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Date:   Fri, 12 Feb 2010 20:17:44 -0500
Reply-To:   Dennis Haynes <d23haynes57@HOTMAIL.COM>
Sender:   Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:   Dennis Haynes <d23haynes57@HOTMAIL.COM>
Subject:   Re: Friday OT...automatic trannys and driving habits observed
Comments:   To: Don Hanson <dhanson928@GMAIL.COM>
In-Reply-To:   <6bc66ccf1002121313q2650af7cpeeaa3b593149b532@mail.gmail.com>
Content-Type:   text/plain; charset="US-ASCII"

Modern day automatics do not lose a lot of energy shifting. Since the adoption of the lock up torque converter there is very little efficiency gain of a manual versus automatic. On a lot of vehicles the autos even have an advantage as they can use a higher final drive gear since any need to accelerate can result in a down shift vs. lugging in the higher gear. These trannies shift a lot to really keep the engine at the ideal speed for existing speed and load. Few people really know how to get the best use of a manual box and this option is gradually disappearing as automatics are more programmable for economy and emissions.

As for those of us in those 40 foot diesel pushers we as a group are more aware of what is going on back there than you might imagine.

For starters most of us are enthusiasts and while our spouses love the Corian counter tops, appliances, and leather seats, us men sit around the campfire and talk about the equipment. We will tell you all about our Cat engines coupled to the Allison trannie driving the Dana axle. We know and can recite our engines serial number on demand. We not only know horsepower but torque. We will give you the data of all our electrical goodies, furnaces, etc. As much as the engine is in back, everything these engines do is transmitted to the front. We know and se it all. In addition to all the normal engine gauges we also watch the front and rear air pressure. If it is 26,000 pounds or more it air brakes. In most states we have had to have a license upgrade to drive it. Most of these folks have been with a number of RV's some starting in tents and pop ups. To most of us the DP is the dream and many have given up fixed homes to have one. I moved my retirement out many years for mine.

Most of them have 6 speed transmissions and they need to shift a lot since real Diesel engines have very limited speed ranges. My Cat runs out at 2,400 rpm. Many larger engines top at as low as 1,800 rpm. Yes we need third gear to get out of a parking lot. We also downshift going downhill so that the exhaust brake can do some work. You don't stop 30,000 pounds using friction brakes any more than needed. Yes, we know how to use the engine for braking. Diesels have no throttles so they do not slow down just by lifting your foot.

Yes, we know what is going on back there.

Dennis

-----Original Message----- From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of Don Hanson Sent: Friday, February 12, 2010 4:14 PM To: vanagon@GERRY.VANAGON.COM Subject: Friday OT...automatic trannys and driving habits observed

Someone gave my wife a 2.5 Subaru Forester, automatic, has about 195k miles on it. It runs really well, the couple who gave it to Marie were getting a little worried about the miles on it so they got another one..they are palentologists and travel the back country a lot in remote parts of the west, a bit aged so anyhow....I've been driving it while we're in the desert SW. My first encounter with a automatic shift vehicle as a daily driver...and I don't much care for it. Around the city, I can see how people might want them but out in the mountains and desert it seems to waste a lot of energy moving through the gears all the time. We're camped about a half mile off a highway in the desert, one that's pretty busy with RVs at certain times of day and days of the week. The desert quiet sometimes let one hear a vehicle as it negotiates the road for about 5 miles in the wee hours and I marvel at some of the huge RVs going by....,.Roaring along up a very slight grade, shifting up and down, sucking down the diesel fuel while mom and pop sit about 40' away from the motor, blissfully un-aware of all the activitiy behind in the engine bay. Often you can hear regular cars and pickups cycling back and forth through a couple of gears...4 or 5 shifts as they go through the hearing range..Doesn't that 'bug' the drivers? I find myself hearing a few WBX Vanagons, too. I glance out when I hear the distinct Vanagon sound and see them out on the highway...I just can't help comparing the Vanagons to the Gigantor Mo-Hos...though the ratio is about 1 vanagon per 500 motorhomes...I often wonder if the dweebs in the mo-hos are having about 25,000lbs more fun...Prolly not.. Don Hanson


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