Manual Shifting When Towing

[stevem]

we tow a 4000 lb(real weight!) tt with a dodge dakato(v6, 2wd, 4 spd auto), and we've towed for several years, no issues at all

we always tow with "tow haul" engaged and on long hills, we always shift the transmission lever into "2nd" when the transmission shifts down automatically.  and we hold it there until we feel the truck is ready to shiftup again, like at the top of the hill.  in "second", we never exceed 3000 rpm(or in any other gear), so of course we go slower.

my rule is if the truckers are going slower up a hill, I can too and not impede traffic

my brother in law, who also tows, thinks we're nuts.  he's more of a "put it in drive and go" type and just pushes the gas pedal harder

on really steep downhills we'll also shift down a gear or even two and when I say steep I mean a hill that would require constant braking to control speed, on those hills we also use the brake controller manually lightly, again just to maintain a safe speed and to spread the braking effort
after all trailer braking doesn't come on until the controller senses the vehicle actually slowing down

I'm nuts there too, according to him

comments?  anybody use their shift lever and manual trailer braking?

 

[Gary RV_Wizard]

Downshifting on the downhill side is wise, though the "tow-haul" on many trucks does this for you.  But why do you change the tranny selector going uphill after the transmission has already shifted?

I vote with your Brother-in-law. It's pretty hard to shift smarter than your auto trans, which is watching the engine revs and adjusting to stay in the peak horsepower range when under load and peak economy range otherwise. About the only time I would recommend that is when the terrain has frequent little hills and the tranny is continuously up/down shifting. A human can anticipate shifts where the tranny cannot see ahead to do that.

 

[kdbgoat]

And no real need to stay below 3000 rpms. Your engine probably redlines at about 5000 rpms. You may want to find out where your peak horsepower and torque points are. It can get a bit noisy, but you should be able to move on smartly if desired.

 

[stevem]

we do find that if left in top gear, the tranny sometimes does tend to shift back and forth when maintaining 3000 rpm up a long hill and the truck looses speed when it shifts back up into high of course.  remember Im talking about long and steep hills, truckers are creeping up at 50kmh(30 mph)

engine redline is actually 6000 rpm, peak horsepower and torque is around 4000 rpm, typical small v6 tuned more for a car than a truck towing a trailer.
2500 rpm or lower and it sucks!!

 

[Gary RV_Wizard]

I'm not suggesting that you should drive faster on the hills - pick the speed you are comfortable with. I often run about 35-45 on long hills myself.  I just feel that the days when the driver can out-perform an automatic transmission are long past. If you do everything right you can maybe equal it for efficiency and least engine wear.

 

[stevem]

maybe we're being overly cautious and babying the truck too much, I does perform very well for a v6 in a fairly heavy truck towing 4000 lbs

biggest issue is getting it from 90 kmh to 105, takes forever it, 105 seems to be the "sweet spot", but 95? its shifting down every tiny upgrade

 

[8Muddypaws]

I prefer to downshift sooner than the transmission would.  I can keep my RPMs in the sweet spot that way.

 

[keymastr]

You may not like the noise but your engine will be happier at 4000 than 3000 when pulling a load uphill. With a 6000 redline you have plenty of safety margin, running at 5000 for a few minutes will not hurt anything. Revving is better than lugging when towing. And if the tranny is shifting back and forth then hold it in the lower gear. Shifting creates heat and heat kills trannys.

 

[Prior member]

I agree with you on most of what you do, but on going up hill, I let the transmission do the shifting, unless the mountain is so steep that it is shifting back and forth and in that case I will done shift and leave it there at a constant speed until I feel it is comfortable to put it back in drive

It sounds to me that you are a very sensible driver

Jack L

 

[robertusa123]

Do that all the time with my van.  Thats why the shifter does that.... Also why I added a after market tachometer to my van

 

[grashley]

I agree with most!  My big question is if the tranny downshifts to 3 going up a hill, why shift down to 2????  I will manually shift down to 3 to avoid the up/down shifting, but 3 should be fine!!

 

[longhaul]

Auto tranny braking/down shift  and upshift programs vary widely depending on the transmission. Not all TH modes are the same and vary greatly.
The wifes 2016 1500 chevy 5.3 6L80E 3.42 gears will not down shift for down hill braking unless the operator manually selects a lower gear. Completely different than our sons 2015 chevy Dmax/A.
I use M mode or the manual mode on her truck as I can decide which gear is needed before the tranny can and better anticipate more go pedal for the next hill. Besides at 35-40 mph I don't want the transmission in OD lugging along at 1200-1500 rpm then drop two gears at the next small hill. I can keep the rpm in the 2000 range at any speed when poking along and eliminate constant up and down shifting. All the mode in this tranny does is hold the TC clutch open longer before TC clutch lock up or upshift.
  I will say I'm not a fan of electronic shifting. When I stab the go pedal I expect the truck to go and when I toggle down a couple of gears for engine braking I want it now ...not 3 sec later or
a hundred yards farther down the hill.

 

[Gary RV_Wizard]

I can keep my RPMs in the sweet spot that way

Which presumes the "sweet spot" is known to the driver and followed religiously.  Both peak torque & hp rpms, and the width of that power band. Some engines have a fairly sharp peak, while others may have a broad band where power stays largely the same.

 

[Oak]

I live in Colorado on the West Slope. (West side of the divide). As we travel often to the east side we are always going through several mountain passes. I haul primarily with a 2005 GMC 3/4 ton dually with the 6.4L gas engine and auto transmission, hauling around 7,000lbs of stuff.  We too go very slow up hill because it keeps the engine cooler. The truck would pull much faster if I asked it. I also use the "tow/haul switch. But I leave the tran. in drive. On the downward side of passes I will usually shift into the lowest gear practical for traffic so as to ride the brake less. Have never tried just braking with the trailer to slow us down, what do you guys think of that practice? I noticed  Stevem mentioned that in his original post but no one commented on that. Is that an OK practice? Would it put too much strain on the trailers brakes?

Oak

 

[outofhere2]

From what I understand TT brakes will over heat rather quickly and should be saved. Also the op should leave his trans out of overdrive (his tow-haul mode may do that for him.) I know that on my truck if I leave it in OD it will shift up and down all the time. Very hard on the trans

 

[8Muddypaws]

I've used the trailer brakes to control sway on the rare occasions it happened.  You can lock up your trailer brakes and barely feel it in the TV.  Probably not a safe practice to do this often.

 

[stevem]

thanks for all the comments, we leave on a 5000 mile trip next week and we really need to look after the transmission.  its been flawless for 7 years now with 100,000 miles.  a third of that towing our trailer.

this will be our first long trip with a new to us heavier trailer(extra 600 lbs)

general consensus seems to be let the tranny shift down, then pull the lever down to hold it there if needed.  and don't be afraid to rev the engine more!

 

[Telemark46]

The need to control shifts manually depends on the engine/tranny/trailer combo.  Our 2007 V8 4Runner will often drop to 21-2200 RPM before downshifting, so I do it manually (trailer is about 3600#).  I rarely let it rev much over 3000 uphill, so maybe I am too conservative. 

If you have electric trailer brakes, I think they will engage (lightly) if you are using the TV brakes to maintain a constant downhill speed.  Considering that the TV likely has 4 wheel discs and the trailer brakes are probably drums, you always want the TV to do the vast majority of the braking.  Discs are less susceptible to fade and probably cheaper to service.  I assume you test your trailer brakes on every trip.  Otherwise, I don't see a need to use the trailer brakes alone unless you are trying to dampen sway.  Then again, I am a relative novice, so perhaps someone will straighten me out on this topic.

 

[donuts]

Why would you manually use the brake controller for the trailer? The only time I do that is to check the trailer brakes.
Your going down a hill and you manually deploy the trailer brakes as you see fit to slow the trailer and truck? If this is what you are doing, I agree with your brother-in-law.
As soon as you push on the brake pedal your trailer brakes should activate. If you use your transmission correctly, you will keep your braking to a minimum which will help preserve them.

Stan