Introduction/My first month owning 2017 Sierra Denali

[SS2Sierra]

Hey guys,

 

Just wanted to do an introduction post now that I'm about 1month into owning my 2017 Sierra Denali with the 6.2 and Ultimate pkg (35K miles). I figure I should create a profile instead of lurking like I have been.

 

I'll briefly share my experience so far and then I have a few questions for you folks. So far it's been OK owning the Sierra. I love the truck's looks, comfort and the 6.2. I don't see myself doing much modification other than a level and tires, it looks amazing as is. The ride quality is not quite what I expected though. I had the dealer swap the 22s out for 20s for that reason (plus I just didn't think the 22s were fitting for a pickup). That helped a little. However, my two main complaints are the transmission and vibrations at cruising. Which brings me to my questions:

 

1. What could fix these vibrations? Symptoms: Far as I can tell, only happens once the truck has warmed up a little. Also only happens under throttle (usually just light throttle), doesn't matter whether it's in V4 or V8 mode, happens intermittently for about a second or two at a time. I feel it most in the steering wheel (it's significant enough to make an hour drive on the highway borderline unbearable), and RPMs jump a little when it occurs. Some research indicates there was a TSB for this issue being related to the transmission, but as far as I could find, it was only on 2015-2016 models. Is there an updated one for 2017?

 

2. The transmission seems to have some odd shift points and it hunts for gears a LOT. The 1-2 shift is sometimes jarring enough to feel like the dang thing is about to drop out under the truck. Some cars just shift hard, is that what you guys experience too, or am I just lucky?

 

3. My front fender measures 4" lower than my rear fender (measured from ground through center of wheel to fender). Most I'm seeing on here is people have a 2-3" difference. Is that normal? I was hoping the 1.5" leveling kit from suspensionmaxx would be enough to get rid of most of the rake (i'm fine with a little rake), and fit 33s. Am I wrong?

 

4. What's y'alls favorite product to clean the bed and get it back to that new fresh black look?

 

Looking forward to learning more about this gorgeous truck, and wish me luck on the vibrations -- I'm taking it to the dealer this Friday!

 

Cheers

SS2Sierra

[CamGTP]

Kinda sounds like the torque converter for the vibration/shudder. It's kinda common for people to replace that on the 8 speeds. Most will also use the new GM fluid for the 8 speeds as well.

[dmorrisL86]

Welcome to the forum and congrats on the truck. As stated above, sounds like the vibrations could be the dreaded transmission shudder issue. I also have the 6.2/8speed. I’m sitting at 28k miles and have had 2 trans flushes with new fluid so far. After the first flush, it took about 15k miles for shudder to appear again. Hoping this second flush solves it for good. As for the level, I used a ready lift 1.5” front level, nothing in the rear. I fit 33” ridge grapplers with no issues/no trimming. I also dumped my 20’s for 17” method wheels. This helped with ride quality, though handling suffered a little. But it’s not a sports car, so that doesn’t bother me. 

[L86 All Terrain]

They put a reman 8L90e in my 2015 last year. Been great ever since. The original trans also had the TC done before they changed the trans. Are you sure its the transmission or could it be the "Chevy Shake" at 65-80mph? Either way, it is going to cost you thousands to get rid of it. Some users have replaced half their truck with aftermarket parts trying to cure it. 

[Joe98]

Welcome to the forum and congrats on the truck.  I have a 2018 Sierra Denali Ultimate with the 6.2 as well.  I’ve only owned it for 3 months barely, and can honestly say I’ve never experienced the transmission shudders or vibrations.  Mind you, my mileage on the truck is very low.  You should still have warranty hopefully, get the fluid flushed or updated converter.  Definitely get it checked out, before it gets worse.  As much as I love the look of my 22” wheels, I agree they don’t belong on a pickup truck.  I’m grateful that I have good roads to drive on as this truck will probably never see any off road trails.  

Good luck...

[SS2Sierra]

Quick update - Got the truck back from the dealership yesterday and they flushed the transmission and filled it with the new fluid. The shudder is gone, the truck drives SO MUCH better now. So much smoother.

 

I'm still unsure about my 3rd question on the original post about how much difference there is between my front and rear height. Anyone have any input on that? Thanks