GMT400 vs GMT800 Suburban

[PGW]

My Yukon XL 2500 has dual piston calipers all around. The calipers are all beefy and heavy. The rotor diameters are surprisingly similar to the 1500's. Mine are 12.8" front and 13" rear rotors. But there is more to a braking system than just rotor diameter. Newer Duramax trucks rated to tow 15,000lbs or whatever have 14" front brakes, which isn't really a huge difference in size. In fact I think all of the newer HD trucks run 14" or so front brakes. Some 15" or whatever rotors and calipers from a sports car would probably not be worth a ******* on a heavy truck. Really, brakes are not an issue for the GMT800 and newer trucks 1500 or 2500 anyways.

I held out for an 8.1L truck. Why? Because it is a ************** engine, I wanted it, and I could afford it. This is a hobby/recreational vehicle so mpg isn't an issue. The 2500's are heavier, but all of that weight is down low, so in theory the COG should be lower than a comparable height 1500. Mine has been through some pretty tough trails and has had no issues so far. Even with its weight it is pretty planted and well balanced and traction isn't usually an issue. My rear 14 bolt has hung up a few times so I will need to shave it some. Even getting hung up on the 14 bolt on an obstacle, I just needed to shift over a bit and then I was up and over.

But I would say 2500's probably aren't necessary for most people (probably not even necessary for me), but this is a free country so if you want one, get one. Not sure why some people criticize others for their vehicle choices, but then again I'm not a d***head with too much free time on the internet.

 

[CampStewart]

All my calipers have 2 pistons just like some of the 2500, most 2500s only have single piston rear calipers. My front disks are over an 1" larger diameter and pistons themselves are approximately 1/2" larger diameter than 2500 front brakes. My rears rotors are almost 2" larger diameter and pistons are also approximately 10mm larger diameter than same year 2500s. Bigger piston + larger diameter rotor = more clamping force = better brakes, so my brakes are way better than any 2500 brakes.



I was highly surprised by that fact also, how can a 1500 have significantly better brakes than a 2500. I am leaving hydroboost out of this because in 4x4 low at idle my vacuum brakes overpower the crappy power steering pump GM put in our trucks. The answer is quite simple: 4L80, thats it. 1500 have a 4L60 which if driven hard sucks and needs constant rebuilding. 2500s run a much more durable 4L80, which makes sense if you have ever towed anything, you don't use brakes to control your downhill speed you use the engine and the transmission. Since the user will rely on the 4L80 and torque converter to tow, you don't need big brakes on a 6-7,000lbs truck for daily driving. Thus 1500 soccer mom race car wanna be Suburbans get bigger and stronger brakes at the expense of a less reliable transmission.

My good friend had a 1/2 ton Suburban the same year as my 04. We swapped vehicles back and forth a few times. I have driven his with and without a trailer, and pulled trailers with and without brakes. I can say that there is no doubt in my mind that the brakes in my 2500 are far more powerful than in his in every circumstance. I am aware that 4l80's can be custom built to have engine braking but was completely unaware that they came that way from the factory. I did a bit of web searching before posting this and was unable to find any information that they came that way from the factory or that because of that they gave the 2500 weaker brakes. Rather than quote numerous sources of information that they don't have factory braking that I came across Drei could you please give some links to this information that they do so I can better educate myself on this feature? Idon't want to confuse tow/haul mode which is available in 4l60 and 4l80 with what you have referenced.

To anyone reading all this silliness probably 95 percent of the parts on 1500's and 2500's are exactly the same. In order to enable the suburbans to tow heaver trailers and carry more payload they looked at the vehicles and upgraded parts they deemed to be weak links for the 2500's. If you wish to think the engineers would weaken the brakes when increasing the payload and towing ratings or that the modifications they did to the vehicles make them less reliable, rugged, durable, and capable then you might want to think twice about a vehicle designed by these people.

 

[lilkia]

Looking back on it I did replace and upgrade some parts in my truck turning it into a lighter version of a 2500. Factory radiator, factory tranny cooler, factory brakes, I'll get to it later. And suspension upgrade was for stiffer springs so I can blast through the desert at 45-60mph safely. All the parts are 1500 parts on my truck except the motor. I have a Summit tow cam ($220), custom tune ($200) and about to put on the traiblazer SS intake manifold ($100) so for $500 plus gaskets my LM7 cranks out more HP and torque than a 6.0 LQ4 or an LQ9.



All my calipers have 2 pistons just like some of the 2500, most 2500s only have single piston rear calipers. My front disks are over an 1" larger diameter and pistons themselves are approximately 1/2" larger diameter than 2500 front brakes. My rears rotors are almost 2" larger diameter and pistons are also approximately 10mm larger diameter than same year 2500s. Bigger piston + larger diameter rotor = more clamping force = better brakes, so my brakes are way better than any 2500 brakes.



I was highly surprised by that fact also, how can a 1500 have significantly better brakes than a 2500. I am leaving hydroboost out of this because in 4x4 low at idle my vacuum brakes overpower the crappy power steering pump GM put in our trucks. The answer is quite simple: 4L80, thats it. 1500 have a 4L60 which if driven hard sucks and needs constant rebuilding. 2500s run a much more durable 4L80, which makes sense if you have ever towed anything, you don't use brakes to control your downhill speed you use the engine and the transmission. Since the user will rely on the 4L80 and torque converter to tow, you don't need big brakes on a 6-7,000lbs truck for daily driving. Thus 1500 soccer mom race car wanna be Suburbans get bigger and stronger brakes at the expense of a less reliable transmission.



Correct, 1500 is an excellent truck and so is the 2500. It's only downside is that it's not as stout reliable or capable when towing a large trailer than a 2500. 1500 are made for soccer moms who are too cool to be seen in a minivan, 2500 are made for soccer dads that are too poor to buy a diesel.

The 1500 doesnt have significantly better brakes and if you would actually get the specs you would see that. Its funny that when you pull the calipers up on any autoparts website the 1500s are single piston. My 2500 has dual pistons front and rear. The one reason they have the size rotors they do is wheel fitment. Most E rated tires then were 16". You dont tow or carry the capacities of the 2500s on the C rated tires of a 1500.
As for driving a diesel truck, I have one for the farm its an 07 3500 dually. I dont like the stink of diesel and I dont need to drive it everyday. I bought a gmt 800 suburban because I wanted a big GM SUV with barn doors and the 8.1 neither of which they make anymore. I spent 6 months and quite a few thousand dollars over average asking and blue book to find a low mile very clean well maintained truck. Affording it or the extra $500 a year in gas isnt a problem. If GM still made a 2500, 8.1, barn door I would have bought a brand new one.

 

[plumber mike]

If GM still made a 2500, 8.1, barn door I would have bought a brand new one.

You and me both. Except it’d likely be 80+ grand if they did. I’ll just keep a few thousand set aside for a crate motor since I’ve decided I don’t want to let the old girl go. Finally broke down and rebuilt the transmission when reverse went out at around 275k

 

[Bojak]

My .02 is the GMT 400 series is the last generation of gm trucks that stands any chance of ever being a classic or collectible. I've owned 4. I currently own a 94 blazer. I've owned 2 GMT 800 vehicles. The 800 is a better engineered series. The engineers figured alot of things out during the 400 times and applied them to the 800s. I like the 400s more because I'm old and this is the era of truck I like. Not that I think other than style wise it's any better. Remember even a 2006 is 13 years old now.

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[lilkia]

My .02 is the GMT 400 series is the last generation of gm trucks that stands any chance of ever being a classic or collectible. I've owned 4. I currently own a 94 blazer. I've owned 2 GMT 800 vehicles. The 800 is a better engineered series. The engineers figured alot of things out during the 400 times and applied them to the 800s. I like the 400s more because I'm old and this is the era of truck I like. Not that I think other than style wise it's any better. Remember even a 2006 is 13 years old now.

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If I could have a 96-99 2500 7.4 4x4 barn door as clean and as well cared for as this one I would have bought it instead. I love the gmt400. I found three that were perfect except they were 2x. Best looking truck gm has built since the 70s. My next project will be a 96-99 or 71-74 suburban or blazer.

 

[jeep-N-montero]

If I could have a 96-99 2500 7.4 4x4 barn door as clean and as well cared for as this one I would have bought it instead. I love the gmt400. I found three that were perfect except they were 2x. Best looking truck gm has built since the 70s. My next project will be a 96-99 or 71-74 suburban or blazer.

They do come up for sale every few months, the one I posted on page one that sold in 14 hours only had 94k miles if I recall correctly and they had it priced well. I miss my 95 diesel Silverado with manual trans, if it had been a 4-door crew cab I never would have parted with it, but car seats and an extra cab do not mix well.

 

[CRolandLJ]

woah this thread really took off.... and got personal...

For those asking about my need for a 2500 - I don't NEED a 2500 all the time.... but I would like to get a travel trailer in the next few years (once my newborn son is old enough to sleep in a regular bed and go to the bathroom by himself) and that would open up a lot more options than a 1/2 ton.

Great info in the 6.0 vs 8.1 and oil usage. Like I mentioned before, I hadn't really specifically pursued an 8.1 previously but now that I've been looking specifically they are a lot less common. I think for my use a 6.0 should be just fine....but I'll keep an open mind. The unloaded (or slightly loaded) mpg would also be nice but I'm not terribly concerned about mileage from a cost or range perspective. My family's bladders and restlessness range is always much less than a full tank of fuel anyway.

 

[Martinjmpr]

woah this thread really took off.... and got personal...

Great info in the 6.0 vs 8.1 and oil usage. Like I mentioned before, I hadn't really specifically pursued an 8.1 previously but now that I've been looking specifically they are a lot less common. I think for my use a 6.0 should be just fine....but I'll keep an open mind. The unloaded (or slightly loaded) mpg would also be nice but I'm not terribly concerned about mileage from a cost or range perspective. My family's bladders and restlessness range is always much less than a full tank of fuel anyway.

WRT MPG, gas has been cheap for quite a while. Back in 2014 when I still had my 4runner on a trip to Yosemite and gas was over $4.00/gallon it hurt every time I filled up. And that was in a V6 4runner.

Those with longer memories might remember that the last time gas prices spiked up there were threads here (and elsewhere) of people saying "I love this truck but the fuel costs are killing me." Lots of guys with built-up 80 and 100 series LCs were leaving them parked and taking the Subaru instead because they couldn't stand getting raped at the gas pump.

My point being that on an internet forum it's easy to say "go for the bigger engine, you won't notice the loss of MPG" because the person posting that isn't the one who's having $90+ charged to his credit card every time he fuels up.

 

[lilkia]

6.0 or 8.1 either is fine. If youre pulling big loads >7000lbs regularly or towing in the mtns all the time the 8.1 makes it nicer. If youre towing a 3500lb camper trailer go with the 6.0 and youll be more than happy. I may not "need" the 8.1 power all the time but to be honest it is as much a happy thing as anything else. The mapping has been redone and the active torque management removed and I smile like a five year old on his first big wheel every time I mash the skinny pedal.

 

[plumber mike]

6.0 or 8.1 either is fine. If youre pulling big loads >7000lbs regularly or towing in the mtns all the time the 8.1 makes it nicer. If youre towing a 3500lb camper trailer go with the 6.0 and youll be more than happy. I may not "need" the 8.1 power all the time but to be honest it is as much a happy thing as anything else. The mapping has been redone and the active torque management removed and I smile like a five year old on his first big wheel every time I mash the skinny pedal.

Was this done with a tuner? Any info or a link? Thanks.

 

[jeep-N-montero]

Was this done with a tuner? Any info or a link? Thanks.

Black bear performance is who will be tuning ours, currently running a Hypertech that is mediocre in comparison.

 

[plumber mike]

Black bear performance is who will be tuning ours, currently running a Hypertech that is mediocre in comparison.

I’ve heard very good things about them, but I was under the impression that they did that in person rather than ordering a tuner with a tune online. I live in BFE so that just isn’t practical. It seems the next logical step in making my Yuk a fun toy/practical hot rod

 

[lilkia]

Was this done with a tuner? Any info or a link? Thanks.

Black Bear in person tune for now. Mapping was changed to increase performance. The shift points were changed and the ATM was also turned off. It is a beast. The mileage isnt bad as long as you keep the rpms under control on the highway and its very civil around town no weird or clunky shifting. When you stomp the skinny pedal the thing just jumps.

 

[lilkia]

I’ve heard very good things about them, but I was under the impression that they did that in person rather than ordering a tuner with a tune online. I live in BFE so that just isn’t practical. It seems the next logical step in making my Yuk a fun toy/practical hot rod

Black bear does several different ways. You can do a traditional where you pay a core and the send a new control module and then send yours in. EFIlive where you buy the scan tool. Save your stock tune, then load the BB tune. Or in person.

I will be adding headers and opening up the exhaust a bit more. It works well on highway, towing, and offroad. I had it out on a "small" (15k acres!!!) ranch a friend has and it did real well on some climbs, crossings and actually had better ledge clearance than I thought it would. Hi4 in 1 went over everything with very little throttle input and its very smooth delivery. No lurching or over revving.