abominable z71

Dealer told me vibes were below GM specs but match mounted and road forced my factory tires on their own dime. They have about 2500 miles on them. Moderate improvement. Went back to les schwab told them about the vibrations I feel in my after market setup. 18" racelines with 10 ply toyo at 2's all tires road force at 10 lbs or below 2 of them are only 7 lbs. but the vibration is definitely worse with the after market setup. Les Schwab is known for their exemplary customer service. Manager pulled out the rim catalogue and said choose another set of wheels and we'll give them a try. Didn't drive the truck just took my word about the vibes. New wheels with same toyo tires will be on tomorrow we shall see what that does for the vibes. Switching from racelines to fuels. I'm hoping the improvement that was made by match mounting the factory setup can be further improved with a good quality after market wheel.

I believe GM picked a vibration threshold value high enough so that most trucks fall into the "functioning within spec" range because every single truck they have produced has some form of vibration making it into the cab. The natural frequency for the truck is right on line with the frequency of rotating parts at highway speed and everything makes it way into the cab. Has anyone else been next to a vehicle with aftermarket exhaust or a harley with exhaust??? You can feel the sound waves resonate through everything in the cab, it's like a tuning fork.

Dropped the truck off at the dealer this morning. They called a few hours later and said they can't feel the vibration and asked where I was driving the truck that I felt it, so I told them the particular stretch of freeway, service rep said OK we will check it out. Picked the truck up this afternoon and this is what I was told. We put the pico meter on the truck and drove it on the freeway where you experience the issue, your truck has a vibration in the frequency range as you stated but it is within GM's specifications, Gm will not authorize any warranty repair unless the vibrations are above a certain value on the pico scope. Service manager had the tech road force and match mount the tires and wheels on the dealerships dime even though everything was within GM's spec and gave me my truck back and said there was nothing more they could do, that the truck was operating within specifications but to drive it and see if the rf and match mounting helped. Service rep said the tech worked on it all day trying to get the tires as perfect as he could. First thing I did was head to the freeway to see if anything changed. The vibration wasn't gone but noticeably reduced, Still there at the same frequency though. At this point I suppose I'm on my own to either track down the vibration source, live with it, or get rid of the truck and get something else. I still suspect ring gear, one weekend I'll open the diff and check run-out, back lash and tooth size and pitch. If there is no smoking guns there it's probably time to admit defeat.

I got your post in my email before it was deleted. And you're right it does feel like they went straight there.

Truck goes in for it's first service this week, I'm going to talk to the service manager about my vibration issues and the vibration data I have already gathered. we shall see if I get the "I've never heard of this before" or drove the truck and didn't feel anything, operating normal. I pulled all the aftermarket suspension parts off and reinstalled all factory components and factory wheels and tires, vibration is still there at the exact same frequency. I even put the truck and jack stands to eliminate the road surface and ran it at 70 mph, and guess what... vibration at the same frequency all though the amplitude was less severe. Not sure if anyone else has tried it but when you run the truck with the wheels off the ground the computer freaks out, turns off stabilitrak and traction control and every other feature, disables the steering assist and flashes calibration mode and says you need to service this, that and the other even disables the lane control, parking assist and trailer brake controller, everything went back to normal after driving it a few hundred feet. I'm convinced its a rear end issue in my case, hopefully I can convince them to bypass the multiple sets of tires and countless rf balances and go strait to the rear end. If they don't have a pico I might try another dealership or just take it straight to a local rear end shop and pay them to open it up inspect it and let me know what they find.

Congrats man, I was at the dealership yesterday myself. Haven't pulled the trigger yet. Best of luck withe new rig it looks really nice.

Mine decided to show up at 2000 miles

I have yet to test drive the Ram but figure it would probably make me sick with regret to have to get back in my GMC. Probably time to start considering taking a loss and regaining my sanity.

If I could get rid of the vibration I have no problem putting a couple grand into suspension improvements to get the best ride possible, I have to get rid of this vibe first. Trucks going back to les schwab too see if the problem is the wheels or tires. Right now it has raceline wheels and toyo at 2's that cause a much more noticable vibration than the factory wheels and SRA's which the goodyears are known garbage tires. Les Schwab assured me they'll stay on it til its fixed even if it means a new set of rims. All 4 tires are below 11 lbs road force variation and the vibration is third order 41 hz at 70 mph so definitely not simple dynamic balance.

Same here, I've been spending some time on the ram website building and pricing trucks, kicking myself for going with the truck that looked the best, when I could have got more truck for the money with features GM doesn't even offer.

I hear you on that, I had 3 acuras and a lexus before this truck and gave serious thought to an suv from either one before getting this truck. Now I'm thinking I probably should have.

So after 200 miles on the road today, I can't yet give a solid opinion on these shackles, it's like this truck suffers from multiple personality disorder or something. It rides differently on the same stretch road from one trip to the next. It seems like when the truck has set for a while the ride is pretty decent but if it's been operating for a while like an hour or so the ride is much worse on the same strip of road. My only thought is shock fade possibly road force on the tires, GM says road force can change as much as 25 lbs on tires as they warm up and that's why they should be road forced right after being driven? Anyone else have a theory or notice the same behavior in the sense that the longer you drive the truck the ride quality seems to diminish or change?

You have to register the TPMS sensors with the truck after you switch wheels. Each sensor has a unique number that is registered by the computer and then that number is assigned a location, front right, front left and so on. Switching corner locations but keeping the same sensors the pressure readings will still show but be in the wrong location, the computer doesn't know you moved the fronts to the rear or however they were switched. Switching your rim set altogether to a set that has a second set of sensors installed requires that the new set of sensors be registered into the computer and then assigned their location. I have two sets of wheels and tires as well and it usually takes 30-45 minutes before the computer realizes there is no sensor data and the values disappear from the display. I'm not sure if the computer can have more than four unique sensors registered to it or not. Apparently moving the wheels and tires during a tire rotation and telling the computer where the wheel is located can be done with a 70 dollar tool. But telling the computer that there are different sensors than before and registering them takes a much more expensive tool. A local shop here in town said the one they have is $1700. They do the sensor registration for free.

That matches up to the K2XX pretty well except for the step where you raise the rear end up to get the top bolt out. On our trucks there is a pinch weld directly above the spring that doesn't allow you to raise the spring up far enough to remove the bolt. you have 2 options, Cut a notch into the pinch weld for the spring to clear or unbolt the bed and lift the bed off the frame about 1/2" to allow the spring to raise up high enough to get the bolt out. I took some pictures of it that I'll post later after I download them from my phone.

Busy weekend, Installed some new amp power steps and got the sulastic shackles installed as well. My conclusion is that I'm getting too damn old to be rolling underneath a truck and wrenching on it. The shackles are a giant pain in the ass to install. In theory it's 4 bolts 2 each side, in actuality you have to completely remove the hitch and unbolt the entire bed to get those 4 bolts out. Install instructions are generic and meant for all trucks. I can put a detailed install walk through together if anyone is interested that plans on installing them themselves, should be able to shave some time knowing the obstacles you'll encounter during the process. Took about 4 hours working at a moderate pace by myself. Ride height stayed the same. I have only put a few miles on them since finishing the install today. Overall ride quality has significantly improved around town 45 mph +/-. The small imperfections in the road surface no longer make their way into the cab, Ride on the freeway appears to be significantly improved as well but I'll have better data on that after Tuesday, I only hit the freeway to check their influence on the 70+ vibrations, which is the million dollar question I'm sure everyone wants to know the answer to. First test, vibrations are still there slightly mitigated at their worst speed which for me is 72 mph. The one thing that I did notice which I need to collect more data on before I can say for sure is that the range in which they occur has narrowed down to between 70 and 75 where they used to be felt at 68 - 85 mph. Ride improvement: undoubtedly but comes with a trade off in the form of increased body roll which is to be expected with more compliant suspension, If the ride improvement is significant after more testing I'm going to install a hellwig rear sway bar to fix the body roll issue, which makes this endeavor now $750. Vibration Fix: Definitely not (on my truck at least) slight improvement... Maybe time will tell Worth $400 and 4 hours and getting covered in the black sludge gm puts all over the frame of these trucks: not sure yet. Post my thoughts Tuesday night after more miles and hours. Any other questions or something particular regarding these shackles just reply to this post.

Precisely why I haven't taken mine into the dealer, I'm afraid they'll start throwing parts at it and make a slight vibration a terrible one in the process. Lots of posts about vibrations moving around after repairs was at 45 now at 70 was in the seat now in the steering wheel and so. 2 years of this and gm still doesn't have a fix, what a joke. This was the first gm product I have bought in over a decade, switched because of poor quality control I guess nothing has changed, hopefully Toyota gets up to speed technology wise on the tundra. Probably more American labor in the tundra than my Mexico built sierra anyways.

I have the same vibe but from 70-80. Have you noticed the vibe to be much worse during colder weather? Where I'm at the temp swings 35 degrees from when I go to work to when I come home, vibration is less severe in the afternoon .

Make sure you tell the dealer you are aware of the vibration issues in these trucks and request they let you take the truck for the day, Find a nice stretch of smooth freeway and drive the truck in all speed ranges through 80 mph if you can. My vibrations are really light compared to a lot I've seen video of and they're not noticeable and rougher roads because the larger amplitude road imperfections mask them. The only way they're noticeable in mine is smooth asphalt they start at 70 mph the worst at 72 and disappear at 85 mph. I'd also wait on the 2016 models, I suspect there will be some unannounced changes to fix or remedy these issues.

Nice truck, I thought about going with a 6" lift but can't get myself to start cutting things off the frame of a truck with a 100000 mile warranty. I thought about going back to my factory 20's with wheels spacers but had a bad experience with them on my last truck. I looked at the trailsport like you have on yours. The picture of them online looks like they're hubcentric about the hub pilot but I don't see a machined lip on them to pilot the rim onto the adapter is this case, or do the center on the hub and center the wheel as well? Thanks in advanced for the info.

Well the sulastic shackles showed up yesterday, bought them direct from sulastic through ebay and saved 20 dollars. $398.00 delivered versus 420 through their website. Ordered them on the 7th arrived the 10th, not bad Texas to California. Quality is decent, the cross pins are plug welded and ground down by hand and then painted, not the prettiest by a long shot, but should be fine strength wise. Should have time this weekend to install them and then I have a 90 mile trip next Tuesday on a strip of pretty bad road that I've traveled just recently to give them a good test and comparison. I'll report back on the install and ride quality after for all who are interested.

What type and size of lift are you running? Truck looks good.

I agree masking a problem isn't the proper way to go about eliminating the vibrations. I'm looking at the shackles to improve overall ride quality as I drive the truck unloaded 99 percent of the time and I think the rear springs are too stiff without any weight in the truck, I'm hoping they take away some of the harshness out of the spring rate of the rear springs. If they eliminate the vibration I'm feeling in the cab I'll let everyone know that too. I agree that the vibrations could lead to fatigue failure but the amplitude of the principal stresses also plays a large part in the number of cycles to failure and if they're below the critical limit they are just going to be annoying and never lead to fatigue failure. When I was in college we did fatigue testing on a bunch of 6061 aluminum rods and loaded them in pure torsion with equal alternating loads and varied the input torque for each sample and the test machine counted cycles til failure. As long as the stress stayed in the elastic deformation range on the stress strain curve for the material the part never failed this is also a possibility on these trucks an annoying vibration that's just that, annoying but not detrimental to any component, at that point all you need to do is remove the transmission path between the source and occupants in the cab. This is the route I would expect to see from the manufacture as well. Different body mounts that insulate the occupants from the vibration source. Dodge did this in the current Ram 1500 by attaching dampers to the frame and GM did this with GMT 900 HD trucks to mask the frame beaming problems by changing the rear cab mount. I agree masking a problem isn't the proper way to go about eliminating the vibrations. I'm looking at the shackles to improve overall ride quality as I drive the truck unloaded 99 percent of the time and I think the rear springs are too stiff without any weight in the truck, I'm hoping they take away some of the harshness out of the spring rate of the rear springs. If they eliminate the vibration I'm feeling in the cab I'll let everyone know that too. I agree that the vibrations could lead to fatigue failure but the amplitude of the principal stresses also plays a large part in the number of cycles to failure and if they're below the critical limit they are just going to be annoying and never lead to fatigue failure. When I was in college we did fatigue testing on a bunch of 6061 aluminum rods and loaded them in pure torsion with equal alternating loads and varied the input torque for each sample and the test machine counted cycles til failure. As long as the stress stayed in the elastic deformation range on the stress strain curve for the material the part never failed this is also a possibility on these trucks an annoying vibration that's just that, annoying but not detrimental to any component, at that point all you need to do is remove the transmission path between the source and occupants in the cab. This is the route I would expect to see from the manufacture as well. Different body mounts that insulate the occupants from the vibration source. Dodge did this in the current Ram 1500 by attaching dampers to the frame and GM did this with GMT 900 HD trucks to mask the frame beaming problems by changing the rear cab mount.

Hopefully I end up being the hero and not the guinea pig that wasted 400 dollars.

Well I pulled the trigger on the sulastic shackles. They have a lot of good reviews so we shall see. Should have them next week and install them next weekend. I'll let you know how the install goes and if they improve the ride quality.