Yup, they've used the aluminum driveshaft in the duramax since 01 in crew-cab short beds - Quite a few switch to a custom aluminum one for weight savings (I want too say the steel version weighs close to 40lbs or so). They're also fairly strong, guys are running well over 1700ft lbs. with them; but those are 5inch diameter shafts.
How are you measuring your mileage? I'd ponder if the trip computer is off or getting tripped up. The only logical sense I could think of is driving in 4x4 or AWD unloads the control arms bushings a bit and changes the tire alignment (your alignment may be off, but I can't imagine it being 1-3MPG penalty off) - the front tires are being pushed when in RWD mode and GM set the alignment to compensate for this vs. when in AWD or 4WD the front is also pulling. Also, you're unlikely to experience any problems within the warranty period driving in auto 24/7, the cases and clutches are much more robust than people on the forums give them credit for. A lot of the bad tastes comes from the earlier autotrac cases, specifically the np246 - which the earlier versions of that case would cause grief driving it in 2wd (eats encoders, motors burned out, clutch clearances were set incorrectly by rebuild shops, pump rub, etc.). The 3023 doesn't have those issues and is 100x more intelligent.
Ehh, a lot of mis-information here. Fwiw, GM uses a Magna-Steyr 3023 in the Silverado/Sierra. It is a selectable system between Active AWD, part-time 4WD, 2HI, 4LO and neutral - this is straight from the manufacture of the transfer-case - Magna. It's also known internally to them as the Ultimax chain drive 2-speed active transfer case. During 4auto the torque is modulated by a software which they call "Diff-Mimic active torque control", it varies torque based off wheel slip, steering angle and throttle input - according to their literature (which is a bit in layman's terms in comparison to how the system is actually programmed). During 4auto operation, the TCCM reads data from the bus like: wheel speed sensors,vehicle speed, brake pressure, yaw rate sensor, steer wheel position sensor, any information relating to stabilitrak or traction control activation and throttle % from my memory. From there it compiles that data to determine torque bias rates. A variable bias from about 98%R/2%F to 50%R/50%F. So any regards to saying the system shoots to 50:50 anytime there is slip is incorrect - First off, that would be incredibly harsh on several mechanical parts and induce more NVH to the passengers (think dropping a clutch in a manual car); second off, the motors used to activate the clutches would overheat (they can consume anywhere from 17-24 amps from what I've personally measured on 100% activation and they're not designed to shed that heat load rapidly). Also, the system is way more preemptive than you think. If you give it 100% throttle from a stop, you can watch the TCCM command the encoder motor to start modulating torque before there's any sign of discernible traction loss - Granted, I have to the tools at my disposal to watch the data. Personally, I don't see what the huge argument is here? It is a selectable system that has AWD as one of it's functions, it's way more advanced than using a mechanical means of differentiating like the Silverado SS (it doesn't use viscous coupler that requires traction loss to heat silicone to start working, nor does it require brake biasing from the EBCM like the older denali/escalades) . Heck, most AWD cars now use an electronic or electro-hydro means to control a biasing clutch unit: BMW, Cadillac, Nissan GT-R etc., mechanical differentiating is antiquated in a transfer case to be frank and rare in new production cars. Then you can lock it in 4x4 (100% clutch activation and the motor brake is on) for off-road etc and have 4low... Now, why didn't GM label it AWD, no idea. I would imagine that they want to reduce the chances of customers running in AWD 100% of the time for warranty claims. The 3023 is used in certain Jeeps; however, that unit is only AWD,4H, 4LO and N, but it also allows the driver to select different biasing profiles: snow, sport, off-road, etc. They do have a few minor internal differences in the form of bearings, one of which is part of the clutch system which I know GM uses a lower quality bearing - which could be one of the reasons. Fwiw, I also have a custom NP246 autotrak that I have in my duramax which has around 1k FT.LBS. of torque and weighs 8200 pounds. I have a ton of miles on the case, it lives in 4auto and I floor that thing multiple times a day. So I have a bit of experience with these systems as I've taken them all apart and even done data bus hacking to modify crap for the hell of it.
Hmm, my truck was involved in a roll-over brand new and 2-rear ends later on and even 240k miles later no-one can tell which side it flipped, nor does it rattle. Granted, I bought it used (at a deep discount). As long as it's a good body shop, you'll unlikely be able to tell on a cab-over-frame design. I would be sure to inspect the truck during the repair process. Now a sub-frame car, 9/10 I can tell when one has been wrecked. They almost always drive "twitchy" or have a noticeable handling "detail" to them.
That's off a ways, I can get a new one for under $1500 from the dealer and I could get a full rebuild kit for under $400, clutches are under $150 IIRC. Then if you really want to go at it, Alto makes higher capacity clutches too - part#126710 While you're in there replace the ball bearings in the apply arms with 3x 10mm G16 carbon steel ball bearings.
I liked auto; I used it anytime I decided to accelerate briskly, or there was the slight possibility of rear traction loss (rain, sleet, etc.). 4x4 was always reserved for snow, sand, or any condition in which you're constantly engaging and disengaging the clutch pack. Also, certain Jeep models exclusively use the MP3023 - the same transfer cases as the Silverado. However, their's only provides Auto4wd and 4x4Low - there isn't an option for setting it to 2wd. In fact, SRT8s use another similar transfer case: MP3010 and vectors thrust between the front and rear with the same clutches as the 3023 - so they're very robust transfer cases. IIRC, the Silverado's are similar in logic to the Jeep's too; in that it will also monitor throttle input and predict traction loss. Hence, when you floor it from a stop, you don't get the bang or sudden engagement feel of the older NP246s in the 99-06 models. Auto will diminish a bit of economy as well; as it engages the collar in the front differential and that in turn will cause the front drive-shaft, output gear, and chain to turn (30-50bs of extra rotational force); then the clutches will pre-load to roughly 5-10% of their torque capacity, which will increase with loss of traction and finally higher vehicle speeds. 4x4 and 4x4Low will do the same fashion as above; however, the clutches will engage to max torque capacity and the transfer case encoder motor will engage the motor brake to lock it into it's position. Simple put: I wouldn't use it 24/7 on dry concrete due to a bit lower economy and frankly, it is a little bit more of wear and tear. But that said, I wouldn't be afraid of using it when I want and/or need more traction. Especially, when it is as simple as turning a knob for the appropriate situation.
TM is for driveline protection - It reduces the sudden loading of parts experienced during torque requests. E.g., gives time for full clutch engagement, etc.. The biggest use is for longevity of stock parts using lesser materials or design. Not saying that won't last without TM, but you'll reduce the service life without it. In the diesel world(Duramax), little difference has been found between turning off TM/defuel - At least not big enough to reduce the longevity, even with high capacity clutches or builds. Some lag can also be attributed to a GM tcm programming to allow line pressure to build off idle as well (Although, I can't say how the TCM is programmed in this application): being that the 6l90 is a clutch-to-clutch, I fairly positive it must go into defuel during the clutch hand-off, similar to an allison 1000 too.
Pulling a 5th wheel is beyond me with a 1500. I find it very doubtful you'll find a trailer that won't exceed the tongue weight once loaded(Most 5th wheel weigh more than a 1500 empty). Buy a 2500 or 3500, they're not that much more expensive and a lot safer for you, your family and others on the road. Simply put: You have the wrong truck for that job.
It's a collar that slides onto a shaft that engages the front differential, didn't mean to give the impression the it locks as in a locker differential. Engagement would have been a better choice for wording on my part. Binding does occur in 4x4 systems from spreed differences between the front and rear set of tires. The awd and auto4wd system allows a speed difference while 4x4 does not. Auto applies 5% torque to the front as soon as you turn it on, then up to 25% during highway speeds and will vary up to 50% during traction loss.
While I wouldn't drive in auto 24/7, as it causes the front differential to lock with the passenger side - increasing rotational resistance in the driveline, hence lower mileage. You won't hurt anything turning it on for play, rain etc. The mp3023 is a very stout case, it's used in several jeeps for full time intelligent awd and several performance lines. In fact, their's go through much higher stresses than what the GM TCCM commands of. E.g., performance based biasing 20/80, 30/70, 40/60. The only difference mechanically is the clutch plate has bearings that reside in ramps. Jeep's are 100% duty while GM's are not, leading to the occasional bearing failure after 50-100k miles of auto 24/7. If you want to run auto 100% of the time, these bearings should be replaced with stronger units. On my 2500 I have a MP3024 that is heavily modified(bearings, added clutched and chain) to cope with 1400fts lbs daily; not worried one bit about it if I want to run it in auto 24/7.
NICE! How would you rate the output compared to JL13.5 or 2 10s sealed? Do they have good subsonic impact(feel the bass in the chest/nose, lol)? I was debating 2-3 of those or 2-3 Stereo integrity BM IV's.
Most OnlineNewest Member
Who's Online 93 Members, 1 Anonymous, 526 Guests (See full list)
- Scooter Scott
- CNC Repairman
- Edwin Funes
- dodge stomper