Tow/Haul or not Tow/haul..

[tomstehr]

Re: Tow/Haul or not Tow/haul..

Do you think it is wise to modify the stock cooling system on this truck? I thought extra cooling was part of the towing pack offered by GM..?? I am nothaving overheat issues, but still curious.

 

[gtochris]

Re: Tow/Haul or not Tow/haul..

For a 2,000 load you might be OK with it off, I use it almost all the time, especially with towing the boat in my sig.

 

[Chip Chester]

Re: Tow/Haul or not Tow/haul..

It would be worth noting the engine temperature and transmission temperature as you drive the route with and without the boat, and with and without tow/haul when you are towing the boat. I think that info will inform your decisions.... You do have a trans temp gauge, don't you?

I use tow/haul and no OD when towing my enclosed car trailer with my 2500 Suburban -- even at 65. I use standard settings and OD when towing my 16' wood runabout.

Folks often focus on weight (which influences acceleration, braking, and tow vehicle 'levelness') and overlook trailer frontal area (aerodynamic drag/fuel "economy") when evaluating towing characteristics. Most boats are much more streamlined than cargo/camping trailers. In general, choosing the drivetrain settings that result in the lowest engine and transmission temperatures will be the best course of action.

Chip

 

[Jlawsen]

Re: Tow/Haul or not Tow/haul..

Ok. So I researched this a bit to find out what exactly that button does to or for MY truck. For the 2007 Silverado Z71 I drive, the tow/haul button changes the shift charecteristics by increasing line pressure on the clutch plate packs, and increasing the engine speed at which the transmission shifts. It also allows for a faster shift, thus reducing slippage of components and preventing exsessive wear. It does not eliminate overdrive, which is any gear greater than a 1 to 1 ratio, but may cause the converter to not lock or lock at a higher speed. One of the recommendations was to use the tow haul to get up to speed, or when entering the highway, or of course in mountains and hills. Turning the tow/haul off during higway operation would allow the converter to lock and the transmission to run cooler. Hope this helps my fellow Chevy and GMC drivers out! Thanks everybody for your replies, and any additional comments or suggestions are always welcome.

Can't get much more correct than that! Your research is right on the money. In layman terms it's basically on the fly reprogramming of the transmission to use shift points that are more conducive to hauling and towing. For Ford Owners that have it, it works the same way. I use it often with my F350 SD 6.4L, it's helpful in many conditions. When comming down mountains and hauling, a lot of people with automatics like mine think of it as the answer to the Jake Brake although the functionality is completely different. I think it's one feature that no owner should be without if it's available on your vehicle.

 

[tomstehr]

Re: Tow/Haul or not Tow/haul..

It would be worth noting the engine temperature and transmission temperature as you drive the route with and without the boat, and with and without tow/haul when you are towing the boat. I think that info will inform your decisions.... You do have a trans temp gauge, don't you?

I use tow/haul and no OD when towing my enclosed car trailer with my 2500 Suburban -- even at 65. I use standard settings and OD when towing my 16' wood runabout.

Folks often focus on weight (which influences acceleration, braking, and tow vehicle 'levelness') and overlook trailer frontal area (aerodynamic drag/fuel "economy") when evaluating towing characteristics. Most boats are much more streamlined than cargo/camping trailers. In general, choosing the drivetrain settings that result in the lowest engine and transmission temperatures will be the best course of action.

Chip

Yes, as a matter of fact I do have a trans temp gauge. I have driven most of the routes I plan on using without a trailer behind me. I know when I go to Oklahoma, I will probably be turing on the tow/haul once I get out of Texas. That is where I will start to encounter changes in elevation and winding roads where changes in speed and gears will start to factor into my trip. From the Gm tech perspective I recieved, there is no benefit to using tow haul during high speed hiway driving if the road is level enough that I can maintain speed without the truck hunting gears. Thanks for your perspective Chip!

 

[coolbri70]

Re: Tow/Haul or not Tow/haul..

OD is ok @ half tow capacity I believe it will tell you in your manual, if you allready have an extra trans cooler it should be ok just watch the temp. And keep an eye on the fluid. If you check the fluid it should be red if black I recommend trans flush

 

[Philster]

Re: Tow/Haul or not Tow/haul..

My Dodge Ram Hemi tow/haul mode makes my transmission run 20 degrees cooler on days with modest temps, and up to 30 degrees cooler with hotter weather. This is towing a boat package that is only about 65%-70% of the total towing capacity. Fuel economy either way is close, depending on conditions.

 

[tomstehr]

Re: Tow/Haul or not Tow/haul..

A friend suggested getting a programmer. I looked at the Edge Evolution tuner. It has a power setting for towing. It reprograms the ECM and PCM. The guide does not say use in conjunction with the tow/ haul mode though. Anybody have thoughts or experience here?

 

[jbetzelb]

Re: Tow/Haul or not Tow/haul..

A friend suggested getting a programmer. I looked at the Edge Evolution tuner. It has a power setting for towing. It reprograms the ECM and PCM. The guide does not say use in conjunction with the tow/ haul mode though. Anybody have thoughts or experience here?

Not worth it on a gas engine. Not usually a good idea to pull with a tuner. Shouldn't need anything to pull 2000 pounds. Any full sized truck made by the big 3 in the last 10 years should pull 2K pounds in overdrive anywhere you want to go.

 

[kenmyfam]

Re: Tow/Haul or not Tow/haul..

never hurts to keep the fluid cooler i would do

I totally agree with that.First thing I did with my Trailblazer was to put an additional tranny cooler and a filter and fluid change.

 

[jeffnick]

Re: Tow/Haul or not Tow/haul..

Humans are curious creatures. If you're out to satisfy your curiosity get the tranny cooler, chip and whatever else tickles your fancy. If you want to tow something from A to B, you'll be doing yourself a favor if you keep your transmission from hunting.

 

[tomstehr]

Re: Tow/Haul or not Tow/haul..

Humans are curious creatures. If you're out to satisfy your curiosity get the tranny cooler, chip and whatever else tickles your fancy. If you want to tow something from A to B, you'll be doing yourself a favor if you keep your transmission from hunting.

Aye, Cheif! Good copy... will do! I am gonna get muffler flaps for the truck, a programmer, fuzzy dice for the mirror, an all that. And whenever I hook my trailer up, I will keep inmind that all that really matters i that i dont keep hearin the transmission shiftin back an forth!
Seiously though.. thanks! That sounds like a very sound piece of advise.

 

[Philster]

Re: Tow/Haul or not Tow/haul..

When towing, to be easiest on the transmission, you want to avoid heat and stress.

Slip = heat
O/D = stress (depending on how the particulat O/D is engineered, so follow owners' manuals)
hunting = stress and/or heat

Each of the above can be somewhat managed by a keen operator who is connected to how his transmission functions and acts accordingly, or can be managed to various degrees by using tow/haul/etc modes.

I see people discounting the delayed shift points of tow/haul mode. That helps avoid slip. This is important.

I see people discounting O/D lockout. Locking out O/D can reduce stress on many transmissions. Some will run hotter in O/D because of how little the fluid circulates in O/D in some types of transmission.

I know many people who are capable of managing 80% of what any tow/haul mode can do, and probably 90% of what O/D lockout can do. Rare is there a person who is managing every aspect of how the truck accelerates, shifts, downshifts, engages O/D, etc. Sorry, but you don't have the luxury of calculating the algorithms the computer is using. When a shift point or downshift is selected, ain't no way you are getting it as right as the computer, and you probably aren't even managing shifts 100% of the time.

Yes, you know generally how to tow. At the end of the day, you will lose at an alarming (100% rate) to the engine/trans computer, as it will kick your know-it-all butt in managing all the criteria needed to preserve the mechanicals involved in towing.

.

 

[Silvertip]

Re: Tow/Haul or not Tow/haul..

Yes, you know generally how to tow. At the end of the day, you will lose at an alarming (100% rate) to the engine/trans computer, as it will kick your know-it-all butt in managing all the criteria needed to preserve the mechanicals involved in towing.

.

I disagree with that statement. While it may be true for much of the motoring public don't understand the mechanics of transmission and generally, that's ok. However those that do understand what's going on in their vehciles and the conditions under which they are operated, you need to remember that a team of folks in an engineering center decided how those algorithms would be structured. As such there is no 100% correct "automatic" operation. Here is just one scenario. Cruising on a flat stretch of road will eventually lead you to a hill and it doesn't matter how steep it is. With cruise control engaged, as the vehicle enters the grade, speed will begin to drop and the cruise control begins to add throttle. At that point MORE throttle needs to be added to not only make up for the lost speed but to add sufficient throttle to maintain that speed. If the grade is steep enough, the cruise control may not be able to compensate so a downshift occurs. Now -- consider this. If you are an attentive operator, you see the hill coming and experience tells you that cruise will not be able to prevent a downshift. So you accelerate just a couple MPH on the flat just before entering the hill which then allows you to overcome that initial lag before the cruise control realizes it is losing ground. You can then continue to remove you foot from the accelerator as you crest the hill. The extra fuel it take to accelerate on the flat is but a fraction of what it takes to overcome lost speed on a hill. No downshift occurs on even relatively steep grades. The problem with cruise control and transmission controls is that there is no "anticipator" meaning something must happen first before any algorithm can take place. That reaction must "overcome" the event rather than having a way to anticipate it where much less throttle is needed. So a good, attentive driver can indeed out drive cruise control. I do it consistently. To me cruise control is a convenience and does not provide the best economy. For most drivers however, cruise is the best way for them achieve optimum economy. The same principle applies to use of tow-haul or manual operation of the transmission.

 

[Jlawsen]

Re: Tow/Haul or not Tow/haul..

All correct Silvertip and not arguable in my book. In my younger years while searching for a career choice I drove a Transtar Golden Eagle with a 40' refer all over the 11 Western States. My best friends were my boost gauge, temp gauge, Tach and above all, my eyes and ears. If you know your vehicle as well as I got to know that truck you can drive it to it's limits and not hurt it but you don't have time for much more. Jf you fail to pay attention for just a few minutes you can end up all messed up. Let technology do it's thing, the tuners and such are there for people that like to take their vehicles past the limits and if you're not paying attention you will hurt your vehicle.

 

[Philster]

Re: Tow/Haul or not Tow/haul..

I disagree with that statement. While it may be true for much of the motoring public don't understand the mechanics of transmission and generally, that's ok. However those that do understand what's going on in their vehciles and the conditions under which they are operated, you need to remember that a team of folks in an engineering center decided how those algorithms would be structured. As such there is no 100% correct "automatic" operation. Here is just one scenario. Cruising on a flat stretch of road will eventually lead you to a hill and it doesn't matter how steep it is. With cruise control engaged, as the vehicle enters the grade, speed will begin to drop and the cruise control begins to add throttle. At that point MORE throttle needs to be added to not only make up for the lost speed but to add sufficient throttle to maintain that speed. If the grade is steep enough, the cruise control may not be able to compensate so a downshift occurs. Now -- consider this. If you are an attentive operator, you see the hill coming and experience tells you that cruise will not be able to prevent a downshift. So you accelerate just a couple MPH on the flat just before entering the hill which then allows you to overcome that initial lag before the cruise control realizes it is losing ground. You can then continue to remove you foot from the accelerator as you crest the hill. The extra fuel it take to accelerate on the flat is but a fraction of what it takes to overcome lost speed on a hill. No downshift occurs on even relatively steep grades. The problem with cruise control and transmission controls is that there is no "anticipator" meaning something must happen first before any algorithm can take place. That reaction must "overcome" the event rather than having a way to anticipate it where much less throttle is needed. So a good, attentive driver can indeed out drive cruise control. I do it consistently. To me cruise control is a convenience and does not provide the best economy. For most drivers however, cruise is the best way for them achieve optimum economy. The same principle applies to use of tow-haul or manual operation of the transmission.

That's a certifiable strawman argument.

1 - don't tow w/cruise control
2 - if discussing cruise control use only outside of towing, I was not referencing cruise control and it's not a dynamic function that correlates to tow/haul mode at all.

Cruise control use is not analogous to tow/haul mode use.

You can't choose the combustion parameter for your engine every millisecond. That's more analogous.

 

[tomstehr]

Re: Tow/Haul or not Tow/haul..

Wow.. quite the informative and some what controversial subject! Previously I had posted what information I had gathered from GM technicians. What I know from that is: Tow/Haul is best for acceleration and driving on changing road elevation. One of the functions of the feature delays the engagement of the TCC(Torque Converter Clutch) which causes more heat because it is a fluid coupling versus a mechanical couplin when the clutch engages. If I am driving on a generally flat road surface and have acheived my desired speed, turning off the Tow/Haul mode will allow the clutch to engage and lower the fluid temperature and increase fuel milage.

 

[tomstehr]

Re: Tow/Haul or not Tow/haul..

Also, if I were to start encountering hills or some other anomily that would put more load on the drivetrain, it would be wise to re activate the feature.

 

[TheLucille]

Re: Tow/Haul or not Tow/haul..

Wow.. quite the informative and some what controversial subject! Previously I had posted what information I had gathered from GM technicians. What I know from that is: Tow/Haul is best for acceleration and driving on changing road elevation. One of the functions of the feature delays the engagement of the TCC(Torque Converter Clutch) which causes more heat because it is a fluid coupling versus a mechanical couplin when the clutch engages. If I am driving on a generally flat road surface and have acheived my desired speed, turning off the Tow/Haul mode will allow the clutch to engage and lower the fluid temperature and increase fuel milage.

On the GM Allisons, it's quite the opposite - tow/haul mode engages the TCC far earlier, as the TCC eliminates slippage. You get more power to the wheels. I use tow/haul whenever I have heavily loaded trailers - about 7k or more. The DMAX/Allison combo raises the shift points and increases line pressure as well.

 

[tomstehr]

Re: Tow/Haul or not Tow/haul..

On the GM Allisons, it's quite the opposite - tow/haul mode engages the TCC far earlier, as the TCC eliminates slippage. You get more power to the wheels. I use tow/haul whenever I have heavily loaded trailers - about 7k or more. The DMAX/Allison combo raises the shift points and increases line pressure as well.

Awsome! If I had a DuraMax i dont even know if I would notice my little boat behind it!