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Author Topic: Transmission Temps Towing  (Read 1728 times)

twscfltx

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Transmission Temps Towing
« on: November 28, 2016, 01:26:35 PM »
Any advice on transmission temperature towing trailer up mountains? How do I figure out my truck/trailer limits / gradeability to avoid routes that would exceed my truck's limits.

2014 RAM 3500 DRW LB Crew
6.7L I6 / 68RFE 6-Speed
3.73 Axle Ratio
27,000 lb GCWR
19,000 Towing Capacity
Fifth Wheel: 16,000 lb GVWR

Last week I was worried about my transmission towing up a narrow winding 6% grade. The transmissions temp was 220F for maybe 10 mins and peaked at 226F. No warnings lights.
1200' climb over 3.5mi
2400' elevation
40F outside temp
~14,750# trailer
~750# in truck

1. The advice I received was to avoid 220-240F. Is that right? That did not seem like a serious climb to hit the transmission temp limits.

2. We maybe averaged 15mph. Would it have been better to go faster to increase airflow and maintain momentum? At the time, I thought I was helping by going slow. I maybe could have done 25 mph.

3. Are there more expensive transmission fluids ATF products that improve heat transfer?

Thank you,
Tyler

OBX

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Re: Transmission Temps Towing
« Reply #1 on: November 28, 2016, 02:51:34 PM »
You may want to research the type of transmission fluid you have and what it is rated for.  You should also check the specs for the transmission.  I had similar concerns with my vehicle and feel much more confident after doing the research.

RLSharp

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Re: Transmission Temps Towing
« Reply #2 on: November 28, 2016, 05:15:31 PM »
Any advice on transmission temperature towing trailer up mountains?
Check this posting.
« Last Edit: November 28, 2016, 05:19:48 PM by RLSharp »
Richard & Linda
Rochester, NY (summer)
Tucson, AZ (winter)

RLSharp

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Richard & Linda
Rochester, NY (summer)
Tucson, AZ (winter)

keymastr

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Re: Transmission Temps Towing
« Reply #4 on: November 28, 2016, 05:28:22 PM »
You really want to keep the RPMs up in the power band. Going slow may sound like the engine is working less but lugging creates much more heat and stress.

rbertalotto

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    • RF "Farkle" Projects
Re: Transmission Temps Towing
« Reply #5 on: November 28, 2016, 07:54:52 PM »
The biggest issue with these Dodge transmissions is they do not lock up the torque converter in second and third gear. Therefore you are running on pure fluid and it heats up real fast.

I'm having a BD Tow/Haul transmission installed in my 2006 Dodge Diesel next week. These "built" transmissions lock up in all gears so you are not spinning on fluid when pulling up a long hill.

The various Doge foruns show how to install a simple switch to lock the torque converter in the lower gears. You just need to remember to unlock it when coming to a stop.

As far as temperature, it all depends on where it is being read. You might want to check some of the Dodge diesel forums for a better explanation of this.

220 degrees can be no issue in some areas of the transmission and a cause for concern in others.

I read the transtemp in my 2006 through a Juice with Attitude tuner and it reads from the OBD connection. On a few really long pulls I've seen 260 degrees for upwards of 15 minutes......YIKES! And I'm only pulling 9,000 pounds.....
RoyB
South of Boston
2006 Dodge 2500 Diesel
2011 Forest River Grey Wolf 19RR
Whole bunch of motorcycles
www.rvbprecision.com

8Muddypaws

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Re: Transmission Temps Towing
« Reply #6 on: November 28, 2016, 09:06:35 PM »
I had the same problem with my Ford diesel.  I added a rather large transmission cooler in front of all the other radiators so it got the coolest air and best flow.  This was in addition to the other two coolers For put on it.  Never had a problem after that.  I towed a 12,000# fifth wheel.
Retired computer professional
Musician, songwriter and music director
2006 Bounder 34H, 2008 CR-V Toad

twscfltx

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Re: Transmission Temps Towing
« Reply #7 on: November 29, 2016, 02:14:24 PM »
Can I get the torque converter to lock in 2nd or 3rd? What speed would that be?

Russ+Chris

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Re: Transmission Temps Towing
« Reply #8 on: November 30, 2016, 08:41:57 PM »
You really want to keep the RPMs up in the power band. Going slow may sound like the engine is working less but lugging creates much more heat and stress.
He's got a diesel, not a Hemi. Best pulling is around 2,200 to 2,800 rpms. With a Hemi, between 3,600 to 5,500 rpm.

If you are worried about heat. Install another tranny cooler. I did. Goggle atf temperatures. Bunch of charts. If you go over 240F for any length of time. Change your fluid.
« Last Edit: November 30, 2016, 08:48:58 PM by Russ+Chris »
Russ and Chris (Both retired)
Jake, the furry kid. (Golden) Cooper RIP
Brownsville Pa.
'09 Fleetwood Discovery 40X  350HP DP
'13 Jeep Grand Cherokee TrailHawk Toad
'11 Nismo Track Car
'08 Power Wagon Off Road Beast
'07 Honda VFR

Past;
'14 Bounder 36R Gas (The Wobbly Goblin)
'11 Outback 277RL

rbertalotto

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    • RF "Farkle" Projects
Re: Transmission Temps Towing
« Reply #9 on: December 01, 2016, 04:50:48 PM »
Do a search....There is a simple wire that you cut and add a switch that keeps the torque converter locked in any gear. You just need to remember to shut it off when coming to a stop as the truck will stall or you'll hurt your leg standing on the brakes trying to stop the truck (Diesel especially)

Some folks have installed a switch under the brake pedal to disengage whenever the brake is applied.

It is not an elegant solution, but lots of folks hauling big trailers on back roads are doing it.

Depending on the year and make of the truck, BD Diesel offers devices that accomplish this much more elegantly.
RoyB
South of Boston
2006 Dodge 2500 Diesel
2011 Forest River Grey Wolf 19RR
Whole bunch of motorcycles
www.rvbprecision.com

twscfltx

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Re: Transmission Temps Towing
« Reply #10 on: December 07, 2016, 08:54:50 AM »
The transmission fluid dip stick looked clean. I'm still trying to figure out what routes I can take without watching my trans sump temp the whole time.

Please give advice to compare aftermarket options:
Deep pan vs Cooler

8Muddypaws

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Re: Transmission Temps Towing
« Reply #11 on: December 07, 2016, 12:11:06 PM »
Coolers are more efficient, cheaper, and easier to install.  But they don't look as cool as a deep finned aluminum pan.

Put your hand near (not on) your rear diff cover after a long pull.  (It will be hot!). That's where you probably need the aluminum fins.
Retired computer professional
Musician, songwriter and music director
2006 Bounder 34H, 2008 CR-V Toad

twscfltx

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Re: Transmission Temps Towing
« Reply #12 on: December 14, 2016, 03:36:57 PM »
Is it better to install the cooler underneath adjacent to the transmission or upfront in front of the other coolers?

Would an auxiliary transmission cooler make a significant difference for a 68RFE towing 16,000#?

This does not change the heat generation. Should I consider options to manually lock up the torque converter in 2nd and/or 3rd gears? What are the risks? Is this a DIY project? Does it void powertrain warranty? Does it require reprogramming tuner?

Thanks again.

8Muddypaws

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Re: Transmission Temps Towing
« Reply #13 on: December 14, 2016, 06:49:00 PM »
If the additional cooler is installed in front of the radiator and charge air cooler (intercooler) in a turbocharged engine that's probably all you need.  Installing it underneath limits the airflow unless you put a fan behind it to suck air through it.

In my opinion the first option works better, less expensive, and the cooler won't be exposed to road grime, rocks etc.

I never found it necessary to modify the torque converter lockup. 
Retired computer professional
Musician, songwriter and music director
2006 Bounder 34H, 2008 CR-V Toad

Russ+Chris

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Re: Transmission Temps Towing
« Reply #14 on: December 15, 2016, 08:25:45 PM »
Put the tranny cooler in front of the other heat exchangers. It has to be in the air flow. Next to the tranny is useless.
Russ and Chris (Both retired)
Jake, the furry kid. (Golden) Cooper RIP
Brownsville Pa.
'09 Fleetwood Discovery 40X  350HP DP
'13 Jeep Grand Cherokee TrailHawk Toad
'11 Nismo Track Car
'08 Power Wagon Off Road Beast
'07 Honda VFR

Past;
'14 Bounder 36R Gas (The Wobbly Goblin)
'11 Outback 277RL

twscfltx

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  • Posts: 40
Re: Transmission Temps Towing
« Reply #15 on: December 21, 2016, 10:57:36 AM »
Does the aux Tran Cooler need the thermostat sensor or should I just run it all the time?
What is the best terminal for power supply?

8Muddypaws

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Re: Transmission Temps Towing
« Reply #16 on: December 22, 2016, 11:10:21 AM »
Good question. 

If you install a cooler and the transmission never warms up you might need a thermostatic valve.

Some transmissions have them built in.  Some don't.
Retired computer professional
Musician, songwriter and music director
2006 Bounder 34H, 2008 CR-V Toad

 

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