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PostPosted: October 29, 2014, 11:42 am 
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So I have had this idea rolling around in my head for the last year or so. I have come to the point where I can’t find the answers to the questions I have. This is what brings me here. To ask everyone if it is possible.

The concept is not a new one. The idea is to copy what hot rodders did back in the 50’s and 60’s before torque converter technology advanced to make custom stall converters. They replaced the converter with a clutch and flywheel. They had different names but the most common one was called the clutch-flite. It got that name because it used the torque-flite transmission as its base. The basic concept is you have clutch pedal that you would use to start from a stop, then when you were moving you would just shift the transmission into the gears as you moved along. The transmission was fitted with a manual valve body so you could hold it in gear just like a manual. The clutch that was used had a special type of pressure plate that a sprag would engage the pump in the transmission to supply the fluid for the trans. The down fall of these transmissions was that they ran at full line pressure all the time, so they would shift really hard. I remember reading someone say that they would shift so hard it would pull the fillings out of your teeth.

So my idea would be to find a modern auto and find a clutch to replace the converter. Then instead of the sprag for the pump just use a power steering pump to provide the fluid power for the transmission. To get around the hard shifting I would just use the computer to adjust the line pressure to the transmission and then set it up for the style of driving I want to do. So if I’m just out for a cruise set it at a low pressure to shift nice and smooth, then when you get to the drag strip you set it to “race” and run a higher pressure to get the thing to shift faster and harder. Seems simple right?

Now it’s your turn to tell me I’m crazy and it will never work. What I want to know is why it won’t work. My knowledge of automatics is limited so this is why I’m asking here. What have I overlooked in the mechanics of the transmission that will not make this possible. Please ask questions and help me figure this out. Thanks


-Vince


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PostPosted: October 29, 2014, 11:48 am 
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Challenge accepted:

Ahem... "You're crazy, and it will never work"

there you go! glad to help. ;-)

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PostPosted: October 29, 2014, 12:44 pm 
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:lol: I appreciate the reply. Now read the next line in my first post. Haha


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PostPosted: October 29, 2014, 3:50 pm 
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Don't see why not. Pick an auto transmission to start with. Hell, I have a 4r70w which is busted right now. It's a modified AOD, and you can find those everywhere. I'm debating on getting rid of the Mountaineer with the transmission down anyways.

Consider a moment that the Model T's transmission was very similar to those used in modern day Automatics. Lots of information to cull from studying of how it worked.

Also, there apparently are a few companies still doing the Clutchflite conversion, and information out there. http://ggordon528.tripod.com/shop/cpe/clutchflite.html

I say go for it and let me know if I can help.


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PostPosted: October 29, 2014, 4:16 pm 
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clutched auto,

1. when you come to a stop, what happens, do you just press in the clutch, the trans usually stays in high gear until the vehicle stops ?

2. what about down shifting ?

3.in transmissions like a torque flite or a turbo 400 or an aod, the govenor controls the shift points with inputs from the throttle valve.

4. do not use an aod, there is no converter clutch, it has direct drive in 3rd and o/d unlike an aode or a 4r70w which do have a clutch but they both have duel input shafts like most overdrive automatics..

5. usually in a race situation with a clutch in front of an auto, at the end of the strip, you would click it into neutral.

6. have you any idea how a valve body works in an automatic ?

7. do you know anthing about accumolators ?

8. do you know anything about the different pressures that an automatic runs during a drive cycle ?

9. do you know what a constant pressure valve body is ?

10. do you know anything about delayed upshift ?

when you have got that info under your hat, ask the question to yourself, then you may have some answers.

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PostPosted: October 29, 2014, 9:16 pm 
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The pre-war (Brit) Wilson pre-selector gearbox was a planetary gearbox with a clutch. So why not?

The key concern with many current automatics could be that that they rely upon the torque converter to get a decent first gear ratio for standing starts. So picking an auto with overdrive would be a good starting point so that the trans/diff combination can be geared appropriately (i.e. using a 'shorter' differential ratio) for standing starts in absence of the torque converter.

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PostPosted: October 30, 2014, 3:02 am 
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Warren, having owned several vehicles with wilson gearboxes and also repaired several commercial vehicles with said gearbox, i beg to differ.

they rely on a fluid flywheel not a clutch, the third pedal is an engaging pedal which engages in a pawl on a band, clamping the selected gear drum with spring pressure, all the gears are engaged this way.

boy do you know when you are out of adjustment with the selector because the spring will shoot the engaging pedal up and bash your shin

i have also worked on the later commercial units that use air pressure as the spring.

it should be noted that with an eppicyclic gear train only two ratios can be achieved plus reverse unless you add another complete train for each additional gear.

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PostPosted: October 30, 2014, 4:32 am 
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Far easier to achieve would be electronic control over an auto. Flappy paddle gearchange and an aftermarket gearbox ecu. It will shift up and down the box as and when you tell it and retain the benefit of the torque multiplication you would lose if you junked the torque converter for a flywheel. All these later boxes have a lock up clutch in the torque converter which can be activated in any gear so it would not be slushy. All this kit could be stripped from a BMW in a breakers yard.

Bob

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PostPosted: October 30, 2014, 8:23 am 
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John,

(Blush) It has been many years since I'd been in a Riley with a Wilson, so please forgive my poor memory.

Warren

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PostPosted: October 30, 2014, 11:09 am 
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bob wrote:
Far easier to achieve would be electronic control over an auto. Flappy paddle gearchange and an aftermarket gearbox ecu. It will shift up and down the box as and when you tell it and retain the benefit of the torque multiplication you would lose if you junked the torque converter for a flywheel. All these later boxes have a lock up clutch in the torque converter which can be activated in any gear so it would not be slushy. All this kit could be stripped from a BMW in a breakers yard.

Bob

Megasquirt offers a transmission controller module as well.


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PostPosted: October 30, 2014, 11:59 am 
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Vince

i used to build dune/desert truggies (front/midship engine with individual transmission & quickchange rear ends ....not trans-axle buggies)

one of the biggest advantages of my cars was the ability to use full manual planetary transmissions (usually highly modified TH350/400)
we used sequential shifters that you could "slap" up and down in a split second (safety gated to avoid accidental shifting into reverse & park)
the manual valve body was modified to allow engine braking ("drag race" manual VB`s usually dont have/need that feature)

however, we still used a torque converter, but a very "tight" one with very low stall speed (near no slip)
this allowed us to skip the clutch and gave us the ability to shift under full throttle without braking our necks :P

in sand (high rolling resistance!) the advantage of full throttle shifts is HUGE :twisted:
power flow is never interrupted ... rpm drop is very minimal... turbos dont loose boost
downside was that we had only 3 gears
(but the final drive ratio tune-ability of the quickchange rearends helped a lot to adjust the gear ratios to different driving areas)

one of my cars has an all aluminum 572 cid twin turbo / intercooled dry sump Brodix engine (well over 1000 hp at the rear tires :ack: )
with a "one off" TH400/ Alison hybrid transmission,
the "mortar shell" like sound of the upshifts under full throttle in that car is something that i will never forget :mrgreen:

anyway .... what i try to say is imho i dont really see an advantage of using a clutch
a "tight/low stall" TC will eliminate the slushbox feeling but still gives you the advantage of "cushioned" shifts

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PostPosted: October 31, 2014, 9:28 pm 
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I have no first hand experience but I was thinking the same thing as Stephan. I say keep the torque converter.

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PostPosted: November 1, 2014, 5:18 am 
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http://www.youtube.com/watch?v=y6-mHgfJdB8

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PostPosted: November 3, 2014, 11:50 am 
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The way I took it was to make a sequential shifting system using a stock planetary gearset, but not necessarily the full hydraulic valve setup from an automatic. Akin to how the old Model T worked. I could see this working, even with a computer control.

Which reminds me, why has everyone stuck with the hydraulics and not gone for a full computer control of the planetary setup?


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PostPosted: February 6, 2015, 11:41 am 
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Bringing this back to life, because we didn't answer what I think is a pretty good question.

Downix wrote:
Which reminds me, why has everyone stuck with the hydraulics and not gone for a full computer control of the planetary setup?

Everybody (transmission manufacturers) still does hydraulics because of the forces required / involved.

Simply put, a planetary transmission goes from one gear to another by activating a clutch (or band) and deactivating something else (clutch, band, etc). The forces required to activate those clutches are not insignificant, and electronics / electrical components don't have that capability within the packaging constraints. Hydraulics have the power. They also have the ability to lubricate and cool components to extend their service life.

Modern automatic transmissions utilize electronically controlled solenoid valves to control the hydraulics, giving you the desired control features with the required mechanical power to do the job.

JustDreamin


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