Downshifting while towing uphill
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Senior User
Joined: Nov 2004
Posts: 196
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From: Texas
Downshifting while towing uphill
I have a question for you veteran drivers.
When towing a load up hill is it better to manually downshift the automatic transmission to second (and then manually bring it back to third) or just give it more gas and let the automatic drop to the lower gear on its own and shift back to the higher gear when it reads it?
This is with a V-10 and a 4R100 tranny.
When towing a load up hill is it better to manually downshift the automatic transmission to second (and then manually bring it back to third) or just give it more gas and let the automatic drop to the lower gear on its own and shift back to the higher gear when it reads it?
This is with a V-10 and a 4R100 tranny.
Cargo Master
Joined: Dec 2003
Posts: 2,182
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From: Saint Augustine, FL
The 4R100W is a 4 speed. Are you towing in OD (4th)? Or 3rd (OD canceled)?
I tow in OD pretty much all the time. When I come to a hill which I know I can't pull in OD I maintain the throttle position and let the speed drop until it hits the point where it can comfortably downshift and pull 3rd up the hill. I then hit the OD cancel button and downshift before it does on its own. This lets me pull the hill at a comfortable speed and doesn't lug the motor or trans. I then pull the hill at a comfortable pace and as I reach the top I hit the OD button again. This allows the trans to upshift back to OD as soon as it clears the top and the load lightens.
This method works great. It allows me to maintain my speed and is easy on the transmission and motor.
However, if you are already towing in 3rd and need to downshift to 2nd, then I would let the trans downshift by itself. In most 4R100Ws if you let it do this the converter will lock up in 2nd and keep the trans temps down.
Steve
'95 Clubwagon XLT
I tow in OD pretty much all the time. When I come to a hill which I know I can't pull in OD I maintain the throttle position and let the speed drop until it hits the point where it can comfortably downshift and pull 3rd up the hill. I then hit the OD cancel button and downshift before it does on its own. This lets me pull the hill at a comfortable speed and doesn't lug the motor or trans. I then pull the hill at a comfortable pace and as I reach the top I hit the OD button again. This allows the trans to upshift back to OD as soon as it clears the top and the load lightens.
This method works great. It allows me to maintain my speed and is easy on the transmission and motor.
However, if you are already towing in 3rd and need to downshift to 2nd, then I would let the trans downshift by itself. In most 4R100Ws if you let it do this the converter will lock up in 2nd and keep the trans temps down.
Steve
'95 Clubwagon XLT
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Senior User
Joined: Nov 2004
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From: Texas
Thanks Clubwagon.......
I tow out of OD. I just didn't know whether to let the transmission do it itself or pull it down myself. I would rather the tranny do it, but I didn't want to ruin anything.
I tow out of OD. I just didn't know whether to let the transmission do it itself or pull it down myself. I would rather the tranny do it, but I didn't want to ruin anything.
Posting Guru
Joined: Jul 2004
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From: West Valley Utah
The real point of this would be depending on the load, the length and grade of the hill and ambient temp, a lot of times it would be better to manually drop a gear and back out of the throttle and avoid overheating.
It's a judgement call depending on condtions. Not a one size fits all.
It's a judgement call depending on condtions. Not a one size fits all.
Postmaster
Joined: Mar 2001
Posts: 4,968
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From: So Cal
I have a 94 F250 and tow an 8,000# trailer. I tow in OD all the time, unless the tranny is hunting gears.
When I approach a long hill that I know will cause the tranny to downshift, I usually manually downshift to 3rd before I get too far up the hill. I want to maintain or build up speed before I get too far up the hill. This seems to be easier on the tranny, and experience tells me that I can maintain speed better if I downshift before the hill rather than wait to loose momentum and let the tranny downshift.
If I think I am going to need to downshift to 2nd, I usually do it before I lose too much momentum there.
I have driven up the California Grapevine in blistering heat in 2nd for several miles. Ditto the Blue Mountains outside of Pendleton Or. My tranny temps rise maybe 10-20 degrees above my normal 180-190 tow temps during these long uphills, but other wise every seems to be fine.
Like the other guy said, all depends on load, climb, even traffic.
Good Luck,
Jim Henderson
When I approach a long hill that I know will cause the tranny to downshift, I usually manually downshift to 3rd before I get too far up the hill. I want to maintain or build up speed before I get too far up the hill. This seems to be easier on the tranny, and experience tells me that I can maintain speed better if I downshift before the hill rather than wait to loose momentum and let the tranny downshift.
If I think I am going to need to downshift to 2nd, I usually do it before I lose too much momentum there.
I have driven up the California Grapevine in blistering heat in 2nd for several miles. Ditto the Blue Mountains outside of Pendleton Or. My tranny temps rise maybe 10-20 degrees above my normal 180-190 tow temps during these long uphills, but other wise every seems to be fine.
Like the other guy said, all depends on load, climb, even traffic.
Good Luck,
Jim Henderson
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Post Fiend
Joined: Jun 2001
Posts: 5,228
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From: Running Springs CA
When climbing highway 330 up to my cabin, if I let it shift itself, it is hunting between second and third constantly. That cant be good for it. Once it starts "hunting", manually down it goes.
BTW, it is also advisable to manually downshift when going downhill. Yesterday, I followed a Dodge towing a trailer down 330. He was riding the brakes all the way and you could smell burning brake linings, stupid. With the correct gear selected, I hardly touch the gas or brakes.
Jim, I can take the Grapevine in third only if traffic doesnt slow me down too much. Once the momentum is lost, forget it.
Jim
BTW, it is also advisable to manually downshift when going downhill. Yesterday, I followed a Dodge towing a trailer down 330. He was riding the brakes all the way and you could smell burning brake linings, stupid. With the correct gear selected, I hardly touch the gas or brakes.
Jim, I can take the Grapevine in third only if traffic doesnt slow me down too much. Once the momentum is lost, forget it.
Jim
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Cargo Master
Joined: Dec 2003
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From: Saint Augustine, FL
Originally Posted by jim henderson
When I approach a long hill that I know will cause the tranny to downshift, I usually manually downshift to 3rd before I get too far up the hill. I want to maintain or build up speed before I get too far up the hill. This seems to be easier on the tranny, and experience tells me that I can maintain speed better if I downshift before the hill rather than wait to loose momentum and let the tranny downshift.
Like the other guy said, all depends on load, climb, even traffic.
Like the other guy said, all depends on load, climb, even traffic.
And if you think the Grapevine is tough, try towing I-70 from Denver to I-15 in Utah. My little 5.0 Clubwagon was really working hard to clear those 8000 ft passes, not to mention the 11,000+ ft Eisenhower Tunnel.
Steve
'95 Clubwagon XLT
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Joined: Nov 2000
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I installed a tach, allows me to shift when apropriate. My e150 5.8 with 3.55's has no reserve when going up the grapevine with 6000lbs. Have to keep in the power band. On these electronic transmissions the trans see an electrinic signal wether shifted manually or by computer, so shift like you have a manual trans.
Postmaster
Joined: Mar 2001
Posts: 4,968
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From: So Cal
Yup, I hate it when I loose momentum. If I downshift in time I can sometimes accelerate up the hill, but if I loose momentum, it bogs down and then it is thrashing in a lower gear and never getting back up to speed.
Tons of fun going up the grapevine in second if you loose momentum. I never realized I could get even worse gas mileage until that trip.
Jim Henderson
Tons of fun going up the grapevine in second if you loose momentum. I never realized I could get even worse gas mileage until that trip.
Jim Henderson
Postmaster
Joined: Mar 2001
Posts: 4,968
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From: So Cal
I did the grapevine on a 105+ day with a forest fire thrown in for fun while towing my 8,000# trailer. I did some of it in second since I wasn't used to towing at that time, but once I built up momentum I was able to cruise mostly in 3rd at 50+ and even got to 60+ in OD when things got easier.
Yeah, I filled up at the bottom of the grapevine and by the time I got to about Gorman, I got a real surprise at the amount of gas I added to top it up. I think my tow mileage went from a normal 8-9mpg to something like 5 or less. I could literally watch the gas gauge go down, kind of like you can see the minute hand on a clock move if you pay attention.
Gonna get to do the Grapevine again this month when I move the family south. Should be fun since I am almost sure we have the rig overloaded. And this time I bet gas is around $3/gallon instead of the outrageous 90 cents they wanted my first trip in 1998.
Jim Henderson
Yeah, I filled up at the bottom of the grapevine and by the time I got to about Gorman, I got a real surprise at the amount of gas I added to top it up. I think my tow mileage went from a normal 8-9mpg to something like 5 or less. I could literally watch the gas gauge go down, kind of like you can see the minute hand on a clock move if you pay attention.
Gonna get to do the Grapevine again this month when I move the family south. Should be fun since I am almost sure we have the rig overloaded. And this time I bet gas is around $3/gallon instead of the outrageous 90 cents they wanted my first trip in 1998.
Jim Henderson
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From: Chino, California
tbax46,
To answer your question directly and specifically, it does not hurt a thing to allow the tranny to find its own gear. It also doesn't hurt it either to force down shift it. I do both with my V-10/4R100 rigs.
One thing I try not to do is to allow it to downshift on its own while in cruise control. It seems the cruise control is only interested in closing the gap between set speed and actual speed and will down-shift to a lower gear thann is needed to hold or regain momentum winding up the engine too much. (Eventhough the V-10 works very well at high rpms).
I tow with a V-10 SD equipped with a Gear Vendor gear splitter. Trailer weighs 10,000 pounds. I can cruise on flats in 4th without a strain.
To answer your question directly and specifically, it does not hurt a thing to allow the tranny to find its own gear. It also doesn't hurt it either to force down shift it. I do both with my V-10/4R100 rigs.
One thing I try not to do is to allow it to downshift on its own while in cruise control. It seems the cruise control is only interested in closing the gap between set speed and actual speed and will down-shift to a lower gear thann is needed to hold or regain momentum winding up the engine too much. (Eventhough the V-10 works very well at high rpms).
I tow with a V-10 SD equipped with a Gear Vendor gear splitter. Trailer weighs 10,000 pounds. I can cruise on flats in 4th without a strain.
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Senior User
Joined: Nov 2004
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From: Texas
I appreciate all the feedback. Seems I haven't been doing things wrong. Sometimes a grade sneaks up on you and the tranny downshifts on its own and then back to third when it gets to the right spot. I just wanted to make sure this wasn't harder on the tranny than when I manually downshift and upshift back up.
I have atransmission temp guage (aftermarket) and I generally keep an eye on it when pulling hills. I don't believe I can ever remember getting over 190 or 195.
I have atransmission temp guage (aftermarket) and I generally keep an eye on it when pulling hills. I don't believe I can ever remember getting over 190 or 195.