Joe97281

Check the inner fender liner. I had single loud "clunk" for 40K miles. Always happens when turning left. Dealer couldn't find anything. I found a spot where the fender liner was rubbing and cut out a small section. It wasn't rubbing all the time, but had an obvious contact spot in the frame grease. Noise is gone now. I was convinced it was the suspension or steering because of how loud it was.

I have been meaning to graph the contribution torsion bar vs jounce bumpers to draw conclusions about ride stiffness. I was too cheap to buy a a line pot for a data acquisition unit, so I never got anywhere. It would be very easy to do for someone with access to basic mechanical instruments at a college, tech school, or employer. The question to answer: What is the spring rate of the jounce bumper? With that info you can make decisions about modifying it to get a lower overall effective spring rate. Maybe drilling a hole down the center of the bumper solves all problems and no one needs new torsion bars. Pic attached demonstrates the concept of overall spring rate. At some distance of suspension travel, the jounce bumpers make contact with the control arms and the overall spring rate of the suspension is increased. This is the blue shaded portion of the graph. If anyone knows spring rates of the torsion bars or equivalent conversions as if it was a coil spring, that would help as well. Also, I have always understood the spring rate of torsion bars to be linear, therefore cranking the keys does not change ride quality, all it does is lift the suspension. This is a common misconception from people with cranked keys because the upper control arms kit the service stops on down travel, making for a crap ride. The concept of "preload" for linear coil springs and torsion bars resulting in a rougher ride has no merit. This is not true for a progressive rate coil spring. Fingers crossed someone here is a physics teacher and measures and generates a graph accounting for the torsion bar, and 2 jounce bumpers corrected for motion ration.

$1k for a shock spacer. Cognito product description seems to have been written by a simpleton. “Torsion key clocking” doesn’t accurately describe the ZRX front lift. Also, they admit the ugly control arms are not needed. Recommend you jack the front of the truck to measure suspension travel. The 2 inch droop claim seems low.

The official chevrolet and gmc parts websites are having a 35% off sale right now. I got both zrx knuckles shipped to the dealer (free shipping this way) for $225. Probably a good time to get all the conversion parts if you have been on the fence about it. The big discount parts centers might have better prices, but shipping on the heavy items kills the deal.

Mine squeals on cold startup if i press the brake too hard. If anyone has a cold start noise, but not while driving, try less pressure on the pedal.

I think your brake lines and sensors are fine unless you want to fit the dssv shock. The extra size of it causes interference with the sensor wires and brake line bracket. I am hoping my 2022 gets crushed by a tree so i can start fresh with a 2024 WT. Brake pipe change on pass side of 2023 and older for DSSV to fit looks like too much work. I might be able to snake it through from the pass side wheel well. Transfer case skid fits great. Had to drill new holes. Crossmember is very thick. You are going to struggle with normal drill bits.

Brake hoses and speed sensors arrived, and appear to be correct with all brackets included. Passenger side will need a hole drilled into the frame for the mounting bracket. It might be impossible to change the RH hard line. It is probably the second step in truck assembly after coating the frame in crappy black wax. It runs from under the steering column to the radiator, across, and then down the other frame rail. Lots of crap on top of it. pics of MY 2024 brake junction box needed to see what happens with hardline and hose.

Front skid arrived. Takes 5 minutes to change with a 15mm socket and needle nose pliers. Pliers are needed to get the keeper off the two rear engine shield bolts. It sits lower than the stock steel piece (to allow for diff drop). Oversize shipping made it the same price online and shipped as ordering to local dealer.

I think the parts catalog is wrong. I know it says i already have that brake line. But what i really have is 84826611. I cannot find that part number anywhere. i think 2024 has hardlines that connect towards that back of the vehicle, 2023 and older have lines that connect by the front pivot point of the control arm.

And they delivered half a pint of beer! Have you looked to see where your brake line connections are? My pass side intermediate line has a part number on it that doesnt exist on google, and all parts websites claim I should have the brake lines that connect behind the control arm. ( i dont) Maybe my truck is a Frankenstein due to COVID shortages.

The bends on 84751583 look like it places the connection behind the control arm. https://parts.gmparts.com/product/gm-genuine-parts-front-passenger-side-forward-brake-pipe-84751583?body=Crew Cab Pickup&bodyId=22&bodyNumDoors=5&bodyNumDoorsId=5&categoryId=3074457345616983764&drive=4WD&driveId=8&engine=6.6L V8 GAS&engineId=17733&make=Chevrolet&makeId=47&model=Silverado 2500 HD&modelId=494&trim=ZR2&trimId=528&wheel=Standard Box&wheelId=349&year=2024&bac=114792%2C323092%2C288285%2C318147%2C112603%2C278292%2C202223%2C313643%2C172834%2C278294%2C116427%2C112629%2C117865

I think this is the *79,

85637479 Should be an aluminum one piece that replaces the stock plastic splash shield and engine skid. (Zr2 and at4x). I ordered one on 12/15 but am still waiting on shipping confirmation. Alot of the other stuff is bison specific and you need the $5k front bumper to tie it all together. drop brackets arrives. The distance between corresponding mounting surfaces is ~95mm. I have nothing to compare it to, but maybe someone else does.

@BuckWallace, duck down and look at the brake line routing on your 2024. If the connection is behind the upper control arms (toward the rear of the vehicle) than you should have less problems. It might be possible to add dssv to the front and leave the brake lines alone, but the clearance for the lines and associated bracket is tight. will post pics of the brake lines and speed sensors when they come in.

Your 5100s will be fine. All the issues i have are from the physical size of the double piggyback dssvs

I did not try the control arms, and I am not going to until the I can get the knuckles and complete everything at once, or I can get enough of the brake line parts to make it necessary to use the additional mounting locations on the upper sontrol arms. ZR2 does indeed have different wiring and brake lines than my 2022. I was able to find a pic on the internet showing the setup of the passenger side. On the ZR2 (possibly all MY2024 and above) the pass side front brake line follows the frame rail and goes over the shock mount, then down to the caliper. They cleared out the area for the larger shocks. It looks like brake lines head back toward the rear of the truck, and sensor wires head toward the front. My brake line stays forward of the shock mount. All sensor wires and brake lines clobber the space needed for the shock body. This means I need 2 new hardlines, 2 new hardline to caliper hoses, and new wheel speed sensors. I am assuming the wheel speed sensors have the appropriate bracket attached for mounting to the holes in the zr2 upper control arms. I have already ordered: 86512135, 86512134, 86546952, 86546950 parts.gmparts identifies those as the L/R speed sensors and brake lines for chassis package ZRX. Now I need to know if all 2024 front hardlines are the same, or if ZR2 has special ones, and if they are a direct fit for MY2022. I cannot find ZRX specific hardlines on the gm website (yet). It would also be nice to know the part numbers for the bolts and nuts that attach the brackets for the previous items to the upper control arms. This has gotten to the point where it is no longer fun.

Does not matter. They dont fit my 2022 gmc. They smash the wheel speed sensor wires and brackets. 2024s must have different brackets, or zr2 might have special ones. bottom pic has the 10 mm bolt removed from the black metal bracket, otherwise i couldnt even wedge the shock into place.

Does anyone have a stock front shock they can measure? I do not want to install the DSSV shocks on the front if they are going to get destroyed because I have not installed the zr2 lower control arms yet. My concern is the overall stroke length of the DSSV. I have read many times that the shocks on these trucks limit droop. An incorrect length shock would top out and limit travel, or the upper arm would hit the service stop. That would mean I cannot damage the shocks too badly in that direction (droop travel), but what happens at full compression? I assume that compression of the jounce bumpers take the force of suspension compression meaning the shock will never "bottom out." I have the lowers, but the knuckles are on backorder. I am not going to change the arms until I can do uppers, lowers, and knuckles all at one. I tried to spend some time figuring out what is different about the zr2 lowers. This is difficult since the stock ones are installed on the truck. My shoddy measurements show that the shock mounting hole on the zr2 arms is ~10mm higher than the stock ones. This makes sense if the engineers were trying to keep the original shock length as the 10mm would correct for the 1.5 in lift. I do not currently have the space to jack up the truck or lower control arm to measure extended / compressed shock length with stock suspension components. Measurements and insights are appreciated.

Measuring centerline to centerline of the holes in the shock, I get ~ 15 inch compressed and 18.75 extended. 3.75 inch of travel. That seems low. Rock Auto has specs for a lot of shocks, (https://www.rockauto.com/en/moreinfo.php?pk=14077621&cc=3450533&pt=7556&jsn=473). Even though the reference points for measuring is different, the extended - compressed for the stock shows 4.14 inch of travel. Monroe replacments advertise 4.250 travel, and Rancho RS7 shows 4.41 in travel. This makes me wonder if the Zr2 lower control arms have the shock mounts moved slightly inboard towards the centerline of the truck, or that the mount is taller. Does anyone have a lower control arm not installed on the vehicle that they can take a picture of?

We look forward to seeing pics when the stuff arrives. Thanks for the GM parts direct mention, they were the cheapest, and have lowest shipping to my location. I wouldn't worry about the "Diff drop" brackets, I think it is a full carrier support bracket with a deeper bend in it, therefore giving it a "drop". I'd love to know how much... the full 1.5 inches or something less? I know some aftermarket diff drop pucks provide washers to lower the engine skid plate. That might make the one piece aluminum one have more value to you since we know it is intended to work with all the other parts. It is the part I least excited about installing. Vid below for rough idea.

I am going to order the front skid anyway. The stock setup is a plastic splash shield with metal engine plate. The Zr2 is aluminum one piece. The Specs tab of the gmparts website matches the dimensions of the plastic + steel on normal trucks. Before there was alot of info out, I used a tape measure to verify the dimensions because there was no pictures. I trust it will fit without anyone else confirming because the front splash shield has been the same for a long time. ZR2 transfer case skid arrived today, and it is probably twice as thick as the standard. It will need 2 holes drilled in the crossmember, and at least one additional bolt.

Strongly suspect it is the 3500 bolts, as the listing shows they are 50 MM longer. This makes sense as the 3500 should have extra springs in the pack. Jounce... I think 2500HD ZR2 is all stock for this. The Colorado ZR2 has fancy DSSV hydro bumps. I have tried to find the Colorado bumps on the site, but have not had any luck. Just curious as to how much they cost. I don't think 3/4 tons have had anything other than rubber or micro cellular poly bumpers since the Enhanced Mobility Package. ( https://www.motortrend.com/how-to/129-0601-2005-gmc-duramax-jounce-shocks/ ) Additionally, the picture of the transfer case skid you posted shows that the vehicle may have a gas tank skid as well. I don't think that made it into the final production models. Look at the extra bolt in the crossmember directly behind the driver torsion bar (and the giant black steel gas tank skid plate).

I think figured ~ $1700 for ZR2 front suspension only, pre tax/shipping, from the online retailers. Almost all part numbers are available on parts.gmparts.com , but you have to be smart about how you search. Add the full vehicle details (2024 zr2 or AT4x), and then check the "fitment notes" to verify it is for the ZRX package. 85144990 / 91 = Lower Control arms 86787383 / 84 = Diff brackets 86559719 / 20 = Non Bison DSSV front shocks 85144996 / 97 = Knuckles Also available is the bison / F60 front shocks but I did not write down the part number since I do not want them. Tasca wouldn't sell me the the Diff brackets, Knuckles, or shocks. They claim "national backorder", but I was able to order the shocks through the gmparts website. I suspect Tasca couldn't get them at their listed 40ish % off like they advertise on the site, and canceled my order instead. I am trying to collect all the stuff while it is still available, since I assume it will become scarce with the upcoming 2500HD trailboss. I suspect the trailboss will be ZR2 suspension minus DSSV. Have a look at the gm parts website for some other fun items, like the bison transfer case skid (over $1k list) or the $5K rear bumper. I am hoping the shocks come in soon so I can measure the compressed/extended length and make a decision as to if I want to install them while waiting for the rest of the parts. Please post if you find any parts available. TASCA had Upper and lower control arms this week, as well as the extended transfer case shield (85569359). Cars.com has a pic of it at https://www.cars.com/articles/2024-chevrolet-silverado-hd-zr2-tows-off-the-beaten-path-464932/ I haven't crawled under the truck to see what it attaches to on the back end though, fingers crossed that the crossmember is there.

Can confirm ZR2 upper control arms are designed with additional clearance for the service stops. I do not have a stock control arm to compare ball joint angle. part numbers 85144988, 85144989. With these at 88 dollars apiece, aftermarket companies might have trouble selling tubular ball joint control arms for use with raised front suspension. Would love any info on changes to the lower control arm and dssv shock length.