Interesting graphs about brake specific fuel consumption

[sdifox]

Let me try again. It's an automatic tranny. It does what it is programmed to do. Don't like what it is doing? Drive stick or get a better/different automatic tranny.

 

[DivideBYZero]

Well, technically it does because cruise can't change gears for you. Get to a steep enough incline, where it would make sense to downshift, and it will obviously just give as much throttle as possible to compensate.

Of course, but D1 was talking in absolutes, and in that case it doesn't hammer on the gas endlessly. If it did I would be dead. 343hp and a manual with cruise that hammered on the gas would have me doing 183 mph. It does, however, cut cruise if the engine is lugging. Too high a gear, too low revs and a gradient will cause the car to exit cruise.

 

[PlasmaBomb]

 

[sdifox]

snip

I wonder how long it took to assemble that. I do love the picture though.

 

[ShawnD1]

Let me try again. It's an automatic tranny. It does what it is programmed to do. Don't like what it is doing? Drive stick or get a better/different automatic tranny.

I will definitely remember this. When the cruise control is on, the automatic tranny will automatically unlock the torque converter, automatically drop 2 gears, then automatically burn the shit out of the transmission. Maybe this is the safety plan against unintended acceleration. Just let the throttle stick for a minute and the car will stop once the transmission melts.

343hp and a manual with cruise that hammered on the gas would have me doing 183 mph. It does, however, cut cruise if the engine is lugging

I'm curious what you were doing when you tested this. You're in a car with 343hp, top gear, on the highway. You approach a hill that even your car can't climb in top gear. Were you pulling a trailer full of rocks or something?

 

[sdifox]

I will definitely remember this. When the cruise control is on, the automatic tranny will automatically unlock the torque converter, automatically drop 2 gears, then automatically burn the shit out of the transmission. Maybe this is the safety plan against unintended acceleration. Just let the throttle stick for a minute and the car will stop once the transmission melts.



I'm curious what you were doing when you tested this. You're in a car with 343hp, top gear, on the highway. You approach a hill that even your car can't climb in top gear. Were you pulling a trailer full of rocks or something?

Go Build Your Own...Obviously you are much smarter than the mechanical engineers that came up with the tranny in your car.


Here is a hand up, a cross section of an 8-gear

 

[JCH13]

Any automatic that I've driven with cruise control would floor the throttle before down-shifting... have you ever thought that maybe your crapolla just doesn't have enough torque in top gear to get up the hill?

 

[ShawnD1]

Any automatic that I've driven with cruise control would floor the throttle before down-shifting... have you ever thought that maybe your crapolla just doesn't have enough torque in top gear to get up the hill?

Always a possibility.

Go Build Your Own...Obviously you are much smarter than the mechanical engineers that came up with the tranny in your car.

Toyota's transmissions are purchased from Aisin Warner. To be a better engineer than a Toyota engineer, all one needs to do is buy a better transmission than the one picked by Toyota. That's pretty simple. I want a Honda transmission since they don't disintegrate under full throttle.

 

[LTC8K6]

Even race cars do not climb hills in top gear. They have plenty of power and torque. An F1 driver will not try to climb a hill in high gear. Neither will a Nascar driver. They will downshift.

Only the mildest hills are taken in high gear.

Big trucks have torque out the wazoo and they don't climb hills in high gear either.

 

[sdifox]

Always a possibility.



Toyota's transmissions are purchased from Aisin Warner. To be a better engineer than a Toyota engineer, all one needs to do is buy a better transmission than the one picked by Toyota. That's pretty simple. I want a Honda transmission since they don't disintegrate under full throttle.

Toyota owns 51.9% of Aisin AW. Who do you think Toyota is going to source trannies from?

http://en.wikipedia.org/wiki/List_of_Aisin_transmissions

As of 2005, Aisin AW surpassed General Motors Powertrain Division as the largest producer of automatic transmissions in the world, producing 4.9 million units, with a market share of 16.4% of the global market for automatics.
.
.
.
Aisin AW supplies automatic transmissions to 35 automotive manufacturers around the world,[citation needed] virtually every major OEM. These include General Motors, Ford, Mitsubishi, Nissan, Porsche, Audi, VW, Volvo, Hyundai among others.[citation needed]

 

[ShawnD1]

Even race cars do not climb hills in top gear. They have plenty of power and torque. An F1 driver will not try to climb a hill in high gear. Neither will a Nascar driver. They will downshift.

This is a thread about fuel efficiency and you're saying what race car drivers do. Race car drivers try to keep the rpm close to maximum power so the car can accelerate as hard as possible. I'm not a scientician, but I'm guessing that keeping the engine buzzing at 6000rpm all day is not great for gas mileage.

Big trucks have torque out the wazoo and they don't climb hills in high gear either.

They do when they're not hauling anything 😉

 

[ShawnD1]

Toyota owns 51.9% of Aisin AW. Who do you think Toyota is going to source trannies from?

That shakes my faith in them even more. All this time I thought they were just purchasing poorly made transmissions, and now you tell me Toyota is the one making those crap transmissions.


If you want to see something funny, go to google and type (without quotes) "automatic transmission up hills". First result:
http://www.rav4world.com/forums/99-...n-keeps-switching-up-down-cruise-control.html

first post:
Went on cruise control at 65mph, I just noticed that on up hill freeway the transmission keeps switching up and down every 3 second or so. Is there TSB for this?

Toyota fail. I swear I made a thread about my Corolla transmission changing gears 20 times per minute as a rough guess. Someone quoted it and remarked at how silly it sounded that the transmission would change gears an average of every 3 seconds :awe:


Next post down

Transmission Hunting is Bad!
It'll heat up the Fluid quickly and the protection of the tranny will dwindle.

In other words it totally is Toyota's fault that my transmission is all busted. I'm not the one telling it to gear hunt. The cruise control tells it to do that.
Keep in mind where all this heat is coming from. The transmission screws up because you're burning all this extra gas, getting horrendous gas mileage, and that extra gas goes directly into heating and melting your transmission. Toyota = r gooder ungineerz

 

[DivideBYZero]

I'm curious what you were doing when you tested this. You're in a car with 343hp, top gear, on the highway. You approach a hill that even your car can't climb in top gear. Were you pulling a trailer full of rocks or something?

Here's a clue:

Firstly, note that the plot starts at 3.3k rpm, pushing only 128Hp and that all lower RPMs will produce even lower numbers.

Notice how that motor doesn't make 343hp all the time? Notice how it doesn't produce 260ft/lb or torque all the time? That is why any motor can be lugged if in the incorrect gear for the current road speed.

As for my example, the car was in 6th and RPMs were slowing to about 1800 and pulling up an incline, which is low for a car with an 8000 rpm red line. It was a specific test I was carrying out with my car, the ECU cancelled cruise to protect the motor, and I dutifully changed to a more appropriate ratio and continued.

See, the issue here is more to do with your fundamental misunderstanding of why a vehicle has a transmission with gear ratios in the first place, rather than an epic oversight by the entire motor car industry in the design of transmissions.

I'm not a scientician

I think we can both agree on this.

 

[sdifox]

That shakes my faith in them even more. All this time I thought they were just purchasing poorly made transmissions, and now you tell me Toyota is the one making those crap transmissions.


If you want to see something funny, go to google and type (without quotes) "automatic transmission up hills". First result:
http://www.rav4world.com/forums/99-...n-keeps-switching-up-down-cruise-control.html

Toyota fail. I swear I made a thread about my Corolla transmission changing gears 20 times per minute as a rough guess. Someone quoted it and remarked at how silly it sounded that the transmission would change gears an average of every 3 seconds :awe:


Next post down

In other words it totally is Toyota's fault that my transmission is all busted. I'm not the one telling it to gear hunt. The cruise control tells it to do that.
Keep in mind where all this heat is coming from. The transmission screws up because you're burning all this extra gas, getting horrendous gas mileage, and that extra gas goes directly into heating and melting your transmission. Toyota = r gooder ungineerz

They are just buying tranny that is cheap and serve most of their customers well.

 

[Zenmervolt]

If the engine were having problems, wouldn't it make the car shake? Generally that's what people are talking about when they say the engine is lugging or bogged down. At 2500-3000, there was never any shaking or weird sounds. It would just maintain speed (maybe drop from 70mph to 65mph) and that was it. There wasn't anything dramatic happening.

If you legitimately believe that an engine isn't lugging unless something "dramatic" is happening, you've made a mistake. If you have your foot to the floor and the car is losing speed, you're lugging it.

If flooring it up hills was bad, then those little 50HP economy cars would never last more than a couple years. Those haven't been made in the past 10 years but you can still buy used Chevy Sprints and Pontiac Fireflies and they still work. Maybe GM just has better engineers. Who knows.

You really only hear what you want to hear, don't you. Flooring it isn't bad in and of itself. Flooring it in top gear while going up a hill with a fully-loaded car while the car is losing speed is bad. If you're unable or unwilling to understand that there's a difference between climbing a hill in 2nd gear and climbing a hill in the top gear then there's really nothing that can be done for you.

Nice trick question. [bunch of intentionally-misunderstood bullshit]

An automatic builds heat when the torque converter slips. At low levels of slippage, this heat can be dissipated by the transmission cooler. If the car is continuously overloaded or if the driver is not familiar enough with how cars work to know to take the transmission out of overdrive to prevent hunting on hills and while carrying heavy loads, then the slippage will become excessive and you will build more heat than the cooler is designed to be able to dissipate. When used within the design parameters, most automatics are very reliable.

Hey don't blame me for that. If it were up to me, it would stay locked the whole time. The guys at Toyota are the ones who specifically wanted the torque converter to unlock under load. If unlocking the torque converter generates tons of heat, destroys my transmission fluid, then destroys the clutch packs, it's because Toyota wants that to happen. I can't figure out why they would want that since they're currently replacing the transmission under warranty, but I assume they have their reasons.

If the torque converter stayed locked all the time, the transmission wouldn't be able to shift. However, I'll assume that you only meant it should stay locked while in gear and address your assumption that way.

As stated above, at low levels of slippage, the heat is able to be dissipated by the transmission cooler. Low levels of slippage also allow the torque converter to function as an "extra gear" in a way. This ability to multiply input torque and function effectively as a reduction gear allows the use of taller final drives and superior fuel economy at cruise despite having typically fewer true gear ratios than manuals.

Also as stated above, an attentive owner will have read his car's manual and know that he is supposed to take the transmission out of overdrive for hilly sections or when carrying heavy loads to prevent hunting between gears.

Pointing out how flat even the steepest highways are actually proves my point more than it proves anyone elses. I said a Corolla can't deal with steep hills. You correct me by saying there are no steep hills. Fine, then I change my statement to read: Corollas can't deal with near-flat ground. Put a Corolla on a 6% grade and the transmission will burn up. A Honda (or any other car in the world) on that same hill almost-flat ground never has a problem.

A 6% grade is not "near-flat ground". It's the sort of incline that has "truck lanes" because semis can't maintain speed and runaway ramps in case someone's brakes fail. Additionally, the variable here is not Honda v. Toyota, but rather manual v. automatic. On a steady 6% grade, any automatic will downshift. My Volvo does, my Honda did, and my Lincoln did. That's just how they're supposed to work. If they start hunting between gears, the driver is expected to lock out overdrive to prevent excessive slip.

My correction wasn't to say that "there are no steep hills"; my correction was to say, "you can't estimate inclines for shit and clearly have no idea about how a 'small' incline can create a massive amount of extra work for a car".

So far, what you've demonstrated is a near-total lack of practical understanding and a continuous intentional refusal to hear anything other than what you have a-priori decided to be true absent any rational basis.

ZV

 

[Demo24]

blah blah blah, more automatic transmission crap

Sure 'gear-hunting' can exist. I've experienced at times in my previous 1995 Subaru Legacy wagon with 2.2l engine and 4spd auto, and all 120hp. It could happen when going up reasonable inclines under the following conditions..a) not enough throttle applied b)a speed in which neither gear appropriately satisfies the speed/acceleration requested. Through some correct driving techniques I could make it stay in 3rd gear going up these inclines without drastically exceeding the speed I wished to maintain.

Since then I've driven a number of cars with automatic transmissions, all newer cars and some even with 4spd autos. None gear hunt constantly, none downshift so hard I get whiplash, and none have blown up in 60 thousand miles.

Your problem is you blame all this on the car, when it's distinctly obvious you know nothing about it nor how to even drive a car besides steer it and go from a to B. You can yap all you want about the civic. Fact is on any significant incline that car will need a downshift. Going from 75 to 60 on a hill means you were not in the correct gear, it should maintain the speed you were going. I've driven a number of hondas, guess what their autos downshift on hills too. I've driven manual variants too...surprise, to properly maintain speed, efficiency, and load on the engine you...DOWNSHIFT.

 

[Sukhoi]

rock solid reliability of automatic transmissions is why pickup trucks built for hauling large loads almost always have an automatic transmission

They do...

Pointing out how flat even the steepest highways are actually proves my point more than it proves anyone elses. I said a Corolla can't deal with steep hills. You correct me by saying there are no steep hills. Fine, then I change my statement to read: Corollas can't deal with near-flat ground. Put a Corolla on a 6% grade and the transmission will burn up. A Honda (or any other car in the world) on that same hill almost-flat ground never has a problem.

I drove my '95 Corolla 3-speed auto up and down the Sierras many times with 0 issues.

 

[ShawnD1]

Z, thanks for the explaining why it unlocks the torque converter

Your problem is you blame all this on the car, when it's distinctly obvious you know nothing about it nor how to even drive a car besides steer it and go from A to B.

Because that's the whole point of owning an automatic. If I wanted to pay attention to what I was doing, I would have bought a manual. I just want to set the cruise control, stay half awake with one eye open, and get to my destination.

I drove my '95 Corolla 3-speed auto up and down the Sierras many times with 0 issues.

That's because 3 speed autos run near max torque (about 4000rpm) on the highway. If it downshifted, the thing would explode.

http://www.corolland.com/corolla/1993-1997/transmissions.html
1st 2.810
2nd 1.549
3rd 1.000

Your highest gear is 1:1. Here is the gearing for a 2010 Corolla 4 speed:
http://www.autotropolis.com/2010/toyota/corolla/309332/specs.html
1st 2.85
2nd 1.55
3rd 1.00
4th 0.70

 

[Sukhoi]

That's because 3 speed autos run near max torque (about 4000rpm) on the highway. If it downshifted, the thing would explode.

It did downshift. Most of the driving was in 2nd gear. I could only make it up in 3rd gear if I could maintain 75-80 mph, which was rare due to bottlenecks from truck traffic. If I dropped out of 3rd gear there was no way to get back until a long flat stretch.

 

[yh125d]

Alls I know is, my commute has loads of 3-8% grades and my car goes up them all at 75/83mph fine without having to downshift

 

[Zenmervolt]

That's because 3 speed autos run near max torque (about 4000rpm) on the highway. If it downshifted, the thing would explode.

http://www.corolland.com/corolla/1993-1997/transmissions.html
1st 2.810
2nd 1.549
3rd 1.000

Your highest gear is 1:1. Here is the gearing for a 2010 Corolla 4 speed:
http://www.autotropolis.com/2010/toyota/corolla/309332/specs.html
1st 2.85
2nd 1.55
3rd 1.00
4th 0.70

You need to take the final drive into account as well. The 4-speed as a 4.13:1 final drive while the 3-speed has a 3.72:1 final drive (in the US).

That makes a pretty meaningful difference; the overall ratio for the 3-speed in 3rd is taller than for the 4-speed in 3rd even though both have the same transmission ratio.

ZV

 

[DivideBYZero]

I just want to set the cruise control, stay half awake with one eye open, and get to my destination.

I am so very glad the Atlantic prevents you from being on the same stretch of road as me or anyone I care about.

 

[ShawnD1]

You need to take the final drive into account as well. The 4-speed as a 4.13:1 final drive while the 3-speed has a 3.72:1 final drive (in the US).

The older models also have smaller tires.
1995 corolla uses 175/65R14 (23.0" diameter
2010 corolla uses 205/55R16 (24.9" diameter)
difference = 8.3%

Difference between 3.72 and 4.13 ratio is 11%

Those 3 speeds scream on the highway 😉

 

[LTC8K6]

This is a thread about fuel efficiency and you're saying what race car drivers do. Race car drivers try to keep the rpm close to maximum power so the car can accelerate as hard as possible. I'm not a scientician, but I'm guessing that keeping the engine buzzing at 6000rpm all day is not great for gas mileage.




They do when they're not hauling anything 😉

You can't make up your mind what a hill is.

If the auto trans doesn't downshift, then it wasn't much of an incline. Same for the driver.

 

[LTC8K6]

That shakes my faith in them even more. All this time I thought they were just purchasing poorly made transmissions, and now you tell me Toyota is the one making those crap transmissions.


If you want to see something funny, go to google and type (without quotes) "automatic transmission up hills". First result:
http://www.rav4world.com/forums/99-...n-keeps-switching-up-down-cruise-control.html

Toyota fail. I swear I made a thread about my Corolla transmission changing gears 20 times per minute as a rough guess. Someone quoted it and remarked at how silly it sounded that the transmission would change gears an average of every 3 seconds :awe:

Yes you did say your trans was shifting 20 times a minute. I said if it was actually doing that, then it was broken. Autos shouldn't do that.

Plus, when the trans is gear hunting, proper response is to take it out of O/D.
If it still gear hunts, then something is wrong with it.