Towing, Suspension Sag, Gearing

[Corry]

We're yet to take delivery of our 'Sports Luxury', which is top of the range here in Aus, just wondering for those that tow heavy trailers with it, do they suffer from suspension sag at all in the rear?
On occasion I'll be using it to tow our boat, 2.8t (6000lb), which has a tow ball weight of around 280kg (620lb) and I'm wondering if I need to do anything to the rear to keep it all level. Weight distribution bars aren't really an option with a boat trailer.

Also, when towing with my 79 Series Cruiser Ute, it's recommended not to use 5th gear, only 4th as it is 1:1 ratio and the overdriven 5th gear isn't designed for heavy towing. Wondering if there is anything different that I should be doing when towing heavy trailers with the GX?

 

[ColoradoOutdoors]

Check out this review for the answer to the sag question. Sort of a clickbait title for this video as the GX peformed well.

 

[ColoradoOutdoors]

Actually this video around the 11 minute mark where they measure sag-

Video: Does the All-new 2024 Lexus GX 550 Twin-Turbo V6 Tow Better Than Ever?

It's time to see how the all-new 2024 Lexus GX 550 handles a large and heavy trailer. We take this GX 550 Luxury+ model and hitch up a premium ATC toy-hauler tr

tfltruck.com

 

[Corry]

Thanks for that ColoradoOutdoors, that one dropped around 2". Would be good to know what the tow ball weight is of the trailers.
I guess I'll find out when we get ours delivered.

 

[nopantz]

The suspension is designed to sag with tongue weight. Example spring rates are 200 pounds per inch, meaning 600 pounds would compress it 3 inches. I believe the GX springs are stiffer.

Weight Distribution Hitches more importantly shifts weight on to the front (steering) wheels to give better control.

Here is my 5000# trailer with approx 800# tongue weight and another 100# WDH.

I'm not sure if the Tow Haul mode locks out overdrive in Auto, which I believe is gears 9 & 10 on the GX. I tend to cut over to Manual shift. Cruising fast on flats, I might use 7 or 8. In the mountains I tend to use 5 or 6, maybe lower in steep sections.

 

[Corry]

That's interesting info nopantz, would be interesting to find out what the sorting rates actually are on the GX. Sagging 3" I'm guessing would have an affect on how the vehicle handles.
I won't really have the option of a weight distribution hitch with the boat due to the amount of reversing it'll do.
I wonder if anyone will end up doing an air bag assist kit or the likes
Thanks for the info, very interesting.

 

[BackRdRnr]

Hi you prob already have balanced your boat on the trailer, but keeping the weight center directly on the trailer wheels really helps the hitch weight on the tow. Like stow your cooler etc gear aft of the wheels. your 10SPD is a great option to have. Take some time to feel out the performance in the gear ranges!!