GMT-800 Suburban lift options?

[Jelorian]

Justcuz,

Thanks for taking a moment to reply. I definitely want to stiffen my rear. I do have the 1" aluminum spacers in there now with the stock springs, so I do have that as an option. I am going to do the H2 springs in a few weeks, I hope. I have a hunting trip coming up that will let me decide for sure. Running up to ranch last weekend (a bit of 4 wheeling) unloaded, I was trying to really focus on the "ride" so to speak. My Av does recover from dips correctly, just a single bounce, but overall with the front lift keys and spacers in the rear, the overall ride seems a little soft. Maybe it's just 24 years in the seat of a really stiff Jeep YJ, or maybe just stock Chevy springs with 134K on them. Either way, I want as little more truck, and little less Suburban feel.

For those of you stuffing the 285's, are any of you doing anything with the speedo calibration? I had a dog of time with my Jeep and taller tires, with getting the correct speedo gearing. Would that be something the dealership could program, or perhaps a tuner deal? I am a few years out from needing to replace my 265-70-17's, but having the factory 4.10's makes me think that it could be an option.

Craig

I'm running 285's. I didn't do anything to recalibrate my speedo. The size difference isn't big enough for me to really notice. Not sure if the dealer would do it, but a tuner would no problem. Having factory 4.10's is definitely nice to have if you decide to go to 33's or bigger. IMHO, if you go bigger than 285's then it couldn't hurt to get a tune and your speedo recalibrated.

Here is a pic of my 285's compared to my stock tires.


Check out this website.

https://tiresize.com/comparison/

The 285's are only about an inch taller in height which means .5" overall tire difference.

 

[justcuz]

Justcuz,

Thanks for taking a moment to reply. I definitely want to stiffen my rear. I do have the 1" aluminum spacers in there now with the stock springs, so I do have that as an option. I am going to do the H2 springs in a few weeks, I hope. I have a hunting trip coming up that will let me decide for sure. Running up to ranch last weekend (a bit of 4 wheeling) unloaded, I was trying to really focus on the "ride" so to speak. My Av does recover from dips correctly, just a single bounce, but overall with the front lift keys and spacers in the rear, the overall ride seems a little soft. Maybe it's just 24 years in the seat of a really stiff Jeep YJ, or maybe just stock Chevy springs with 134K on them. Either way, I want as little more truck, and little less Suburban feel.

For those of you stuffing the 285's, are any of you doing anything with the speedo calibration? I had a dog of time with my Jeep and taller tires, with getting the correct speedo gearing. Would that be something the dealership could program, or perhaps a tuner deal? I am a few years out from needing to replace my 265-70-17's, but having the factory 4.10's makes me think that it could be an option.

Craig

I've run 285's for years. The speedometer/odometer is more accurate with the 285's than factory size tires. When I drive by motion detected speed signs, I am right on the money.
If you haul weight you will like the H2 springs, try them without the spacers at first and if you want it higher put them back in. I don't think you will want them after you install the H2's. Avalanche's are lighter in the rear than a Suburban, I bet you see 2" of lift minimum.

 

[Martinjmpr]

FWIW I got about 2" just by going from my stock (old, tired) LT springs to Z71. I read somewhere that Z71 and H2 springs are identical but I don't know if that's true. The diameter of the coil on the LT spring was about 5/8", while the Z71 was 3/4". If you look back a few pages you'll see the side by side comparison of the two coil springs.

 

[Bear in NM]

Thanks for the replies. The 285's would be much further down the road, as my 1 year old KO2's only have 3-4 grand on them. And my trailer 265 KO2's only a few hundred. It will probably not be worth the money, but maybe.

As to the springs, yes I have looked at the pictures and researched. The sort of unknown is whether the H2 springs would net the same ride height as the Z71 spring, which mine has right now, with a 1" spacer. The LT certainly looks smaller, all the way around. I would love to ditch the spacer and end up at my current height, with stiffer compression. And correct, the answer is try them out with and without the spacer. The hard part is guessing which to try first, to save a couple of hours of jacking and unbolting.

I am pretty sure my rig was used for a decent amount of towing, as it came with a brake controller. This makes me think that my current rear springs, with 134k and previous towing are likely on the soft side. Once I get the time in a few weeks, I will order the H2's and detail my measurements. It will be nice to finally nail down the h2 v. Z71, for this thread.

Craig

Edit: Oops, forgot. My 265's are on the low side of GPS measurements, perhaps a 1/2 to a full mph. Not bad, and I could live with a couple mph's difference. But thanks for the confirmation on the tuner. I know zip about them, but think I may not be able to resist going down that road, eventually.

 

[rayra]

both our GMT800 Z71s are equipped with the factory towing package and both came with the trailer brake controller wiring harness as an 'extra'. zip-bundled in a bag. It plugs into the options panel low on the firewall by the driver's left foot.

 

[Burb One]

Thanks for the replies. The 285's would be much further down the road, as my 1 year old KO2's only have 3-4 grand on them. And my trailer 265 KO2's only a few hundred. It will probably not be worth the money, but maybe.

As to the springs, yes I have looked at the pictures and researched. The sort of unknown is whether the H2 springs would net the same ride height as the Z71 spring, which mine has right now, with a 1" spacer. The LT certainly looks smaller, all the way around. I would love to ditch the spacer and end up at my current height, with stiffer compression. And correct, the answer is try them out with and without the spacer. The hard part is guessing which to try first, to save a couple of hours of jacking and unbolting.

I am pretty sure my rig was used for a decent amount of towing, as it came with a brake controller. This makes me think that my current rear springs, with 134k and previous towing are likely on the soft side. Once I get the time in a few weeks, I will order the H2's and detail my measurements. It will be nice to finally nail down the h2 v. Z71, for this thread.

Craig

Edit: Oops, forgot. My 265's are on the low side of GPS measurements, perhaps a 1/2 to a full mph. Not bad, and I could live with a couple mph's difference. But thanks for the confirmation on the tuner. I know zip about them, but think I may not be able to resist going down that road, eventually.

Bear- I recently took out my coil spacer and went with"Sumo Springs" I was going to wait to recommend them but now with two trips and a few 1000 miles, I feel pretty confident in them. I so far like them over a spacer (and they are more "bellet proof" than air bags which I was also looking into). Gives me about the same "lift" but seems to have a little bit more compression (at least what I can tell, hard to feel what is going on in the back off road. On road it feels the same. Super easy to install. Just need to jack the side of the truck off the ground to decompress the coil, and then use some dish soap to slide them in.

Saying that, my experience is with a 6inch lift so maybe a tad different. I simply had too much lean in the rear due to hauling all the stuff and the springs the 6 inch lift came with ended up compressing more than I wanted. I compensated a 2" blocks for awhile as I couldn't find tall enough air bags. These may be a better solution then going with new springs and blocks. I like the fact they still compress compared to a block, also should give you your "current height, with stiffer compression. "

https://supersprings.com/pages/index/coil-sumosprings-overview

 

[Martinjmpr]

both our GMT800 Z71s are equipped with the factory towing package and both came with the trailer brake controller wiring harness as an 'extra'. zip-bundled in a bag. It plugs into the options panel low on the firewall by the driver's left foot.

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Yeah mine came with that too but it proved to be unneccessary as I ordered my brake controller with a harness that is compatible with the plug on the firewall. It was completely plug-and-play, in fact the most difficult thing was figuring out where and how to mount the controller itself. I went with screws into the lower dash, which I don't really like (hate putting screws into plastic) but I couldn't get the heavy duty tape to stick to the curved surface of the lower dash. Now I wish I'd mounted it higher and further out because I'm constantly bumping into it with my knee.

 

[LostChord]

Very nice.

 

[Stryder106]

just measured, I'm sitting at 37.5" to the trim over the center of the rear hub and I'm on 265/70-17, which are measuring at ~31". About 20gals in the tank, 75-lb of gear and 200-lb of mortar sitting in the rearmost. 1500 Z71. LATE EDIT, front wheel well trim height is 36.5"

I had Rough Country RS9000s on my pickup for a very long time, along with their suspension lift kit and it's served me well for decades. And the shocks worked quite well in the desert conditions and driving I did. And which I'm intending for this Sub. So a kit like this seems reasonable to me -
http://www.amazon.com/dp/B00B28T2KS...=UTF8&colid=QWZ1BSZYG6VW&coliid=ICLAP269QEI95

.

Rayra - you mentioned a few things in here that caught my eye.

1) I have CST keys (assuming Ford for the lift) and custom Eibach shocks. My Avalanche is sitting level at 39.5" on each corner with 285/70-17s that are worn to being under 32". My rear springs are stock, though on an 02 Avalanche NFE 4WD - I'm not sure if they Z71 springs in it or not - it did come with the G80, 4.10 gears, and 17" wheels with A/Ts on them. So - I would assume so.

2) You mentioned you had a Rough Country lift for decades...........I'm looking for a functional lift for overlanding. Rough Country caught my eye because they are the only ones with a Non-Torsion Drop kit for my Av - meaning the torsion bars stay tucked up where they are stock - not dropped down. Translation: Real Ground Clearance Improvement. BUT - I've heard a lot of negative comments on their quality - but ALL of those comments seem to be 5+ years old. I'm really hesitant to pull the trigger on this kit as I will have my family out in the middle of the desert or trails somewhere and I don't want thing to cave on me leaving us stranded. I'm not concerned about the shocks - Eibach will build me new ones so I won't use the RC ones anyway. Would LOVE to get your opinion of the RC lift kit.

FYI - a 6" lift kit - be careful with how you interpret that. Most of them mean - you will get 4" in the rear, 4" in the front, then turn your keys up to get the remaining 2" equating to 6" in the front.

I'm trying very hard to figure out a solution for my rig as I AM going to 35" tires - but since I have trimmed my front, I really don't think I need 6" to fit them. I was trying to stay around an additional 2"-3" in the front and rear from where I currently sit. But, I wanted that without my keys turned up so I could get my CV angles back to near neutral.

There are a lot of kits - but they are jungle gyms underneath which I'm not interested in.

 

[Bear in NM]

Bear- I recently took out my coil spacer and went with"Sumo Springs" I was going to wait to recommend them but now with two trips and a few 1000 miles, I feel pretty confident in them. I so far like them over a spacer (and they are more "bellet proof" than air bags which I was also looking into). Gives me about the same "lift" but seems to have a little bit more compression (at least what I can tell, hard to feel what is going on in the back off road. On road it feels the same. Super easy to install. Just need to jack the side of the truck off the ground to decompress the coil, and then use some dish soap to slide them in.

Saying that, my experience is with a 6inch lift so maybe a tad different. I simply had too much lean in the rear due to hauling all the stuff and the springs the 6 inch lift came with ended up compressing more than I wanted. I compensated a 2" blocks for awhile as I couldn't find tall enough air bags. These may be a better solution then going with new springs and blocks. I like the fact they still compress compared to a block, also should give you your "current height, with stiffer compression. "

https://supersprings.com/pages/index/coil-sumosprings-overview

Geron,

Thanks for link on those. I did not know such a thing existed. I really need to change out my current springs, due to the age of mine, and unknown towing history of the vehicle. I figured I could add air for the times that I tow, but those Sumo spacers look like a viable option to bags. I already have 1" blocks, so I would not need to spend more money. But, based on the folks here that have done the H2's, I have my fingers crossed they will work, without spacers.

Yes, sounds frustrating for you, as once you lock into a dedicated lift, you start to run out of options, if your lift maker does not have them. I am actually very pleased with my Av with just a bit of front leveling to the rear, now I just need to clean up the rear a little.

Craig

 

[Martinjmpr]

DONE done!

So this will (hopefully) be my last posting to this particular thread since I'm now officially DONE! New wheels/tires went on this weekend. Here's what she looks like (I'll include the "before" and the last "after" pic):
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Driveway pic with new-to-me 16" wheels and tires. Tires are Falken Wildpeak AT3W in 285/75/16:
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Before:
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After:
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(Sorry for the small photo - Photobucket is REALLY acting up and despite numerous attempts, I could NOT get the photo to show up!)

 

[ExplorerTom]

If looks count for anything- I think it looks better. The smooth sidewalls and rounded shoulders of the old highway tires just didn't look right.

 

[Burb One]

Lookin good!

 

[Martinjmpr]

Ah, forgot to give the final measurements with the new tires:
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All measurements taken from the ground to the bottom of the wheel well opening:
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LF: 38.25 (+2.75" from stock)
LR: 38.5 ( + 2.125")
RR: 39.125 ( + 2.5")
RF: 37.75 (+ 2.25")
Trailer Hitch: 15.625 (+ 2.25")
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Got her all washed and shined, vacuumed out and put the 3rd row seat back in: Now that we're done with camping she's the "Wintertime Family Bus." :elkgrin:
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[BKeeling]

Ive got a few questions about this, ideology. I didnt check the date so sorry for the necromance. Undoubtedly someone would complain if I started a new thread and tell me to search. Basically the residents on an internet forum will be upset if someone posts anything at all. Obviously forums are just for reading and not posting. Thats why they allow new members to sign up and leave a box here for comments....

ANYWAY, my question is, it really seems like EVERYTHING on the H2 is better. The front and rear half frames are 2500 and 1500 GMT800 respectively and the center frame is boxed. BUT the h2 is wider so those arms axles and everything are LONGER, right? Like a poor Mans long travel correct??? The h2 has the same wheelbase as a Burb so for you guys LITERALLY SWAPPING CABS would yield the best of both vehicles, smaller lighter cab AND the chassis would be way higher performance because of the weight reduction. You only really get boned on the departure angles... there are numerous other cool features of the h2 frame like the integrated hitch and the frame slider wings on the sides as well. Idk if the hitch would be much help as it would be up under the truck tho because of departure angle differences etc. But a GMT820 Burb or avalanche would be worth the hassle for sure...

BUT, Ive got a Yukon, like a Tahoe with the shorter wheelbase. And frankly boxing the center section is way simpler than swapping a cab, especially since I don't run a shop with a lift and a forklift anymore (we body and bed/box swapped LS powered NPR trucks all the time, so Im knowledgeable here actually, everything rarely lines up perfect but I can weld as well)

SOOO, what Im really getting at is will the 2500 arms bolt into the pickup points of a 1500 front chassis? Or would I need to cut those off the 820 chassis??? Which tbars make more sense? The h2 dampers are a huge upgrade as well, longer and better valved than the pepboy ranchos of the z71. But Im afeard the h2 tbars might be too stiff for the lighter front and I like to do hoonicorn type ******** over ruts and woops (driver mods are the best lol)

Another question is 4WD vs 2WD front chassis, whats different? Im going awd with this so h2 diffs and axles with the elockers to dash switches and either an h2 tcase if I can hack a manual control for the lowrange, or just a denali/tblazer ss tcase (id prefer low range for driving in the Tony Mantana but I mostly hoon sand/chinchilla dust.

Yes I hoon my overland truck. What Im aiming for is a blend of a Baja Chase Truck, and a Dakkar rally truck. Im not going to half frame it, ******, (a guy said this on gm fullsize when I asked about the jdfab extreme long travel, he said all prerunners are half framed and tried to send me to kibbe lol. He claimed to build koh ultra4 truggies but my suspicion is he masturbates to YouTube, sorry for the side story)

Anyway, so there are my questions hidden in a longwinded novella lol.

Basically, tbar specs, do 2500 and 1500 front arms share pickups, do 4x4 and 2WD fronts share pickups, can h2 tcase lowrange be controlled with a switch and wires, oh, and how much longer are the h2 arms?

Yes, I know shortening the h2 chassis is the best thing to do here but basically if Ive got to find resources for that I would be to tempted to just buy an m998 chassis from surplus and weld at least three feet of Yukon chassis in the center with the numbers and frame to cab pickups on it lol. Yes Im sure other stuff would also need fenagling but the Honky Donk is a Mudmaro made this way, if a car fits then a Yukon fits as well and that predator longtravel for the h1 is BANANAS... probably the most competent awd desert racer available short of an ultra4 or a pro AWDTT (even the TT wont have portals or IRS)

Also the m998 frames come in a 12k lb capacity. Which would be impressive. Yes, you can tow with IRS, The HMMWV program WAS ENGINEERED WITH TOWING AS A REQUIREMENT.

Log axle guys are like Dino oil guys. They used to say you couldnt finish Baja with IFS either LOOOL

Okay NOW Im done, sorry