LocostUSA.com

Learning how to build Lotus Seven replicas...together!
It is currently Fri Oct 31, 2014 12:49 am

All times are UTC - 5 hours [ DST ]




Post new topic Reply to topic  [ 11 posts ] 
Author Message
PostPosted: Wed Oct 29, 2014 11:42 am 
Offline

Joined: Sat Mar 17, 2007 5:59 pm
Posts: 21
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


Top
 Profile  
 
PostPosted: Wed Oct 29, 2014 11:48 am 
Offline

Joined: Sun Aug 12, 2012 6:38 pm
Posts: 1390
Location: worcester county, Massachsetts
Challenge accepted:

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

there you go! glad to help. ;-)

_________________
My build log: http://www.locostusa.com/forums/viewtopic.php?f=36&t=13941


Top
 Profile  
 
PostPosted: Wed Oct 29, 2014 12:44 pm 
Offline

Joined: Sat Mar 17, 2007 5:59 pm
Posts: 21
:lol: I appreciate the reply. Now read the next line in my first post. Haha


Top
 Profile  
 
PostPosted: Wed Oct 29, 2014 3:50 pm 
Offline

Joined: Sun Nov 20, 2011 10:09 pm
Posts: 186
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.


Top
 Profile  
 
PostPosted: Wed Oct 29, 2014 4:16 pm 
Offline

Joined: Mon Oct 19, 2009 9:36 pm
Posts: 1603
Location: meadview arizona
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.

_________________
drag racers lament

oh to go down to the strip again where the blacktop meets the sky
all i ask is a small block and some fuel to make her fly
with slicks a smokin pushrods pokin next round i'll get a bye

she's up on song the shift was strong in the finals to boot
it's back to the pits and take it to bits and don't forget the shute
the final round was good and sound so come on give me the loot


Top
 Profile  
 
PostPosted: Wed Oct 29, 2014 9:16 pm 
Offline
User avatar

Joined: Fri Jan 02, 2009 1:45 pm
Posts: 916
Location: Halifax, Nova Scotia
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.

_________________
Warren
Isuzu Pickup/SR20DE, +401 COLD frame
Build Log: viewtopic.php?f=35&t=11601


Top
 Profile  
 
PostPosted: Thu Oct 30, 2014 3:02 am 
Offline

Joined: Mon Oct 19, 2009 9:36 pm
Posts: 1603
Location: meadview arizona
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.

_________________
drag racers lament

oh to go down to the strip again where the blacktop meets the sky
all i ask is a small block and some fuel to make her fly
with slicks a smokin pushrods pokin next round i'll get a bye

she's up on song the shift was strong in the finals to boot
it's back to the pits and take it to bits and don't forget the shute
the final round was good and sound so come on give me the loot


Top
 Profile  
 
PostPosted: Thu Oct 30, 2014 4:32 am 
Offline

Joined: Tue Aug 19, 2014 5:17 pm
Posts: 146
Location: England
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

_________________
Build Log viewtopic.php?f=35&t=16640&p=187700#p187700

Mancave http://s1116.photobucket.com/user/mypic ... ow/mancave


Top
 Profile  
 
PostPosted: Thu Oct 30, 2014 8:23 am 
Offline
User avatar

Joined: Fri Jan 02, 2009 1:45 pm
Posts: 916
Location: Halifax, Nova Scotia
John,

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

Warren

_________________
Warren
Isuzu Pickup/SR20DE, +401 COLD frame
Build Log: viewtopic.php?f=35&t=11601


Top
 Profile  
 
PostPosted: Thu Oct 30, 2014 11:09 am 
Offline

Joined: Sun Nov 20, 2011 10:09 pm
Posts: 186
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.


Top
 Profile  
 
PostPosted: Thu Oct 30, 2014 11:59 am 
Offline
User avatar

Joined: Sat Jul 27, 2013 3:16 pm
Posts: 259
Location: Cedar City UT
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

_________________
- Stephan - Image


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 11 posts ] 

All times are UTC - 5 hours [ DST ]


Who is online

Users browsing this forum: No registered users and 1 guest


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
POWERED_BY