'07 2500 HD: Ghrank's First Drive

[Ghrankenstein]

2500 HD: Ghrank’s First Drive

by Ghrankenstein


We’ve had the new heavy-duty Sierras for over a week now, but my combination of business and extreme tact has meant that I haven’t been able to get ahold of one until today. It also means that a couple of other reviews have beaten mine to the web, but as usual I’ve hopefully got some stuff they don’t.

The first item of contention, and of great debate and criticism is the issue of the frame. It’s not all new, but it is improved, and it builds on what was already right on the last trucks. The frame rails are indeed the same, but the frame itself benefits from two additional crossmembers. For reference and comparison, and because I’ve been dying to do so, I’ll include some strength statistics at the end of this article.

The next highly discussed feature is the new heavy-duty 6L90E Hydramatic. I don’t have a huge amount of information on the new automatic, other than its basic clutch-to-clutch groundplan, which uses both a rear ring gear and sun gear, and that the 6L90E has stouter, heavier gears and guts. Maximum torque on the 6L90E is 531 lb-ft, versus approximately 430 lb-ft for the 6L80. I was surprised to find out that the first gear ratio is the same on the 2500HD as it is on the 6L80E-equipped Sierra Denali, since the 6L90E includes a “1” shift option in addition to the manual shift mode.

Finally, the 2500HD uses the latest version of the iron-block Vortec 6000 (LY6), in contrast to the aluminum 6.0L Vortec Max (L76). Both engines are strong, but the powerbands, especially down low, nominally favor the L76. The LY6, and the 2500HD, have charms of their own.

Behind the Wheel

I was astonished when I read one major magazine post that the three-quarter ton Chevy and GMC pickups drove similarly to the half-tonners. While it’s good press, it was enough to leave me confirming front suspensions and steering systems just to make sure there wasn’t any merit to the comment. As it turns out, the heavier trucks are still, to noone’s surprise, equipped with front torsion bars and recirculating-ball steering. Just as mundane, noone in their right mind would ever mistake the 2500 for a half-ton truck in driving dynamics, just like no sane individual would mistake a half-ton truck for a heavy duty tower or hauler.

The accommodations are the same, for sure. I still like the “true-truck” dash, for its simple and efficient ergonomics, and I think the two-tone cloth seats in the work truck package are so nice that the unknowing would never realize that they were indeed sitting in a work truck. That might just be enough to sway a vulnerable critic.

Steering, and handling are pretty much the same. That’s not a discredit by any means, since the three-quarter ton trucks are still amusing in their own funky way. Recirculating-ball steering mandates a certain level of on-center deadness, and there’s inherently less feel than with the rack-and-pinion system of the 1500’s. Engaging a three-quarter ton work truck is a goofy challenge that involves a fair amount of guesswork until you can figure out exactly how to tell it what it really doesn’t want to do. I’ll take goofy, and a regular-cab 3500 SRW (single rear wheel) Duramax is plenty goofy, and 9900 lbs of pure GVW fun.

The 6L90E is clearly not a 6L80. It’s a tool, meant to work hard and not break, and it carries quite a bit of inertia with it that the lighter 6-speed lacks. It’s also programmed differently, more like the Acadia, and it wants to save you gas when its Tow/Haul mode isn’t engaged. I like the Tow/Haul mode, since it allows a much sportier response, but I appreciate the approach of saving the commercial truck owner gas money. Fortunately, you can have it both ways. Surprisingly, the utilitarian manual-shift mode is just as crisp in the 6L90E as it is the 6L80E.

I’ve not been shy about my disappointment in the half-ton Vortec Max. The VVT L76 takes its time to build power, and it leads me to believe the complaints about PCM software. I think the Max’s advantage is purely psychological, and that the four different incarnations of the 5.3L Vortec are collectively a fine engine. The LY6/2500 sounds much better, even if its response can be rather weird. It’s louder, meaner, and sportier sounding than the quiet Vortec Max. Like the other Vortec applications, most of the sounds come from the front, rather than the back, but I like their collective implications of refined power rather than flowmaster testosterone. The response of the LY6 is similar to the Max, but it asks for linear inputs. Sudden flooring can lead to bogging, just as with the Max. Part of that is the tranny’s program, and it’s reduced in Tow/Haul mode, but it’s not a hair-trigger by any means.

It’s worth a separate paragraph to mention that the classic GM truck “sticky-throttle” syndrome wasn’t noticeable in my test drive, and I was looking for it. A co-worker with whom I drove this truck was also looking for it, and he agreed. I’ve experienced the same improvement in the Yukon and Yukon Denali, and I’ve sensed the annoyance in the Vortec Max, but that’s just me. At any rate, I didn’t have any problem backing up in this 2500, nor have I in most of the new body-on-frame trucks. I’m hoping that the one Vortec Max was an anomaly.

One final note: we got our first LMM Duramax today. I was in cleanup when they pulled it in. I saw a big white HD crew, and thought it was an odd-sounding gas engine. I was listening for “diesel” sounds, and it took me several seconds before I could determine that it actually was the LMM. I’ve been surprised in the past at how quiet the successive incarnations of the Duramax were, but never to the point of wondering if it was a gas burner. Killer.

The Duramax was already sold, so I didn’t get to drive it, and I don’t know when I’ll get to drive one, but I’m already psyched. Frankly, I’m psyched about the new 2500HD, even if I have to be reminded of its utilitarian purpose.

Thank you for reading,

Ghrankenstein



Frame statistics (from gmfleet.com, sorry so crappy!):

Vehicle YS SM RBM

’07 1500 Classic 40k 3.430 137,200

’07 1500HD Cls 40k 5.162 206,500

’07 1500 60k 4.397 226,000

’07 2500 HD 40k 6.519 260,800

YS: Yeild strength, psi

SM: Section modulus, cubic inches.

RBM: Resistance bending moment, YS times SM (lb/inch)

[mbukukanyau]

Did you take pictures of the truck?

[telo]

Sounds good, hope you have some pictures.

[redimpss5]

I hope that new tranny makes it into the van with the d-max.

[BerettaZ]

Thanks for the nice review. The work truck seats, when I saw them on the base model 1500 Sierra, were impressive to me as well. You're right - the 2 tone, durable cloth looks and feels very upscale for a work truck.

[bone]

I thought the HD's had an Allison 6-speed option. Is it still available?

[bowtie8_3]

The 6 speed Ally is only on the Duramax trucks. The 6 speed in this article is teamed up with the 6.0L gasser.

[Al465]

Originally Posted by mbukukanyau

Did you take pictures of the truck?

It's strange how some people are reacting to front wheel drive cars today. I remember when Japan came out with FWD many years ago and GM was criticized for being too slow in converting from FWD to RWD. Today it's just the opposite. GM is being criticized for not converting from FWD to RWD fast enough. It's to show some people don't know what there talking about.

[Big Dog]

We got our first C-Cab Diesel about 2 weeks ago. I have driven it by myself but yesterday I took a test drive with a customer who pulled up in a 1-Ton Dodge, he just came from a Dodge store. He was very impressed with our truck. He raved about the interior, the dash, the power and couldn't believe how quiet this truck is. This new HD is great and we've got a tremendous truck to sell.

[DanDaSalesMan]

I had the opportunity of driving a 2500HD Silverado with the Duramax/Allison combo and all I have to say is WOW!

[mikest00]

Originally Posted by BerettaZ

Thanks for the nice review. The work truck seats, when I saw them on the base model 1500 Sierra, were impressive to me as well. You're right - the 2 tone, durable cloth looks and feels very upscale for a work truck.

I was also very impressed with the work truck seats. I also had a chance to drive a new 2500 with the duramax/allison with 4 wheel drive and it had no problem smoking a four wheels!! One bad a$$ truck!! I know I should've taken pictures, but if anyone gets a chance to see the 2500HD with the duramax check out the tail pipe (after you've drooled over everything else). You can fit you whole foot in it!!

[pontiacfan]

We have 12 cab and chassis 3500's in stock a regular cab SLE 2500 and and ex cab SLT. All diesels and the latter two being 4x4's. All I can say is wow! They are so quiet so nice to drive its unbelievable. I definitely know what I'm driving for a demo next year. All are GMC's by the way. On the interior graphite is the only colour to get We have been having alot of complaints of the tan and light Grey staining to easily. We have some very dissatisfied customers over this. We will only be ordering graphite for stock.

[88montess]

Originally Posted by DanDaSalesMan

I had the opportunity of driving a 2500HD Silverado with the Duramax/Allison combo and all I have to say is WOW!

We've had Two LMM trucks in both in LTZ trim, Ive been able to drive both of them. At a stop light I started to roll off the line at about 15-20mph I decided to floor it, the rear wheels immediately began spinning and the rear floated to the right. What fun!! One of them is going to a company that already has a 08 Ford after 3 weeks in the ford they are not happy with it, they are excited to run this truck with it for awhile and get good feedback.

Also we just finished in stalling a 6 inch Pro-comp Lift on the first LMM with beefy 18 inch wheels, WOW WHAT A TRUCK!! the owner owns a diesel performace shop so we'll be getting some great feedback from him. By the way that big chrome bumper looks good 6 more inches in the air..

[Highlander]

Awesome review and insight... Thanks! I appreciate the clarifications on the updated frame, and the suspensions set up.

Also, I never heard of the sticky throttle syndrome until I started experiencing it on my 2002 2500HD with the 6.0 a few weeks ago. And I didn't realize what it was until I had it fixed last week with a throttle plate cleaning and adjustment. I thought is was just a sticky linkage when it started recently. Based on your review I guess this is a common issue that somehow slipped past my attention. Thanks again for the info!

As a side note on the sticky throttle, I did read about GM changing the PCV valve, some hose routing, and the throttle by-pass to keep crud from building up around the throttle plates on the previous Vortecs. Maybe they now have it perfected? Although it did take 75,000 miles before mine developed the stick.

EDIT: Here's some info on the old throttle stick and GM's "fix" (sorry, I know I'm on a tangent here)
http://www.mightyautoparts.com/pdf/articles/tts1003.pdf

[HoeyHimself]

Great write up. Ideally, I would like to see myself in a new 2500HD Duramax 4x4 within the year...and much of my concerns have been whether or not I should wait untill the next year to purchase because of the changes that will be made. Ofcourse I dont doubt the competency of the 800's frames..and I know that GM wasnt going to leave it completely untouched when they brought out the new 2500 and 3500..but ya kinda always want to get the newest and greatest if you can. While I cant say I will use every bit of the 2500HD's diesel potential..I do know that I will be in many situations that the 1/2ton wont cut it, even with the 6.0l(which I think is a strong motor.) I havent been to the dealership lately to look at their stock of HDs yet...but I am anxious to hear the Duramax at idle and with a little bit of throttle..I like they way a diesel sounds, but I dont nessecarly love the way diesel sounds..so any bit of toned down grumble will be accepted from me. I almost wanted to laugh when you said that a major magazine said it handled like the 1/2ton..laugh because I believed that someone thats supposed to be credible enough to write for a magazine would say that, sometimes I really question the authors that are supposed to be such authorities. It's no doubt that a 2500 or 3500 wouldnt and shouldnt feel like a 1/2ton..honestly, there is more credible feedback from guys who do evaluations such as yourself often times. The 6L90E is sounding pretty good...and I like what you said about it being a tool, because thats what it has to be, in the HD models they need to put a kevlar vest up on the drawing board and just say "We need to make this thing bullet proof..make it happen!" Because at the end of the day, thats what makes these trucks the nessecary pieces of equipment that they are..these trucks allow guys to pay the bills and put food on the table..you see a guy in a 3/4 or 1ton truck that he uses for work, and he has no resentment for the large sticker price and often times not even for the gas it guzzles..most of the time they will tell you that the truck pays itself off and then some by providing them a tough work horse that can make the cut when they need it most on the job site.

Again, great write up, and hope to hear something when you can get your hands on a diesel!