Jeff Harvey

The shims are installed between the leaf springs and axle housing to raise the pinion angle. Someone asked if I had tried 4X4 yet. My truck is 2wd. I have also read some post from people not believing pinion angle can change or cause vibration. If you've ever put a lift on a truck one thing that thet come with are wedge shims to correct the angle so there is no vibration.

Here is the part number for the shims. It states Qty 2 FP Number 23469809 Description Shim kit 7.518 N

I posted a few days ago that my truck was repaired using wedge shims to raise the pinion angle. Believe me it worked I have no vibration. My dealer replaced the ring and pinion, the tires and hooked up the monitor system to test the vibration. I've driven about 2500 miles since the repair and I'm satisfied. We have scheduled to have the same done to my brothers truck. My reason for commenting on this again is it seems as only a couple of people actually read my post and asked questions. I will post the part numbers for the repair parts tomorrow. It can't hurt, ask your dealer.

My dealer checked my pinion angle and installed shims between the sprngs and mounting perch raising the pinion. It has fixed my vibration on my 14 GMC I am taking my 15 Silverado in and have the same done to it.

I didn't read thru the entire post so if this has been mentioned I apologize. There is a TSB on the headlight bulbs on the 14 GMC's, I don't know about the Chevy's. They replace the bulbs with a different manufacturer and reprogram the BCM to increase the voltage to them. I just had mine done and it made a huge difference.

It is between the leaf spring and housing.

Update to my previous post. My dealer has replaced the ring and pinion in my truck which got rid of low speed whine. After driving it for a month I took it back for the vibration. They kept it a week and tried a few different things. One of those was to get a new GM tool for checking the pinion angle I'm thinking an angle finder. They ordered a shim kit and raised the pinion which I am glad to say has fixed my vibration. I drove the truck for a week before commenting to make sure it was fixed. I have taken it out and hammered the crap out of it. Driven it to 95 mph, no vibration. I recall reading in this thread somewhere a gm mechanic stating something about the shims.

He doesn't live far from me. I haven't talked to him in many years.

So let me "set" this straight. The 3rd truck vibrates when you go over 70 MPH. I did not drive it to an interstate where I could maintain this speed during the test drive. The other 2 vibrate starting around 40 to 50 mph. I do have faith that my dealer will get the problem repaired. So far they have not let me down. We purchase a lot of vehicles from them and use the service department religiously. I have 24 GM vehicles to maintain and have found them to be more honest than any of the independents we have tried. It also doesn't hurt that I bought a truck that had sold for $44K 13 months ago and I paid $30K for it with 7,900 miles on it and was given all the factory warranty back. So for that, I can deal with them working to fix the problem that was created by a GM supplier. They also give me what ever I want to drive when it's there with the exception of a Z06, Z28,ZL1 or CTS-V. And if anyone is interested the dealer is Bradshaw Automotive

I didn't read through all of the replies, so if this has already been commented on I apologize. That being said, we have a family business that purchased a 2015 Silverado 1500 with the max trailering package and a 2015 Yukon XL last April. Both have the driveline vibration. They replaced the ring and pinion in the Silverado within the first 500 miles. It took a lot of the vibration out. but not all of it. After multiple trips to the dealership with the Yukon we took it to a different dealership who immediately did the same repair as the Silverado. It did not fix the problem so dad traded it in. 2 weeks ago I purchased a 2014 Sierra Z71 2wd with 7900 miles on it. I too have the vibration. I however am not as forgiving as my brother or my father. They have replaced my tires and ring and pinion. It is going back next week to see what else can be replaced. GM obviously has a problem. I will update on any solutions.