Towing with the 5.3 V8

[nando87]

Question for those that have towed up long grades with the 5.3 and 3:42 gears.

 

I towed my Toy Hauler for the first time this past weekend, coming from a 2007 V-Max NHT (4spd/4:10 gears) package I was happy with the results but I will say my last truck would pull the hills better but I blame that on the gearing vs the power.

 

In my last truck I would just put it in 2nd gear, rev to about 5000-5500rpm and pull any hill at ease. In this truck when approaching a hill around 65mph and going into WOT the motor would only rev to 4k (even when in manual mode), well 4k doesn't have enough power to pull up a hill so I would loose speed halfway up the hill down to about 53mph where the tranny would finally down shift and rev to 5500 and start to gain speed again. This was very annoying to me that every hill I hit I would loose over 10mph then have to gain it back up.

 

Has anyone else experienced this issue?

 

Another thing that happened, on the really long hills when I would be at the 5500rpm area for some time the truck would shake and the motor would go to 6k for the remaining climb. This would only happen after holding 5500rpm for some time when finally it would just jump out of no where to 6k. But it wasn't a smooth transition but more of a harsh shake, I even let off the first time it did it because I thought I blew something.

 

Has this happened to anyone as well?

[iCryWheniGoPoop]

Holly crap.... WOT shift point is at 5600rpm and you are holding that on long grades? I was going to say get your truck tuned but after hearing that I would wait and see how that motor holds up first because I don't think voiding your warranty is a good idea at this point. You are way down on torque at those RPM's as well and 3500-4000 should be about peak torque numbers which would be the best RPM range to be in.

 

What does toy hauler weigh?

[nando87]

Holly crap.... WOT shift point is at 5600rpm and you are holding that on long grades? I was going to say get your truck tuned but after hearing that I would wait and see how that motor holds up first because I don't think voiding your warranty is a good idea at this point. You are way down on torque at those RPM's as well and 3500-4000 should be about peak torque numbers which would be the best RPM range to be in.

 

What does toy hauler weigh?

Yup! On a long grade I'll be about 4k and 65mph and start to loose speed half way up the hill, once I'm about 53mph it will down shift to 5500rpm and pull me back up to speed (65mph). If the grade is Really long it will hold the 5500rpm for most of the hill and out of no where it will go to 6k for the rest of the climb and hold at 65mph.

 

Not sure the full weight, It's a 21ft tow hauler and had it loaded with a 1600lb buggy in the back along with the usual camping necessities.

[iCryWheniGoPoop]

I would run e85 on trips hauling the toy hauler

 

21ft toy hauler is probably 6500 empty, putting you at 8100 w/out gear and passengers... If you can post a weight you may get some apple to apple comparisons though

[nando87]

I would run e85 on trips hauling the toy hauler

 

21ft toy hauler is probably 6500 empty, putting you at 8100 w/out gear and passengers... If you can post a weight you may get some apple to apple comparisons though

I thought about this as well but it's not really available in places we go camping, I run 91oct.

[wandern]

Question for those that have towed up long grades with the 5.3 and 3:42 gears.

 

I towed my Toy Hauler for the first time this past weekend, coming from a 2007 V-Max NHT (4spd/4:10 gears) package I was happy with the results but I will say my last truck would pull the hills better but I blame that on the gearing vs the power.

 

In my last truck I would just put it in 2nd gear, rev to about 5000-5500rpm and pull any hill at ease. In this truck when approaching a hill around 65mph and going into WOT the motor would only rev to 4k (even when in manual mode), well 4k doesn't have enough power to pull up a hill so I would loose speed halfway up the hill down to about 53mph where the tranny would finally down shift and rev to 5500 and start to gain speed again. This was very annoying to me that every hill I hit I would loose over 10mph then have to gain it back up.

 

Has anyone else experienced this issue?

 

Another thing that happened, on the really long hills when I would be at the 5500rpm area for some time the truck would shake and the motor would go to 6k for the remaining climb. This would only happen after holding 5500rpm for some time when finally it would just jump out of no where to 6k. But it wasn't a smooth transition but more of a harsh shake, I even let off the first time it did it because I thought I blew something.

 

Has this happened to anyone as well?

 

The forum has erased two lengthy replies.

Long story short:

2,000 mile+ trip last week, pulling 6,500lb travel trailer (large frontal area). Excellent acceleration up 6%-7% grades from 40mph-70mph, no problem keeping up with diesel pickups on acceleration. Altitude from sea level to 5,000 ft. Twice during the trip the truck went into some idiot mode and would sit at 3,800-4,000RPMs and refuse to downshift, leaving me dead on the grade. The rest of the time, it performed admirably.

 

Also very satisfied with grade braking performance on the long downhill grades.

[nards444]

Question for those that have towed up long grades with the 5.3 and 3:42 gears.

 

I towed my Toy Hauler for the first time this past weekend, coming from a 2007 V-Max NHT (4spd/4:10 gears) package I was happy with the results but I will say my last truck would pull the hills better but I blame that on the gearing vs the power.

 

In my last truck I would just put it in 2nd gear, rev to about 5000-5500rpm and pull any hill at ease. In this truck when approaching a hill around 65mph and going into WOT the motor would only rev to 4k (even when in manual mode), well 4k doesn't have enough power to pull up a hill so I would loose speed halfway up the hill down to about 53mph where the tranny would finally down shift and rev to 5500 and start to gain speed again. This was very annoying to me that every hill I hit I would loose over 10mph then have to gain it back up.

 

Has anyone else experienced this issue?

 

Another thing that happened, on the really long hills when I would be at the 5500rpm area for some time the truck would shake and the motor would go to 6k for the remaining climb. This would only happen after holding 5500rpm for some time when finally it would just jump out of no where to 6k. But it wasn't a smooth transition but more of a harsh shake, I even let off the first time it did it because I thought I blew something.

 

Has this happened to anyone as well?

3,42 with any sort of serious towing isnt going to be terrible and can work good, but is not the best option for sure. I know GM went to 3.42s due to MPG, but for towing they would have done better going to 3.55s as the base gearing.

[nando87]

3,42 with any sort of serious towing isnt going to be terrible and can work good, but is not the best option for sure. I know GM went to 3.42s due to MPG, but for towing they would have done better going to 3.55s as the base gearing.

Yea I do agree with that! I just don't like the fact I loose so much speed going up a hill.

[music]

Question for those that have towed up long grades with the 5.3 and 3:42 gears.

 

I towed my Toy Hauler for the first time this past weekend, coming from a 2007 V-Max NHT (4spd/4:10 gears) package I was happy with the results but I will say my last truck would pull the hills better but I blame that on the gearing vs the power.

 

In my last truck I would just put it in 2nd gear, rev to about 5000-5500rpm and pull any hill at ease. In this truck when approaching a hill around 65mph and going into WOT the motor would only rev to 4k (even when in manual mode), well 4k doesn't have enough power to pull up a hill so I would loose speed halfway up the hill down to about 53mph where the tranny would finally down shift and rev to 5500 and start to gain speed again. This was very annoying to me that every hill I hit I would loose over 10mph then have to gain it back up.

 

Has anyone else experienced this issue?

 

Another thing that happened, on the really long hills when I would be at the 5500rpm area for some time the truck would shake and the motor would go to 6k for the remaining climb. This would only happen after holding 5500rpm for some time when finally it would just jump out of no where to 6k. But it wasn't a smooth transition but more of a harsh shake, I even let off the first time it did it because I thought I blew something.

 

Has this happened to anyone as well?

 

I'm glad you posted that, since it jives with my hand calcs. I pull a camper weighing in at just shy of 7000 lbs, and have wondered many times how it would perform w/ the 6-spd vs my current truck. I don't think that there's a "right" answer here. The 4-spd/3.73 hits just shy of the 5.3 sweet spot on the torque/power curve at 60 to 65 mph, and will pull pretty strong @ 3900 to 4300 rpm (60 to 65 mph). A 4.10 ratio puts it right dead into torque peak at those speeds. A 6-spd/3.42 is going to be closer to 3300 to 3700 rpm at the same speeds. The trade-off, is that on those smaller and rolling hills, the 6-spd doesn't need to shift to such a high rpm to hold speed, where the 4-spd may. That's the only real complaint that I had on mine, but rather than change trucks, I retuned the tow shift pattern to my tastes. Much happier. It would be nice to have that closer 1->2 shift too, but I don't hit that point very often on a steep hill, so I don't really care.

 

I'm actually surprised that you can't pick a gear you want, and force it to hold there. I don't like the sound of that... or did I misread?

[nando87]

 

I'm glad you posted that, since it jives with my hand calcs. I pull a camper weighing in at just shy of 7000 lbs, and have wondered many times how it would perform w/ the 6-spd vs my current truck. I don't think that there's a "right" answer here. The 4-spd/3.73 hits just shy of the 5.3 sweet spot on the torque/power curve at 60 to 65 mph, and will pull pretty strong @ 3900 to 4300 rpm (60 to 65 mph). A 4.10 ratio puts it right dead into torque peak at those speeds. A 6-spd/3.42 is going to be closer to 3300 to 3700 rpm at the same speeds. The trade-off, is that on those smaller and rolling hills, the 6-spd doesn't need to shift to such a high rpm to hold speed, where the 4-spd may. That's the only real complaint that I had on mine, but rather than change trucks, I retuned the tow shift pattern to my tastes. Much happier. It would be nice to have that closer 1->2 shift too, but I don't hit that point very often on a steep hill, so I don't really care.

 

I'm actually surprised that you can't pick a gear you want, and force it to hold there. I don't like the sound of that... or did I misread?

yes you are correct about the 4:10 gears, my last truck was a Vortec Max with 6.0 and 4:10 gears. Hitting a hill in 2nd gear, 5k rpm, it would climb with ease.

 

These new trucks do let you manually shift the gears, however it only allows it when it wants to. When I'm climbing and start to loose speed, I will try and down shift it but it won't do anything it will just keep loosing speed until I get down to about 53mph and then the truck will take my down shift. But by then I've already lost over 10mph and have to now gain speed back.

 

My biggest issue is that I can get stuck behind a big rig since my truck can't keep speed causing me to get into the slow lane, by the time she will downshift and gain speed it could be to late leaving me stuck on a hill for a slow climb if I can't get over in the next lane.

[music]

My biggest issue is that I can get stuck behind a big rig since my truck can't keep speed causing me to get into the slow lane, by the time she will downshift and gain speed it could be to late leaving me stuck on a hill for a slow climb if I can't get over in the next lane.

 

My opinion, for what little it's worth, is to let it slow down and go up a little slower... rather than fighting it. I've done it both ways under many situations, and don't mind "slow and easy". It's lower stress, and has almost no impact on my time. The only time it bugs me is if I'm following my FIL w/ his Dmax. That thing will zip up a mountain towing double the weight, and I doubt he's hitting 3k rpm. I don't mean that it bothers me that he's faster, but just that I need to "keep together".

 

My rule is pretty simple: find the "sweet spot" for my gearing/power and use it. Fighting it will be a journey in frustration!

[Jon A]

It's really unfortunate, most all those issues can easily be fixed with programming. I don't know if GM was trying to make people get the best mileage, improve durability, make it "seem like" it's hunting for gears less by not allowing a downshift when you want one, or if they just got it all wrong with the programming. If you're trying to maintain speed up a hill, tow/haul mode is actually worse not allowing the downshift to second until you've lost a ton of speed.

 

On the subject of gears, it's also too bad they didn't offer 4.10's as an option. When you're shifting between 2nd and 3rd on a hill with 3.42's, with 4.10's you'd be doing the same thing between 3rd and 4th. 3rd and 4th are closer together so you can downshift earlier without overspinning the engine so you stay in the engine's sweet spot much better. If you're going to do a lot of towing, a swap to 4.10's will be very helpful--hopefully it'll be cheaper/simpler for these new rear ends soon.

[chuckl1218]

My factory brake controller don't seem to be compatible with my electric over hydraulic trailer brakes. Any thoughts or ideas?

Hmmm. No experience with electric over hydraulic trailer brakes in my 2014... However my 2014 Silverado Owners Manual indicates on page 9-100 and following pages..."The vehicle may have an Integrated Trailer Brake Control (ITBC) system for use with electric trailer brakes or most electric-over-hydraulic trailer brakes." But they don't explain what "most" means. Another quote, "Use the ITBC system only with electric or electric over hydraulic trailer brakes." This would indicate to me that it SHOULD work, but then again, what does "most" mean?

 

And in the 2015 Silverado features list, they specifically say that it will...New for 2015 HD trucks, the Integrated Trailer Brake Control is now compatible with electric over hydraulic trailer brakes. The Integrated Trailer Brake Control system can be used to adjust the amount of power output, or Trailer Gain, available to the trailer brakes. The control panel also allows manual application of the trailer brakes.

[nards444]

It's really unfortunate, most all those issues can easily be fixed with programming. I don't know if GM was trying to make people get the best mileage, improve durability, make it "seem like" it's hunting for gears less by not allowing a downshift when you want one, or if they just got it all wrong with the programming. If you're trying to maintain speed up a hill, tow/haul mode is actually worse not allowing the downshift to second until you've lost a ton of speed.

 

On the subject of gears, it's also too bad they didn't offer 4.10's as an option. When you're shifting between 2nd and 3rd on a hill with 3.42's, with 4.10's you'd be doing the same thing between 3rd and 4th. 3rd and 4th are closer together so you can downshift earlier without overspinning the engine so you stay in the engine's sweet spot much better. If you're going to do a lot of towing, a swap to 4.10's will be very helpful--hopefully it'll be cheaper/simpler for these new rear ends soon.

Bingo. Its all about MPG and saving warranty claims. Also being able to publish those claims as we have talked before. Gear and program the truck right you wont get the MPG, of which its hard to quantify or advertise better towing vs numbers like MPG.

[redwngr]

Hmmm. No experience with electric over hydraulic trailer brakes in my 2014... However my 2014 Silverado Owners Manual indicates on page 9-100 and following pages..."The vehicle may have an Integrated Trailer Brake Control (ITBC) system for use with electric trailer brakes or most electric-over-hydraulic trailer brakes." But they don't explain what "most" means. Another quote, "Use the ITBC system only with electric or electric over hydraulic trailer brakes." This would indicate to me that it SHOULD work, but then again, what does "most" mean?

 

And in the 2015 Silverado features list, they specifically say that it will...New for 2015 HD trucks, the Integrated Trailer Brake Control is now compatible with electric over hydraulic trailer brakes. The Integrated Trailer Brake Control system can be used to adjust the amount of power output, or Trailer Gain, available to the trailer brakes. The control panel also allows manual application of the trailer brakes.

FWIW, the older HD ITBC also had variable power out (gain) and ability to manually operate, but was not the electric-over-hydraulic compatible.