Towing oddity

[hammerheadfistpunch]

Was looking up some towing information in the user manual as a reference for my 08 GX470 and I found this nugget under towing

"●Set the vehicle height to the “LO” mode and turn off the rear height control air suspension to prevent the vehicle height from automatically changing."

P.185

is this even possible to do?

Also this gem

Due to the added load of the trailer, your vehicle’s engine may overheat on hot days (at temperatures over 85°F [30°C] when driving up a long or steep grade.

Yeah, I think mostly the transmission. Anyone else notice how hot the transmission gets towing? I'm seeing 211c [EDIT: 111C} up long hills with moderate loads (2000-3500 lbs)

Finally this

●Do not exceed 45 mph (72 km/h) or the posted towing speed limit, whichever is lower. A instability (swaying) of the towing vehicle-trailer combination increases as speed increases, exceeding 45 mph (72 km/h) may cause loss of control.

Im glad we have J2807 now as it addresses speed, heat and grade, but who on earth things that towing with a 45 mph limit is even remotely reasonable?

Just random things on the chit chat

 

[hammerheadfistpunch]

As an aside, I looked at a 2021 GX460 which meets J2807 and found these things

"● If the gross trailer weight is over 5000 lb. (2268 kg), a weight-distributing hitch with sufficient capacity is required."
Which isn't mentioned in the 470 manual.

"Lexus recommends that the vehicle-trailer speed limit is 65 mph (104 km/h) on a flat, straight, dry road. Do not exceed this limit, the posted towing speed limit or the speed limit for your trailer as set forth in your trailer owner’s manual, whichever is lowest. Instability of the towing vehicle-trailer combination (trailer sway) increases as speed increases. Exceeding speed limits may cause loss of control."

"● Set the vehicle height to the LO mode and turn off the rear height control air suspension when you connect a trailer, otherwise the vehicle height may change due to the automatic leveling function, and you may catch part of your body in the vehicle, resulting in an accident."

I would guess this is what meant in the manual for the 470. preventing you from "catching part of your body" as the vehicle raises.

The same heat warning and temp (85F) is still there,

"Due to the added load of the trailer, your vehicle’s engine may overheat on hot days (at temperatures over 85°F [30°C]) when driving up a long or steep grade. If the engine coolant temperature gauge indicates overheating, immediately turn off the air conditioning (if in use), pull your vehicle off the road and stop in a safe spot."

Which is odd because J2807 requires 100 F ambient temps and no overheating with the AC on full blast on recirc.

 

[cesslinger]

Is your temp correct? 211 Celsius is 411 Fahrenheit. That would be a bad day on the tranny.
I tow up mountain grades with a 2800 ish pound off road trailer and my temps get up around 220 F. Temps drop within a few minutes after the road levels out.

 

[hammerheadfistpunch]

Is your temp correct? 211 Celsius is 411 Fahrenheit. That would be a bad day on the tranny.
I tow up mountain grades with a 2800 ish pound off road trailer and my temps get up around 220 F. Temps drop within a few minutes after the road levels out.

Derp. 111C, not 211C. Seems like towing in Utah in the summer with a 3500 lb trailer I am usually in the 100-105 c range(212-221f)...which is too hot for my liking.

 

[Rednexus]

The transmissions in these have a big flaw for towing (or driving....) in mountainous areas. The torque converter unlocks in 3rd and below (and locks/unlocks/hunts) in 4th and things get REALLY hot. Even driving around here in the Ozarks, where we have lots of short, steep, repeating hills, my trans runs around 195 unloaded. In CO/UT it got all the way to 217 with even very careful driving. If the gearshift is held in 4th (and it stays locked) it rarely gets over 180. I don't tow anything over a 1,700 lb utility trailer but hope to get a pop-up or other small camper, which will definitely require upgrades to the GX in order not to cook things.

The simple fix is to add a bigger transmission cooler (which I'll do this winter for <$100) and a torque converter override switch (maybe next year): Wholesale Automatic Transmissions - - https://cruiserbrothers.com/brands/wholesale-automatic-transmissions/#product-listing

 

[CO_Hunter]

I noticed mine running in low 220s with a 1000# Scamp last weekend. Thanks to my new Scangauge 2! Slow steep secondary highways and I was trying not to push it. I have a bigger transmission cooler that got delivered today.

 

[kerner]

Semi related as I'm planning to tow a 2,000lb teardrop with my new to me 2008 470 - I've got OBD2 data via torque pro but not sure how to see the transmission temp. Any tips?

 

[Rednexus]

You have to add it as a custom sensor value. Search google for "toyota transmission temperature in torque" and the equation should pop up.

 

[Cooperd0g]

My 2006 manual recommends trailer brakes over 1000 lbs and anti-sway over 2000 lbs. It has the same warning about overheating and 45 mph towing.

If you read close about the height control it is for connecting and disconnecting; you can still run AHC once all set up.

I have towed my camp trailer that is in the neighborhood of 1200-1500 lbs and had my transmission fluid get to 216 F and coolant to 219 F when going up long hills in hot Arizona and southern CA weather. I upgraded the transmission cooler with the Mountain Passes Off Road kit and never had the transmission temp get over 207 towing a 4500 lb trailer. And that was on a low elevation, steady low grade climb in 95-100+ temps. Highest coolant temp I saw on a two week trip was 221 and that was on a fairly short and steep incline.

 

[cesslinger]

The transmissions in these have a big flaw for towing (or driving....) in mountainous areas. The torque converter unlocks in 3rd and below (and locks/unlocks/hunts) in 4th and things get REALLY hot. Even driving around here in the Ozarks, where we have lots of short, steep, repeating hills, my trans runs around 195 unloaded. In CO/UT it got all the way to 217 with even very careful driving. If the gearshift is held in 4th (and it stays locked) it rarely gets over 180. I don't tow anything over a 1,700 lb utility trailer but hope to get a pop-up or other small camper, which will definitely require upgrades to the GX in order not to cook things.

The simple fix is to add a bigger transmission cooler (which I'll do this winter for <$100) and a torque converter override switch (maybe next year): Wholesale Automatic Transmissions - - https://cruiserbrothers.com/brands/wholesale-automatic-transmissions/#product-listing

You have to get the valve body to use the override switch - I called Cruiser Bros about it. It's on my short list.

 

[Rednexus]

You have to get the valve body to use the override switch - I called Cruiser Bros about it. It's on my short list.

Thanks for the info. I definitely want the valve body too, and will probably put that as next on my upgrade list. The lazy stock shifting gets a bit old, even for just driving around unloaded.

 

[kerner]

Thanks for the info. I definitely want the valve body too, and will probably put that as next on my upgrade list. The lazy stock shifting gets a bit old, even for just driving around unloaded.

Both of these are on my list, but I've got to say the shifting issue on the GX is way less noticeable than it was on my Tacoma. Towing 2,500lbs with the GX is a huge improvement even with the issues.