Tow Haul down shift - Fiberglass RV



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Old 06-20-2019, 09:47 AM   #1
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Name: Henry
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Tow Haul down shift

I have a 2011 Toyo Tundra 5.7L 4x4. Does anyone have a Tundra, and can you tell me if it the transmission will shift into successively lower gears when the brakes are applied?

This is really important to me because I usually use manual gear selection when going down steep mountain roads. It would be nice if the above were true. I got this idea form another forum, the gentleman has a Ford F250 which shifts down when in tow haul and brakes are engaged while going downhill.

When descending, and not infrequently, I have to brake very hard, then manually downshift into a lower gear. To me this is a white knuckle situation. I mean downshifting into First gear, not downshifting into second. I sear the Tundra will do hold the trailer going downhill in second gear. Somebody said it is ok to almost redline in this situation. I have chicken out and apply brakes before the RPM's get that high...
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Old 06-20-2019, 04:42 PM   #2
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We tow with a 2016 Tundra 5.7L 4X4 in the tow/haul mode. I prefer to use S mode manual shifting mode for engine braking down mountains and towing up long grades towing our 4900 pound Ollie. When approaching a downhill grade stay ahead of the rig by using a safe speed and gear that does not need too much brake application. Many times on downhill mountain twistys I'm below the speed limit using engine braking so I don't have to ride the brakes the whole way down the grade, not saying I don't use brakes, too.

In the following Video Toyota discusses using tow/haul mode on a 2014 Tundra discussing throttle response, transmission shifting, and braking.



Additional information:

https://toyota.custhelp.com/app/answ...-operate-it%3F
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Old 06-20-2019, 06:27 PM   #3
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Thank you CamperBill, the video helps a lot.
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Old 06-21-2019, 12:12 AM   #4
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indeed, do not fear your redline.

I always manually downshift my automatic transmissions when in the mountains to keep the rpms up. even on my f250 7.3L diesel, if I'm coming to a grade at a speed that I know 4th/Overdrive can't maintain, I'll drop to 3rd just *before* the grade, so the tranny shifts and the torque converter can lock up before I have to get hard on the throttle. if the speed allows the 7.3 to maintain 2000 RPM or higher, then I can generally stay in OD on hills, but if the hill calls for 55MPH or less, OD puts me around 1500 rpm, and it won't hold that speed in top gear, so downshifting to 2000 rpm or so makes it happy. note that 7.3L diesel is redlined at like 3500 rpm. on really steep grades towing a heavy load I've run it as hard as 3000 rpm in 2nd up the hill.

only time I've used 1st gear is on steep hills on low speed dirt roads in 4x4.
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Old 06-21-2019, 05:28 AM   #5
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Quote:
Originally Posted by John in Santa Cruz View Post
indeed, do not fear your redline.

I always manually downshift my automatic transmissions when in the mountains to keep the rpms up. even on my f250 7.3L diesel, if I'm coming to a grade at a speed that I know 4th/Overdrive can't maintain, I'll drop to 3rd just *before* the grade, so the tranny shifts and the torque converter can lock up before I have to get hard on the throttle. if the speed allows the 7.3 to maintain 2000 RPM or higher, then I can generally stay in OD on hills, but if the hill calls for 55MPH or less, OD puts me around 1500 rpm, and it won't hold that speed in top gear, so downshifting to 2000 rpm or so makes it happy. note that 7.3L diesel is redlined at like 3500 rpm. on really steep grades towing a heavy load I've run it as hard as 3000 rpm in 2nd up the hill.

only time I've used 1st gear is on steep hills on low speed dirt roads in 4x4.
I know every vehicle and engine combination is different and we all do what works for us. I have found that my 2019 Ram 1500 which has no place to shift to a lower gear, other then to go into 4 wheel drive which would make on sense when pulling a trailer. One thing I have found is that when I switch to "Tow Mode" I do not have a 8th gear (overdrive is 8th) and the RPM does go up around 400-500 RPM, but I do get better fuel mileage, usually around 1 MPG, I find that odd. If you have a vehicle that the computer will do the job, then let it do it for you, I fine it does better then when I had a tow vehicle that I did it manually. Ram, Ford, and GM have made great improvement in there engines and transmissions for towing, technology is a great thing.

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Old 06-21-2019, 07:38 AM   #6
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Quote:
Originally Posted by trainman View Post
I know every vehicle and engine combination is different and we all do what works for us. I have found that my 2019 Ram 1500 which has no place to shift to a lower gear, other then to go into 4 wheel drive which would make on sense when pulling a trailer. One thing I have found is that when I switch to "Tow Mode" I do not have a 8th gear (overdrive is 8th) and the RPM does go up around 400-500 RPM, but I do get better fuel mileage, usually around 1 MPG, I find that odd. If you have a vehicle that the computer will do the job, then let it do it for you, I fine it does better then when I had a tow vehicle that I did it manually. Ram, Ford, and GM have made great improvement in there engines and transmissions for towing, technology is a great thing.

trainman
Both my 2014 & 2019 Ram 1500 had / have ERS which allows you to limit the top gear . When going down a steep grade you can set the top gear by pushing the buttons in the steering wheel and selecting the proper gear
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Old 06-21-2019, 09:59 AM   #7
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Quote:
Originally Posted by trainman View Post
I have found that my 2019 Ram 1500 which has no place to shift to a lower gear, other then to go into 4 wheel drive which would make on sense when pulling a trailer. trainman
I'm considering the Ram 1500 as my next tow vehicle, and the one I was looking at (basic 2WD with V-6) does have the ability to downshift manually.
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Old 06-21-2019, 11:53 AM   #8
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Name: Josh & Sonya
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Braking downhill with Tundra

Quote:
Originally Posted by CamperBill View Post
We tow with a 2016 Tundra 5.7L 4X4 in the tow/haul mode. I prefer to use S mode manual shifting mode for engine braking down mountains and towing up long grades towing our 4900 pound Ollie. When approaching a downhill grade stay ahead of the rig by using a safe speed and gear that does not need too much brake application. Many times on downhill mountain twistys I'm below the speed limit using engine braking so I don't have to ride the brakes the whole way down the grade, not saying I don't use brakes, too.

In the following Video Toyota discusses using tow/haul mode on a 2014 Tundra discussing throttle response, transmission shifting, and braking.



Additional information:

https://toyota.custhelp.com/app/answ...-operate-it%3F
Hi Henry,

I agree completely with Bill. I tow our BF 25RQ with a 2015 Tundra CrewMax 4X4. The transmission does seem to downshift in tow/haul, but nowhere near enough; you really do have to stay ahead of it with manual downshifting to avoid riding the breaks on steep downhills. Perhaps the auto downshift might work with no, or even a small trailer in tow, but it doesn't seem to be able to handle a heavy load on a steep decline (or incline).

Going up steep inclines, you can leave the transmission in tow/haul and D, but I find the frequent up- and down-shifting to be annoying, so I usually downshift to the gear that will keep an "appropriate" speed, until we are finished with the climb. I usually try not to go above 4000rpm for any length of time. On rare occasions, usually winding, downhill dirt roads, I have gone as low as 1st gear, but obviously going very slow.

(Having said all that, I haven't seen the video yet...)

Josh
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Old 06-21-2019, 02:12 PM   #9
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Name: Henry
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Thank you Josh. This is exactly the info I need.

Will you be keeping the Tundra or do you plan on getting a 3/4 ton or 1 ton truck?

We are going out of town for a few days so I will not be responding to your response probably until the middle of next week.
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Old 06-21-2019, 02:25 PM   #10
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While my 2018 10 speed F 150 does automatically downshift on hills (at least when in cruise control, and even sometimes just while going down a hill without cruise control) I agree with Bill & Josh - it doesn't do it soon enough. The F 150 lets you downshift (and back up) with a pushbutton on the shifter, or manually shift into any gear (assuming you won't redline it shifting).
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Old 06-21-2019, 03:04 PM   #11
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that ford 10 speed transmission is apparently quite a work of engineering. the torque converter is only enabled when you're at a full stop in 1st, as soon as you're rolling, its locked up, and it stays locked up as it shifts through the gears, the ECM momentarily lets up on the engine torque during shifts, and it does this so smoothly you don't notice them, since the 10 gear ratios are so closely spaced.

the gearbox actually only has 4 gearsets in it, and various combinations of these 4 gears provide the 10 gears.

apparently in MY 2020, they are bringing a heavy duty version of this gearbox to the SuperDuty F250/F350 trucks.
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Old 06-21-2019, 06:55 PM   #12
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Name: Josh & Sonya
Trailer: '97 Casita SD 17; 03 Bigfoot 25RQ
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Towing with Tundra

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Originally Posted by Rzrbrn View Post
Thank you Josh. This is exactly the info I need.

Will you be keeping the Tundra or do you plan on getting a 3/4 ton or 1 ton truck?

We are going out of town for a few days so I will not be responding to your response probably until the middle of next week.
Hi Henry,

The short answer to your question is that Iím a Toyota addict, so Iím keeping our Tundra. If Toyota had a 3/4 ton truck available in the USA, I would have bought that without hesitation.

My main concerns with the Tundra are overshooting the payload, and overloading the rear axle. Iíll try to attach a photo of CAT scale weights from the last big trip we took, which ran from 20 Oct/18 to 26 Feb/19. That was about a 15k mile run, and the weights were done on the same scale at the beginning and end of the trip.

If the CAT scale photo doesn't show after I submit this, I'll send a follow up reply with the numbers typed into the text.

IMG_7173

We are prepping for our next big trip, so I happened to have done preliminary tongue weights today, to help guide my final loading. Unfortunately, we are still packing, so the trailer is probably about 2/3s loaded in terms of food and clothing, and the truck is empty. I know that's not ideal data, but it's the best I can do for now.

Tongue weights (TW) were done using a Sherline Tongue Scale with a 2000 lb gauge.

1. Trailer partially loaded, all three liquid tanks empty, one full and one 1/3 full propane tanks: TW = 770 lb

2. Same as #1, with addition of 13 gallons of RO water in one gallon containers (from our home R0 system; we refill at Walmarts along the way). Most of the containers are stored in the shower. TW = 780 lb

3. Same as #2, with full FW tank, and two full propane tanks: TW = 910 lb (!!!). Assuming our packed weight will probably be about 6500 lb, tongue weight is currently about 14%, and we only have about 550 lb of payload left for the truck.

After doing the tongue weights, I took some vertical measurements of ground to edge of the front and rear wheel wells at the center of the tires. I also measured from the ground to the outside top of the tongue ball socket.

1. Empty truck without the trailer: Front WWH = 36 3/4 in; Rear WWH = 39 1/4 in; Top of ball socket = did not measure

2. Same as #1, with trailer attached but without spring bars for weight distribution hitch: Front WWH = 37 3/4; Rear WWH = 36 3/8 in; Top of ball socket = 23 1/2 in (front WWH went up one inch; rear WWH went down about three inches)

3. Same as #2, with spring bars installed: Front WWH = 37 3/8 in; Rear WWH = 36 7/8; Top of ball socket = 25 7/16. Note: trailer is level, with nose slightly down. (Front WWH up about a half an inch, rear WWH down about two and a quarter inches.)

So Iíll need to be very careful with weight distribution for the rest of the load, trying to put more into the rear of the trailer so as not to put more tongue weight or too much payload on the truck. Have to be sure not to go into the fishtail zone.

Fortunately, the Tundra (and the BF) have very good brakes, so weíve never had a problem with stopping or not being able to control downhill runs, and there has been no fishtailing.

Hope this helps.
Josh
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Old 06-21-2019, 07:02 PM   #13
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Scale data for previous trip with Tundra and BF 25RQ

Quote:
Originally Posted by Josh and Sonya W View Post
Hi Henry,

If the CAT scale photo doesn't show after I submit this, I'll send a follow up reply with the numbers typed into the text.
$%^&ā! photo did not attach to the first reply, so here is the CAT scale data:

Start of Trip (20 Oct/18)
Steer axle: 3360 lb
Drive Axle: 4160 lb
Trailer Axle(s): 6400 lb
Gross Weight: 13920 lb

End of Trip (26 Feb/19)
Steer axle: 3280 lb
Drive Axle: 4180 lb
Trailer Axle(s): 6500 lb
Gross Weight: 13960
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Old 06-21-2019, 07:38 PM   #14
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Originally Posted by steve dunham View Post
Both my 2014 & 2019 Ram 1500 had / have ERS which allows you to limit the top gear . When going down a steep grade you can set the top gear by pushing the buttons in the steering wheel and selecting the proper gear
Well that's just something else I have to look for, but I probably won't ever use it.

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