Towing Speed / RPM dilemma

[wowens79]

Bought a TT, and I can't find my happy speed. Here are the paticulars
2002 Chev 1500HD 6.0l, 4 speed auto 3.73 rear end
2016 Heritage Glen 29BH ~7500lbs loaded

On the interstate, if I'm running 65, I'm only turning 2000 rpm, in 4th gear, and it wants to shift down to 3rd and 3000 rpm. If I bump the speed up to 73-75, the rpms are around 2500, and it will hold that speed. I really don't like towing at 75, and don't plan on doing that regularly.

I don't really want to spend the money on this truck to put 4.10 gears in it, since it's 4x4, and would be expensive, and the truck has 192k miles on it. I'll be getting a new truck in a couple of years, but I'd like to get get about 3 more years out of this truck.

Should I just drop it to D3, and let her spin? I've read that the 6.0 likes to run at a higher RPM.

Thanks for any input.

[Skelshy]

I towed with a similar vehicle, a 1999 F150 with a 4 speed automatic. It was the same thing, I could tow in 4th if there was no wind and the road perfectly level. Anything else it would gear hunt. Obviously the gears are really far apart and the gear changes are somewhat jarring. Never had a problem with the engine/transmission and the trans had 190k miles on it.

I would never throw serious money after an old truck. The new and newer used are so much better. My 2015 ecoboost F150 has no trouble running at lower RPMs since with the turbo it can just add more fuel. RAM has had an 8-speed for a while, which solves the problem in a different way. Chevy had their 8-speed transmission available on the 6.2 earlier and I think they moved it to the 5.3L V8 as well. Next year Ford will offer 10 cogs AND turbos, you can see where this is going.

[deltabravo]

wowens79 wrote:
I have, I am rated at 65, that is why I'm staying at 65, I discovered that it pulled better at 75 after bumping up to 75 to get past some trucks. That extra 500 rpms really made a difference.

Fuel mpg goes downhill exponentially above 65.
I had a 2002 6.0L and it was a GAS HOG towing a 7k DF 21SW
I'd get about 7-8 mpg at 65.

[CavemanCharlie]

3000 RPM is no problem. Back in the day 3 gears is all we had and we were often spinning 3000 RPM on the interstate. But, very few people had tachometers and didn't know that they were spinning the engine that fast.

I had a 302 in a Ford as a boy that I had put in bigger cam, ported the heads, added a 4 barrel carburetor, and duel exhaust on. When taking off in a hurry I would shift it manually at 5500 RPM. I had to. I did not change the valve springs and the valves would float after 5500 and it would not spin any faster. Beat on the car for years with no problems.

[kevden]

I had gears swapped from 3.73 to 4.10 in my yukon. It has towed our outback from maine to florida and back several times and many miles locally. It spins 3000rpm in 3rd all day long no problems. I use 4th only on flat land with the converter locked (i bought a bully dog gt tuner that shows when tc is locked). It has the 4l80e trans, I would not use 4th with a 4l60 (killed one in a 1/2 ton chevy avalanche)

[TomG2]

$2,000 will buy a thousand gallons of gasoline and if you drive night and day for three years you might save some of that back. Of course you will have a million miles on your pickup by then. Save the two grand to help with the trade.

[dodge_guy]

If you are for sure keeping it for 3 more years I would do the gear swap, it will be well worth the money. I would even suggest going the next step up in gear ratio. Whatever GM uses after a 4.10. You will pick up around .5 mpg towing and the truck will not work as hard. Also the engine will be running about 2600 rpm. Not high enough to drive you crazy for an 8 hour drive and not low enough as to lug the engine.

[Campfire_Time]

wowens79 wrote:

Should I just drop it to D3, and let her spin? I've read that the 6.0 likes to run at a higher RPM.

Thanks for any input.

The short answer is yes. You'll save the cost of replacing a transmission too. With the older 4 speeds never, ever, tow in 4th gear. As you've already learned it will constantly hunt between 3rd and 4th. That hunting generates heat. Keep it in 3rd and you're torque converter will lock and keep the trans temps even. You see temps go a up a little when towing in the wind or up hill but it will generally stay locked.

Also try running a little slower, 62/63. That'll knock a couple of thousand off the RPMs too. This is also the speed that most of us have found is the "sweet spot" when towing.

[Golfcart]

APT wrote:
Higher engine speed does not always mean more fuel used. Many people that tow RVs in your situation actually use less fuel using the next lower gear because engine load is lower. Engine is operating at a more efficient speed/load point. You don't have the vehicle slow down, downshift to speedup cycle either. Many people that tow frequently or drive in the city change gears (to numerically higher axles ratio) also use less fuel. Regardless, any difference is fuel used will not be measurably different. Your trans temp and driving experience will be.

This is very true

Ive pulled many many miles with my current set up and after years of tinkering, I find that my truck pulls much better when its rolling steady at a higher rpm(truck is 6speed, 3.08 rear end)

Because of my rear end, my truck loves higher rpms at no real difference in fuel mileage

[APT]

Higher engine speed does not always mean more fuel used. Many people that tow RVs in your situation actually use less fuel using the next lower gear because engine load is lower. Engine is operating at a more efficient speed/load point. You don't have the vehicle slow down, downshift to speedup cycle either. Many people that tow frequently or drive in the city change gears (to numerically higher axles ratio) also use less fuel. Regardless, any difference is fuel used will not be measurably different. Your trans temp and driving experience will be.

[DutchmenSport]

Not the same vehicle, but we had a 2005 Chevy Suburban (1500) and towed our first travel trailer with it. I ended up destroying the transmissions and had a new one (rebuilt) installed. I was towing in 'D' and over drive. I should have kept it locked in a lower gear so it would have never shifted into Drive or Over Drive when towing and just let the engine race a little. It would have saved me a bunch of money on a new transmission. FYI, the new transmission never worked right. Within 6 weeks of the new transmission install, we traded it for a 3500 duly Silverado (gas) tow vehicle.

[wowens79]

Thanks for the feedback, I'll just wind her up and let her spin.

[93Cobra2771]

Spin it.

[bartlettj]

I have a Tahoe with a 5.3L with the same gearing. I have a lighter trailer, but the same issue with engine RPM's- the transmission needs more gears. I usually just tow in 3rd. I've done some fairly extensive experimentation (I have about 20k miles on the trailer) and I find I don't really have an MPG penalty running in 3rd gear over 4th unless I find a semi that I can draft. I've had no issues with the engine or transmission. My rig has 155k miles on it now.

[TomG2]

3,000 rpm in third gear won't hurt the engine. It may lower fuel mileage a couple of tenths, but better throttle response and almost no downshifting will be worth it. You will love it when you upgrade to a six speed.