LML towing Manual vs auto

mario430

New member
Jan 8, 2014
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Phoenix Arizona
I have a 12 LML complete stock when I tow I always have the tow haul mode and exhaust brake turned and I have it in Manual 5 should I keep it in Manual mode or should I just put it in D and go? I'm in AZ and we do have some mountains.

What is best D or Manual RV is maybe 10K on the high side.
 

Bdsankey

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Feb 1, 2018
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Larsen, Wisconsin
I have a 12 LML complete stock when I tow I always have the tow haul mode and exhaust brake turned and I have it in Manual 5 should I keep it in Manual mode or should I just put it in D and go? I'm in AZ and we do have some mountains.

What is best D or Manual RV is maybe 10K on the high side.

Tow Haul turns off 6th gear, OD off turns of 5th. So tow haul=manual 5.

Personally I'd run tow-haul when there are hills and drop it to 4th if it starts hunting for the proper gear.
 

gmduramax

Shits broke
Jun 12, 2008
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Nor cal
I have a 12 LML complete stock when I tow I always have the tow haul mode and exhaust brake turned and I have it in Manual 5 should I keep it in Manual mode or should I just put it in D and go? I'm in AZ and we do have some mountains.

What is best D or Manual RV is maybe 10K on the high side.

Put it in drive and leave it. :thumb:
 

clrussell

pro-procrastinator
Sep 23, 2013
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Should say on the tap shifter trucks/conversions. My father's LBZ would lock out 6th when tow-haul was on factory.

I was under the impression that they carried over that logic since 6th is just double overdrive.

I’ve never seen tow haul lock out 6th..

Just takes longer to shift there..


Op, it all depends on how fast you’re running. Towing heavy with my lbz or Lml under 70 I run 5th. If running 80 I run 6th.. I try to keep rpm above 2k
 

Bdsankey

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Feb 1, 2018
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I’ve never seen tow haul lock out 6th..

Just takes longer to shift there..


Op, it all depends on how fast you’re running. Towing heavy with my lbz or Lml under 70 I run 5th. If running 80 I run 6th.. I try to keep rpm above 2k

Guess I've got a case of the Mondays, my bad guys!
 

Chevy1925

don't know sh!t about IFS
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Oct 21, 2009
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Phoenix Az
at 10k and pulling the hills out here, you will probably be hunting between 5th and 6th on small grades. if you get into 6th and it pulls along just fine, id run it. depends on speed like Corbin said. when i tow to flag and back, i just stay in 5th but im at 15k trailer. to the dunes or out west, im in 6th at 75-80 the whole way.
 

HWI

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Feb 7, 2016
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FL
I pull in 5th for the most part, but I'm also on 35's with stock gears, so pulling in 5th helps me stay in the power band. Imo, the rule of thumb to go by is if it's lugging in 6th then manually shift it down to 5th.
 

Hoser

Active member
Jun 19, 2016
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Farmington, MN
Taking the tranny out of D and putting it in manual mode deactivates grade braking and IIRC, a few other things. Leave it in D with T/H on and and don’t worry about it, the truck is smart enough to know what to do.
 

2004LB7

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Dec 15, 2010
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I use M when on hilly or winding roads where the transmission would hunt a lot. For everything else it is pretty much D. If I find myself in situations where I am speeding up and slowing down often, or where when it upshifts during low throttle and you start to loose power because the rpms have dropped so you end up pressing the accelerator more to compensate and then it downshifts because of it. If this is happening often I switch to M.

In those situations I'm normally not going more then 35 to 45 mph. I'll put it in M and 3rd or 4th and let the rpms rise and fall between" 1800 and 2600 or so. This provides grade braking when lifting off of the throttle like when approaching a curve and good power when coming out of the curve and prevents it from constantly shifting

If the roads are long or straight and you have plenty of time to build momentum and keep it then it is in D

I don't know about the trucks with the exhaust brakes but with the others you most certainly still have engine braking when in M. Its just that you have more to its function now instead of the confusers do. You want some grade braking, just down shift. You want less, up shift
 

Warnercon

On a Time Out
Jan 2, 2019
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ah yes, , ok.......by pulling the gear selector lever over into the manual mode


will that help with fuel consumption too? and keep the heat down