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PDX_Zs's avatar
PDX_Zs
Explorer
Apr 12, 2017

Suburban 2500 (GMT900) towing build - 11th gen -

So we have been rolling with our 2006 Expedition for the past several years. Great truck. Really like it. Super durable and comfortable for the family. Towed like a champ. I would buy another one in a heartbeat if they had a greater tow capacity.

Needing a bit more family room and tow capacity, but still and SUV. As you all know, the list is short. I didn't want a vehicle as old as the Excursion, so that left the 3/4ton Suburban.

We found a super clean, loaded, 2011, with low miles. As many of your know, these things are unicorns. Very rare. Only a small percent of the Suburbans went out as 3/4 tons, and of those an even smaller percentage went out decently optioned. Of those, even rarer are ones that haven't been wrecked or beat down. Happiness.

First part of the build was easy. Bistein B6 or 4600 yellow shocks. Hellwig front sway bar. Absolutely transformed the handling.

Then on went 275/65-18 BFG All-Terrain tires wrapped over some 8.5" wheels with a little less offset. This widened the track just a bit and added just about 1/2" of overall tire height, which is about all the more the truck will take without rubbing. Also wanted to not increase the effective gear ratios.

Now the biggie... The truck is a beast. 14 bolt rear end, stout frame, strong motor. And then they put this wimpy hitch receiver on the thing. It's only rated to 1,000 lbs tongue weight and visual inspection shows the factory hitch to be uninspiring to say the least. This combined with some internet horror stories about poor performance, led me to find a solution.

Obviously, full custom is an option. What I found is that, a quality aftermarket receiver from the previous gen Suburbans (GMT800) are a very close fit. They pickup factory hard points in the frame, but the frame does need to be clearanced in a couple spots. No big deal, the modification are obvious and can be handled with a grinder and sawzall in a few minutes.

So here is when the hassle starts. The aftermarket hitch will sit about 5" below the factory hitch. This means it runs into the factory bumper cover, which will require some trimming or other mods to get the hitch to sit below the bumper.

So this is where I sit. I am exploring my options for getting a more robust aftermarket hitch to fit. I am leaning towards trimming the bumper cover, but there is no emergency and I want to stare at it for a long time before cutting anything. So you all now, the PN for the Curt hitch is 15324.


Any thoughts, ideas, suggestions, experience appreciated.
  • PDX.Zs wrote:
    Anyway, draw.tite makes a hitch that is narrower in the top section that may fit in between the channel and actually reaches further forward than even the Curt unit. But it is only rated to 1200lbs. Even so it is clearly more robust than the stock unit.


    PDX Zs, Did you ever get a chance to check out the Reese 45013 hitch? You may find that it too is "narrower in the top section" than the Curt, as well as "reaches further forward" than the Curt, just like the DrawTite 41930... only instead of being limited to 1,200 lbs WD, it is rated to 1,400 lbs tongue weight WD.

    Furthermore, being a 2.5" receiver, the Reese 45013 can handle WD ball mounts that are rated up to 1,700 lbs, where the typical 2" WD ball mount is often limited to 1,200 lbs.

    In case you hadn't had a chance to look it up yet, I'm going to post a photo of each, so you can see the similarities between the DrawTite Ultra Frame and the Reese Titan (both produced by the same company Cequent), as well as note their differences.

    The Reese has an extra hole in the forward most mounting foot, for a total of eight (8) attachment points versus the Drawtite's six (6) attachment points.

    And, as earlier mentioned, the Reese receiver is larger in cross section (diameter) of the cross member tube, as well as the receiver itself.



  • PDX.Zs wrote:
    BigToe wrote:
    Lots of great info


    I am however stumped as to why the frame in that area has the unused weldnuts in the frame. My assumption was that it was because the GMT900 Suburbans share a frame with the trucks which use those nuts for their hitch.

    And so the questions continue.



    Those questions continue in your head based on your assumption, not based on reality. Let that assumptions go, and at least one of those questions will be relieved.

    Absolutely, positively, without any lingering doubt whatsoever, the GMT900 Suburban does not, has not, and indeed cannot "share a frame with the GMT900 pickup trucks" that you are assuming "use those nuts for their hitch." The pickup and SUV 2500 frames are different, in both the rear AND the middle sections. Period. Bonafide fact. Inarguable, indisputable, inescapable reality.

    If you came to RV.net for answers and advice, you've found a good place to ask. It's entirely up to you whether or not to believe the answers, but just in case you think I am guessing or speculating on the differences in the frames, know that this is not a guess. It is a certainty. The frames are different.

    How is that for clear and unequivocal? :)
  • BigToe wrote:

    Absolutely, positively, without any lingering doubt whatsoever, the GMT900 Suburban does not, has not, and indeed cannot "share a frame with the GMT900 pickup trucks" that you are assuming "use those nuts for their hitch." The pickup and SUV 2500 frames are different, in both the rear AND the middle sections. Period. Bonafide fact. Inarguable, indisputable, inescapable reality.

    How is that for clear and unequivocal? :)


    I see... so what you are trying to say in your own understated manner is, "Not the same frame."

    I think I get it now. Can't actually argue with someone who has mic'd the stupid thing.

    Thanks again for the info and thoughts. I will report back. That 2.5" unit looks very nice, though I was hoping to not have to replace my supply of stingers. Are those adapter sleeves safe? Do we like those here?

    The two units above appear to use the same basic sideplatd. At lease shape and thickness. The major difference being the 2.5" vs. 2" square tube. Good find.

    Any and all added thoughts appreciated.
  • I was just a wee bit "understated" wasn't I? Sorry about that. I just grasping at words to try and find a way to convince you, without digging up GM's diagrammatic line drawings and dimensional data for each of the frames (which I have in pdf form, but on a different computer)converting them to jpgs, hosting them some place online, and posting them so that you too could see and be assured of the differences.

    But it is easy enough to look at the outsides of the 2500HD pickup versus the 2500 Suburban and see the difference for yourself.

    - The frame channel depth can easily be compared without having to get on the ground by simply peering through the open space in the rear wheel wells.

    - The shortest possible wheelbase to a GM 2500 pickup is 133.6", which is still 4" longer than the longest (and only) wheelbase of a 2500 Suburban/YukonXL, which is 130"... so the midsection of the frames between the wheels by definition already have to be different in length...

    - And the midsections are also different in purpose. The mid section pickup frame is designed to support and stabilize a separated bed and cab that articulates independently, whereas the midsection Suburban frame is designed to support and stabilize a single unitized body. The differences in the frame rails between the two types of bodies can be seen in the upturns and downturns (and lack thereof, and location thereof) in the frame flanges, as well as differences in channel depth and flange width and material thickness.

    - Further variability increases with wheelbase and type of cab as well.

    - The rear section of the frames aft of axle differ in purpose also, where the pickup only carries a spare tire, but the Suburban holds a fuel tank AND carries the spare tire. This makes a CRITICAL difference in the depth and design of the tubing and/or H-frame CROSSMEMBER(s), as the case may be, between the two types of vehicles. Obviously, without the fuel tank in the way, the pickup can "spare" haha much more room between the rear frame rails above the spare tire for frame strengthening structure commensurate with the hauling capacities of the pickup.

    - Rear spring leaf lengths, and spring hanger stamping designs, also differ between the SUV and the pickup 2500. Even where the GVWRs are the same, the anticipated range of variability in actual weights between empty and loaded is much larger in a pickup than in an SUV. In very generalized numbers, the SUV might have an 1,800 lb cargo capacity, whereas the pickup might have a 3,600 lb cargo capacity (equipment depending). Obviously, a full unit bodied SUV with seats for 9 passengers is going to weigh more "empty", than a regular cab long bed will weigh "empty". Hence the rear suspension design in the SUV is optimized for a narrower range of potential loading, whereas the rear suspension in the pickup is optimized for a wider range of potential loading.

    The only 2500 semi "pickup" that actually does share the same frame... front, middle, and rear... with the 2500 Suburban is the 2500 Avalanche. It too, is a unibody, despite having an open back. There is a structural reason why the Avalanche is designed to have "rally bars" in the rear that angle backwards from the rear window to the short bed. That angled back bar, covered in plastic, is the critical gusset that unifies bed and cab areas, that takes the place of the fully covered canopy that encloses the rear greenhouse of the Suburban.

    Ok, I thought I saw that horse's eyes blink, so I gave it another beating.

    On to your question comparing the two Cequent hitches... here again, there is more than meets the eye at first glance between the two.

    I'm running out of time with this posting, so I can't pull out the microscope this time around, but do notice

    - the additional hole in the rear mounting cleat on the Titan version

    - the cast steel entrance collar on the mouth opening of the Titan receiver

    - the downturned strengthening bend of the chain loop gusset on the Titan

    - the larger holes to accommodate stronger chain loops.

    - the receiver tube passes all the way through the cross tube, and is welded on both ends. No upper gusset is needed with that design, that cannot twist out. The top and bottom chords of the cross tube (where the greatest tension and compression occur) are left in tact.

    - there actually may be a side plate material thickness difference between the 41930 and the 45013. I would need to verify that first before saying for certain. This was information I knew off the top of my head a decade or more ago, but have since forgotten. I can tell you this... I own both a 45013 and a 45014 (different vehicle application).

    The 45014 is made with 5/16" thick side plates... of this I am absolutely certain. I've mic'd the side plate thickness, after being informed by Reese application engineering that increasing plate thickness was their strategy for side plate stability in certain Titan hitches, instead of adding bends to bottom edges of the plate.

    Since the 45013 does have stiffening bends formed along the bottom edge of the plate, and since I can't recall what the plate thickness was when I measured that model of Titan, I'm not confident that the Titan is any thicker than the Drawtite Ultra Frame, but there is that possibility. However, I am confident that the Titan has the two extra mounting holes (one on each forward plate mounting cleat), but you can see that in the photos.

    I bought the 45013 about a dozen years ago, when the writing became clear on the wall, after Cequent acquired the formerly separate and competing Reese, DrawTite, Hidden Hitch, BullDog, and other long standing brand names of towing equipment manufactures in North America... that American and Canadian production was about to shutter and get shuffled to China.

    However, since I've not had a problem with my GM OEM hitch, I've not replaced it. I just kept the 45013 new in the box, stored for the day and time when I think the GM hitch will no longer be adequate for the 2500 Suburban's ratings. For me, that day has never arrived yet, but I see now that the 45013 imported from overseas costs more today at some resellers than the North American made version did a dozen years ago. $408 is a significant chunk of change, although I did find a reseller that claims to sell the same hitch for $225, free shipping.

    There is yet another reason why I did not rush to replace the stock GM hitch with the Titan. And the DrawTite and Curt hitches mentioned in this thread are all three guilty of the same sin... that being there load path through the side plates is conferred upon the open floating edges of the lower frame flanges, rather than vertical web supported sides of the lower frame flanges.

    The side plates, in all three aftermarket hitches, lining up with the unsupported open end of the C channel frame, regardless of upturned or downturned lips, still applies load leverage across the width of the flange.

    If you held your left hand in front of you, forming it into a C shape, with your thumb acting as the lower flange, and your fingers acting as the top flange, and the bulk of your palm acting as the vertical web of the frame... and then took a yoyo string that had a 10 lb plate weight attached, and slipped the yoyo finger loop over the very tip of your thumb, at the fingernail, and left it there... how much strain would that apply to your thumb?

    Now, slide that yoyo fingerloop down your thumb, moving it closer to the palm of your hand, as far as it will go. Would not the weight of the 10lb plate dangling at the end of the yoyo string be more bearable, the closer the string is moved to where the root of the thumb is supported?

    Such is the same idea with line of load transfer through the side plate of the hitch. For some reason, probably due to cross tube length, as well as the rear spring hanger support stamping underneath the frame, most of the aftermarket hitches for the 2500 Suburban align the side plates with the open, non supported edges of the frame flanges... whereas all three of these hitch brands align the sideplates of their aftermarket hitches fitting other vehicles with the vertical webs of the frames, on the supported edge of the frame flanges.

    This is another issue to stare at and think about for a while, as you consider what you are "improving" (or applying excess stress to, beyond the OEM's intent) with any hitch change.
  • Can only Internet analyze it so much without benefit of spec's and drawings... :(

    Possible options would be to:


    Just live with the 1,000 lb WD tongue rating


    OEM spec be danged and just go with it over the limit (not my kind of metric, just throwing it out there...but you need to decide if you believe in spec's/ratings/limits/etc). This one will break sooner than later


    Modify an aftermarket and this is what I'd do

    Still like the Curt a lot, but BigToe is right...these newer designs has every ounce of margin squeezed out...knew that when still working and saw one of our customers using our super computers designing their next gen high end bicycles and at a Ford design center. Management dictates that every penny be squeezed out


    So, the Curt type of design is for my Sub's generation frame...where it needs less force distribution and can be kept on a smaller foot print

    The Reese is better for your or these latest frames where the rear portion is really not made for towing heavy. Plus, IMHO, think the designers no longer know enough about towing heavy...just CAD jockey's and we coined them "Red/Green Light designers"...design it...run the simulation and fix whatever vectors the super computer says to...then done...

    By having a longer end flange, it moves more of the forces forward towards the frame/axle arch

    On that, since a 6,000 lb GAWR on the rear suspension...the spring perches should be designed for that specification and then some margin

    Getting some or lots of the tongue forces into that area is the smart thing to do...

    Key is to NOT weld on the frame and keep welding to a min on the receiver

    Transition plate on the rear most flange of the receiver to frame web.

    Ditto transition plate on the forward flange to frame and this one might have more room to box in the frame section...without cutting/welding/etc

    Good luck...more later...off to buy the Easter Leg of Lamb
  • BenK wrote:
    Can only Internet analyze it so much without benefit of spec's and drawings... :(


    Ben... you are famous on rvnet for analyzing... so here is a food for your fodder. Not quite a leg o lamb, but will have to do.

    The following photos establish, via specs and drawings, that GM's GMT900 platform 2500 pickup truck frames, in every possible wheelbase, bed, and cab length configuration, are wholly different than GMT900 2500 Suburban/YukonXLs of the same generation.

    Since this thread is about hitches for the 2500 Suburban, I've only taken the time to label the Suburban drawings. If the drawing has identifying text in very LARGE LETTERS saying "GMT-900 2007+" on it, then that drawing is for a 2500 Suburban. Otherwise, all other drawings WITHOUT any large letter text added to them are for the GMT900 HD 2500 pickups. There are simply too many configurations of pickups to label them all.

    I didn't even post all of the GMT900 truck drawings. I just posted the drawings of the 2500 pickup frames that one might assume would be the same, or near the same, as the 2500 Suburban, so that an anyone who cared to get that deep into the weeds with detail could visually compare the elevation profiles and cross check the measurements to their own satisfaction.

    Beginning with 3 Suburban pictures, and continuing with the comparative pickup pictures, we have...























    So Ben, hope this turns your :( (sad face) into a :) (happy face).


    .
    • Jasonmoore001's avatar
      Jasonmoore001
      Explorer

      Where can one find clearer/download able dimensions for for an 07 suburban/avalanche 1500 4wd? Thanks

      • way2roll's avatar
        way2roll
        Navigator II

        Not sure if you are aware but this thread is 7 years old. You may get more traction on your question if you started a new thread. 

         

  • COOL !!!...just back from the butchers with a BIG leg of lamb (plus lamb shanks) and prepping it with fresh rosemary sprigs n garlic cloves inserted into the middle n tied back together (dad was a master butcher...am only a journeyman cuz dad said there is only room for one master butcher in this family...)...funny you used that leg of lamb comment... :)

    Yes, find it VERY enjoyable and challenging noodling possible design/modification improvements...miss the design side after moving into management side...

    Can only guess at the force vectors via these docs...though am impressed you came up with these!!!
  • PDX...this kind of stuff is fun for me, but to not lose sight of you the OP's plight...

    Going from a WD 1,000 lb tongue max rating to something like 1,200-1,500 lb isn't going to need major redesign...just enough material (thickness, box section, etc) to distribute that 'extra' weight/loading (force vectors) to a wider portion the frame is NOT rocket science...

    Suggest you do consult with a ME/PE for peace of mind and documentation for your own liability (never leave that stuff to chance, IMHO)

    Unless you have the mind to and the shop, it might cost a few more coins than me with three different types of welders, a plasma cutter (modifying it for 1/2" plate...think upping the air PSI will do that and not blow the handle/gun to pieces), cut-off band saw, 80 gallon 2-stage compressor, and two 55 gallon steel barrels filled with scrap metal for this kind of stuff...

    I'll still noodle this, but DO NOT depend on my comments other than just suggestions, as I have zero skin in your game...just an Internet interest in this kind of stuff

    HAPPY EASTER !!!!
  • Great info here and wanted to check back in.

    I went with the Curt 15324 unit. Super easy install. Well, it was a full day, but pretty straightforward. I took the whole back end apart to do it right and clean.

    A few observations.
    - This hitch is beefy. Full .25" everywhere. Weighs a full 55lbs. A serious piece of kit. Very impressive. The install is doable by one. But I have a full shop and lifts. Better to bring a friend.

    - Factory bumper / hitch is very light duty. It weighs about half of what the Curt does. The welds are sloppy, and the metal is thin. It is possible to visually observe torsion in the bumperhitch when load is applied. Ugh!

    - Did end up grinding the factory reinforcement plate on one side. The additional metal of Curt bolted in that area more than makes up for any potential loss in that axis. FEA confirmed. :-). You are basically losing 3/8" of support in the y--axis, but adding back in several inches with the hitch. So the frame is supported better than it was prior to mods.

    - The factory bumperhitch needed clearancing where the frame extension meets the bumper tube as well to fit the Curt unit. I then cut off the factory tongue so it could be never be used as a hitch again because of this. Then I will just place one of the factory covers.

    - The plastic bumper itself comes off easy enough. I cut a nice little clearance notch with a fine blade jigsaw. Looks darn factory if I do say so myself.

    - If anyone decides to do this, you will also need a fab a little 1"x3"x.060" spacer to slide under the rearmost mounting holes as the Suburban frame is not flat here, but the hitch is.

    - The hitch comes down exactly 4" from stock. This puts it at a much more normal height relative to other tow rigs.

    - I replaced all,the hardware with slightly longer brand new metric 10.8 and blue loctite. This was a wobbler as I had a decision as to using the factory hitchbumper mounting plate or not. After inspecting it, I decided it is a very robust unit, the nuts were of high quality, and the full length reinforcing plate is an advantage. It would be possible to use aftermarket hardware here, but you would need to fab a little plate to slide in the frame. No big deal, but the factory hardware was nice in that area.

    - My next step is going to be to add some side plates to the hitch to extend it further up the frame. This was described in another thread, and I like the idea.


    Additional words are appreciated. I don't claim to have all the answers. My hope was to provide a nice source of info for other owners of these otherwise nice tow rigs.

    Stand by for my report on heavy.duty tie rod ends, Rare Parts pitman and idler arms, as well as a very small lift. :-)
  • Would love to see a pic of the install.

    Since you were asking about receiver failures, here is what happened on my '01.