1998 Grand Caravan

Page 3 of 13  


Once again, an engineer talking down to someone, knowing nothing of the other persons credentials... and you wonder why we "common folk" get tired of your crap.
I don't consider it acceptable. In fact, despite my dedicated following of Chrysler, I would never buy something with an A604/41TE etc in it.
Will you next be defining "is"? I ask because you seem to think "accepted" and "acceptable" are terribly different. If you choose to do so, make it succinct (that means 'cut the bullshit out and get to the point')
--
Max

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Max Dodge wrote:

You've just proven your ignorance of the English language. Wow - I was only halfway kidding that you would be equating 'accepted' and 'acceptable' - I didn't think anyone could be that ignorant, but I guess I was wrong (see - I can admit mistakes on my part). But I guess to you, someone stating facts is "talking down" to you. I'm starting to understand your inferiority complex.
I could explain the difference between 'accepted' and 'acceptable' but something tells me that you still wouldn't get it and/or would want to continue arguing against the obvious. I bet my teenage daughter understands the difference. I try to avoid such imbecilic discussion - though with you it is difficult. I have said before that sometimes it is difficult to separate out dishonesty and stupidity, and you're illustrating why (you have to make up explanations to justify an erroneous position that you don't even understand but don't even realize).
Bill Putney (To reply by e-mail, replace the last letter of the alphabet in my address with the letter 'x')
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The only "inferiority complex" around here is those who feel they need to wave diplomas and position at others in order to "win" an otherwise factual discussion.

I could explain thats its merely a matter of tense...
Main Entry: acceptable Pronunciation: ik-'sep-t&-b&l, ak- also ek- Function: adjective 1 : capable or worthy of being accepted <no compromise would be acceptable>
Main Entry: accepted Function: adjective : generally approved or used - acceptedly adverb
But I'd bet you would argue with Merriam Webster about it, so I'll just let it be at that.

Yeah, I bet she does... she likely does things to be ACCEPTED that you don't find ACCEPTABLE.

Except that you engage in it almost every time you post.....

Not really, drop the pretentious attitude and you'll find that most people will like you better.

Ya see, I knew ya couldn't do it. I asked you to be succinct, and you failed. You instead resorted to personal attack as a means of reply. And that after I tried to explain to you why you get perceived a certain way.
So go ahead, continue your acrimonious behavior, and stop asking why people think of engineers as pretentious and egotistical.
--
Max

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Max Dodge wrote:

Keep your thumb here - you'll need to come back to that sentence of yours.

Oh really? What tense of the adjective is that? Sorry - adjectives do not have 'tense'.

Again - adjectives do not have 'tense'. Looks like you could have used some more of that there book-learning that you despise so much.

No - no problem with Merriam. What's really sad is you think you're in agreement but are not.
Here - I'll use the two words in a sentence (though not sure why I'm wasting my time): "33% is the *accepted* power loss figure on the 300M Club for the 42LE transmission, but those same people complain about that huge amount of inefficiency and think that it is not *acceptable*."
If the two words mean the same thing, then you have to not believe that it is possible for the same person to accept the 33% figure, yet consider it as unaccpetable inefficiency in a transmission. If you can't understand that, then there is no hope for you.
Bill Putney (To reply by e-mail, replace the last letter of the alphabet in my address with the letter 'x')
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Exactly the point I'm making!!!! If that's the loss in OD, then it's 1.65 TIMES the loss of a 727 or 904 in direct with a 2.76 - 3.55 : 1 axle. That's gotta hurt economy.
That's not traditional Chrysler engineering. The 8.75 (8 3/4) axle had the lowest internal friction losses in the industry, and, it'll make someone mad, Ford had the highest with the early 9" that would burn up if run too hard.
--
Budd Cochran

John 3:16-17, Ephesians 2:8-9
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Budd Cochran wrote:

I wonder where they got the 33% loss figure. Frankly, that sounds like BS to me. If the transmission really is dissipating 1/3 of the engine power input as heat, then you'd need a transmission cooler bigger than the radiator to cool it when running the car hard at all.
Matt
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Matt Whiting wrote:

--
Bill Putney
(To reply by e-mail, replace the last letter of the alphabet in my
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Matt Whiting wrote:

I suspect at least some of that 33% is not true loss, but, as I said in another post, some have speculated that a seemingly excessive loss figure is due to DC's possible exaggerated engine output claims being eplugged into the efficiency formula as the input.

Well you just shot your argument in the foot because LH cars do in fact have *two* coolers: The radiator tank (of course acting more as a temp. stabilizer or buffer), plus an air coil hung out in front of the radiator.
Bill Putney (To reply by e-mail, replace the last letter of the alphabet in my address with the letter 'x')
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Bill Putney wrote:

Wouldn't be the first time. :-)
Is the cooling capacity of these two equal to the engine radiator? If it is, then maybe the 33% loss is closer to reality, but I still HIGHLY doubt it. Is the fuel economy of this car much worse than similar weight and horsepower cars?
Matt
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Matt Whiting wrote:

Not even close...
but I still HIGHLY

Actually I think there is some good evidence that the DC electronic transmission family does have an inefficiency issue compared to others. I haven't ever really researched it hard, but here's my hunch about why its a bit on the lossy side:
Like all automatic transmissions, its gears are in constant mesh so in various different drive ratios (by which I mean "first gear" versus "4th gear" etc.) some of the whirly bits are spinning at various speeds but aren't actually in use. All automatics do that... but what all automatics *don't* do that the A-604 derivatives do is have multi-plate clutches that are released but the drive and driven plates are spinning at different speeds while in cruising gear. I think the shearing of the fluid due to the driving and driven plates spinning at different speeds is a loss mechanism that other transmission designs (for example, the old rear-drive Torqueflites in both 3-speed and 4-speed models) do not have. In high gear with an A-904 or A-727, both of the multi-plate clutches are engaged and the whole gear-train is locked into what amounts to a solid shaft, and only the bands are released. Bands don't exert a lot of shear force on fluid when released- multi-plate clutches do. In the case of the 4-speed versions (A500 and A518) the O/D clutch is released in 3rd gear, but in 4th its locked and the gears in the OD unit are working, but the main transmission section is still locked into a solid shaft.
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Bill Putney wrote:

Hi Bill...
Find it terrible terrible hard to believe :)
That's an incredible amount of heat to get rid of; stand well back before the whole thing melts!
Take care.
Ken
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Ken Weitzel wrote:

You're right. It has been proposed by some that the "losses" are not real, and are purely a result of the manufacturer's overstated engine output blindly plugged into the efficiency equations with the dynamometer-measured horsepower at the wheels. On the other hand, maybe that's why the ATF properties are so critical.
Bill Putney (To reply by e-mail, replace the last letter of the alphabet in my address with the letter 'x')
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Budd Cochran wrote:

I'd like to hear your explanation on this. If the overall ratio from engine to wheel is the same, why does it matter where reduction comes into play?

I don't care about your opinion, but I am very curious to see your technical explanation as to why you believe this to be true. Use Archimedes or anyone else for that matter, but tell us your technical explanation.
Matt
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I don't agree entirely with Budd, but.....
If you put the engine first at a mechanical disadvantage (OD ratio) then back to an advantage (rear axle ratio), you are sacrificing energy in the OD ratio (more effort to move a load, due to mechanical disadvantage). This is, I suppose, subject to mathematical calculations and would vary due to ratio, amount of power input, load on the output end, etc. and could be extremely variable.
But you won't get out of the parasitic loss encountered when you convert rpm/torque once, and then twice, between engine and tire. A direct ratio would eliminate one of the losses. As such, you've effectively lowered useable hp at the wheel by using an OD ratio. Thus, it could be assumed that you would use more fuel to make up for the loss in power, dropping MPG figures.
So it doesn't matter where reduction comes into play as much as it matters how many times you change the "reduction" in a drivetrain.
An interesting example would be my LeBaron GTC, where the 4th ratio is in fact a mild OD (0.94) and the 5th ratio a normal OD ratio (0.69). MPG between the two is not significantly different....at least, in several checks over the years, the MPG indicator on the dash never changed significantly (2 MPG or more) despite a ratio change with driving conditions remaining constant, including road speed. OTOH, a shift down to 3rd would significantly lower MPG figures on the dash display. Take from that what you will, I'll not claim any scientific structure.
--
Max

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Since a drivetrain is a proven to "lose" power to begin with, regardless of ratios, adding a gear ratio that aggravates the situation is just plain dumb.
I had three transmission choices on my Cushman scooter: simple centrifugal clutch / jackshaft ( single overall ratio), a three speed ( low/direct/OD) that would have required either gearing the final drive quite high numerically (not feasible) or using a 1:3 underdrive input ratio, or a two speed ( low / direct) with a 1:1 input ratio . . . .I went with the latter since I only have 7 hp to work with and my estimated top speed is about 62 mph at 4200 rpm.
Choice number one gave a top speed of 41 and yet have good acceleration. Choice number two gave a estimated 70 mph with a 1:1 primary belt ratio, but that would have been only on paper. In reality, I don't believe I had enough power to get over 30 mph in OD.
--
Budd Cochran

John 3:16-17, Ephesians 2:8-9
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Budd Cochran wrote:

The gear ratio has virtually nothing to do with it.
Sure, more gears will consume power due to the frictional losses, but this has little to do with the ratios. If you want to change the overall ratio by 6:1, it doesn't matter if you do 3:1 first and then 2:1 or 2:1 followed by 3:1.
Matt
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Excuse me, but have the laws of physics been repealed?
(btw, I've only added the parasitic back in because you guys were in tears over their absence.)
If you cut available torque by 2/3+ (frictional losses too) then try to multiply it back by doubling (minus frictional losses) you've got : ((x * .66)*2)- 2FL. OTOH, (x/6)-FL saves a power loss because one less power robbing loss is avoided.
And the other situation is just as bad.
--
Budd Cochran

John 3:16-17, Ephesians 2:8-9
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Budd Cochran wrote:

But that has nothing to do with the gear RATIO. It has to do with how you achieve the overall reduction ratio, but it isn't related to the ratio itself, that is the point. Sure, if you use 10 sets of gears to achieve a 2:1 reduction that will have more parastic loss than using one gear set. However, it doesn't matter what the reduction ratio is. It could be 10:1 or 100:1. What matters for frictional loss is how many mechanisms you traverse, not what the ratio is.
Matt
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Yes, it does. OD ratios are inefficient, like it or not.

The lower the efficiency of the ratio plus the extra parasitic losses from extra gearsets equals a stupid design. (KISS principle).
--
Budd Cochran

John 3:16-17, Ephesians 2:8-9
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Budd Cochran wrote:

It doesn't matter if I life it or if you like it. It is simply a dumb statement. A gear ratio is neither inherently efficient or inefficent. A given engine runs efficiently within a certain RPM range. A given gear ratio may or may not keep the engine in that range, but it doesn't matter if the ratio is an OD ratio or not. Some diesel engines are most efficient between 1500 and 2000 RPM and often an OD ratio is just the ticket to keep them in that range.

There is no efficiency to a ratio so it can't be lower (or higher) as it simply doesn't exist. For one who keeps referencing math and physics, you have a very meager comprehension of either.
Matt
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