abominable z71

I haven't been on this site for quite some time so I apologize for lengthy post, I was hoping that this thread was pretty much dead and someone had found the fix for the dreaded Chevy Shake. I'm sad to see that's not the case. I gave up after countless hours and thousands of dollars, I replaced damn near everything underneath the truck including the drive shaft even though I knew it wasn't the issue I was desperate for a fix and it was a failed hail Mary attempt. I followed this thread from the beginning and posted quite a bit while I was in deep trying to find a fix it this was about the same time Jesse Davidson was fighting for a buy back and traded a brand new Denali in for an F-150 at that point several competing dealerships knew about the vibration issue and were offering pennies on the dollar to trade or flat out refusing to take a GM trade in. Basically a few trucks got fixed with tires a few with shocks a few with drive lines and a few new rear ends or swapping the factory axle shafts for a set of Yukons but they are the exceptions and the majority have an inherent design flaw that is causing a third order harmonic vibration. Generally nth order vibrations are weak and absorbed by the mass of the machine/structure but when the input frequency matches the natural frequency of the machine/structure you have resonance and the vibration is magnified. So here we are with another batch of consumers trying to find a fix for a problem that a fix doesn't exist and GM barely acknowledges that a problem exists I'm sure many people have been told that your truck is "operating within the GM specification for NVH" an abitrary number that didn't exist until this issue did, I feel for you guys I really do I have been there. For anyone still trying to fix their truck because the cost to get out of it is too high, you first need to determine the frequency of the vibration you're feeling at a given speed. At 70 MPH a 12.5 +/- hz is a first order tire and probably a balance or runout issue. Multiply that by your rear end ratio say a 3.42 which is roughly 43+/- hz this would be a drive line that has a balance or run out issue. Now the 38+/- HZ this is a third order tire and this is the thus far unfixable chevy shake. The problem is that at 70 mph nothing on the truck is rotating at that angular velocity that's how you know it's a harmonic of the tire speed and there's a whole slew of parts rotating at the same angular velocity as the tires, harmonics are never a balance issue. My story; I wanted out of the truck for quite a while but wasn't willing to take the financial hit, gave up trying to fix it and just dealt with it. Vibrated like clockwork at 68 MPH plus. I drive a lot of California freeway, speed limit is 70 on most stretches, afters 3 years I had 70k miles on the truck and the vibration had gotten worse, to the point I loathed the truck. Add in the new issues that were popping up, leaking passenger side door seal, failed AC condenser, premature brake pad failure, the slide pins had stuck and were not allowing the inside brake pads to retract, outer pads had 60% left on them and inner pads were almost down to the rivets, return springs on the rear brakes were hitting the rotors making an awful screeching noise even though they still had about 60% of the pad left, failed navigation module, lower seat cushion would shift during turns and make a clicking sound, last but not least the paint was peeling off of the rear drivers side door due to bad prep, you could see the imperfections in the primer coat that were causing bubbles in the base coat. Enough was finally enough and I decided I was trading out regardless of the financial hit. Turns out I got a trade offer that was beyond my wildest dreams and jumped ship to a competitor (I'm intentionally not mentioning the brand to spare the haters the need to mention all the issues I'm going to have with __________ <---enter brand here) because they know a guy that bought one and the truck went rogue and castrated him in his sleep, then murdered his family exploded and burned the whole house to the ground. The fact of the matter all mfg's have their issues and all have their fanbois that will defend their brand to the death. I'll take my chances with another manufacture having issues and trying to fix them versus giving GM my money and having an issue that they haven't corrected in 5 years of production and barely acknowledge. Loyalty is earned not given and GM has done nothing in its history to earn anyone's loyalty, the few on here who have gotten buy backs had to fight tooth and nail to get them and even then GM tried to screw them. To anyone reading this that has the dreaded shake. I feel for you and if you find yourself driving at those speeds often ask yourself what your sanity is worth and just dump the POS if you can with the new GM platform out now you can bet there is no attention being paid to this issue from GM. Their customer care hotline is a joke don't waste your time, I was told they were working on it an anticipated a fix in a few months, over 3 years later and nothing.

My AC failed yesterday 48K miles. Seems GM has been using a condenser on this gen truck they know cracks and develops a leak.

i wouldn't be surprised to see a revised body mount that just happens to fit right into the K2 body mount perches without modification. Not an official fix the they would promote, but a word of mouth kind of thing that spread across the forums that people could buy a set of body mounts for the new trucks that smooth things out on the K2XX. GM then never has to admit to any design issue.

After scouring the web looking for project boxes I came to the same conclusion, A mold and potting them is the most economical, not sure how well they'll dissipate heat and potting will also make them irreparable.

I've heard the same thing, that they are having transmission issues. A friend of mine encountered a lady that couldn't get the key out of the truck because the truck thought the tranny was in gear when it was in park, couldn't start the truck either because of the same reason so he hit up another friend that's a mechanic and he said the colorados and canyons have been having a lot of transmission issues.

The 4 wd has an adapter where the 2wd tail housing would bolt that connects the t-case to the transmission. It's just a hollow piece, not to say the t-case doesn't have issues at the intergrated tail piece where the drive shaft conncets. If that really is the issue it explains why GM doesn't want to fix it. 2 grand a pop plus labor for the t case.

Here's something I noticed just recently though. My neighborhood is at the end of dead end street and everything just got repaved perfectly smooth and very little traffic. I let the truck idle in drive for a good 1/8th mile we are talking like 3 mph or so. There's a rough spot in something that is turning. Rough enough it'll shake water in a water bottle in the cup holder. Feels like a bad spot in a bearing. Problem is everything feels fine on the jack stands and spins smooth, if its a wheel bearing it's like it needs the weight of the truck on it before it becomes noticeable. If its somewhere in the drive train its like it needs a load to work against. Whatever it is I'm sure it will continually get worse until it fails then I'll know for sure whats causing it. Not sure i'll keep the truck long enough to find out I drive about 30 miles a day at speeds above 70, after 2 years I'm pretty tired of wasting time and money trying to fix it and making payments on a truck that I hate driving.

Nope haven't had anything changed in the steering, Is this something you have done?. I've read posts of people having a new improved steering bushing design installed which didn't help.

Vibrations at these speeds are typically linked back to out of spec ring and pinions. More specifically a pitch line run out issue on the ring gear. Too much variation on the back lash between the pinion teeth and ring gear teeth this is why you feel it during acceleration. Thanks for the info on the rear, I have been considering trying some lateral track bars on the rear this would definitely take care of front to rear movement now to convince someone to drive next to me at 80 mph and see if the wheels are moving front to rear before investing in some track bars.

Truth

Look on the bright side, at least you and a few others on here are only in leases. A lot of us have bought these pieces of $hit.

In case anyone wants more information regarding the PICO scope and how it works and its readings and what they mean, below are links to 2 videos posted by the professor at Weber State University Auto tech department. Videos are a little long but very well put together, Someone nearby WSU in Utah with a vibration problem in one of these POS K2XX should drop off their truck and ask him to use it as a teaching opportunity since GM doesn't want to solve the problem.

Most dealers will make you remove everything and put the truck back to stock before they will touch it a few have gone through the process which ultimately blames the tires and they go through countless number of tires finding the right ones to "fix it" that never do. Even if they are willing to work on it with the aftermarket stuff, if it gets to the point where they need to bring in a "GM field engineer" (which I believe is a very loose use of the word engineer) guaranteed he will point at the parts and say there's your issue and wash GM's hands of the problem. Save your money and go to a tire shop with a hunter road force balance machine and have them vector match the tires to the wheels to get the numbers as low as possible. If it still vibrates after that which will probably be the case it's likely not the tires.

maybe 1/8" lateral movement. The axles have a strong 1/8" of radial run out. I thought they might be the issue so I pulled them out, bought some old axles from a wrecked truck and disassembled them to use the outer stub shaft to hold the hub assembly together (your other option is use 2wd hubs) Anyone reading this **DO NOT DRIVE A 4WD TRUCK WITHOUT THE FRONT AXLES INSTALLED YOUR HUBS WILL FALL APART. Didn't affect the vibration at all without the cv shafts in there.

It really depends on the speed I can feel it at every speed but its most noticeable above 68 MPH. After 70 is where it shifts from being more in the steering wheel to the seat and center console to about 75 then it goes back to the steering wheel and pedals and kind of back and fourth between the 2 locations depending on the speed. The vibration is also the least noticeable when the fuel tank is either almost empty or completely full after filling up. It's like the fuel in the tank is doing to same thing as the water bottle in the cup holder.

I have a running list of parts replaced and things I have tried similar to yours I don't want to list everything or think about all the time and money I have wasted. I removed the front drive line and drive shafts completely to test the front diff theory. This is the same front diff design gm has been using for 20 years, it's not the diff.

Oh yeah, Everything is perfect to half a thousandths. You can get hub centric rings for aftermarket wheels basically a plastic or aluminum insert to match the outer diameter of the hub pilot 78.1 mm for these trucks if I remember correctly the outer OD of the ring has to match whatever the wheel manufactures hub bore spec is, I think the fuels I'm running are 108 mm. Can't say there is much of a difference with or without them though.

its easier to check this with the rim and tire on since they are hub centric, the hub pilot dictates the centering of the rim not the wheel studs. Check the run out on the the edge of the rim. If it is moving up and down or left and right mark the high spot with some tape take the rim and tire off rotate it 180 degrees. If the wobble is still happening at the tape mark its wheel, if the wobble is now 180 degrees from the tape its the hub and likely the pilot is off center if its moving radially (up and down) or the hub face is warped or bent if you got lateral run out (side to side).

Just watched your video, That drivers side is really bad. I wouldn't be surprised if the Yukons improve things significantly. I have been tempted to swap my axles out for Yukons as my final attempt/investment before getting rid of the truck and switching manufactures for good, the 2018 F-150 with the updated 5.0 and 10 speed tranny is looking pretty good right now, I'll wait and see what your results are after the axles have been swapped for a few thousand miles.

Wouldn't that be something if a little tube of lubegard solved the problem?

I've exhausted looking at wheels, tires, hub, rotors, drive shafts, axles, rear end R & P, springs and shocks. I sometimes think transmission even though the vibration isn't changed at constant speed whether in 4th, 5th or 6th gear and my reason for this is: 1. Sometimes the vibrations are terrible while other times on the same stretch of highway at the same speed they are gone or hardly noticeable which is rare but it does happen. Which makes me think something in the controls like lock-up or slip control on the TC. 2. This is the most recent thing I've noticed and it happened today on a 70 mile drive down freeway 99 between Fresno and Visalia not sure if you or rhino are ever this far north on 99 but this section has been redone recently for the 3 lane widening and is buttery smooth. Anyways the truck is riding perfectly smooth at 75 mph. I lay into the throttle to get around some cars RPM's up above 4500 get around everything slowdown from about 90 back to 75 MPH and the truck is shaking about as bad as normal. I've been following this shit show since page 1 and quite a ways back a member had a 14 silverado with the shake, trade assisted out of it and into a 15 sierra that also started to shake and ultimately got rid of it and got something non GM. in one of their last posts they said the truck would start shaking above 68 MPH which we all know to well but they also said that regardless of what speed they were going they felt the exact same shake anytime the truck was above 4500 RPM. 3. Sometimes the truck feels like it is a lot more effective at getting power to the ground meaning accelerating with the rpms in the 3500 to 4000 range the transmission feels tight like everything the motor is sending is getting to the tires other times it feels like a transmission with 250000 miles on it just leaking power through slippage of its internals. not sure if anyone else has noticed things like this. I'm not sure if blackbear performances data collector they use for writing custom tunes can monitor things that are going on with the tranny to see if there is something going on that is creating these conditions. I've though about contacting them to see what they say but haven't got around to it. Right now I'm at the point I just want to get rid of the truck get something else and never consider purchasing another GM product.

Being that you're down in riverside you have an option not a lot of people have. There is a tire shop in signal hill that trues and balances tires while on the truck. This would take into account any imbalance from from the hubs and rotors that traditional tire balancing can't account for. Nate Jones tire in signal hill is one of the few shops left these days that can still perform this kind of work. It's a lot more common on trucks running large tires like 37's and bigger but it's something to keep in mind and might be worth a shot.

This has been brought up in the past and only a few people have opted to spend the money to put in a set of Yukon axles or machine the factory axles and the results have been mixed. Not nearly enough data to say whether or not it helps. As far as vibrations are concerned they consist of 3 components the actual mass of the imbalance the distance of the mass from the rotational axis and the angular frequency or RPM at which the assembly turns. So in this case a 1/4 ounce located on the hub 3 inches from the center has little influence compared to say a quarter of an ounce 15 inches from the center like the edge of the tire. in the video you can see that the edge of axle hub has not been machined and the still is still in its raw state from when it was forged. This makes the axle cheaper to manufacture because it is one less op while the axle is in the machining center getting turned, faced and drilled. The real question is whether or not the majority of trucks produced that don't vibrate have this condition, just because trucks that vibrate have it doesn't mean that trucks that don't vibrate don't have it, which makes investing 3 or 6 hundred dollars depending on whether one or both axles have the issue hard to do. If you have a shop swap out both rears I'm guessing you're looking at somewhere between 800 to 1200 dollars for parts and labor. If you go this route hopefully its worth the investment.

Have you got a chance to watch the "24 hour war" documentary regarding the whole Ford versus Ferrari battle. Really good flick if you like documentaries. Ford wanted to buy Ferrari to compete with GM on the racetrack, Ferrari backed out and so the GT team was developed, For the first few years Ford still couldn't compete with Ferrari. It wasn't until they brought on Carroll Shelby and his team that they were competitive and swept the podium. Shelby get's most of the credit but Phil Remington Shelby's chief engineer is the guy that made it happen.

To elaborate on the HID portion. 2016+ SLT's had the option for the T4L it wasn't denali specific but all 2016+ denalis have the T4L which are the LED high/low beams. 2016+ HD trucks have the old style housing but with an HID projector/bulb combo. 2016+ 1/2 tons without T4L will have the new style housings with HID bulbs/ballast. Side note on the HID, GM used a new ballast on bulb style HID that is only rated at 25 watts, that being said replacing the projector ballast and bulb will give better light out put then the 2016+ HID systems will. If you're looking for optimal light output without major modification go with 2016+ LED headlights. Cheapest way to get great light output is to open your factory housing and replace the project with a rx350 or FXR, get ahold of some denso ballasts and put in some OSRAM CBI bulbs.