Zach-91

Mines been doing it a lot more the last week or 2. Happens at least half the time when at operating temp. Only 9000 miles. 2019 rst 2wd 8 speed. I have done 12 quarts of the new fluid earlier this year. I came across this post today and hope to try it soon.

Pretty sure it was just regular 10mm nuts. The nuts had silicone on them and there were rubber washers embedded on the exterior side. I've still heard the noise on mine since doing this but its not as frequent.

Use c clamps to hold the leaf pack together. I also had to use some ratchet straps to pull the axle to get the center pins back in their locating holes. Chock the front wheels and set the ebrake to try and minimize how much things shift around.

This video is great. Wish I had seen it before doing the install. I'm surprised they are selling their kit for $1200 though. I got my parts for right around $820. And that was a full spoiler rather than just the light assembly.

I didn't see any numbers on it.

Ebay. There was a reseller that had take offs. Wasn't any cheaper than the gmparts websites but it works and I'm happy with it.

Installed mine today. Thanks for all the part numbers and install tips!

Pulled mine off today to install a new one that has the rear view mirror camera in it. Took some photos to see if there were any differences and the only thing I found was some rubber washers on the yellow clips. Hasn't been long enough to know if the problem is gone but I'll follow up when I've had some more time with it.

Following as I think I have the same issue. Mine normally happens the loudest when I first pull out of the driveway and the rear drops the couple inches onto the street. Don't hear it again the rest of the day. I pulled the rear brakes apart a few thousand miles ago and greased the contact points. No change. Pretty sure its the lead springs.

This thread has the info. For me, it happens whenever it is hot outside and the roof starts to cool off. Does it really bad when I wash the truck in the afternoon and I spray water on the spoiler.

FYI, I have been watching ebay for parts since this thread was started and there is now a seller that is selling spoiler assemblies for 225 that are painted and look to include the needed harness. I've also had the tapping noise coming from my spoiler so I've ordered all the parts to do the camera upgrade and hopefully fix the tapping at the same time. Managed to get the mirror for $540 and the cable for $30. https://www.ebay.com/itm/333602342491 Excited to give this a try.

Mine felt like rumble strips before flipping the shims around around 30-40mph. Only drove a few miles like this so I don't have much more than that. Also had new tires installed by the dealer at 5k because the old one vibrated above 60

https://ihcsuspension.com/product/2019-chevy-gmc-2wd-4wd-3-5-lowering-kit-with-helper-bags The description for this one shows that to avoid the notch, you do a flip kit for 6" and then +1" shackles to do a 3/5 drop.

I used c clamps to hold the leaf springs together and take the tension off of the bolt going through them. Just chock your wheels and be ready to have to push/pull the axle into place if you have to lift the truck enough to allow the alignment pins to come out of their holes. I used ratchet straps to pull the axle in the direction I needed to to get them back into place. If you can get the center bolt loose without having to clamp the bolt head you're good.

I have a carven catback progressive series. Very mild and can be had for less the $600. Doesn't have any flappers so it does make a little helicopter noise without dfm disabled. Edit- sorry guess mine is the short bed and you're asking about the longer one.

Mine is within 1/4-1/2" all the way around. Not sure it'll get much closer than that.

Several of us have already replied saying that new tires fixed the problem.

To be fair, these numbers were before the original road force. After they road forced the old set they were around 30 and below but i think they told gm this to get approval

Finally got approval to have my tires replaced. Attached are the notes from the service. Still don't entirely understand the lbs unit of measure but am happy that with a max of 22 the vibration is not felt in the cab anymore.

1st step should be to measure the angles per the link that is above and determine what angle you actually need. That said, I think the shims that are on my truck are 2 degrees. flipping the shims means we are changing the pinion angle by 4 degrees in the opposite direction because it is double the opposite direction. So if you just want to know what to buy, I'd buy a set of 2 and 4 degree shims and start with the 2 and work my way up to see if 2 is enough. Shims are cheap enough, it's just annoying to pull everything apart a bunch of times which is why it's best to measure. Mine is back at stock height as I have been back and forth with the dealer to get new tires for another vibration. Just got the truck back today so I plan to go back to the drop shackles now. I'll try and get some measurements stock vs dropped with flipped shims since I have to go through the trouble of doing it over again..

There's a guy on Ebay that sells precut kits. I did it on my 2019 rst. It's a pain. And imperfections are very noticeable. I got mine good enough and got much better at it towards the end but there are several pieces I'll probably rebuy and redo. Definitely worth $800-$1000 for a professional install.

That's frustrating. I got word on Friday that GM approved for me to get a new set. Just waiting on them to setup the appointment and let me know if I can choose the tire or if I'm stuck with exact replacements.

I did have some weird vibration clunk noises on takeoff on my 2019 with drop shackles and it turned out to be the bolts for the drop shackles that has loosened up over time.

Only when going over large bumps like speed bumps and pulling in the driveway

They told me when I asked but did not give me a work order since the job isn't complete. When the 1st dealership I went to did it they gave me the numbers and i had a 6, 13, 15, & 16 and things were pretty good for a while but I could still feel a slight shimmy sometimes. when this 2nd dealer got involved they told me I had 2 around 32 and the other 2 were below 20 before they balanced them. After doing the swapping they were all at or below 22 but did not give me the exact numbers. He had them written on a paper so I could see them but didn't take a picture or get a copy. Pretty sure 2 were at 22 and the others were the low teens. He told me that GM said anything under 30 is in spec. But when I drove it after everything being under 22 it felt worse than when I took it in when they told me a couple were over 30. I am guessing the 22's are more finicky and prone to transferring the vibration. Seeing that others have much higher numbers tells me it must feel like riding in a shopping cart with a flat wheel..