Sheen

So swapping the torsion bars, I calculated 8% less volume, did nothing for me? I noticed a difference, but not a major one I guess.

M Parr, Did you ever find a solution? I'm in the exact same boat. 2021 AT4 2500 6.6 duramax, snowplow package, 20 inch wheels. All factory 1. Lowered Tire Pressure 55 F 45 B (referenced data sheet from goodyear) 2. Replaced snowplow/camper torsion bars with (non)snowplow torsion bars from a 2020 silverado. Verified part numbers with GM. 3. Rake is about 1.25 to 1.5 inches. Jounce stops about 1/8 inch above control arms. Things are notably better, but still pretty rough to be honest. Nest steps I might try: 1. Replace fox shocks as suggested in this thread. 2. 18 inch wheels 3. Cognito Comfort Torsion bars. I'm loathe to go through step 2 and 3. I'm hoping you can tell me what solved this for you. Thank you in advance.

Thank you. I've got it set right at 2 inches now and my front jouncers are compressed just a little. If I lift up the front as to just kiss the jouncers to the control arm the ride is notably worse. I was wondering if having them compressed just a little is ok.

Does anyone know, the exact factory rake of a brand new 2021 AT4 2500? Thank you!

Thank you MTU Alum!

So I actually ended up getting a set of 2020 Silverado 2500 torsion bars on ebay. These are the stock bars that would have been in my AT4 had I not bought one with the snowplow package. Measuring the diameters and calculating volume they had 7 or 8% less volume than the snowplow bars. I installed them, (super easy) and the ride is notably better. However, what I'm learning is that the relationship between the jouncers and the control arms are VERY important. Interestingly also, there are 4 jouncers on the front end of the truck. I'll call them extreme forward and middle forward, not to be confused with the rear jouncers above the leaf springs. The extreme forward and middle forward jouncers do not meet the control arm at the same time. In other words as you lower the rake of the truck the middle forwards will touch the control arm before the extreme forwards. I"m guess there is maybe 1/8 to 3/16 of an inch difference in when they touch the control arm. I have found through experimentation that squishing the middle forward jouncer just a little to allow the extreme forward jouncer to just kiss the control arm results in my best ride so far. If I raise it up from there where the middle forward jouncer kisses, and the extreme forward jouncer is about 1/8 inch above control arm, this has a noticeably worse ride. Obviously the higher the rake from there the worse the ride gets. ( I do drive the truck aggressively over bumps after every adjustment before I even check measurements or jouncer positions) As far as tire pressure: I reached out to Goodyear and received the documents to account for different psi allowable under different loads.( thank you Logan) I'm assuming my truck carries 60% of its weight on the front wheels and 40% on the back. Assumption is based on multiple weight reports that show a 57/43 % split, albeit on older duramax trucks. And just for daily driving (not towing or hauling) a very comfortable figure of 9500 gross weight (full gas tank, myself, wife, and two kids, and 400 lbs of whatever else I put in the truck) allows me to go down to 55psi in the front and 40psi in the back. I've got 56 in the front and 46 in the back right now. Interestingly I had 56 in front and 50 in back and the ride seemed better than when I dropped the rears to 46. I'll continue experimenting there, but at least I know I'm 100% safe running those lower pressures now that I have the tire docs. Just can't forget to inflate before I haul. And I won't. If anyone has any thoughts or concerns for me that don't include "why would you buy a HD truck and then ****** about the ride" I'd love to hear them. By the way, I've improved the ride already without compromising the handling or towing capacity or payload. From what I can tell so far using the stock non-snowplow torsion bars reduced my forward axel allowable weight from 6600 to 6000 but this has zero implication for towing or hauling at the levels I will be using it for. If I still cannot get satisfied my next step will be upgrading the Rancho shocks, moving to an 18 inch wheel vs the 20 I have. Because I test drove a SLT 2500 non-snowplow with 18 inch wheels and it felt so much better than my AT4. But it didn't look as cool Lol.

Hello, I was wondering if anyone had any thoughts on how much fuel 'active grill shutters' would save you? mpg with -vs- mpg without. I've got a 2021 6.6 Duramax with snowpackage (so active grill shutters were deleted) and I'm just curious what I'm missing out on. I found one bit of information from 2015 saying it was only about 0.5 % savings on fuel economy. This seems barely worth it. Is it really that low? Thanks!

Will do.

Oh and Logan, about the PSI. My door sticker calls for 60 Front, 70 Back. I've taken the front down to 54 and the back 52. Cold. The ride does seem a lot better. Could I actually go lower than that without a problem? Sidewall max is 80.

That is excellent advice. Rest assured I always fully disclose whenever I sell anything. I believe very strongly into treating others the way I would like to be treated, but I appreciate the reminder none-the-less. And great idea! I'll keep those bubble wrapped in the basement, and they'll stay brand new. And who knows, maybe one day I'll get a camper;) Also, for sure I'll report back - promise. Thanks Logan!

Ok thanks guys. I ordered up the non-stow prep bars. I'm gonna throw them in and see. I see what you're saying about the crossmember. Should be able to get that out fairly easy. Luckily it's new and not all rusted up yet, so I'm hoping be a little easier to pound that bar out of the control arm. Ps. You might be right newdude. I'll report back. Might be a couple weeks tho.

So not to beat a dead horse, but to be abundantly clear: If I go to GMC build site and select AT4 2500 Duramax. And I build one with the 10,000 GVWR option and on with the 11,350 option, and have them both delivered, I will receive two identical trucks, springs, suspension et al. But one will have lower stickered weight ratings for regulatory purposes only!?

I could definitely handle the job myself IF the bars can be negotiated out by just removing the torsion bar keys. If I'd have to remove the control arm etc, then no, I don't want to get into that. What!?!? I'm missing the louver system too? Yep, you're right, not there. Even if you could have that installed, would the software be present to run it!? How much better on average do these things improve mpg you think? Thanks so much for your help.

From what I've determined the Snow/Camper upgrade to the 2021 AT4 Sierra 2500 [with regard to suspension] includes a heavier duty torsion bar. I purchased an AT4 with this package, even though I didn't need or desire the package, because it had everything else I wanted. Would it be possible, and how involved would it be, to revert the torsion bars to the stock versions (like an AT4 without the snow/camper package)? Now I will catch a lot of heat from you guys I know, for bringing up ride quality in an HD truck. However I have a feeling this would make a notable improvement. Why have stiffer than necessary? I will be towing with it in the near future, but will do a lot of daily driving too. In addition, I keep reading the rancho shocks are no bueno. Thoughts? Thank you gents!