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Old 12-04-2004, 03:38 PM   #15
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There are a lot of interesting perceptions in this discussion.

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A manual tranny provides a positive lock between wheels and engine, allowing good compression braking. Most automatics permit slippage, dramatically reducing the effect of compression braking.
You realize that slipping goes into the torque converter creating heat? This means the energy dissipation is spread over both engine and tranny? In my experience there is negligable difference between tranny types in regards to compression braking if the transmission is used properly, especially with modern transmissions and modern engine plus tranny controllers.

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The thing I like most about a Manual trans for towing is the ability to avoid a lot of the forced downshifting of an automatic trans
Then run the gears down, just as you do with the manual! Proper choice of gears for conditions is a necessary skill every driver needs to learn for whatever equipment is being used.

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find I have much better control with the manual transmission in difficult driving conditions
this one I'd like to understand because the opposite is actually the case. In difficult driving conditions you have a lot of attention taken off of driving to manipulate gears and you have a lot less control over the application of torque to the wheels.

What you do often get with a manual transmission is more gears. This is necessary because you don't have the torque multiplication you get with a torque converter. The downside of a lot of gears is a lot less control of torque to the wheels. Creative clutch slipping is much more difficult with a manual tranny!

It seems to me that a lot folks are offering opinions using rationalizations that are not well founded. I don't have any problem with a preference one way or another but I would much rather see positive reasons for the preference rather than questionable rationales that trash the unselected choice.
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Old 12-04-2004, 03:48 PM   #16
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this is my reason for not having a manual transmission.

ever change the clutch in a 4 wheel drive truck? i have and don't plan on doing it again! bench pressing a 4 speed with a transfer case is not my idea of fun every 80,000 miles or so!

a well cared for, properly sized slush box should out last the sheet metal on any tow vehicle!

john
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Old 12-05-2004, 08:14 AM   #17
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John, you're likely correct in most situations. However, in the past those of us who did a great deal of heavy duty towing with diesel engines and the diesel's much greater levels of torque could not get much beyond 30 to 40 thousand miles out of our automatic transmissions no matter how well we maintained them while we had no issues at all with the manual transmissions over a span of several hundred thousand miles. I think things have now changed in the past 3-4 years. I think the Allison transmissions in the GM products as well as the Ford transmissions in the super duty trucks will now likely stand up to the additional torque strain of the diesel motors. I just don't know much about the Dodge products.

In the past, it was also NOT true as someone above stated that there was no difference in engine braking between the automatic and the manual. That may have also changed, but in the past I've had white knuckle experiences having to brake going down 8% grades in western Colorado with 8-10 twelve hundred pound horses in the trailer in addition to 100's of pounds of tack and gear. Putting the transmission in low gear did not keep the truck and trailer from gaining excessive and dangerous speeds. Before long, we'd not only be going way too fast, but there were also issues of turning too many RPMs. Going down those same grades with the manual often never required that I brake at all - or that I only needed to brake a little here and there in order to negotiate a particularly sharp corner. Rarely have we ever had an issue regarding excessive RPMs. BIG DIFFERENCE.

In certain situations, I also really appreciate the super low "granny gear" on the manual transmissions though I realize that the automatic is capable of roughly the same gear options. I do think that there is little question that the automatic is more useful in negotiating certain slippery conditions such as mud and snow.

Having argued on behalf of the manual transmissions, I may very well try one of the new automatics when I order my next truck, but I've been very well pleased with the manuals I've had on my last three trucks.
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Old 12-05-2004, 10:14 AM   #18
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gs,

you are correct in your views too! i think 2 of the big three truck makers have made great strides in trannys in the last 4 year.

my last truck with an automatic made it well past 250 k, even with the trouble prone 700R4! i never did a thing to it except change the fluid and filter every 50 k.

before i got my new international at work with an allison in it, the last thing i wanted to do after work or on vacation is sling gears!

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Old 12-05-2004, 03:11 PM   #19
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I can certainly understand that position. There is little question that an automatic is easier to drive. We have automatics in our two cars and in one half ton pickup. I certainly enjoy driving them when given the opportunity even though I am very used to driving the manuals. Of course, we don't tow anything with any of these vehicles.

I don't think there is a right and wrong transmission. There are so many variables to consider for each individual. Who else will be driving the vehicle? Is it equipped with a gasoline or diesel engine? What differential ratios is coupled to the transmission? Will it ber towing light or heavy loads? What percentage of the time is the vehicle used in towing?

As we both seem to agree, most all of my objections to the automatic have probably been addressed in the newer, stronger automatic transmission designs that are now on the market.

GStephens

PS John, I notice your various posts and want to commend you for the thoughtful and helpful way that you respond to member's questions.
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Old 12-05-2004, 05:13 PM   #20
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I did a test in my 1992 Ford F150 with Auto Transmission when it was less than 2 years old.

I was in the mountains and without any load or trailer, I put the transmission in Super Granny Low Four Wheel Drive - no foot on the gas and just let it roll downhill in drive to see how fast it would go. At 40+ miles an hour I decided to stop and end that silly experiment before I tore something up or broke the sound barrier (that being me screaming).

I still wonder to this day how fast it would have gone if I hadn't braked.

I now own a manual transmission Ford that will literally crawl down the mountainside with no brakes. I like that and besides it saves wear and tear on my on seatcovers and underwear.
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Old 12-05-2004, 06:08 PM   #21
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did it upshift when you went down the hill?

it would be interesting to see what would have happened if you had it in low on the tranny.

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Old 12-06-2004, 07:11 AM   #22
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As well as I remember, (it was over 12 years ago) I ran the same test in low as well and couldn't tell any difference.

Can't remember if it upshifted in drive or not. Just remember that there was no holding back in either mode. Pucker factor remained tense in both!



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Originally Posted by john hd
did it upshift when you went down the hill?

it would be interesting to see what would have happened if you had it in low on the tranny.

john
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Old 12-06-2004, 12:49 PM   #23
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Quote:
Originally Posted by mtjim
As well as I remember, (it was over 12 years ago) I ran the same test in low as well and couldn't tell any difference.

Can't remember if it upshifted in drive or not. Just remember that there was no holding back in either mode. Pucker factor remained tense in both!
That doesn't make sense to me. If you had it in low range and then put the tranny manually into 1st, it would have/should have held down at about 5-10 mph, possibly with an occasional tap on the brakes if the grade was really steep, since an auto isn't nearly as low in first as a hd manual with granny low. I have had many autos in hd trucks, both GM and Ford, and used them in low range-low gear to creep down steep muddy forest roads, as well as when working on my property which has a 40-50% slope in sections.

My guess is you had it in Drive and it simply shifted right up through the gears, possibly even into OD. The tranny in those years wouldn't have known any difference, ie. that you were in low range, on a hill, etc.
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