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Towing Report- 1991 Suburban and 32 foot camper

Discussion in 'Towing & Trailer Tech' started by Crawdaddy, Jan 3, 2013.

  1. Crawdaddy

    Crawdaddy Moderator Staff Member Platinum Contributor 1000 Posts

    I have finally taken my camper out for the first time with my 1991 Suburban from December 26-30. I'm sorry it's taken me this long to report, but I've been busy trying to get projects done on my vacation before I go back to work.

    The tow vehicle was my beloved 1991 Chevy Suburban that I've converted from a 1/2 ton truck to a 3/4 ton truck complete with a 14-bolt full floating rear axle, 3/4 ton front control arms and spindles, Firestone airbags on the rear springs, a massive transmission cooler, external transmission filter, and deep transmission pan with trans temp sender in it. I've got more mods done to the truck, but those are all the ones I think are relevant to towing. I also have a cheap towmaster brake controller to handle the trailer brakes.

    The camper is a 32 foot camper that weighs about 9500 pounds with no water in the tank. According to the date plate, a full tank of water would add another 380 pounds to it.

    I hooked the camper up to the truck and set my weight distributing hitch to 5 links hanging. The trailer was sitting level and the front fender clearance to the ground was about 1" higher than it started unloaded. I then aired up the airbags in the rear until I reached approximately the unloaded ride height. Hooked up chains and trailer lights, and tested them. Bad connection at the trailer light connector, but that was easily remedied with a screwdriver moving a prong on the trailer side. Pre-tripping the rest of the truck revealed I had virtually no transmission fluid. Pretty big issue. Luckily I had some to put in and filled it up. Now, my transmission has had a history of leaking and I used up the last of the ATF I had, so I stopped at the parts store on the way out. There, I looked under the truck and found I had a pretty good ATF drip coming from a cooler line. After spending 45 minutes fiddling with the hose clamp to tighten it, I refilled the transmission and continued on my way.

    The engine and transmission knew the trailer was there, but didn't show any signs of distress. Engine coolant was normal at around 190F and the transmission temperature was no higher than 150F. I attribute these abnormally low temperatures to the cool ambient temperature; my transmission usually runs at 175F when cruising at 70mph in overdrive. I had the transmission locked into 3rd since towing in overdrive is a big no-no.

    I was only able to do 45-48mph on the way out. The wind was pretty strong and whenever I'd try to go any faster, the sway of the trailer got to the point that I didn't feel safe. On the way home, I was able to make 55mph pretty easily, bursting up to 60 and even 65mph. At these speeds, I was running 2500rpm pretty much the whole time. Since this was my first time towing the camper and being the biggest thing I've towed, I took it easy and made sure to swing wide and give myself plenty of clearance at the tail of the trailer.

    Feeling good, I stopped at a local truck stop and scaled the truck and trailer both with and without the weight distributing hitch bars hooked and unhooked and just the truck. Here's the results of that; all numbers are in pounds:

    [table="width: 500, class: grid, align: center"]
    [tr]
    [td]Setup[/td]
    [td]Steer Axle[/td]
    [td]Drive Axle[/td]
    [td]Trailer Axle[/td]
    [td]Gross Weight[/td]
    [/tr]
    [tr]
    [td]Truck Only[/td]
    [td]2660[/td]
    [td]3260[/td]
    [td]0[/td]
    [td]5920[/td]
    [/tr]
    [tr]
    [td]Trailer w/weight bars unhooked[/td]
    [td]1960[/td]
    [td]5400[/td]
    [td]8160[/td]
    [td]15520[/td]
    [/tr]
    [tr]
    [td]Trailer w/weight bars hooked[/td]
    [td]2260[/td]
    [td]5000[/td]
    [td]8260[/td]
    [td]15520[/td]
    [/tr]
    [/table]

    So, referring to the table, I only transferred 100 pounds onto the steer axle...not enough. So, I think next time I'll add another link or possibly even 2 to the weight distributing bars to try to get some more load on the steer axle. When I weighed the truck, I didn't have any water in my fresh water tank or a full tank of fuel, so I think with both, I'll be close to 16000 pounds gross.

    Fuel economy was interesting. Unloaded, I can average 15mpg. With the trailer, I calculated I only made 8.5mpg. Horrifying by itself, but considering the load and lack of aerodynamics, I think I did pretty well. I'm going to try to gain some mpg with a couple mods including upgrading the ignition with a hotter coil and bumping up the timing, an e-fan install, and a couple of other things. I am also planning on replacing the rubber hose and hose clamps for the transmission cooler setup with stainless braided hoses with the good fittings on the end to try to reduce the possibility of leaks like the loose hose clamp I had.

    I think I covered everything I wanted to. If ya'll have any questions, I'll be more than happy to answer them as best I can. So, here's a couple pics:

    This pic was before I added air to the airbags. The back of the suburban was a little higher than that when I towed it
    IMG_0403.jpg

    The camper setup at the campsite
    IMG_0564 cropped.jpg
  2. mfleetwood

    mfleetwood New Member ROTM Winner 1000 Posts

    Wow, nice write up. It sounds like you did everything right when upgrading. Glad to see it all went well for your road-trip!
  3. Crawdaddy

    Crawdaddy Moderator Staff Member Platinum Contributor 1000 Posts

    Two things I am going to change that I forgot to mention. First, I WILL be getting a sway control setup to try to control the sway. Sway is evil and I'd like to be able to go 60mph with no sway. I've read that the Hensley hitch is the best for sway control, but that the weight distribution setup for it is not good. I'll have to do some research.

    The second thing I want to change is I want to get a better brake controller. The brake controller I have is a cheap time-based controller and I didn't like the way the brakes on the trailer reacted. I played with the gain a lot and it was either too little braking , or the brakes would grab too fast. I also had the truck brakes lock up a couple of times. I'm hoping to find a nice inertia based controller or a controller that senses brake line pressure and grabs the trailer brakes accordingly.

    I've tried to make the Suburban as capable as possible to haul my camper and other heavy loads well and have a nice interior, but I made some choices that are not optimal, but a lot were made with specific reasoning. For example, all the springs are still the original 1/2 ton springs. I did this because finding proper springs was proving very difficult and I didn't want to lose the great soft ride when running unloaded. To compensate, I put the airbags in the back to help take the weight. The other thing I need to work on still is stiffening the frame with braces. From the specifications I've been able to find, the frame for the 3/4 ton suburban is slightly thicker, but we're only talking in 2 or 3 decimal places. So, the braces should stiffen it enough to match or exceed the 3/4 ton specs. Finally, I don't yet have the parking brake situation sorted out, and I feel I need them to hold the truck in place before putting the transmission in park.
  4. Boonduff

    Boonduff New Member

    I have the Tekonsha Prodigy controller in my 97 Suburban and love it. It's by far the best controller I've ever had.
  5. Jamm3r

    Jamm3r New Member

    Nice. Here's my rig:

    photobucket-1104-1351737549636-1_zps7d97c8da.jpg


    I have the MaxBrake controller in both my trucks and it is fantastic, and I recommend it. They were out of production for a while but are now available through ProPride.

    If more people did that the world would be a safer place.

    Maybe more than 2 links or you may need heavier bars. What rating bars do you have? You want the steer axle to weigh as much as it does unhitched, ideally, or at least within a few hundred pounds. I have a scale ticket somewhere but have been able to do this, with 1200 pound bars pretty well tightened up. That will also help take some of the weight off the drive axle.

    You haven't mentioned tires -- be sure they're up to snuff for the load you're putting on them. Have you considered Load Range E tires among your other upgrades?

    I get 9 mpg at 55 mph, 8 mpg at 65 mph, and 7 mpg at 75 mph. I think you're doing fine.

    Switching from worm-gear type hose clamps to the screw-and-nut ones may be all you need. That's what I use on transmission coolers, and they are much less prone to leakage because they can be tightened down more. It takes more clamping force than a radiator hose.

    I use the ProPride hitch which is very similar to the Hensley with a few improvements for convenience and long-term reliability. The sway control is excellent with either however there are reasons to consider other hitches which I can share privately if you're interested.

    The MaxBrake I mentioned upthread senses brake line pressure with a transducer that you T into the master cylinder. They are absolutely fantastic, with rapid and smooth brake application and release.

    I guess I too am one of the few people who spends time and money on parking brake maintenance. With a heavy trailer you have to be careful. I make liberal use of chocks.
  6. Crawdaddy

    Crawdaddy Moderator Staff Member Platinum Contributor 1000 Posts

    Interesting, that looks nice. That's definitely in the running. I noticed that Hensley also makes a brake controller with an impressive product description though I have done no research on reviews for it yet.


    Yeah, I scaled it because I wanted to know just how heavy I was and if I had done a good job setting up my hitch. I'd say I was ok, but as you mentioned, I need to get another 400 pounds on the steer axle to really be set. I don't honestly know the weight rating of the spring bars. They're older than I am and I can't find any marking on them. There might be under the many layers of paint, who knows. It was a hitch I was borrowing from a relative until I can buy one of my own.


    The tires are Michelin LT235/85R16 E rated tires, so I'm good there.

    I checked my fuel mileage logs and I noticed I exaggerated my unloaded numbers a bit. I'm more getting 11-13 unloaded. This is definitely an area I'm going to start concentrating on in the future.


    I'll keep that in mind. For the most part the rubber hose hasn't given me issues. It's transmission cooler rated hose.


    Send me a PM with your thoughts on this please. I am a sponge; I love information and subjective reviews.


    Well, when I say I need to sort out the parking brakes, that can be read as I don't have any at all right now. When I upgraded to the 14-bolt axle I never found and installed the proper parking brake cables to make it work. However, my labor may be in vain because I recently found a pair of 14-bolt hubs that are the right style to allow me to do a disc brake conversion on the rear. That would involve finding the proper ElDorado calipers with parking brake provisions to have parking brakes. I don't know what the timeline of this is, and I should be able to reuse the parking brake cables, so I'll most likely go ahead and get them working on the drums. You are absolutely correct in the statement that parking brakes are essential when hauling heavy trailers and in the use of chocks.

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