Towing Gear, what do you use?

Ron Earp

Ron Earp

Administrator
I've been towing in 4th, a 0.83 OD gear in my Lightning with a 4 speed automatic. Turns over about 2300 at 65mph.

However, I have a Predator tuner with the truck that allows me to monitor OBDII stuff as well as a manifold boost/vacuum gauge.

In 4th I'm pulling a vacuum, no boost. But it isn't as much vacuum as I pull if I switch to third, which is a 1:1 gear, at 3000 RPM at 65mph. And, in third it will not creep into boost like it will in 4th pulling a hill. In short, 3rd requires less throttle angle to get the job done and isn't likely to generate boost. Either gear has plenty of power and doesn't result in downshifts, even with medium grades.

I also looked at the OBDII stuff and found that at steady cruise something called LOAD is around 50% in 3rd and under the exact same conditions LOAD is 60% in 4th (and LOAD goes to like over 200%, if I floor it and get 14 lbs of boost it hits mid 200s).

Seems to me I'd be better towing in 3rd maybe, but I didn't figure all this crap out until like 30 miles from home on my last Roebling trip, so I didn't get to test it.

Anyone else have some empirical data on towing in 3rd or 4th and which is better? And, I just realized I didn't specifiy better, I mean better mpg! I'm at like 8-9mpg with a 20ft enclosed weighing in around 5000 to 6000lbs.
 
Ford E-350, 6.8L V-10, 4R100 4-speed OD tranny. I swapped out my final drive from 3.73 to 4.30, and I tow in overdrive. Rarely downshifts. 7.5-ish mpg with a 24-foot 8x8 enclosed. - GA
 
'05 GMC 1500 Sierra, 5.3 ltr that's got add ons, pulling about 325 bhp, 3.23 posi-final. Truck has an electronic gizmo in the shifter for towing. Moves up the shift points, and changes torque converter shifting. I stick it in fourth, set the cruise, and leave it. Open trailer, total towed package is about 3500lbs+. Only wish I'd gone with the 3.42 final...less shifting. Get around 17 mpg towing, 20 without trailer.
 
Sounds like I I'm not that bad on the mpg. I only get about 14 in town empty, so 8-9 towing what I do probably isn't that bad. I did get better, around 12 with the open trailer with car, but now with the big sail of the enclosed trailer behind me mileage suffered. And, I still shouldn't complain as I've got 451hp and over 550 ft/lb with some dang fast 1/4s and 0-60s out of this thing for fun!

My stock rear gear is a 3.73 and I don't plan to change it. Any more gear and I'd not get traction in 3rd, 1st and 2nd are tough enough as is. It tows well in 3rd or 4th, but I was just trying to find out if some had better fuel economy in 3rd over 4th, I might have to do the experiment myself and find out.

R
 
Well actually, it'll go pretty fast while towing, but I meant whilst just running around unladen. :P
 
All I can say is I LOVE my F350 Diesel Dually!! It can pull a house in comfort and get pretty good mileage to boot! I will give mileage reports for pulling the 48 footer this weekend to Daytona. It pulls it at 75 to 80 without a problem and if it is level with no traffic i can put it in OD without cooking the tranny...
 
With my F250, 6.0 diesel, 4.11, 5th gear and tow/haul mode I get 12 mpg pulling my 24' enclosed like it wasn't there. Tow/haul mode winds out each gear more and down shifts using engine braking on decel.
 
I know the mid/late 90s GM trucks specificaly said not to tow in OD. i guess the tranny would shift back and forth between 3rd and 4th so quickly you wouldn't even notice.......til you cooked the tranny.

I have an F150 Super Crew with the 5.4L with 350 lbs of torque. Always leave it in OD. Only down shifts when going up a hill or need to get on it. I get 11 MPG towing and 14 when not.

The GMs and turbo diesels certainly do better on the milage!! :blink: Time to get a new truck!!
 
My 95 GMC Vandura 2500 likes to tow in 3rd. The only time I have pulled a loaded trailer any distance in OD was coming home from Memphis last month with a mother of a tail wind. I have an open trailer.

My drivetrain is: 350 tbi motor, auto (and yes lots of people say don't tow in OD or it will shift too often, burn up, etc. I plan to add a larger cooler to the trans next off season), tow package and a 3.4x gear. I like the tall rear end because when I tow in 3 I don't turn a zillion rpm at reasonable speeds (60-70mph depending on conditions). Gets 8-10 towing, 12-15 empty.
 
I know the mid/late 90s GM trucks specificaly said not to tow in OD. i guess the tranny would shift back and forth between 3rd and 4th so quickly you wouldn't even notice.......til you cooked the tranny.

I have an F150 Super Crew with the 5.4L with 350 lbs of torque. Always leave it in OD. Only down shifts when going up a hill or need to get on it. I get 11 MPG towing and 14 when not.

The GMs and turbo diesels certainly do better on the milage!! :blink: Time to get a new truck!!
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hmm, the manual on my 99 gmc suburban k2500 w/454 says specifically to tow in od. 65k miles of mostly towing a 7500lb 20ft enclosed, runs great. gets 8.5mpg, but tows great in od.
 
The key is to watch your transmission temperatures. Towing in O/D or whatever the high gear is called on your particular truck can lead to high transmission temps. Conventional wisdom, at least on the RV and truck boards, is to leave it in top gear unless you notice either the transmission spending a lot of time shifting up and down, or the temps starting to climb. Amongst other things, the constant shifting of gears can spike the trans temps. Install a transmission temp guage, and if the temps get too high, back off and shift down.

The number I've typically heard for Fords is that anything above 210F is bad news. Typical temps should be around 100 degrees over ambient. This is for trucks with the factory synthetic fill. I am towing an open trailer with a light car, and have a '04 E350 with 3.73 gears and the V10. While towing to Summit Point or through the mountains out to BeaveRun rarely see anything above 150-180 degrees. Two weeks ago on the way to SP it was cold and the gauge never got above 125!

At a steady 70-75 I manage about 12 MPG, which ain't bad, so long as I don't look too closely at the reciept when I fill it. It will knock back 15 if I am not towing anything, but in-town to and from Lowe's mileage is a spectacular 13 (ouch).
 
heh...

I tow a 1700 lb car on a 1300 lb trailer, with a 4.7L dodge ram (5sp manual tranny), and maybe 500 lbs of crap in the bed. I think I'm turning about 2000 rpm at 70mph, and getting about 17mpg....

:lol:
 
I tow with an 05 nissan titan. per the manual, overdrive is ok with use of tow/haul mode. I sit at about 2k rpm at 75mph, from laurel to summit point average 13mpg on 87octane. Transmission temps are fine. tahst a 1200# trailer with a 2300# car and maybe 400-500# of stuff in the bed and cab.

think the titan big tow uses a 4.10 final. But its a 5 speed gear drive automatic trans, I think the older belt based automatics where the worst as far as building up and having issues once they get hot.
 
re: manifold pressure-cars that came with economy monitors. upshift lights, etc, call for upshifting whenever manifold vacuum went up. makes sense. max efficiency when man absolute pressure is high/pumping losses low. If lockup convertor is locked, good plan. If not, low rpms probably cause convertor losses/much fluid heating-bad gambit. phil (better plan-drive the car to the track-35mpg!)
 
If lockup convertor is locked, good plan. If not, low rpms probably cause convertor losses/much fluid heating-bad gambit.
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Biggest issue here guys is this- torque convertor lock-up.

When not locked up, the convertor creates a lot of heat from fluid shear. Also, on many (GM and Dodge for sure, but probably most others) transmissions, fluid does NOT circulate through the cooler until the convertor locks. Essentially, you're making more heat and getting rid of less...

OD is OK so long as-
you don't constantly lock and unlock the convertor or keep it unlocked
you're near peak torque
your trans temps are ok

In my truck (Dodge 5.9 w/ 4.11s, 33" tires, auto obviously, a few bolt-on mods) I kick the OD off when I'm towing below about 65mph- basically anything other than cruising the interstate. I seem to get about the same MPG (about 10) no matter which way I set the trans.
 
When not locked up, the convertor creates a lot of heat from fluid shear. Also, on many (GM and Dodge for sure, but probably most others) transmissions, fluid does NOT circulate through the cooler until the convertor locks. Essentially, you're making more heat and getting rid of less...
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I don't doubt you, but what is the logic behind only cooling the oil when the least amount of heat is generated?

Why would it not use a thermostatically controled bypass like most other oil cooler applications?

Interesting...
 
Because of this thread I tried a few things while towing last weekend.

When the road was nice and flat and we were up to cruising speed I popped it into OD. It felt like the torque converter stayed locked and the trans was not shifting down. I just eased up a bit going up small grades, such as overpasses, and regained speed on the other side.

What I found was a measurable difference (with the OEM guage, so I guess not measureable, just a difference) in engine coolant temperature. It runs hotter in OD than turning more rpm at the same speed in D (or 3). The difference moved me from just below an indicator line to just above - probably 2-3 needle widths of change. So, I will be towing in 3 from now on. I just don't need to add any additional heat to this system.

Again this was 95 GMC Van 2500, 350, tow pack.
 
95 Dodge Ram 2500. 5.9 Cimmins Turbo diesel. Mauual 5 speed tranny, and 4.11 rear end. I carry a static 2000lb load in the bed. Truck is normally scaling 8100lb without driver. It gives me 17 to 18 mpg around town. When towing the race car I unload some of the gear from the bed then tow a 20' enclosed with a 2650lb car and about 500lbs of gear. At 60mph towing in 5th gear I can get 17mph on flat ground. It drops to 12mph at 70mph and when towing through the mountains. The truck has 420XXX original miles and still pulling strong.

Chuck B)
 
Cool thread.

I run a '03 F350 XLT FX4 HD Supercab with the V10. (love those marketing badges) I pull a 26 foot trailer that's all in for about 9,000 for a big weekend. I'll see some downshifting from OD for moderate hills, but the tranny temp never moves. The truck does downshift a fair amount but I just leave 'er in cruise and don't worry since temps remain good and truck seems happy.
 
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