. If you have 4.10's it won't help the scenario either. The "load" on the shaft is what causes it to vibrate, nuetral as you know has no load on the shaft. May not be your issue...but it took me FOREVER to just finally balance the front shaft. (I even balanced it once already when I modified for the 80e installation.)

 

Sweet thanks for the info. I'll try that next.

 

Thanks for the link, I'll check into that too!

 

Pulled front drive shaft and it still vibrates.

 

Did you do the lq4 before the 80e or both at the same time?

Then if you have attacked DS's, angles, wheels, bent rims( I also have this..one whell always takes 3 ounces to balance) then the converter or warped flywheel is your next attack. Ugh how aggrivating...feel your pain bro.

 

Well I guess we will see if the vibration doesn't develope during this 1000 mile road trip this week. When (or if lol) I get back, the 4l80e is coming out once again.

Thanks for all the help dewmanshu.

 

I have the exact same problem. Truck is completely stock and just started a couple days ago. Have you found the problem yet?

 

NOPE! but if I get off my Lazy rear, I'll see if swaping the converter changes anything.