My 8 speed has already had the stator tsb completed as one of its majors is it takes forever to get out of park... It didn't do a thing and is exactly the same as before. If they don't fix anything I will just sell the truck like any other late model piece of junk I have owned. It doesn't even bother me anymore lol. GMT800 for life!... Apparently.

Considering the vibration only appears with weight on the back of the truck unlike most people's I am hoping it's something simple. Right now as is it can't pull a trailer... So if it stays that way... Well down the road it goes. Like this isn't some shaking my water bottle crap I see posted on other GM boards... It's violent and I am afraid something will break whether it be a driveshaft or u joint.. I won't just hang in to it and complain like most people have too...

 

Wow, that sounds severe, you would think something that intense would be easier to isolate.

Mine has a vibration, but not bad enough for me to take the time to look into.
I tow a 7000 lb boat in the summer and no real issues either.

Good luck.

 

They can't find the vibration and immediately blame my tires and then want to charge me for a road force balance on them because apparently warranty doesn't cover that. Now I explained that what I am talking about has occurred with 2 sets of rims and 3 different sets of tires but that's irrelevant I guess lol. If you run my truck after it has sat overnight or what have you it takes a couple miles to get rid of vibration...... It did it with 10 ply KO2's, 4 ply RSA's and these Toyo Proxes.... so it's not the tires. They also didn't weigh the truck down either so I am going to be on my own for this one I think.

I am getting a new valve body now haha.... supposedly GM's next attempt at repairing my 8L90E. Good thing I can't post on GMtruckforums anymore as me saying that would cause nothing but uproar...... GM says you can't open these up and do anything, only change the entire trans...... right.... lol. Those guys are pretty special over there lol.

Since I flip flop on this truck I might keep it and make it a mission haha. I have a 2/3 belltech setup here and honestly even with just the rear block out the truck feels better.... so maybe lower is the answer lol.

 

Gm says you cant open what up?

 

Nothing... According to the geniuses on this other idiot filled GM forum I used to go on dealers were not allowed to open the 8 speed. Yes I know it's bullshit... Stator swap makes it pretty obvious... But you think they would believe that.. Lol. Dealing with morons who can't even change their own oil got really old.

 

Wow.... I bet it did!!

 

The guys at GMTRUCKS.COM can be very opinionated to say the least.

Can you tell us more about your vibration.
Does it only happen after sitting for a while.
Does the steering wheel shake or the whole truck.
Is it brake related.
Could it be the tranny or torque convertor cycling in/out of gear or lock up.
Does it always go away after a short drive.
Does warming the truck up before driving help.
What do you mean by violent.

 

It's simple really in a way so take everything you asked me above and just sort of forget it before reading what I say below lol... It's not from the tranny and it's not from the front of the truck either. Heat, cold, or truck temp doesn't change. I don't have AFM anymore and nothing changed there. This vibration is unique and unlike anything I have read in that 600 page disaster that unfortunately stayed at the top of Tapatalk thus exposing me to a good chunk of it.

It only occurs with weight in the bed or with trailer tongue weight applied, no other time. The rear is shaking and it's easily discerned while the front of the truck is fine. I say violent as it feels like its binding so maybe the slip yoke is bottomed out or sticking too.. It's not something you would typically check on a truck that had 100 miles on the clock when it started while pulling my car hauler home. The rear starts to almost bounce or wobble I suppose... And I don't mean while overloaded either. My LS3 crate engine in the bed is enough to get it shaking in the back. Remove the weight and let the rear suspension relax to normal and it's gone. Apply weight and wait for a u joint to break... Lol. I need to check my angles with the suspension loaded and of course the drive shaft movement... it's a 1 piece shaft so there is no carrier bearing or otherwise to look into.


My other vibration goes away on a short drive cycle and is typical of tire flat spotting and felt throughout the truck... It's much worse with my 22's but it did it with 18's and Sra's as well as with the KO2's with a much smaller time that it lasted. After a tire balance on the KO2's it would typically be totally gone so it stands to reason balancing my 22's wouldn't hurt. I have vibrations in the 05 come and go in the same frequency due to tires so it's not unique to this 2015...... and I have 25000 miles on this 2015 now. In saying that I may get them to do a road force balance today since it's still there getting the valve body swapped. Unless you let the truck sit for a long period after the initial drive it never does it again and I quite frankly don't even care about it as it's tire related.. The driveshaft coming out from under the truck when attempting to do truck like things is much more of a concern.

 

That's weird on the driveline vibration.
Mine is lowered 2/3 as well, I didn't do anything with the pinion angle or tranny mounts and it doesn't shake like that.
305-50-20 Toyo Proxes II., non-factory rims too.
I rarely put any weight in the bed but tow a good sized boat with no issues.

Did you have a chance to drive it with some weight in it before it was lowered?

Sound like you are on the right track with a pinion or slip joint issue.
The dealer may be less willing to commit resources to it since it is not stock, depends on the dealer.

 

No...... you missed something...... The truck is currently stock.... I own a lowering kit but I have never installed it on the truck for a reason. The truck did this with 100 miles on the odometer on the way home from the dealership towing my car trailer with another truck on it. All I have done beyond tire and rim changes is in recent times ( so like in the last 2000 miles) removed the rear block and honestly it seemed to help when I had the engine in the back. I don't own a trailer currently so until my new one is built I really won't know how that feels. The dealership won't do anything because they blame my OEM 22's..... lol. He wants me to swap 18's on it and come back..... well I have to have it loaded so I guess load the bed up with junk and have the 18's on then lol.

If I lowered it and this happened I wouldn't even be posting..... not quite that stupid lol.