lucas287

Agreed on the RAM. Almost bought a new stripped down 2wd RAM because of how nice it rode. Too many other things that bothered me though. Your thoughts on the coil spring design are directionally accurate. Fewer, smaller diameter springs is actually stiffer. More, larger diameter is softer. Generally speaking of course.

Here's an update. Last night I just focused on measuring and correcting angles. It took forever to get the yoke and pinion flanges at just the right angle to get accurate readings, but I got it pretty darn close. 1) Zero'd out my angle finder on the yoke off the t-case. 2) Then I squared it up on my driveshaft. 2.5 degree difference. (For your visualization, imagine the t-case pointed downwards 5 degrees. The driveshaft was half that at 2.5 degrees.) 3) using a deep socket on the cup of the u-joint in the pinion flange, I measured the pinion angle. 2.7 degrees. This means my operating angles of the u-joints themselves are within spec, but they are not equal. On a one-piece driveshaft, the pinion angle should be parallel to the t-case/transmission yoke angle. Rummaged around in my garage and found some 2 degree axle shims. With my impact I loosened the u-bolts and put my floor jack under the leaf pack with the help of a scrap 4x4 wood block. Created just enough separation to slide them inline with the pin. Dropped it down, tightened it back up, and torqued to 100 lb ft. Repeat the other side. Results? Zero'd the gauge on the t-case, measured the pinion angle - BOOM - only .7 degrees difference. This is actually ideal as the pinion will climb under torque. Took her for a drive and the majority of the low speed vibes are gone! Highway is still there though. My shi* Goodyear LS2 tires aren't helping though even though I had them shaved. Next I will put the overloads back in and remove the block and drive it for a few days to evaluate before using some leaf spring clamps.

I suck at documenting work. I'm also a member on thelawnforum and I always forgot to update my journal over there! I'll snap some pics before I put them back in and then after removing the blocks. I only dropped about .75". The blocks should drop 1.25".

Was perusing RockAuto and took a look at the KYB pre-assembled struts. Looks like they are Gas-A-justs which is a monotube shock. New spring, upper mount, whole nine yards. I started to cross reference their part numbers to see if it changes based on RWD and 4WD and it does. Then I looked at Suburban and Tahoe, RWD and 4WD. KYB specs the same part # for a RWD Silverado as a 4WD Suburban. Hmm... makes me think that a Suburban 4wd has similar spring rate to a RWD Silverado. The RWD Suburban has a different part number altogether. Those might be the winner! And BTW they all use the exact same actual shock. The difference in part numbers might be due to upper mounts but I doubt it.

I called Bilstein and asked about the 6112 kit and they said the springs are 750# - too stiff for me! I started researching other options and found this. https://atomicfabandperformance.com/product/07-18-gmt900-front-coilover-package/ This setup seems like the best option for someone wanting complete control over the setup! Pick your ride height and he will select the coilover and spring length needed then you select your desired spring rate based on use. He doesn't recommend going any lower than 650# springs. Plus you get to fine tune compression damping and rebound damping! But maybe all that is a moot point if the rear is still stiff as hell. I do have a Deaver Mini pack that I'm thinking about experimenting with. What if I removed the middle leaf spring? The one in between the overload and top main spring. And in it's place put the deaver mini pack? Which is basically three springs. Should overall reduce spring rate and make it more progressive.

Let's resurrect this thread! I too think the front end is entirely too stiff. Combine that with 275/55R20's and it's a bit much. Also, everyone is entitled to their own opinion of how THEIR OWN truck should ride. I don't think there is any place for comments like "wow, why do you drive a truck?" or "you think that's rough! Try owning a 3/4 ton", or worse yet, "buy a Honda Ridgeline". Anyways, I did some sleuthing on GM Parts and found that there are about a dozen different spring options for these trucks. The same for Tahoes, Suburbans, and Escalades. But it's darn near impossible to find the actual spring rate. I think we can all agree that a LT trimmed Tahoe or Suburban rides fantastic all things equal compared to a Silverado/Sierra. The coils that come on the smooth ride package is what I'd consider experimenting with. I think I'm gonna hit up a Tahoe forum and see if anyone has some coils laying around after a coilover swap or something and see it they'd part with them on the cheap.

Oh yeah - if time permits, I will take some readings of my static pinion and t-case angle. Ideally, they should be equal but opposite. For example, (-3) on the t-case and (+3) on the pinion. That's in a perfect world though, maybe on a 4 link setup where the pinion doesn't climb under load. I'll aim for the pinion being point down 1 degree lower than the t-case. Maybe (-3) and (+2) which will allow for 2 degrees of pinion creep without getting too out of hand.

UPDATE: I've driven around for a few days now and I've introduced vibrations that we're never there before! Right off idle, less than 1500 RPM, I now have some vibes. on the highway - you guessed it - it vibrates. In town - yep - it vibrates. I double-checked the torque on my u-bolts (100 ft lbs) and I'm running 30 PSI air pressure in the back. I think a combination of lowering the ride height with decreased spring rate is causing significant axle wrap which amplifies operating angle issues with u-joints. I was inspecting my overloads and it seems like they were called into action A LOT and I think they were acting a quasi-traction bar limiting how much the leafs twist under torque. I watched a few videos showing just how much axle wrap exists even with the overloads and it's pretty crazy. And those videos were with the 5.3. The 6.2 makes so much more low end torque it's ridiculous, making the problem worse. F150 ecoboost guys really struggle with axle wrap too - because of all that torque! I also firmly believe that's why placing leaf spring clamps forward of the axle helps with vibes. It increases spring rate by engaging the overload limiting the pinion from creeping up. Going against my better judgement, I'm going to change more than one variable tonight. 1) I will put the overloads back... 2) remove the lift blocks 3) place leaf spring clamps forward of the axle 4) tighten the SHI* out of my u-bolts. Probably need new ones anyway they're arguably too long and they're TTY. I'll report back if anything has changed.

Couldn't agree more on your TC comment. They are part of the "rotating assembly" in a sense being bolted up to the flexplate. That's different though than the TCC. For anyone who has HPTuners, or EFILive, or even someone who tunes for you - have them unlock the TC in your highest gear and see if the vibes dissipate. RFV is probably a more meaningful way to assess tires dynamically. Imagine a tire that has a slight concentric shape to it. When that slight protrusion rotates around and becomes the contact patch it alters the ride in a number of ways. I've had several sets of tires that I've had road force balanced where they measure RFV and bust the bead and spin the tire around on the rim then rebalance the whole thing. Massive improvements! I've eliminated pulling, vibrations, and all around shitty feeling tires with a proper road force. Gotta watch the tech like a hawk though. I'm actually one of those annoying guys who lingers on the shop floor and hangs with the tech while they're working. Sadly, it takes that oversight to guarantee a good job is done.

Reviving this thread. Thinking about replacing my rear DS on my truck in the sig. Does anyone know the specs of the stock DS? Specifically, the diameter, length (67"?), and the wall thickness? There's a phenomenon called half critical speed vibrations and that might be the reason why driving above 80 is miserable in my truck.

Just wanted to report on some work I did today on my truck. It's a high country so I think that comes packaged with the Z60 smooth ride suspension. I noticed that the overloads come into play far too often and make the rear end a bit jarring. Its not too difficult to conceptualize actually. The leafs are doing their job oscillating but then they strike the rubber pads on the overload and the party is over. Those overloads are so stiff. I see two benefits to those things: 1) high payload (not me - 99% of the time) 2) axle wrap (especially with a torquey 6.2) So, I pulled em. Left the blocks though. Netted .75" of drop. Also replaced the stock blown shocks with Bilstein 5100s. The result: Fantastic ride quality! The edge of all the little bumps is gone. The big bumps...pshh...what big bumps. Soaks em right up now. Weight transfer during slow speed transitions like in parking lots or neighborhoods is more flat. It's a bit less eager to oversteer too. The bad: axle wrap/slight vibes. Might be pinion angle but I doubt .75" would really cause that. Plus I did this to my QC Ram 5.7 that had a long a** driveshaft and it didn't get any vibes. I was already planning on getting Roadmaster Active Suspension and now I'm committed. They basically act as a three in one sway bar, overload spring, and a traction bar. Tons of F150 ecoboost guys use em to combat the torque rich axle wrap from a dig. Anyways, terrible at documenting things so this isn't a write up, just wanted to share my results.

I can't find this anywhere! Maybe I suck at googling. Though my wife would disagree.

Having a 6.2 I cannot say my brakes (in their current state) are confidence inspiring. I have an NBS silverado that I converted to hydroboost and it's pedal feel is fantastic. I'm going to flush my fluid this weekend and that should help my pedal a bit. I'd like to get more feedback on this topic though throwing money at my current setup.

Let's keep this thread going! Very interested. Just bought a '16 Silverado 1500 with 73,000 miles and it feels like it needs rotors, I've got a shimmy when it under hard braking. It'd be nice to spend a little extra and just upgrade the calipers too.