[Knuckelhead]

Originally Posted by NH2112

I edited my quoted post to close the loophole you found, but the fact remains that by the time you've increased RPM by 3-400 the turbine & impeller are close enough in speed that there's no torque multiplication going on.

Then why can my engine RPM be 1,200+ with the brakes applied and the Jeep is not moving? The torque converter is multiplying the torque.

And that wasn't a loophole, it's fact as to how the 32RH works in my 2000 Sport...

[Jerry Bransford]

Originally Posted by NH2112

I edited my quoted post to close the loophole you found, but the fact remains that by the time you've increased RPM by 3-400 the turbine & impeller are close enough in speed that there's no torque multiplication going on.

No, you get torque multiplication as long as you are doing things like climbing an obstacle, accelerating, etc. which is exactly when the added torque is good to have. When you aren't doing either, you need any torque multiplication.

If you had ever driven an auto in those conditions like I spent doing this weekend while offroading, you'd notice the added power/torque being available during the technically challenging parts of the trail when you are powering up an obstacle, rock, etc.

OF COURSE a torque converter doesn't multiply torque when you're cruising and the input/output rpms of the torque converter are equal. It doesn't take a genius to realize that.

[NH2112]

Originally Posted by Knuckelhead

Then why can my engine RPM be 1,200+ with the brakes applied and the Jeep is not moving? The torque converter is multiplying the torque.

And that wasn't a loophole, it's fact as to how the 32RH works in my 2000 Sport...

Because that's the way a torque converter works. There's no mechanical connection until lockup, so you can heat that fluid up all day long by revving the engine with the brakes on and tranny in gear. As soon as turbine & impeller RPM start getting closer together, torque multiplication drops off. The closer they get to being equal, the less torque multiplication you get. Think of it this way: Smack someone on the back when he's standing still, and then smack him as he runs by you. Which smack will hurt him more? His movement lessens the impact of the slap, even though you're swinging just as hard. When he's not moving, or moving slowly, the difference in relative speeds between your arm and his back multiplies the "torque" your arm can apply. When you're holding the vehicle with the brakes, the turbine is your friend's back while he's standing still and the impeller is your arm.

[NH2112]

Originally Posted by Jerry Bransford

No, you get torque multiplication as long as you are doing things like climbing an obstacle, accelerating, etc.

As long as there's a large difference in impeller vs turbine speed. As that ratio approaches 1:1, your 1st gear approaches 2.84:1 (32RH/RE 1st gear IIRC.) When you first stab the throttle on acceleration the speed difference opens up and creates more torque multiplication, but as soon as the vehicle begins to accelerate they approach 1:1 again.

I'm not saying automatics are inferior to manuals, I'm just pointing out that most people completely misunderstand how they work. Just ask someone what "stall speed" means, or how to check it, and you'll see what I'm talking about.

[Jerry Bransford]

Originally Posted by NH2112

As long as there's a large difference in impeller vs turbine speed. As that ratio approaches 1:1, your 1st gear approaches 2.84:1 (32RH/RE 1st gear IIRC.) When you first stab the throttle on acceleration the speed difference opens up and creates more torque multiplication, but as soon as the vehicle begins to accelerate they approach 1:1 again.

I'm not sure what your issue is, both Knucklehead and I fully understand how torque converters work. We don't need to be taught how they work, this is pretty basic stuff you're trying to give us lessons on.

[Knuckelhead]

Originally Posted by NH2112

Only until turbine & impeller speeds are equal, which happens by the time you're 3-400 RPM off idle*. From wikipedia:
.

Originally Posted by NH2112

Because that's the way a torque converter works. There's no mechanical connection until lockup, so you can heat that fluid up all day long by revving the engine with the brakes on and tranny in gear. As soon as turbine & impeller RPM start getting closer together, torque multiplication drops off. The closer they get to being equal, the less torque multiplication you get.

I understand how a torque converter works. Your comment about 3-400 rpm off idle making the input and output equal isn't true...

Edit: Jerry, you beat me to it...

[mrblaine]

Originally Posted by NH2112

Think of it this way: Smack someone on the back when he's standing still, and then smack him as he runs by you. Which smack will hurt him more? His movement lessens the impact of the slap, even though you're swinging just as hard. When he's not moving, or moving slowly, the difference in relative speeds between your arm and his back multiplies the "torque" your arm can apply. When you're holding the vehicle with the brakes, the turbine is your friend's back while he's standing still and the impeller is your arm.

Somewhat skewed analogy when it comes to fluids though. Take a much less viscous liquid like water for example. You can easily push your hand down into it with practically no effort other than the minimum amount of force needed to overcome residual flotation. Increase the speed of your hand and the force rises exponentially to shove it sideways through the water and that's without counter opposing curved vanes and the much higher viscosity of hydraulic fluid.

[Dryseals]

Originally Posted by NH2112

As long as there's a large difference in impeller vs turbine speed. As that ratio approaches 1:1, your 1st gear approaches 2.84:1 (32RH/RE 1st gear IIRC.) When you first stab the throttle on acceleration the speed difference opens up and creates more torque multiplication, but as soon as the vehicle begins to accelerate they approach 1:1 again.

I'm not saying automatics are inferior to manuals, I'm just pointing out that most people completely misunderstand how they work. Just ask someone what "stall speed" means, or how to check it, and you'll see what I'm talking about.

I think if you truly understood the advantages of a TC and application, you would know the benefits. I love my manuals for everyday driving. But I know when and where a TC does a better job.

[NH2112]

At what RPM does a torque converter provide the greatest torque multiplication? Anyone feel free to chime in with the answer.

[Dryseals]

Originally Posted by NH2112

At what RPM does a torque converter provide the greatest torque multiplication? Anyone feel free to chime in with the answer.

Stall, what's your point? Many have stated that the TC works better for off roading, I happen to agree. If I was doing a ton of off road I would have bought an auto for both the torque multiplier and not having to do heel toe driving while bumping around. The location of the peddles suck for that.

Each tranny has it's place, the torque multiplier gives you a bit of an edge. Besides, I've changed enough clutches in my life, I don't want to do any more.

[Knuckelhead]

Originally Posted by NH2112

At what RPM does a torque converter provide the greatest torque multiplication? Anyone feel free to chime in with the answer.

At stall rpm as stated above. Next question?...

[NH2112]

My point is that a TC with 3:1 multiplication ratio only does that at stall RPM. How much multiplication do you think you're getting down just off idle with the stock converter? Maybe 1.5:1 or 2:1 max, and that's at idle. Nowhere near 3:1, that's for sure. 3-400rpm later you're nearing 1:1 and you've just started to move. So you get a lower stall converter to rectify that, then the engine falls on its face just as it's getting into its powerband.

I've changed MANY more flexplates due to cracks or trashed ring gears than I have clutches, on everything from light trucks & cars to airport equipment like belt loaders & pushbacks to our beast of an L8000 fuel truck. The only time I've ever had to change a clutch was on an '85 Chevy, after a couple dampening spring retainers let go and the springs made a mess of everything as they got ground up. My F350 needs a clutch soon, but that's due to the DMF starting to rattle a bit too much - the clutch still engages & releases like a dream on the 23-year-old truck, but the solid flywheel conversion I'm going with requires a clutch with dampening springs in the hub. Every other time I've had a clutch out of something it was because I was doing a rear main seal or something similar.

Sorry, my experience has convinced me a manual is better in most cases. YMMV, of course.

[mrblaine]

Originally Posted by Dryseals

Stall, what's your point? Many have stated that the TC works better for off roading, I happen to agree.

Set up correctly, neither has an advantage. Don't misunderstand, I'm a huge auto fan and won't even consider owning and driving a manual offroad.

HOWEVER, I wheel with several folks who own and drive manuals on the same difficult terrain I play on and watching and riding with them convinced me that at the end of the day, properly set up, there is no advantage to either.

One is easier to learn and harder to master, the other is harder to learn and much easier to master. It's very much like trap and skeet. Trap seems easier because you can hit a few targets right away and put some scores on paper.

Skeet is harder to learn because the shots seem harder until you figure out that each bird at the individual stations will always be hit with the same shot over and over and over ad nauseum. Trap on the other hand is much harder to master because you never know where the bird is going to be.

[Wheelin98TJ]

I think an auto has a slight advantage in mud being able to shift gears.

Not everyone plays where there is mud, but sometimes you just cannot avoid it.

[JRostron30]

If you've driven a stick you don't want to go to automatic...its as simple as that. Key point its fun and you have a lot more vehicle control. Especially with crap automatic transmissions its just no fun. 5 Speed all the way.