towing question- down steep grades
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Joined: Feb 2001
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From: Pasco, WA
towing question- down steep grades
For all you that tow a heavy trailer with the E40D transmission, when you come to a steep curvy grade, say 6%-8%, with a speed limit of 35 or so, do you downshift to 2nd and let it hold you, or do you go into 1st, and then try second.
Or do you go down in drive and then if going to fast, drop into 2nd, then even 1st. Will the auto let you do this. or will it lock you out from downshifting when going to fast
I have tried this without a trailer, going down hill in 2nd and it seems that you really can pick up some speed. Maybe first would be better.
Coming and going to the inlaws involves 6% mountain pass grades and not going isnt an acceptable answer according to my wife!
any input is appreciated
MC
Or do you go down in drive and then if going to fast, drop into 2nd, then even 1st. Will the auto let you do this. or will it lock you out from downshifting when going to fast
I have tried this without a trailer, going down hill in 2nd and it seems that you really can pick up some speed. Maybe first would be better.
Coming and going to the inlaws involves 6% mountain pass grades and not going isnt an acceptable answer according to my wife!
any input is appreciated
MC
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Joined: Mar 2001
Posts: 4,968
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From: So Cal
towing question- down steep grades
Who hah, the fun part of towing. I tow a 30 foot travel trailer that weighs 8,000 dry, more wet. My rig is a 94 F250 Supercab 4x4, 460 automatic. I have a good weight distributing hitch and a trailer antisway bar.
I tow mostly here in the Great Northwet but I did do one trip from Portland down to Los Angeles including travel through the Cascades and the mountains around Shasta and the infamous Grapevine in Calif. There were plenty of steep grades to go up and down. Many were 6% plus and often quite long. The Grapevine is notorious for killing tow vehicle trannies, only place I have travelled that has water stops at regular intervals to cool off boiling radiators. I actually had more "fast" downhills in Oregon.
In almost all instances I was able to keep the truck and trailer at a comfortable speed by staying in 3rd and occasionally 2nd with intermittent use of the brakes. Only rarely did I feel the engine was approaching unusually high(not redline) RPM. A quick tap on the brakes was usually all that was necessary. I only felt uncomfortable if I was at speed and approaching a curve, otherwise the downhills were not a problem.
Note that I feel relatively comfortable travelling at 55 to 70mph in my trailer so some of my downhill speeds may make others feel uncomfortable. In general on the steep downhills I was passing the big rigs but being passed by cars, so I assume my speed was a happy medium. Naturally Ice and Rain would change my comfort zone. Plus a lot depends on your rig's handling characteristics.
So this is my experience.
Note you might post this question in the towing section, there are many more trailer trash types there. ;^)
Jim Henderson
I tow mostly here in the Great Northwet but I did do one trip from Portland down to Los Angeles including travel through the Cascades and the mountains around Shasta and the infamous Grapevine in Calif. There were plenty of steep grades to go up and down. Many were 6% plus and often quite long. The Grapevine is notorious for killing tow vehicle trannies, only place I have travelled that has water stops at regular intervals to cool off boiling radiators. I actually had more "fast" downhills in Oregon.
In almost all instances I was able to keep the truck and trailer at a comfortable speed by staying in 3rd and occasionally 2nd with intermittent use of the brakes. Only rarely did I feel the engine was approaching unusually high(not redline) RPM. A quick tap on the brakes was usually all that was necessary. I only felt uncomfortable if I was at speed and approaching a curve, otherwise the downhills were not a problem.
Note that I feel relatively comfortable travelling at 55 to 70mph in my trailer so some of my downhill speeds may make others feel uncomfortable. In general on the steep downhills I was passing the big rigs but being passed by cars, so I assume my speed was a happy medium. Naturally Ice and Rain would change my comfort zone. Plus a lot depends on your rig's handling characteristics.
So this is my experience.
Note you might post this question in the towing section, there are many more trailer trash types there. ;^)
Jim Henderson
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Joined: Mar 2001
Posts: 4,968
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From: So Cal
towing question- down steep grades
I wasn't able to read more of your posting while answering.
Naturally on any area posted for extremely slow speeds I did go near the posted speed, never 60mph in a 35mph curvy section for example.
I can't recall any time where I had to use 1st going downhill, but I seem to recall my truck will stay in second until it reaches a speed where the computer allows it to go to 1st, so usually 1st was a waste of time unless you were already going slow.
Usually the really slow stretches were short enough that going in 2nd and hitting the brakes occasionally was enough to keep the speed fluctuating in comfortable ranges. As the engine hits higher RPM it appears to resist going faster so it kind of self limits itself. It seemed to take a fair distance before the speed rose too much for my comfort, so the fluctuation time is probably several minutes.
Jim Henderson
But like I said a lot depends on your comfort factor.
Naturally on any area posted for extremely slow speeds I did go near the posted speed, never 60mph in a 35mph curvy section for example.
I can't recall any time where I had to use 1st going downhill, but I seem to recall my truck will stay in second until it reaches a speed where the computer allows it to go to 1st, so usually 1st was a waste of time unless you were already going slow.
Usually the really slow stretches were short enough that going in 2nd and hitting the brakes occasionally was enough to keep the speed fluctuating in comfortable ranges. As the engine hits higher RPM it appears to resist going faster so it kind of self limits itself. It seemed to take a fair distance before the speed rose too much for my comfort, so the fluctuation time is probably several minutes.
Jim Henderson
But like I said a lot depends on your comfort factor.
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Joined: Jun 1999
Posts: 118
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towing question- down steep grades
mc, Jim,
I can't really offer too much to this matter as my truck is a standard, but, otherwise the same basic setup as the two of you have...
Anyway, I have noticed with my truck, when using a lower gear to retard down hill accelleration, that as the RPMs hit 3000 the engine retards noticably and the truck slows quite a bit until RPMs drop to 2700 then it seems to roll more freely again. Back up to 3000... then down to 2700... and so on. It must be in the ignition timing as it happens when running both gasoline and propane.
I don't know if this is something exclusive to the EEC setup for the standard transmission, but, thought it was worth mentioning. Even if is in the EEC program for the auto tranny... it might not be as noticable... It is very noticable in the manual.
Perry
I can't really offer too much to this matter as my truck is a standard, but, otherwise the same basic setup as the two of you have...
Anyway, I have noticed with my truck, when using a lower gear to retard down hill accelleration, that as the RPMs hit 3000 the engine retards noticably and the truck slows quite a bit until RPMs drop to 2700 then it seems to roll more freely again. Back up to 3000... then down to 2700... and so on. It must be in the ignition timing as it happens when running both gasoline and propane.
I don't know if this is something exclusive to the EEC setup for the standard transmission, but, thought it was worth mentioning. Even if is in the EEC program for the auto tranny... it might not be as noticable... It is very noticable in the manual.
Perry
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