Please forgive my ignorance, I've been a 4 speed man up till now.
I have a 327/PG/8.5 in. 3.08 posi conv and I think I may have found the original rear which is an 8.2 in. 2.73 posi. Since I'm going in to wrong direction with rear gears it will hurt my off the line feel (what little there is).
I was wondering if changing the Stall Speed would help the off the line response, but not hurt the driveablity of the car. Since I don't know what stall speed is I'm at a loss.

Any info anyone could give me would be appreciated. Thanks, Kevin

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69' SS-350 ragtop, M20, 3.55 posi. Totally Disassembled & in boxes (I'm working on it!)
69' Hugger Orange Z-21 ragtop 327/PG, Driver

To test the stall on your current torque converter:
With the engine running, the emergency brake fully applied and the brake pedal held firmly with your left foot put the selector in drive and depress the accelerator fully to the floor with your right foot for four seconds. Your stall speed will be the maximum RPM shown on the tach.

DO NOT HOLD ACCELERATOR TO MAXIMUM RPM FOR MORE THAN 4 SECONDS AND ONLY PERFORM TEST WITH A FULLY WARMED UP VEHICLE and A VEHICLE WHO'S EMERGENCY AND NORMAL BRAKING SYSTEMS ARE IN FACT WORKING PROPERLY.

Hope to have helped you.

the above statement is a new one on me....anyone ?

stall speed is the amount of rpms the converter will let the engine come up to before the car moves, if floored,(<--this is called flash stall.)it will however still let the car move at less rpms unless its a true stall---->won't let the car move untill the stall speed is reached.(race only in my book).
so if your car is basicly stock, it could improve the "take off" by using what is called a factory high stall(about 1800-2000stall)what this does is let the engine come up to its "power band" and move the car easier. hope this helps.

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My68Camaro (http://hometown.aol.com/Dougs68Camaro/index.html)
Doug G.
68 Camaro
406 ci.

Curacao Camaro,

You have given the popular, but incorrect, definition of stall speed. I have heard some people refer to the result of your test as the "flash" speed.

Stall speed is the speed at which the front and rear turbines inside the converter housing begin to spin at very close to the same speed. This number is usually different from the number obtained from the test described above.

As many people may already know, the speed at which a converter stalls is engineered or built into the converter. VERY simply, a convertor with a high stall speed is an inefficient converter. A converter with a low stall speed is a more efficient converter (guys, don't beat me up, I'm trying to keep it simple).

Again, as most performance people know, there are reasons to chose a more "inefficient" design. For example, Ford puts its modular V-8, which makes poor low end power, in a big heavy car like the Lincoln Town Car. Not a good combination! The way they fix this is to use a 3,000 RPM stall in the convertor. This gives the engine a chance to get going before it has to start pulling the car.

Hopr this helps.

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Hugger Orange & white 69 Camaro with supercharged 350, Tremec TKO, and 3.73 12-bolt

See my website updated 9/01/00 at:

www.geocities.com/gheatly (http://www.geocities.com/gheatly)

OK., let's carry this post one step further so hopefully KevinW and I can learn some more.
How does a "trans brake" work and why use one??? I know it's got something to do with power stalling a car before launch. But what??? pdq67

I'm like KevinW, I've never had cars with anything more than wimp-a-- engines coupled to a half worn out or weak auto trannies before except for my four speed Camaro and small V-8 Monza. I don't know the ends and outs of hi-po automatics except for my contact with Art Carr when I asked about and priced a built 200-4R for my big engine in case I shell my M-20 Muncie.

Trans brakes are a pretty neat tool for drag strip racing. I am only vagly sure how it works, but here its goes. Guys, please correct me if I am wrong.

It is an solinoid installed in the tranny that, when activated, through a button suppling 12 volts, lock the tranny in both forward and reverse. This allows you to bring the RPM up to atleast stall speed without moving the car. Once the 12 volts is released, the tranny lock for forward motion.

What this allows you to do is to activate the trans brake and floor the car without moving. If you have a 3500 rpm stall, then you motor will now be somewhere near that rpm. Once your ready to go, just let go of your tran brake button and you off. You have just the automatics version of a clutch dump.



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Mark
1992 Firebird 355/Six Speed
1991 RS 350 / 700-R4
1987 Toyota Pickup 383 / 500 + HP 10.963 @ 119.95 Slicks / 11.997 @ 114.23 Radials
http://personal.lig.bellsouth.net/~racer383/

A trans brake basically does not allow power to get through to the output shaft. Consistency is the name of the game at the drags. By "locking" the transmission and bringing the engine up to a specific (and repeatable) RPM level while staged, for all practical purposes you should get the same "launch" when you release the transbrake. It makes it easier to be consistant at the lights, and gives you yet another variable (launch RPM) under a bit more control.

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'69 Garnet Red Convertible, Ivory over black, 350 w/turbo 400

I have owned exclusively 4-speeds so this is an interesting education. If you were redoing an automatic, what would you ask for in a torque converter for good street performance? I'm assuming you match the stall speed somehow to engine size and power band? Does the torque converter also determine the shift points once the car is moving-like from 2nd to 3rd gear? Or is that inside the tranny?

Shift points are not really effected by a stall convertor, since by your shifting RPM, the convertor is way past locking. It does however make for more slipping at "around town" speeds. Most of the time, the stall is chosen by the torque curve of you motor, however sometimes it becomes a trade off. Do you really want a 4500 stall in your daily driver? It would never lock up, eating gas and creating heat.

IHMO, if you run a convertor on the street, put a real cooler on it. The extra cooling will extend the life of your tranny. I run a glide with a 4200 8" stall. It is cooled by its own cooler with a 9" electric fan on it. Unless I am planning hard, the temp stays between 180 and 190 degrees.

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Mark
1992 Firebird 355/Six Speed
1991 RS 350 / 700-R4
1987 Toyota Pickup 383 / 500 + HP 10.963 @ 119.95 Slicks / 11.997 @ 114.23 Radials
http://personal.lig.bellsouth.net/~racer383/

All, Lot's of good info! Thanks!

But just to recap ...

The higher the stall speed the more RPM the trans takes to 'lock' the 2 halves of the converter.

So if my stock converter is around 1000 rpm (a guess) and I bump it up to 2000 rpm I would have to rev more to get car moving? But this should move the car more quickly right, cause the higher rpm = more HP, right?

This sounds good, but would the times I don't mash the gas feel a little weaker?


Mark, how does the 4200 rpm stall glide feel for a driver? Or do you have 4.10s in it? http://www.camaros.net/forum/smile.gif

Kevin


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69' SS-350 ragtop, M20, 3.55 posi. Totally Disassembled & in boxes (I'm working on it!)
69' Hugger Orange Z-21 ragtop 327/PG, Driver

[This message has been edited by KevinW (edited 09-28-2000).]

You have to match the convertor to the cam and rear end gearing to get the most out of your combination. Getting a good quality convertor is important,and I got mine built so that after the tranny shifts it still falls in the power band.

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68 RS, Ash Gold,pwr windows,Hounds tooth

Stock converters are rated at about 16-1800 rpm "stall". In the mid 80s GM used a higher stall in the Monte Carlo SS to get a little more guts out of the 305 in the heavy car. With a non-lockup converter on the street you want a stall way below cruising rpm or you're just making heat. Also, many performance high stall converters also change the pitch or something in the converter to get a harder lock up. You can really rip the tires sometimes with these. The higher stall converter should really help you in your set up, I'd think.

KevinW, I do have 4.11's with the high stall, but you can still feel it slipping. For a weekend or once and a while driver, it just fine. For a daily driver...... thats really up to the driver. I think it put too much stress on the motor.


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Mark
1992 Firebird 355/Six Speed
1991 RS 350 / 700-R4
1987 Toyota Pickup 383 / 500 + HP 10.963 @ 119.95 Slicks / 11.997 @ 114.23 Radials
http://personal.lig.bellsouth.net/~racer383/

You want to hear something that fits into this but not in a high performance way.
I read something years ago about industrial forktrucks using the old fluid-coupling/stick-clutch setups out of the old Chrysler Corp. '40's "Fluid-Drive" three speed stick transmission cars.
You could leave them in gear or shift the three-on-a-tree transmissions. I had one in a '48 Dodge five pass. coupe but didn't quite know what it was or why it had it.

A second thing is that I also read about great big earthmover type equipment having fluid couplings that used b-b's or fine steel shot in place of ATF as the Fluid. It seems as though the fine steel shot or whatever behaves like a fluid except it doesn't shear but rather centrifically locks solid at speed
and they handle 1,000's of lb.ft. of torque at slow rpm applications.
Just a tidbit, go on past if not interested. pdq67

i have read all of the replys and nobody said any thing else about "FLASH STALL". flash stall is when youre sitting at a idle and you floor borad the car . so if you buy a 4800 stall without a trans break it will flash 4800-5000. now if you break torque the car it will only go 3200 because you dont have the torque to go up to the stall speed. thats why i tell everyone if you drive it every day to buy a 1800-2000 for driveabillty and good gas mileage. thats the other thing if you buy one to big you half to drive it 5000 rpm to drive at 55mph and thats not good on a motor.

[This message has been edited by DEVIL'S LAKE (edited 09-30-2000).]

With a high stall and a overdrive trans that locks up the converter is the best way to go. That way you can run a 3500 converter and still cruise down the highway a 2000RPM. Get the best of both worlds, it is a combo that is hard to beat. A little of the beating path but just my .02 http://www.camaros.net/forum/smile.gif

OK, I'm educated now http://www.camaros.net/forum/smile.gif

I gotta match the drivetrain to the converter. Anyone have recommmendations about my setup?

original 327/210 2bbl (with 350/300 cam) PG trans 2.73 posi or 3.08 posi. 65 mph would be around 2200-2300 (a guess, I'm doing a rear spring replacement now and never had it on the highway)

From all the info the converter should be the 1500-2000 rpm stall speed converter?

Thanks, Kevin



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69' SS-350 ragtop, M20, 3.55 posi. Totally Disassembled & in boxes (I'm working on it!)
69' Hugger Orange Z-21 ragtop 327/PG, Driver

Why don't you run yor combo through this tire diameter/rpm/gear ratio/mph site to see what you are doing???
http://camarotech1.com/refarticles/ref-spd-rpm.html

pdq67

Just had to add a little joke. Stall speed on my Camaro is that point just off idle to when you start moving, if your not carefull it will hesitate and stall. I would say my stall speed is about 2 to 3 miles per hour!!

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