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Old 01-04-2019, 09:40 PM   #1 (permalink)
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Why will this not work??

This just about freaks me out.

The automotive world is producing 6&8 and10 speed transmissions.

Yet all they are doing with them is giving more powerful take off.

And the top gears are not much taller over drives the old 4 speed transmissions have.

Here is what I see and no one is doing: With these lower low gears you can run a lower rear end, at the lowest gearing made, like 2:26 or 2:47 and with such gearing have a great take off, smooth power thanks to all the gears and in your top gears you should get great gas mileage.

I keep thinking I am missing something.

Here is the RPM/speed charts of say a Ford Crown Vic with its stock gears and a 6R80 transmission compared to a 2:26 and 2:47 rear ends.






Last edited by racprops; 01-04-2019 at 09:44 PM.. Reason: spelling
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Old 01-04-2019, 09:46 PM   #2 (permalink)
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In Europe at least, the multi speed transmissions (7,8,9,10speed) are all about having the engine in the ideal power and for fuel consumption testing - essentially inflating the economy of cars..

It's not about speed or drivability day to day - just meeting a desired outcome from a prescribed test
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Old 01-04-2019, 09:52 PM   #3 (permalink)
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Do you mean why is no one putting new transmissions in older cars? or why don't car manufacturers do it?

It sounds good initally, but the cost for the average ecomodder, let alone "average" person, wouldn't make sense for gas savings. The transmission would probably be 300+, then an aftermarket controller to control it would probably double the cost. Not to mention any changes needed outside the transmission swap like driveshaft, mount, etc.
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Old 01-04-2019, 09:53 PM   #4 (permalink)
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ore ears will not raise the top attainable speed, but will let you get there faster., or from anyspeed to a higher speed faster. At some point, shifting takes longer than less gears, unless you have a manumatic.
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Old 01-04-2019, 10:34 PM   #5 (permalink)
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I think cars will increasingly be hybrid despite the recent decline. When that happens, the traditional transmissions will disappear.

I often complain here that my 6th gear on the TSX is worthless both as a racing gear, and as a fuel economy gear. There isn't many racetracks in the world where I could top out 5th gear and need to shift to 6th, yet 6th revs so high on the freeway that I get better fuel economy in stop and go than cruising at 70.
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Old 01-04-2019, 11:22 PM   #6 (permalink)
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Quote:
Originally Posted by M_a_t_t View Post
Do you mean why is no one putting new transmissions in older cars? or why don't car manufacturers do it?

It sounds good initally, but the cost for the average ecomodder, let alone "average" person, wouldn't make sense for gas savings. The transmission would probably be 300+, then an aftermarket controller to control it would probably double the cost. Not to mention any changes needed outside the transmission swap like driveshaft, mount, etc.
I mean why are they NOT doing this set up, a 6/8 speed tranny with low rear end gears like I an thinking of doing.

Well I have figured on about $800.00 to $1000.00 for the transmission, and $300.00 for the controller for the Crown Vic, and for my 93 Van about the same for a 8L90 and controller.

BUT As I plan on keeping my 03 P71 Crown Vic and 93 Chevy large Van until I die, and as I am customizing each to what I want in a car and van it is a LOT cheaper than buying a replacement car/van, and with low cost repairs a lot cheaper to keep.

In fact the only fly in the ointment is the bad MPG each gets, all the rest I love in each.

Rich

Last edited by racprops; 01-04-2019 at 11:30 PM.. Reason: More complete answer.
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Old 01-04-2019, 11:28 PM   #7 (permalink)
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Quote:
Originally Posted by redpoint5 View Post
I think cars will increasingly be hybrid despite the recent decline. When that happens, the traditional transmissions will disappear.

I often complain here that my 6th gear on the TSX is worthless both as a racing gear, and as a fuel economy gear. There isn't many racetracks in the world where I could top out 5th gear and need to shift to 6th, yet 6th revs so high on the freeway that I get better fuel economy in stop and go than cruising at 70.
Well I do not plan on ever trying to top out the top gear.....my idea is to be able to cruse at highway speeds (which in AZ is 75MPH so doing 80/85 is reasonable) at under 2000 RPMs, the Ford 4.6 stock and the Chevy 383 tuned to low RPM torque running a '87TPI with a special PCM running a Lean Burn Cruse setting.

I am running these 6/8 speeds for the combo of great take off equal or slightly better than the stock gears with the stock rear ends with the special rear end gears of the great low RPM at speed.

Rich
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Old 01-04-2019, 11:32 PM   #8 (permalink)
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Here are the ratios of my modified TSX 6 speed transmission which will be going in my Insight, next to the 6AT in the Ford Transit Connect I drive for work.

I like the ratios in my van pretty well; it's quick off the line (especially with torque converter) and even has some wheelspin problems when conditions are remotely slick. It has a good highway 6th gear as well: 2077RPM @ 65mph out of a Mazda 2.5L in a small van isn't half bad, and right now I'm able to get just under 30mpg @ 55mph with a pair of ladders on the roof, wet roads, normally inflated tires and temperatures outside around or below freezing. I think the top gear could be a little taller but if it were a full ratio taller it might not spend much time at all in that gear, what with the ladders I have on the roof.

I'd say with the spacing of the gears, a 7th gear to bring them all a little closer together and maybe push the top gear just a hair taller wouldn't be unwelcome. 5 speeds with the same spread would probably affect drivability. 9 or 10 gears? Yeah, probably too much.

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Old 01-04-2019, 11:47 PM   #9 (permalink)
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C7 Corvette 8 speed autos have either 2.41 or 2.73 final drives, and some rather big diameter tires.
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Old 01-05-2019, 02:03 AM   #10 (permalink)
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Quote:
Originally Posted by ennored View Post
C7 Corvette 8 speed autos have either 2.41 or 2.73 final drives, and some rather big diameter tires.
That is in my ball park.

Will look into them.

Rich

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