The subject says it all!

 

Extra,Extra ,read all about it >

Right here >

http://www.howstuffworks.com/torque-converter.htm

BTW, I have numerous sites like this linked from my web site.

Drop around sometime.


[b][i][font color=red]Dennis[/font][i][b]

[font color=red]Calgary,Alberta,Canada[/font]
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Please correct me if I'm wrong. Horsepower TV on TNN recently explained the torque converter as a means of transferring power from the flywheel to the transmission without a hard, rigid connection. This would seem to protect either the motor or transmission to some extent should the other one fail. The torque converter is like a pair of impellers inside a fluid reservoir. The flywheel is directly connected to one impeller. As the flywheel turns, it also turns that impeller, causing the fluid in the reservoir to spin as well. The other impeller faces the one on the flywheel, but is bolted to the transmission. The spinning fluid spins that impeller, which quickly matches the speed of the other. When these two halves are turning at the same speed, that is what you keep hearing referred to as stall. At stall speed . . . you go.

I'm not a mechanic, but that's the way I understand it. If anyone here has a better explanation, please correct me.

 

The URL I posted in my previous reply > Goes directly to an explaination.

Hightlite > Copy > Paste > Go.
And up comes the page.

Have a read!

[b][i][font color=red]Dennis[/font][i][b]

[font color=red]Calgary,Alberta,Canada[/font]
http://www.clubfte.com/users/mil1ion/Minimorleytruck.JPG

[font color=green]Do You Need To Decode Your 78 Truck Data Plate?
[/font

http://www.clubfte.com/users/mil1ion/FordTruckCodes.html

[font color=red]If New Ford Parts Is What You're Cravin',
Then Buy Them HERE,At Motorhaven![/font]



[font color=green]Please Feel Free To Visit My Website.[/font]

http://www.clubfte.com/users/mil1ion/Mil1ion.html

[font color=red]
Please Don't Ask Me Any Tough Questions,
"I'm Saving My Memory For When I Develop Alzheimer's" [/font]


[font color=blue]78 F-150 429CJ,Silver,Explorer Pkg.
641/2-Mustang 260,Pre-World's Fair Car.
64-Fairlane500 S/C waiting for a 390-4spd.
68-Mustang 289-Sunlit Gold 80,892Mi
78-Buick LeSabre 403 4V [/font]

 

I understand the reading, but here's another question Dennis. What within the converter affects stall speed? I assume it has to do with the blade design??

 

What MRHIGHSPEED was describing is not the "stall speed" but the point called "lockup". They never really lockup unless you have a locking style convertor. I'll get to that in a minute.

Stall speed is the point were the engine can no longer rev against the transmission when the brakes are applied. The fluid action of the convertor holds the engine (or stalls it) at one rpm level. When you release the brake the engine revs like bat out of hell and the car launches. Guys at the track around here call people that use the brakes "footers". I run a bracket class were only footers are allowed.

The guys that do it at the digs (drag racing that is) on weekends that have engines strong enough to over come the brakes will use what is called a "trans brake" to hold the engine at stall. What a trans brake does is engage both first and reverse by applying fluid pressure to both clutch packs at the same time. When the yellow light glows you hit a little switch on your shifter and the selinoid that was holding the pressure to the reverse gear lets go and your flying.

Then you have what is called the convertors "flash stall speed". When you drop the tranny in gear while holding your foot on the floor the rpms that engine drops to is known has the converters flash stall speed. This sounds like its pretty rough on the tranny but if it's built right it's no worse then dropping the clutch at 6000 rpms on a strong manual.

The flash stall is always higher then the real stall speed. People do the flash thing because it delivers a whole lot of torque to the tires in a flash. This "loads" the rear springs and traction bars and forces the car to "sit" on the rear tires. The engine is then "pulled down" to the stall speed and races backup the rpm's. The big trouble here is tire shake. When that happens you lose the "load" and your tires are up in smoke.

Because a torque convertor is a fluid connection it can never really "lockup". There is this freaking thing called the laws of phyics, that says you can't have conservation of energy, and something else about the laws of fluid in motion that says it just can't happen. Because of these unbreakable silly law convertors generally slip on the range or 3-5% for a factory job and as low as 1.5 % for a really tight after market.

But that doesn't mean there are not lockup convertors. Starting in the early 80s some great person (that probably didn't get paid enough) came up with the idea of using a electric-magnet in the convertor to "lock" the engine and tranny together. Next time your driving your 4 speed overdrive count the number of shifts it fells like its making from a stop to 55 mph. I'll bet it makes 4 "shifts". Thats because somewhere (normally around 20-25 mph or just before the 2nd to 3rd shift) in there the convertor "lockedup". Has you slow down the tranny tells the covertor to unlock so you wont stall the engine when you stop at the light.

Ok I think I kind of overstayed my welcome on the topic. I hope this answers the questoin for ya. Sorry for the novel but I haven't slept in 38 hours and I just can't seem to shut up lol.

 

[updated:LAST EDITED ON 03-May-02 AT 04:11 AM (EST)]Ops forgot. Yup its blade design or attack angel and how many there are and how long they are and overall size of stator. The smaller the more stall you have.

PS Examples of convertor size to stall:
Factory 12" 1200 to 1800
Factory 11" 1800 to 2400
After Market 11" 1800 to 2800
After Market 10" 2500 to 3500 some are 3800 depending on stator design
After Market 9" 4000 to 5000
After Market 8" 4500 to 5500

A convertor will not stall at the same speed behind a 351 as it does behind a 460. The reason is engine torque. The more torque an engine makes the higher the stall speed for same size convertor.

For example if you have 250lbs of torque on 351 and the convertor stalls at 1400 that same convertor would stall at 1800 behind a 460 with 300lbs of torque.

And last but not least is vechicle weight. The more a truck weighs the higher the stall speed for the same convertor. If you yanked a 302 out of a stang (weight of ohhh 2800lbs) and the convertor stalled at 2800 when you drop the engine in the truck the stall would be around 3500 rpms. It's because the engine has to make more torque to overcome the resistance of the extra weight, so ya need more rpms (power) scotty.

 

[updated:LAST EDITED ON 03-May-02 AT 12:45 PM (EST)]Hey that's good stuff, thanks for the information Wayne! Reads like a post to print.

 

Scotty...Did Wayne say "Scotty"???

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