What raises the GM 2500HD tow rating to 13k besides 4.10's ?

[calsdad]

I've searched all over the internet trying to figure this out and thought somebody here might know the answer to this question:

The trailer weight rating for the GM GMT900 generation (2007-2014) 2500HD and 3500HD pickups with the 6.0L gas engine (Silverado or Sierra), go from anywhere in the 9000-9700 pound range ( varies depending on body style).

It lists the trailer weight rating for the 4.10 ratio as 13k pretty much across the board.

You can pull the specs from page 10 of this brochure:
http://www.chevrolet.com/content/dam/Chevrolet/northamerica/usa/nscwebsite/en/Home/Help%20Center/Download%20a%20Brochure/02_PDFs/MY13%20Silverado%20HD%20eBrochure.pdf

So the question is: What else (if anything) changes on the truck to increase the trailer weight capacity to 13k besides the gear ratio?

I've searched high and low trying to figure this out and asked a few GM guys I know and nobody can give me the technical details.

From what I can tell searching thru parts suppliers - it doesn't look like there is any bigger brake option. The part numbers for front and rear rotors on all Chevy 2500 & 3500 pickups and the 2500 series SUV's - are the same.

There are slight ratings differences in the HP and torque between the 6.0L in the trucks and the 2500 SUV's - but no published difference for the extra tow capacity.

I did find a listing for an electric cooling fan setup for "enhanced tow package" for the 6.0L trucks. I know the standard setup is an engine driven fan.

The 2500HD pickups and the 2500 SUV comes with the 6L90 transmission, so there's no bigger transmission to go to except for the Allison - and only the diesels get those now.

So is that all it is? Is there just some extra engine cooling in the form of electric fans and the 4.10 ratio in drivetrain?

[calsdad]

mowermech wrote:


That is not entirely true.
There ARE shops out there which are "licensed upfitters". They have the engineering staff (often one engineer) to certify changes to
ANY rating on a truck. They can and will install suspension parts, gearing, etc. to allow heavier loads to be carried or towed. They can replace the factory ratings sticker with a new one.
Of course, the GCWR and/or towing rating are seldom on the sticker anyway. On all the trucks I have owned, it is a rating that only appears in the Owners Manual.
It seems to be a "numbers game" that the manufacturers use so their marketing departments can say "WE are the best!"

I did some searching and found a list of certified GM upfitter companies. There was one listed here in MA that is reasonably close to me. At some point I may inquire with them about what exactly has to happen for them to apply a rating to a vehicle.

In the meantime - I've got a hitch coming tomorrow. I found a B&W that should fit or I should be able to make it fit.

[calsdad]

APT wrote:
Congrats! The 3/4 ton GMT900 SUVs are great!

The 3/4 ton SUVs are not basically the 2500HD with SUV body. The frame is a lot stronger on the pickups. The wheelbase is 14" longer for extended cab/short bed or 23" longer for crew can short bed. The axles are rated higher as well as the wheels.

Now the GMT800 SUVs had tow ratings as high as 12000 pounds with GCWR of 18k pounds I believe. That used the same/similar axles and wheels as the GMT900 SUVs. With the 6-spd, I don't think you'll notice much performance difference between 3.73 and 4.10. You'll be stuck in 4th gear most of the time anyway at 8000+ pounds anyway. If you want to make driver noticeable changes, get 4.56 gears, a Black Bear Tune, OEM-clone towing mirrors, and that receiver. I think you'll want a premium WDH (Hensley/Propride) along with the custom receiver. Someone posted a great thread on adding a second receiver to his GMT900 Suburban/Yukon XL. I'll try to find that.

Here you go.

Thanks for the link. I've seen setups where people have added an additional receiver to the GMT900 SUV's. There's a place out of Florida that does Duramax conversions on the GMT900 Suburbans and Yukons and they've got a Youtube video showing an additional receiver added to one of their conversions. That thread looks good - I'll read thru that.

Adding an additional receiver is (I hope) the solution I am going to go with. I found a receiver I hope will fit this Yukon, there's some rearrangement that needs to happen to get any additional receiver to fit in I think. I'll know better when I have the receiver in hand and have time to scope out how it will fit.

I've seen the frame issue brought up a number of times in other forums. And the first thing to bear in mind is the thing you pointed out: the GMT800 could be had in a version with a 12k tow rating (this was the 8.1L engine with the 4.10 rear BTW). So the frame in the GMT900 should good for at least that.

The other thing to bear in mind when comparing the SUV with the pickup - is that the pickup is basically "split" in the middle. There is absolutely no overall chassis stiffness to be added by the body. So the frame must carry all the weight and torsional forces on the chassis. In the SUV - the body itself adds to the overall strength of the vehicle chassis because it is one piece.

I think a lot of people forget that.

So I think it is reasonable considering those two factors - to think that the 2500 series SUV with the right components could easily be capable of towing 12-13k.

The Yukon XL I have - has the same HD wheels as the pickup truck. The 2500 series SUV's have always had the same wheels as the HD pickups. My 2003 has the chrome 16" wheels that came on all the GM 2500/3500 pickups of that era.

If you look at the Chevy brochure for the Suburban it lists a wheelbase of 130 inches.

A regular cab GMT900 Silverado/Sierra with the long bed is 133" wheelbase.

The max trailer weight for the regular cab is still listed as 13k in the GMC and Chevy brochures.

The regular cab long bed pickup weighs in at 5,556 lbs according to the specs I can find.

A 2500 series Suburban/Yukon XL weighs in at 6,551 lbs.

Does 3 extra inches on the wheelbase trump 1000 extra pounds for making a more stable towing platform?

[mowermech]

edatlanta wrote:
I think we have two questions here. One involves the tow "rating" of the truck and the other is the "capacity" of some of it's "components". While components can be changed that are stronger, etc. than original, it is my understanding that the tow "rating" of a particular truck can not be changed. It is what was the day it left the factory and no changing of parts will change that original rating.

That is not entirely true.
There ARE shops out there which are "licensed upfitters". They have the engineering staff (often one engineer) to certify changes to
ANY rating on a truck. They can and will install suspension parts, gearing, etc. to allow heavier loads to be carried or towed. They can replace the factory ratings sticker with a new one.
Of course, the GCWR and/or towing rating are seldom on the sticker anyway. On all the trucks I have owned, it is a rating that only appears in the Owners Manual.
It seems to be a "numbers game" that the manufacturers use so their marketing departments can say "WE are the best!"

[APT]

calsdad wrote:

The reason why I'm asking this is that I just picked up a 2010 GMC Yukon XL 2500. Which is basically a 2500HD with an SUV body. It has the same 6.0L engine and the 6L90 transmission as the 2500HD pickup. I believe the rear axle is the same also.

Congrats! The 3/4 ton GMT900 SUVs are great!

The 3/4 ton SUVs are not basically the 2500HD with SUV body. The frame is a lot stronger on the pickups. The wheelbase is 14" longer for extended cab/short bed or 23" longer for crew can short bed. The axles are rated higher as well as the wheels.

Now the GMT800 SUVs had tow ratings as high as 12000 pounds with GCWR of 18k pounds I believe. That used the same/similar axles and wheels as the GMT900 SUVs. With the 6-spd, I don't think you'll notice much performance difference between 3.73 and 4.10. You'll be stuck in 4th gear most of the time anyway at 8000+ pounds anyway. If you want to make driver noticeable changes, get 4.56 gears, a Black Bear Tune, OEM-clone towing mirrors, and that receiver. I think you'll want a premium WDH (Hensley/Propride) along with the custom receiver. Someone posted a great thread on adding a second receiver to his GMT900 Suburban/Yukon XL. I'll try to find that.

Here you go.

[calsdad]

blt2ski wrote:

edatlanta wrote:
I think we have two questions here. One involves the tow "rating" of the truck and the other is the "capacity" of some of it's "components". While components can be changed that are stronger, etc. than original, it is my understanding that the tow "rating" of a particular truck can not be changed. It is what was the day it left the factory and no changing of parts will change that original rating.

True, a vehicle stays true to its warranty rating no matter what you do the day after it leaves a dealers lot. BUT, one can still improve its ability by changing out parts. The dealer/manufacture does not have to honor that part with a warranty. OR if it is shown that the improvement broke or hurt another part doing what it is not expected to do.

BUT, it is no illegal to change the numbers depending upon the aftermarket fitting agent does. How it cam off the assembly line. In the OP's case, a burb is a finished product. If it were a cab and chassis rig, then one can add drop axels, tag axels, remove and replace springs tires etc to improve the gvwr rating. It is then up to the aftermarket body builder to certify the gvwr etc of the vehicle. Many times the C&C manufacture will not affix the gvwr sticker to the cab. So it sits in the owners owners manual as it does for my Navistar dumptruck. If pulled over, there is not gvw sticker on the drivers door!

There are ways around things. one has to know how to work around things. Some cases there is not.

Marty

I'm not sure if there is a way to "officially" change the tow rating of the truck or not. As I said earlier: the whole tow rating, axle weights, CDL or no CDL line of discussion seems to just be minefield topic with way too many *opinions* that make it hard to separate truth from fiction. I've read thru some of member Wadcutters comments about doing actual enforcement and see a whole bunch of other info and I'm still not clear what is what.

Be that as it may, my approach to this I think is simple: If GM thinks that a certain set of component upgrades on the 2500HD pickup is good enough to raise the tow rating from 9600 to 13k - then doing those same upgrades to a 2500 Series SUV should give a similar boost in capabilities. If the axle is smaller in the SUV - I'll upgrade the axle. If it's got any other components that are different, I'd do those too. If it's good enough for GM, then that is the best place to start IMHO.

The problem is: I can't seem to find out what other changes there *may* be.

I've considered myself a 'hot rodder' since I was a kid. Read thru magazines like Car Craft or Hot Rod and they will go into DETAIL on how you can take a run of the mill Mustang or Camaro or whatever - and add factory components to make it into the performance version of that same car. If there are major differences - they will let you know (sometimes there are very major changes, like different frames, different body panels, etc.)

I was hoping to figure this out in a similar fashion.

[transamz9]

rhagfo wrote:

Grit dog wrote:

transamz9 wrote:
The park pawl in the transmission has a part in what the tow rating is too. It's not all about what it can actually tow. For safety and legal purposes the truck has to be able to hold the load in park on a grade.

I'm sure it does......but really?
You can't be suggesting that 2 similar vehicles, same trans, have different parking pawls if the tow rating is different.

:S
I really doubt that there is any difference in the parking pral. People forget why their car still has a parking brake! I would never abuse my automatic transmission by depending parking pral to hold it in position especially with a trailer in tow!!

It angers me no end service shops that don't set the parking brake after servicing my truck!!!! :S

Whether right or wrong to not use the parking brake, park has to hold the load without the parking brake. The difference between 3.73 and 4.10 is a pretty big difference at the park pawl in the transmission.

[blt2ski]

edatlanta wrote:
I think we have two questions here. One involves the tow "rating" of the truck and the other is the "capacity" of some of it's "components". While components can be changed that are stronger, etc. than original, it is my understanding that the tow "rating" of a particular truck can not be changed. It is what was the day it left the factory and no changing of parts will change that original rating.

True, a vehicle stays true to its warranty rating no matter what you do the day after it leaves a dealers lot. BUT, one can still improve its ability by changing out parts. The dealer/manufacture does not have to honor that part with a warranty. OR if it is shown that the improvement broke or hurt another part doing what it is not expected to do.

BUT, it is no illegal to change the numbers depending upon the aftermarket fitting agent does. How it cam off the assembly line. In the OP's case, a burb is a finished product. If it were a cab and chassis rig, then one can add drop axels, tag axels, remove and replace springs tires etc to improve the gvwr rating. It is then up to the aftermarket body builder to certify the gvwr etc of the vehicle. Many times the C&C manufacture will not affix the gvwr sticker to the cab. So it sits in the owners owners manual as it does for my Navistar dumptruck. If pulled over, there is not gvw sticker on the drivers door!

There are ways around things. one has to know how to work around things. Some cases there is not.

Marty

[rhagfo]

Grit dog wrote:

transamz9 wrote:
The park pawl in the transmission has a part in what the tow rating is too. It's not all about what it can actually tow. For safety and legal purposes the truck has to be able to hold the load in park on a grade.

I'm sure it does......but really?
You can't be suggesting that 2 similar vehicles, same trans, have different parking pawls if the tow rating is different.

:S
I really doubt that there is any difference in the parking pral. People forget why their car still has a parking brake! I would never abuse my automatic transmission by depending parking pral to hold it in position especially with a trailer in tow!!

It angers me no end service shops that don't set the parking brake after servicing my truck!!!! :S

[TomG2]

I have owned three GM 2500HD's, two with 3.73 and one with the 4.10. They were nearly identical in real world towing capacity. Since you will be towing in 4th or 5th gear with any trailer over 6,000 pounds, the final drive ratio is not a big deal. GM must be using an archaic formula from the days when we towed with three speed manual transmissions. That's when it really mattered. 6th gear and an empty truck, the 3.73's got slightly better mileage.

[calsdad]

edatlanta wrote:
I think we have two questions here. One involves the tow "rating" of the truck and the other is the "capacity" of some of it's "components". While components can be changed that are stronger, etc. than original, it is my understanding that the tow "rating" of a particular truck can not be changed. It is what was the day it left the factory and no changing of parts will change that original rating.

Yes - that pretty much sums it up.

I've read thru far too many towing threads both on this site and on others and what happens is that they seem to inevitably devolved into a sheet show. With all sorts of conflicting opinions about when a CDL is required, what the "law" looks at when determining whether you're over-loaded , etc.

I was hoping one way to not have that happen - was to separate the questions. As you pointed out: there are at least two questions.

Because my experience with tow packages on vehicles goes back something like 35 years, I found it somewhat odd that GM would just publicize an increased tow rating of 13k and only call out the 4.10 ratio as the determining factor. I started searching to see if there was any mention of a tow package - and the only evidence I can find for that is (mentioned in an earlier post) an option for an electric fan for the "enhanced tow package".

So this is what lead to my question: is that all there is to it - just a gear change?

As far as the other question goes (whether the tow "rating" can be changed) - I don't think you can even begin to ask that question without answering the uprating of components question first.

[edatlanta]

I think we have two questions here. One involves the tow "rating" of the truck and the other is the "capacity" of some of it's "components". While components can be changed that are stronger, etc. than original, it is my understanding that the tow "rating" of a particular truck can not be changed. It is what was the day it left the factory and no changing of parts will change that original rating.

[Grit_dog]

transamz9 wrote:
The park pawl in the transmission has a part in what the tow rating is too. It's not all about what it can actually tow. For safety and legal purposes the truck has to be able to hold the load in park on a grade.

I'm sure it does......but really?
You can't be suggesting that 2 similar vehicles, same trans, have different parking pawls if the tow rating is different.

[Thunderbolt]

In the suv you won't have the 10.5" Full floating axle. You have the 9.5" semi floating axle. Not as strong as the full floater, but better than the 8.6" diff in the 1500's. The rear differential gearing in the suv is the only difference in the tow ratings of the suv. The 2500hd trucks are a different platform and have bigger frames than the suv's.

calsdad wrote:
With the Chevy 6.0L engine at least the HP and torque numbers go up some as the RPM's go up. Reading thru some other forums I've seen numerous people say they see the rpm go up 200-300 on the tach at highway speeds going from a 3.73 to a 4.10 ratio.

I haven't sat down and mapped the torque and HP curve to the RPM rise though to see what that gain is.

The reason why I'm asking this is that I just picked up a 2010 GMC Yukon XL 2500. Which is basically a 2500HD with an SUV body. It has the same 6.0L engine and the 6L90 transmission as the 2500HD pickup. I believe the rear axle is the same also.

My line of reasoning is that if the factory has a formula (component list) to raise the tow rating to 13k, I should figure out what the formula is and use it to beef up this truck.

[kw_00]

Calsdad, Yes I know you were trying to find that out, that's why I said what I said. I should have been more clear, but was at work. In all my research in even ordering the truck, it just came down to the gearing nothing else. When you request the 4.10 on order nothing else changes in the GM powertrain just the gears. Which gives more mechanical leverage and vola! higher rating.. I think this year GM went standard with the 4.10 which I would have on my next gas 3/4 ton truck. I do like the fact that Ford offers the 4.30 option on the gas 6.2.