Quote:
Originally Posted by gjc-99
I have a nearly new 2619 and a 2004 GMC Envoy XL 4x4 with a 5.3L V-8. So far I have towed it from the dealer in Northern Illinois to mid-Missouri without any problems (about 300 miles). In fact, I did not notice any difference in the Envoy handling or trailer sway. Even though the owners manual states a WD hitch is not required, I would like some input from experienced TM owners before I set out on my first long trip.
Is a WD hitch necessary for this towing combination? Thanks for your help on this!
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Is a WDH absolutely necessary? No, probably not with the XL version of the Envoy, especially with a relatively heavy V8 up front.
Nonetheless, a WDH is an exceedingly good idea. Amplifying what Texas_Camper and Freedom have said, the following happens when you hookup a trailer
without using a WDH.
1. All of the trailer's tongue weight is applied to the rear suspension. With an
empty 2619, that's only about 351 lbs (factory number for an empty, no-options trailer with nothing in any tank) to around 390 (empty trailer with typical options).
2. On a long wheelbase SUV like the Envoy XL, the ratio between wheelbase and rear overhang (distance from rear axle to hitch ball) is about 4:1. That means that the effect of putting even 390 lbs on the hitch ball is roughly an unweighting of the front suspension of about 100 lbs. A 100 lb unweighting is not much relative to the fairly high weight of the V8 on the front suspension, so no surprise that handling wasn't significantly affected.
3. Finally, the weight that is taken off the front is transferred to the rear. Thus your total rear suspension loading from the
empty trailer is probably around 450 to about 500 lbs. That's substantial but still within the rear suspension's load capacity.
I emphasize empty trailer because...as T_C notes...the tongue weight can rise as much as 200 lbs depending on how much you "stuff" you put in the trailer and whether or not you travel with full propane and/or water tanks. If you heavily load the trailer and especially if you travel with your tanks filled, you will have a tongue weight in the 500 to 550 lb range. And then you will have a fairly serious load on your Envoy's rear suspension (possible overload depending on how much is in the back of the Envoy) and the front suspension could be unweighted enough to both reduce handling/braking and have a "floaty"/bouncy ride.
So don't be mislead by relatively benign handling changes from attaching an empty trailer to your Envoy. When I first got my 2720SL, I thought it towed "just fine" behind the Jeep I had then when I brought it home empty using a lightly adjusted WDH with 550 lb bars. It wasn't after I towed a few thousand miles with the trailer moderately to heavily loaded that I concluded that even a WDH set at max adjustment with 550 lb bars did not provide enough weight distribution (mainly prevention of the front suspension unweighting described in item 2 above). This became quite clear when I slid partway into an intersection with the front tires locked during panic braking...the reason the front tires were sliding is that they'd been so unweighted by the tongue weight that they had greatly reduced grip on the road.
Since my almost-accident, I upgraded to 750 lb bars on the WDH...and moved up to a full size pickup...and now feel I have just enough weight on the front tires in a panic braking situation to stop in relatively normal distances without lockup.
So the bottom line is that with a loaded trailer, a WDH will prevent unweighting of the front tires and can even increase the downforce on the front (if the right strength bars and correct adjustment are used). And until you have to make a max effort, panic stop with a
loaded trailer in tow, you will not know whether or not your front tires/brakes will have enough stopping power.
I therefore strongly suggest the use of a WDH...in addition to improving front steering/braking, it will improve the ride (less bounce) and greatly improve the load capacity of the rear of your Envoy.