Towing

99silveradoz71 · April 21, 2005

I have an enclosed trailer that I use to haul my mower and some yard equipment to do my Grandma's, Parents', and my lawn. The trailer is about 2990lbs, with probably 800lbs of equipment on top of that. I'm towing it on surface streets, with a max speed of 50. I have been towing in OD with tow/haul on. Is that my best bet for ease/tranny life, etc, or should I leave it down in 3? Tow/haul on or off, etc? Thanks. It's being pulled by my 99 Z71 ext cab with 3.73 open diff. and the 5.3

Wingnut · April 21, 2005

I'd just pull it in drive with the tow/haul button pushed. That's how I always towed the boat, and it never gave me a problem.

99-2door · April 21, 2005

With a max speed of 50mph, I would just go ahead and pull in D/3 with the tow/haul on like Wingnut said. With lighter loads you can pull in OD, but at that low speed there really isn't much of an advantage to using the OD.

April 21, 2005

I don't tow with the Yukon but I thought the Tow switch would keep you out of OD until you were well over 50.

sledr · April 21, 2005

I pull a Triton two place enclosed snowmobile trailer with '04 Silverado Z71. When loaded it weighs MAYBE 2000 pounds + wind drag. I tow in OD with Tow/Haul engaged and the truck only hits OD once I hit highway/freeway speeds which is about 95 km/h and up.

On two lane roads at 80-90 km/h the truck stays in 3rd. I set the cruise on the highway and let the truck drive itself. The truck downshifts only when it needs to which is usually a hilly section around Orillia. My buddy with an '04 Avalanche Z71 pulls a Triton Prestige 24ft trailer which weighs 6000 pounds loaded + wind drag and does the same 400 km trip north in 3rd.

You should be OK in OD with Towhaul engaged. If you venture onto the freeway you may want to drive it in 3rd.

snoman · April 21, 2005

With a max speed of 50mph, I would just go ahead and pull in D/3 with the tow/haul on like Wingnut said. With lighter loads you can pull in OD, but at that low speed there really isn't much of an advantage to using the OD.

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Gee, I remember when I used to tow big stock trailers at 65 to 70mph with 4.10'a a no OD too and get about 11 to 12 MPG doing it to when we had horses. That is plain silly to limit speed to 50 mph in drive with a 5.3 and 3.73 because that engine has not even reached its peak VE and torque output yet. SOme people seem to have a hang up about RPM. You could cruise cross country in drive at 65 or 70mph (or a lot faster) with that trailer and not hurt a thing and likely get better MPG too than if you used OD and made engine work a lot harder because the same amout of power is required to move load down the road and the lower the RPM, the harder it works and the less efficent it will be under that load because a engine uses the least amount of fuel per hp hour produced when operated at or near its VE, not when well below it. People that complain of poor towing performance are the ones that keep the gas engines revs so low that there is maybe 100hp or so at best availible without a downshift to actually tow load. While diesel like to turn slower under load because their peak VE is reached at a low RPM, such is not the case with a modern gas engine.

99-2door · April 21, 2005

With a max speed of 50mph, I would just go ahead and pull in D/3 with the tow/haul on like Wingnut said. With lighter loads you can pull in OD, but at that low speed there really isn't much of an advantage to using the OD.

<{POST_SNAPBACK}>

Gee, I remember when I used to tow big stock trailers at 65 to 70mph with 4.10'a a no OD too and get about 11 to 12 MPG doing it to when we had horses. That is plain silly to limit speed to 50 mph in drive with a 5.3 and 3.73 because that engine has not even reached its peak VE and torque output yet. SOme people seem to have a hang up about RPM. You could cruise cross country in drive at 65 or 70mph (or a lot faster) with that trailer and not hurt a thing and likely get better MPG too than if you used OD and made engine work a lot harder because the same amout of power is required to move load down the road and the lower the RPM, the harder it works and the less efficent it will be under that load because a engine uses the least amount of fuel per hp hour produced when operated at or near its VE, not when well below it. People that complain of poor towing performance are the ones that keep the gas engines revs so low that there is maybe 100hp or so at best availible without a downshift to actually tow load. While diesel like to turn slower under load because their peak VE is reached at a low RPM, such is not the case with a modern gas engine.

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If you would have read the first post you would see I wasn't suggesting he limit his speed to 50mph. That is the speed that he stated he pulls the trailer at.

snoman · April 21, 2005

With a max speed of 50mph, I would just go ahead and pull in D/3 with the tow/haul on like Wingnut said. With lighter loads you can pull in OD, but at that low speed there really isn't much of an advantage to using the OD.

<{POST_SNAPBACK}>

Gee, I remember when I used to tow big stock trailers at 65 to 70mph with 4.10'a a no OD too and get about 11 to 12 MPG doing it to when we had horses. That is plain silly to limit speed to 50 mph in drive with a 5.3 and 3.73 because that engine has not even reached its peak VE and torque output yet. SOme people seem to have a hang up about RPM. You could cruise cross country in drive at 65 or 70mph (or a lot faster) with that trailer and not hurt a thing and likely get better MPG too than if you used OD and made engine work a lot harder because the same amout of power is required to move load down the road and the lower the RPM, the harder it works and the less efficent it will be under that load because a engine uses the least amount of fuel per hp hour produced when operated at or near its VE, not when well below it. People that complain of poor towing performance are the ones that keep the gas engines revs so low that there is maybe 100hp or so at best availible without a downshift to actually tow load. While diesel like to turn slower under load because their peak VE is reached at a low RPM, such is not the case with a modern gas engine.

<{POST_SNAPBACK}>

If you would have read the first post you would see I wasn't suggesting he limit his speed to 50mph. That is the speed that he stated he pulls the trailer at.

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Maybe so but the speed be it 50 or 75 is not a factor in the gear selection between drive and OD. The load is what determines that not the speed.

az'03Silverado · April 21, 2005

I pulled a U-haul auto transporter (2000lbs empty) with a '76 VW bus on it (another 1800lbs) from San Diego to Phoenix on I-10 in 3rd gear with tow/haul on with my 1500 4x2 Silverado (chronicled in detail in another thread). Not one problem. I kept it at 65-70 and the rpm was only about 2800 to 3000. I got about 12-13mpg and the ride was smooth as silk. I also have a 6x12 tandem axle enclosed trailer that I haul around town for work. It's not loaded down very heavily and I put it in OD with tow/haul on. Pulls just fine. But I'm also under 50mph in town so it never goes to OD.

Yes, snoman, I have added a trans cooler.

99-2door · April 21, 2005

GAWLDANG!

You want to argue with someone so much that you are picking over details. We both agree that he should pull the trailer in D.

mcreyaufmiller · April 21, 2005

Pulling in OD will add stress to the tranny. The tranny will shift constantly. Your best bet is to tow in D and save the tranny problems. Even at highway speeds, GM suggests that you leave the tranny in D and move slower to reduce wear and un necessary pressure.

Wingnut · April 21, 2005

Just curious (and I'm not trying to hijack the thread) but when you guys are saying OD, are you talking about the D on the cluster?

Because mine has no OD (my '92 does): RNOD321. It (the '02) goes: RND321 on the cluster.

Just looking for a little clarification.

When I was towing my 6-7k lb. boat, I just dropped it in D, punched the tow/haul button, forgot about it, and drove.

Did it that way the entire time I had the boat with nary an issue.

99silveradoz71, I don't think you'll have a problem in any gear, at any speed with that amount of weight back there...Unless you're trying to do 110mph. Then of course, you might want to upgrade the tires on the trailer.

tryn2lrn · April 21, 2005

Thanks Wingnut, that was driving me crazy as well.

99silveradoz71 · April 22, 2005

Thanks folks, I'll probably give it a go in 3 then next time around.

Cranky1 · April 22, 2005

I tow my 5200 lb 24' tandem travel trailer in drive if I am going a consistant speed of 60 mph or better with the shift mode on. If I was on a secondary road traveling at 50 mph I leave it in 3rd. If I am in hilly terrain and want to maintane the speed of 60 mph, I will pull down and leave it in 3rd so the transmision is not searching for what gear it is to be in.

I will not exceed 60 mph in 3rd and if the grade is steep enough that it wants to kick down into 2nd from 3rd, I will let the truck slow down and won't floor it. Transmisions generate the most heat while shifting.

I had a tranny temp gage in my 1997 6.5 TDI 4L80E, while towing a 14,000 lbs 32' enclosed stock car trailer, 1 down shift from D into 3rd and then back into D would raise the temp from 180 F to 210 F. If this type of shift happend 2 times with in a matter of a few minutes, I would see the temp go to 230 F. As for the temp dropping, within 20 seconds the temp would be down in the 190's again.

This is just my own experience. I average around 12 MPG and have gone as high as 14 MPG. I miss the transmision temp gage and will be looking to add one to my things to do list.