Whick gear when towing???

[Ted Thurlby]

I have a six speed manual and I haven't yet towed the 5 wheel. Pick it up on Friday evening. What do other do with the 5 oe 6 speed when towing? I'm sure they try to keep the rpm's from getting too low or high. Just wandering if any can use sixth gear much. Ted from Seattle.

[Ted Thurlby]

I have a six speed manual and I haven't yet towed the 5 wheel. Pick it up on Friday evening. What do other do with the 5 oe 6 speed when towing? I'm sure they try to keep the rpm's from getting too low or high. Just wandering if any can use sixth gear much. Ted from Seattle.

[MakinSmoke]

I am assuming your engine is diesel. Rear end gear matters, tranny matters, engine size matters, tire and rim size matters.

The last diesel pickup I had was a 7.3 Powerstroke with a 5 speed manual tranny. I drove it mostly by the pyrometer. The "sweet spot" for mileage was about 600 degrees. I drove in what ever gear it took to try and keep the pyrometer at 600. When towing uphill, the bottom line for my setup was to keep it less that 1200 F. To do so, i could change gears and get out of the throttle a little. It seemed to be a combination of both. If you don't have a pyrometer, then just listen to the engine. After several thousand miles of you driving, it will tell you when it wants another gear. In the short run, ask your diesel mechanic what he thinks about when to shift YOUR setup and use that as a guide.

[DavidMc]

One other older rule-of-thumb regarding gear selection is to always have some "oomph" left.

That translates to down-shifting IF when you give a brief extra push on the throttle you do not get a corresponding feel of acceleration.

Of course, keeping an eye on the instruments you do have (speedometer, tachometer, pyrometer, etc.) are also key ways to know what is working.

[BookIIRoadtrash]

Ted , I have a six speed manual Dodge like you, but have a few extras installed. The terrain has a lot to do with what gear I am in, I am from the high plains, northwest Iowa and I am pulling in 6th gear most of the time and down to 5th when needed. Now in the mountains there are times I am in 4th to reach the summit and 4th or fifth to descend. Last summer I was in 1st to get to the top of Walkers pass on Ca, #178 west of Ca. #14. I have a Banks exhaust brake and I sure enjoy the benefits of the extra help. It all depends on how fast you want to pull 1600 RPM is my best fuel mileage at 2000 RPM you’ll be using a lot more fuel! Book 2

[Ted Thurlby]

Thanks for the responses. It is a HO 305 hp with a 6 speed manual. Rear end 3.73. Don't really figure I will have any problem, just not sure of the 34' 5th wheel weight when towing. All I ever had before was a 29' alum/lite trailer towed with a 94 dodge van w 360ci. Towed great but when it hit the pass I was doing 28mh. This rig is heavyer and towing with this diesel should be interesting. Ted

[RustyJC]

Ted,

You'll find towing with the diesel is completely different. On a particular 6% grade heading westbound into Kerrville, TX on I-10, our previous 5th wheel (13,500 lbs) had our 1996 V-10 Dodge dually in 2nd gear (47RE automatic) at 3500 RPM to hold 55 MPH. Our current truck (see signature) would pull the same hill with the same 5th wheel at 70 MPH in 6th gear at 2350 RPM.

Rusty

[allendp]

Ted I usually drive by the tach with my 6 speed. If I am in 6th gear and the terrain gets steep enough or traffic conditions warrant slowing my speed down to where the tach is around 1500-1600 rpm I will downshift to 5th gear otherwise I try to stay in 6th at 2000 rpm for my best fuel economy. I always start of in 1st when pulling the trailer and shift at about 2500 rpm thru the gears. The worst thing you can do to a diesel engine is to "lug" it by letting the rpm drop below its power band. The terrain usually determines what gear to use based on what your tach reads.

[Jeff_in_The_Dalles]

My last truck was a HO 305 Cummins with 6 speed, and 3.73...

I asked Cummins about the preferred operating RPM for the 5.9...

They said basically that the engine should not be lugged, which they defined as running with a load on the engine below 1600 RPM, or running in a gear in which the rig will not gain speed when floored.

For upper RPM, they said RPM up to the no-load governed RPM (3200, I belive) is safe for the engine, but that the engine's peak torque is 2700 RPM, so there isn't much reason to run it above that except for road speed.

They also said lower RPM in that range (1600-2700) will give better fuel mileage, and that 1900 to 2100 is often a good balance.

Anyhow, I think you will find on level ground or moderate grades that it will pull your trailer like a locomotive in 6th. Downshift when needed to keep the RPM above 1600 or 1700, or when you start loosing speed when floored.

Two other things I'd mention: I'd say if you tow in the mountains, I'd highly suggest an exhaust brake, like the Jacob or Pacbrake. It's really nice to be able to maintain your speed downhill while keeping the service brakes cool and ready if you need them.

Secondly, I kind of like having an exhaust pyrometer. It won't really get into dangerous temps if the engine is stock, but it's nice for peace of mind, and to take the guess work out of cool down.

[Steve Rankin]

If you have a diesel, then just don't lug it by pulling below peak torque RPM (1400 for the Dodge and Chevy, about 1800 for the Ford). I'm gentle with the Duramax at 1400, but at 1500-1600 it's WOT pulling grades. We stay in high gear (5th with the Allison) down as low as 45 MPH on level ground.

Now, if it's a gas engine, or you have oversize tires, or you have a rear axle taller than 3.73 (say 3.55), then you'll need more RPM to get the job done properly.