Transmission --manual or automatic

Dominic Allan · Post by **Dominic Allan** » Sun Apr 09, 2006 7:17 am

Go pedal...stop pedal...aiming wheel...automatic.

Lorenzo · Post by **Lorenzo** » Sun Apr 09, 2006 8:38 am

DCrom wrote:A point to consider - a lot of the newer hybrids are coming out with Continuously Variable (CV) automatic trannies. Which, supposedly, are just as efficient as a manual (and can be programmed to shift using either a "performance" or "economy" model).

I drive an Maxima automatic once in a while and wonder why it can be engineered to cruise 65mph at 2,000 rpm while my Trooper must run 3,000 rpm at 65mph. I want two lower gears please. And I promise I won't lug it.

Tyler · Post by **Tyler** » Mon Apr 10, 2006 6:50 am

Lorenzo wrote:
DCrom wrote:A point to consider - a lot of the newer hybrids are coming out with Continuously Variable (CV) automatic trannies. Which, supposedly, are just as efficient as a manual (and can be programmed to shift using either a "performance" or "economy" model).
I drive an Maxima automatic once in a while and wonder why it can be engineered to cruise 65mph at 2,000 rpm while my Trooper must run 3,000 rpm at 65mph. I want two lower gears please. And I promise I won't lug it.

The difference in cruising RPMs has to do with the stroke length of your pistons, (i.e., the distance one piston must travel in a given combustion cycle) and the gear ratio of your transmission.
Your trooper's transmission was engineered to be able to pull moderate weight by lowering the ratio in the first two gears... Towing capacty=low end tourque. I used to have a Nissan pathfinder that I transplanted a Vortech tuned supercharged GM V-6 into. The tranny that came with the engine was out of a blazer, which in it's original incarnation was designed for towing. With the added HP I was able to drop the clutch in 3rd gear in 4wd and chirp all four tires because it was geared so low.
Your Maxima is designed to be a sports-sedan, depending on the year, that's why there should be a nice ratio gap between first and second, with the higher gears yeilding a higher transmission rotation per engine revolution. The Maxima can get away with having the ratio gap between first and second because the engine (in v-6 form, depending again on the year) has about 200ft/lbs of tourque at the midrange (265ft/lbs at redline) it's able to bridge that ratio gap easier than another engine with lower tourque.

Lorenzo · Post by **Lorenzo** » Mon Apr 10, 2006 8:28 am

The '03 Maxima (not mine, but I drive it once in a while), I think I mentioned it's an automatic tranny. It has 4 gears--1,2,3, and 3-D--which is probably an overdrive?

Anyway, the '96 Trooper...I wish they didn't have to make cars like that, thinking the owners wouldn't know which gear to drive in...in relation to the terrain or the load. But, I realize they must, to protect their intrests and warranties, or whatever. I still want two higher gears in the Trooper tranny, or a two-speed rearend! I hate cruising at 65-70 and winding the engine up so high. It would do fine at 2000 rpm instead of 3300 (at 70mph). BTW, I coast it in nuetral...down the other side of the mt pass every weekend. I know, I know! But I can maintain 65-70 mph for about 10 miles and about 50 for another 4 miles.

Tyler · Post by **Tyler** » Mon Apr 10, 2006 9:32 am

Lorenzo wrote:Anyway, the '96 Trooper...I wish they didn't have to make cars like that, thinking the owners wouldn't know which gear to drive in...in relation to the terrain or the load. But, I realize they must, to protect their intrests and warranties, or whatever.

They sell those suvs with lower first and second gears so that they'll be able to handle towing, not because people don't know what gear to tow in (if i'm understanding you correctly...sorry, gotta million things goin on here, typical crap-ass monday). If first and second were geared higher, the vehicle and payload would have a harder time starting out, and even risk engine damage.
Also, I did some looking for ya. the trooper (again, deoending on the year) is designed to be able to withstand some pretty challenging offroad terrain, which the lower gear ratio assists in.
I believe you can get the tranny regeared to a different ratio by an offroad specialist; since trucks and SUVs are not my forte I'll refrain from advising more on that subject.

Lorenzo · Post by **Lorenzo** » Mon Apr 10, 2006 9:42 am

I'm fine with 1st, 2nd, 3rd, 4th, and 5th gears in my Trooper. I just want the two higher gears--6th and 7th!!!! It's 4WD, so the lower gearing, or starting out slow with a load, would never be a problem as is.

Tyler · Post by **Tyler** » Mon Apr 10, 2006 9:56 am

Lorenzo wrote:I'm fine with 1st, 2nd, 3rd, 4th, and 5th gears in my Trooper. I just want the two higher gears--6th and 7th!!!! It's 4WD, so the lower gearing, or starting out slow with a load, would never be a problem as is.

But you can get yourself different gear ratios (so you wouldn't have to get a sixth and seventh if such a thing is possible) for your tranny.
You could leave first and second alone, and increase the ratio on gears three four and five, thus, lowering your cruising RPM.

Lorenzo · Post by **Lorenzo** » Mon Apr 10, 2006 10:24 am

Yeah, that might be okay. If I can't find a 6 or 7 speed manual transmission, maybe an automatic wouldn't be to bad...seeing how Mercedes and Honda are coming out with 7 speed autos.

http://www.popsci.com/popsci/bown/2003/ ... 56,00.html

http://uk.cars.yahoo.com/06032006/45/ho ... t-7-0.html

Tyler · Post by **Tyler** » Mon Apr 10, 2006 12:19 pm

this is just from my personal experience, but I see a lot of Mercedes auto trannys in for repairs....I'd go with the honda if you could get a machinist to mate it for you. i'm not entirely sure if it's at all possible, but it would be fun finding out.

Lorenzo · Post by **Lorenzo** » Mon Apr 10, 2006 12:31 pm

Nah, I wouldn't mix models, but I might get that Honda for long distance. Hey Tyler, how does that Honda 7 speed manual/automatic tranny work anyway? Does that mean it has the option of being locked in 7th so it won't jump down automatically to 6th or less?

Tyler · Post by **Tyler** » Mon Apr 10, 2006 12:52 pm

Lorenzo wrote:Nah, I wouldn't mix models, but I might get that Honda for long distance. Hey Tyler, how does that Honda 7 speed manual/automatic tranny work anyway? Does that mean it has the option of being locked in 7th so it won't jump down automatically to 6th or less?

To be completely honest, I've not had the opportunity to work with one yet. If they're like the continuously variable transmission that they make for sale here in the states there's really not a conventional set of "gears" or gear ratios, but a supposedly infinite combination of ratios within the limitations of the engine itself.
(the best site to read about a CV tranny is Wikipedia. They explain it much more succinctly than I can.)
From what I understand, the honda CV7 tranny has a manual "override" that allows electronic switching between seven programmed ratio presets, but I may be wrong. If this is true, one could theoreticaly controll the ratio presets with the right set of interface equipment.
With an aftermarket computer interface control box one could theoretically have any number of preset combionations programmed for different terrain and requirements.

Lorenzo · Post by **Lorenzo** » Mon Apr 10, 2006 3:47 pm

Good article in wiki...hey Tyler, that CVT-7 is suppose to get about 50mpg +/-, do you know of any compact cars (gas engine) that do better on mileage?

Tyler · Post by **Tyler** » Tue Apr 11, 2006 8:51 am

Lorenzo wrote:Good article in wiki...hey Tyler, that CVT-7 is suppose to get about 50mpg +/-, do you know of any compact cars (gas engine) that do better on mileage?

I've seen Geo metros who's owners claim to have tuned them to right around 70 mpg in three cylinder configuration. Here's a good estimate of what a bone stock untouched geo 3-cylinder should get (1990 model, 1995 metro xfi).
The 2006 Honda Civic averages about 32 mpg.
....of course you could always go Mini.....

With a little know-how one can coax about 40-50mpg out of the smaller a-series Leyland engines.
As far as regular gasoline engines that are in factory configuration (not including hybrids) I'd venture to guess that the best one can do with what we have in the states is about 35mpg.
You can look up just about any model of car's fuel economy at this site. It contains user updated real world estimates on what most cars are really getting (what the dealer tells you a car should get is total sh*t).
I am confident, however, that we'll soon see the CVT-7 stateside, as it is a standard transmission in the Honda Jazz, which we will be getting here in the US as a 2007 model, I believe. It may take longer than that, as it appears that demand for the cvt-7 depleted UK supplies when released there.
if pricing remains consistent, one could probably pick up a Jazz (or a Fit as the car will be badged stateside) for about 15k.
From the Fit website it looks like the initial run if the Fit in the US wont have the CVT-7, but I'm sure demand will bring it here eventually, especially if things keep going the way they are.
Honda Tuning Magazene article on the Fit.
Automobile Magazene's trip to the 2006 Detriot Auto Show featuring the Fit.
Wikipedia's articleon the Jazz/Fit.

Lorenzo · Post by **Lorenzo** » Tue Apr 11, 2006 9:14 am

Thanks, mon. Now off to your infolibrary!