# New GMC Truck



## knpc (Oct 22, 2009)

I traded in my 2009 GMC 2500HD ext cab with 100k on her. I got a 2013 2500HD crew cab with plow prep, heavy duty trailering/suspention package, and locking diff. I still have a few things to swap over, my towing/camper mirrors and strobes. We are supposed to get a few inches here tomorrow so I'll get a chance to try her out. hopefully it serves me as well as the the last truck.

Kevin


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## knpc (Oct 22, 2009)

Have you guys been turning up the t-bars on these new trucks ? I put 3-4 turns on my 09 but this one seems to handle the plow a little better


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## tuney443 (Jun 25, 2006)

knpc;1606230 said:


> Have you guys been turning up the t-bars on these new trucks ? I put 3-4 turns on my 09 but this one seems to handle the plow a little better


Yes,it most definitely will handle your plow better with that new beefy front axle rating and heavier frame.Nice ride.


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## bswalks (Dec 9, 2010)

Nice truck. I'm looking at the same thing, but I need a long bed.


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## maverjohn (Jul 23, 2008)

Nice Truck !


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## Cover Guy (Sep 30, 2009)

knpc;1606230 said:


> Have you guys been turning up the t-bars on these new trucks ? I put 3-4 turns on my 09 but this one seems to handle the plow a little better


I haven't touched mine it does just fine


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## 32vld (Feb 4, 2011)

knpc;1606213 said:


> I traded in my 2009 GMC 2500HD ext cab with 100k on her. I got a 2013 2500HD crew cab with plow prep, heavy duty trailering/suspention package, and locking diff. I still have a few things to swap over, my towing/camper mirrors and strobes. We are supposed to get a few inches here tomorrow so I'll get a chance to try her out. hopefully it serves me as well as the the last truck.
> 
> Kevin


Don't you mean a limited slip rear differential?


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## knpc (Oct 22, 2009)

No, I meant automatic locking rear differential 
At least that's the term GMC uses for the option


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## jmac5058 (Sep 28, 2009)

Its called a G-80 locking rearend , limited slip is so 1980s.


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## trevier (Dec 24, 2007)

If you don't mind me asking how much did you get for your trade it? My 07 classic is over a 100k and I'm thinking of doing the same thing.


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## unhcp (Jan 20, 2010)

very nice truck!


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## FF/P215 (Dec 5, 2012)

Nice truck, congratulations.. good luck with it, hopefully it does end up snowing here at some point!!


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## 2006Sierra1500 (Dec 28, 2011)

Its snowing now! Very nice truck. I wouldn't touch the bars, it'll hold the plow way better with the new suspension.


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## ceptorman (Nov 30, 2011)

Nice looking truckThumbs Up
If you have worked it yet, can you tell if it's stronger than your other truck?


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## knpc (Oct 22, 2009)

trevier;1606415 said:


> If you don't mind me asking how much did you get for your trade it? My 07 classic is over a 100k and I'm thinking of doing the same thing.


They gave me 18k for my old truck. The new truck had an msrp of $44,500 and I got it for $36,500, thought I got an okay deal. Always get a little screwed on trade ins, but its worth it to me not to deal with the hassle of selling it myself.


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## knpc (Oct 22, 2009)

Thanks for the compliments guys. I like it so far and it does seem to handle the plow better, though I just had it on driving back from the dealership. It certainly doesn't squat much when the plow is raised.


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## mikes-plow (Feb 26, 2011)

2006Sierra1500;1606535 said:


> Its snowing now! Very nice truck. I wouldn't touch the bars, it'll hold the plow way better with the new suspension.


AGREED, my boss has an '11 2500 hd crew cab with d-max and a 9'6" x-fisher v and hasnt touched the t-bars. truck doesnt even flinch when he picks the plow up


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## 32vld (Feb 4, 2011)

jmac5058;1606413 said:


> Its called a G-80 locking rearend , limited slip is so 1980s.


Does is still have clutch packs?

Does it still allow the rear wheels to be unlocked aka slip?

Then it should not be called a locked rear.

Jeep has a rear that you lock it stays locked. It will not slip.

Now if GM wants to call their "automatic lock up rear" means the rear will automatically lock and unlock without driver input, then all GM did was find a new name and a new way to sell their limited slip rear.


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## vegaman04 (Dec 12, 2007)

32vld;1608131 said:


> Now if GM wants to call their "automatic lock up rear" means the rear will automatically lock and unlock without driver input, then all GM did was find a new name and a new way to sell their limited slip rear.


Limited slip differentials are considered a compromise between a standard differential and a locking differential because they operate more smoothly, and they do direct some extra torque to the wheel with the most traction compared to a standard differential, but they are not capable of 100% lockup.

So; Auto Locking Rear > Limited Slip > Open.


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## 32vld (Feb 4, 2011)

vegaman04;1608184 said:


> Limited slip differentials are considered a compromise between a standard differential and a locking differential because they operate more smoothly, and they do direct some extra torque to the wheel with the most traction compared to a standard differential, but they are not capable of 100% lockup.
> 
> So; Auto Locking Rear > Limited Slip > Open.


I know the answers to my questions.

To say locked means locked. To say open means open/never locks ups.

Whether GM decided that limited slip name needed to be replaced with auto lock it still is a limited slip rear. Hence yellow advertising. Nice truck the OP got but still playing word games on GM's part.


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## 32vld (Feb 4, 2011)

I rewrote my post and reposted because the site wold not let me edit.



vegaman04;1608184 said:


> Limited slip differentials are considered a compromise between a standard differential and a locking differential because they operate more smoothly, and they do direct some extra torque to the wheel with the most traction compared to a standard differential, but they are not capable of 100% lockup.
> 
> So; Auto Locking Rear > Limited Slip > Open.


I know the answers to my questions.

To say locked means locked, and will stay locked even when turning.

To say open means open/never locks ups.

Whether GM decided that limited slip name needed to be replaced with auto lock name it still is a limited slip rear. Hence yellow advertising. Nice truck the OP got but still playing word games on GM's part. Because both names use clutch packs, both names are locked when the truck is going in a straight line and will unlock on their own when the wheels want to turn at different rates as when making a turn.

When a Jeep Rubicon is going down the road it is an open rear. However when the locker is activated the wheels stay locked whether going straight, turning, sideways, backwards, or up side down.


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## knpc (Oct 22, 2009)

I do know there is a difference between the GMC automatic locking diff and a true locking diff, but its good to clarify it for everyone reading. I had a jeep about ten yrs ago that I had lockers put in, that was a true locking differential. It didn't like turning on dry pavement but was great on the trails. As this is a plowing forum, the gmc version of a locking diff is better than what comes as standard equipment on the truck and gives me more traction. That's what its all about in the end, pushing snow and not getting stuck.


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## 2006Sierra1500 (Dec 28, 2011)

Idk but on my 2011 1500, turning around in my driveway definitely locks the diff.


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## scott3430 (Dec 28, 2010)

Nice new 13' GMC! White is the best color imo. Are you going to install Timbrens in the front end?


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## jmac5058 (Sep 28, 2009)

A G-80 totaly locks up when it detects one revolution of slippage in a single tire. Once locked it is exatly like a posi untill disengauged. You can do a posi brake stand and when truning sharply on dry pavement they bind like being in 4x4. It goes from open diff to posi automaticly. It is NOT limited slip it is NOT limitred slip with a new name it IS a true locker that locks up on its own . Ten times better than limited.


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## bswalks (Dec 9, 2010)

knpc;1606578 said:


> They gave me 18k for my old truck. The new truck had an msrp of $44,500 and I got it for $36,500, thought I got an okay deal. Always get a little screwed on trade ins, but its worth it to me not to deal with the hassle of selling it myself.


That seems like a descent price, but I'm not really sure, since I've only really been shopping for a regular cab. What dealer did you buy from & does the truck have any other options besides what you listed in your initial post? Was the plow included in that price? 
Btw, I agree. Selling on your own can be a real hassle, at least in my experience.
I prefer to lose a little $ and just trade.


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## 32vld (Feb 4, 2011)

jmac5058;1609865 said:


> A G-80 totaly locks up when it detects one revolution of slippage in a single tire. Once locked it is exatly like a posi untill disengauged. You can do a posi brake stand and when truning sharply on dry pavement they bind like being in 4x4. It goes from open diff to posi automaticly. It is NOT limited slip it is NOT limitred slip with a new name it IS a true locker that locks up on its own . Ten times better than limited.


Well after doing a second longer google search I now know a lot more about the G 80.

However the internet has shown that G 80 is used for limit slip and eaton auto lock.

I can not find what year limited slip was no longer offered as an option and what years eaton auto lock have been available to determine what rear end one's truck has by just looking at the option code sticker in the glove box.


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## knpc (Oct 22, 2009)

scott3430;1609748 said:


> Nice new 13' GMC! White is the best color imo. Are you going to install Timbrens in the front end?


The truck handles the plow great, barely squats when the plow is lifted. But I think I'll still put timbrens in to take some of the wieght off the suspension and transfer it to the frame. I had them on my last truck, they work great.


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## knpc (Oct 22, 2009)

bswalks;1609915 said:


> That seems like a descent price, but I'm not really sure, since I've only really been shopping for a regular cab. What dealer did you buy from & does the truck have any other options besides what you listed in your initial post? Was the plow included in that price?
> Btw, I agree. Selling on your own can be a real hassle, at least in my experience.
> I prefer to lose a little $ and just trade.


The truck has a few options
- it's an SLE crew cab / reg box
- preffered package- power seat/ stering wheel controls/ ez lift tailgate/ dual climate control
- plow prep - bigger alternator/ higher front end weight capacity
- heavy duty trailering/ suspension package - locking diff/ hitch receiver/ 7 pin/ trailer brake control/ bigger rear springs I believe
- back up camera (didn't want this, but it came with the truck)


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## bswalks (Dec 9, 2010)

I priced a regular cab, it was about 30 with all plow prep, hd trailer pkg, dual batteries & upgraded interior with power locks etc. Plow included. That seemed like a descent price


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## 2006Sierra1500 (Dec 28, 2011)

knpc;1610184 said:


> The truck handles the plow great, barely squats when the plow is lifted. But I think I'll still put timbrens in to take some of the wieght off the suspension and transfer it to the frame. I had them on my last truck, they work great.


I bet it won't touch the Timbrens. Your 09 had a much, much, much, much(insert 10,000 more "much"s here) weaker suspension and frame compared to this new truck. I've seen Duramax 2500HDs with the 6k front drop an inch with a 9'6'' Extreme V(1013 lbs). Theres one here somewhere.


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## BigLou80 (Feb 25, 2008)

jmac5058;1609865 said:


> A G-80 totaly locks up when it detects one revolution of slippage in a single tire. Once locked it is exatly like a posi untill disengauged. You can do a posi brake stand and when truning sharply on dry pavement they bind like being in 4x4. It goes from open diff to posi automaticly. It is NOT limited slip it is NOT limitred slip with a new name it IS a true locker that locks up on its own . Ten times better than limited.


I don't know about the 1 revolution part, but both the 02 and the 04 ( DMax Dually) lock up when you hit the pedal, they will hop around corners until you disengage it.


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## jmac5058 (Sep 28, 2009)

BigLou80;1610572 said:


> I don't know about the 1 revolution part, but both the 02 and the 04 ( DMax Dually) lock up when you hit the pedal, they will hop around corners until you disengage it.


Ok mabey not 1 revolution , but it locks after detecting slippage.


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## 32vld (Feb 4, 2011)

My in depth google research has show that once one wheel is spinning 100 rpm s faster then the other wheel centrifugal weights engage and lock both wheels. They will stay locked under 20 mph.

There is a second set of weights that will disengage the system at 20 mph.
You are going 20 mph you do not need a locked rear.

However if the system is locked an you have the pedal to the floor and the drive train is under load it can delay the disengage mechanism from unlocking the rear.

People trying to do long distance burn outs have known to blow these rear's because they are not designed for such use. They are designed for low speed traction to get the auto out of a bad traction area.

The problem is finding out the change over for the G 80 code.

G 80 some years means a lmited slip, and other years automatic lock up.


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## jmac5058 (Sep 28, 2009)

Oh , so its not a renamed limited slip like you were boasting ?


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## trevier (Dec 24, 2007)

you got 18k for an 09 with 100k on it, holy ****e my friend. If I could get 18k for mine I'd trade it in a heartbeat. Mine's an 07 classic model 1500 ext cab z71 4x4 in excellent condition. man this has me thinking,,,,


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## B&B (Nov 4, 2006)

32vld;1610102 said:


> Well after doing a second longer google search I now know a lot more about the G 80.
> 
> However the internet has shown that G 80 is used for limit slip and eaton auto lock.
> 
> I can not find what year limited slip was no longer offered as an option and what years eaton auto lock have been available to determine what rear end one's truck has by just looking at the option code sticker in the glove box.


1973 through 1976 was the changeover years from the spring loaded clutched Positraction LSD's to the Gov-Locks. The RPO designation never changed as it was used as a blanket reference to any traction adding differential option regardless of what they actually were. Hope that helps.


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## 32vld (Feb 4, 2011)

B&B;1614531 said:


> 1973 through 1976 was the changeover years from the spring loaded clutched Positraction LSD's to the Gov-Locks. The RPO designation never changed as it was used as a blanket reference to any traction adding differential option regardless of what they actually were. Hope that helps.


Thanks for the info. So I thought I had a limited slip in my 01 GMC Suburban. Then I have had an Auto lock up all along. Though I don't remember both wheels locking up when traction was lost.

With limited slip with both rear wheels off the ground when one wheel is turned the other will turn with it.

Where both rear wheels jacked off the ground then an Auto Lock when one wheel is moved the other wheel will stand still, being not enough movement to cause the centrifugal weights to engage the lock up mechanism?


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## B&B (Nov 4, 2006)

32vld;1614763 said:


> With limited slip with both rear wheels off the ground when one wheel is turned the other will turn with it.
> 
> Where both rear wheels jacked off the ground then an Auto Lock when one wheel is moved the other wheel will stand still, being not enough movement to cause the centrifugal weights to engage the lock up mechanism?


Correct except just like an open diff when you turn one wheel the other will turn in the opposite direction when the driveshaft is held stationary (in park). This is why it's difficult to identify whether it's equipped with an open or Govlock diff based solely on this test. Because it closely mimics an open diff for that test. So it's still best to pull the cover and look for 100% verification either way.

And I hope Kevin is interested in some of this discussion because it is his thread after all, and we're a little off track even though we're not in the pic forum. Sorry Kevin.


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## 32vld (Feb 4, 2011)

Next time I have both rear wheels off the ground I will have to check.

I am not pulling off the cover. Never fix what is not broken. Though I am sure if I drive by the dealer and show them the vin they can tell me whether LS or AL. And the option label says G80.

I live on a hill. Years past with the road covered in snow I drove up the hill just to see if I could get up without 4wd. Sometimes I have, sometimes the rear alone failed so then 4 Hi to the rescue.


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## B&B (Nov 4, 2006)

32vld;1615569 said:


> Though I am sure if I drive by the dealer and show them the vin they can tell me whether LS or AL. And the option label says G80.


As mentioned a GM truck hasn't been available with a clutch type LSD since 1976 and thus having a dealer run a line ticket check will simply state "auto locking differential". So I assure you an '01 has a Gov-loc.

Sometimes they just work better than other times- and sometimes they don't work at all.


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