transmissions and stall speed ; again

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transmissions and stall speed ; again

Post by bitterfitter on Sun Dec 28, 2014 12:29 pm

I know this topic is covered over and over.  I am just looking to run these numbers by you guys for some ideas.
 I have a 200-4r trans in my car now, behind a ZZ430.  The engines max torque is at 4000rpm and the max horsepower is at 5800. I think from sitting for a bit or just from age, the trans has began to leak from every little spot.  I am planning on replacing or having it rebuilt.  I also need a new torque converter.  This is where I started trying to figure my needed stall speed.I have looked over writings from alot of knowledgable people and till recently I was always told to use the RPM that the max torque was at.  Always seem to make sense.  Then a fellow explained to me that just because my motor has max torque at 4000rpm, this is not where I want to be.  I will not be racing this car.  Its main use is cruise to work and shows.  If I am running a 3500 stall, it will always be slipping and causing a ton of heat to be generated.  So using tire size, gear ratio (3.73), trans ratio (200-4r), etc...  it looks like I will be spending most of my time around 2300-2500 rpms.  I am assuming I want a stall just around 2300 then.  I understand I will not be getting the best launch from every red light, but the transmission will not be sliping most of the time either.  Am I on the correct path here?  Let me know what you guys think.

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Re: transmissions and stall speed ; again

Post by bracketchev1221 on Sun Dec 28, 2014 12:59 pm

In your case the only thing I would worry about is the size of the cam and idle.  You are correct that in od a high stall converter will be slipping somewhat.  And if racing is not really your concern you don't want a stall speed at max torque.  Find out what the cam duration numbers are and let us know.  I think about 25-2800 may be sufficient for what you are looking for.  Low vacuum cams like a looser converter to idle better.


Last edited by bracketchev1221 on Sun Dec 28, 2014 1:09 pm; edited 1 time in total
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Re: transmissions and stall speed ; again

Post by bitterfitter on Sun Dec 28, 2014 1:02 pm

The ZZ430 has a GM hot cam in it. Here is the info.
Cam Style:Hydraulic roller tappet
Basic Operating RPM Range:Idle-6,000
Intake Duration at 050 inch Lift:218
Exhaust Duration at 050 inch Lift:228
Duration at 050 inch Lift:218 int./228 exh.
Intake Valve Lift with Factory Rocker Arm Ratio:0.525 in.
Exhaust Valve Lift with Factory Rocker Arm Ratio:0.525 in.
Valve Lift with Factory Rocker Arm Ratio:0.525 int./0.525 exh.
Lobe Separation (degrees):112

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Re: transmissions and stall speed ; again

Post by bracketchev1221 on Mon Dec 29, 2014 12:09 am

I think a 2500 would work fine.
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Re: transmissions and stall speed ; again

Post by alowerlevel on Mon Dec 29, 2014 2:45 pm

bracketchev1221 wrote: You are correct that in od a high stall converter will be slipping somewhat.  

Depends on if his 2004r has a lock up converter, no need to worry about high stalls slipping in OD with a lock up converter.

I would go with a good 2800 my self, should run good with that motor.
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Re: transmissions and stall speed ; again

Post by bitterfitter on Mon Dec 29, 2014 10:30 pm

My trans is out of a 1986 monte ss. Do I have to run a lock up converter? It originally had one. Or can I run a non lock up converter?

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Re: transmissions and stall speed ; again

Post by bitterfitter on Tue Dec 30, 2014 8:10 am

So I read a few more articles and have one question left:  How does the stall speed and the lockup work together?  It seems to me that in theory, the lockup can only occur after the stall speed has been reached.  Since the lockup mechanically connects the trans and engine, there can be no slippage as would be needed below the stall speed.  So a 2500 stall converter would only lockup somewhere above 2500rpms?

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Re: transmissions and stall speed ; again

Post by thatfnthing on Tue Dec 30, 2014 9:51 am

The 200-4R can/will lock up in any gear from 2nd through 4th, and is controlled electrically.  Mine is controlled by my TPI computer, but you can hook up a simple switch and flip it yourself when you feel the need.  There are also a multitude of kits out there to do it for you, based on everything from vacuum to throttle position.  Nothing I have read indicates that any certain RPM must be reached first.  You just can't do it in 1st gear.  

You also do not have to run a lock-up converter -- the electrical trigger simply won't do anything if the converter isn't a lock-up model.  However, with a non-lock-up unit slippage will exist at all RPMs (about 200-300 RPM in OD), and the trans will run hotter because of it.  The flipside is that the lock-up converters are heavier and more expensive.

And FWIW I run a 2000 lock-up converter.  The car only ever sees the street, and I am pleased with it and very happy that I didn't go any higher.
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Re: transmissions and stall speed ; again

Post by bracketchev1221 on Tue Dec 30, 2014 10:54 am

Like was said. The lockup portion of the "lockup" converter is independent of the stall speed slipping part. All converters slip to a point. The lockup is a separate device that mechanically eliminates the slippage of the converter and now drives the car at a 1:1
Ratio.
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Re: transmissions and stall speed ; again

Post by bitterfitter on Tue Dec 30, 2014 11:37 am

THATFNTHING - Thanks for the info.  I have a 200-4r in the car now.  It is from a 1986 Monte ss and has the better factory valve body.  I did buy the vacuum switch kit to install to control the lock up.  I just never got to it because the car is still getting finished from the painting.  I still need to get over to meet you and your ride.
BRACKETCHEV1221 - It is not that I do not believe you about the lockup and stall; I just do not seem to get this.  I am missing something here:

So the stall is the point where, no matter how fast, the impeller from the engine spins faster, the turbine connected to the transmission will start to spin.  Unless locked by a brake or other means.

Let's say a torque converter has a stall speed of 2,500 RPM. If the vehicle isn't moving by the time the engine (and therefore the impeller) reaches 2,500 RPM, one of two things will happen: either the vehicle will start to move, or the engine RPM will stop increasing. (If the vehicle won't move by the time the converter reaches the stall speed, either it's overloaded or the driver is holding it with the brakes.)

Lockup is where the turbine is pushed up against the front cover, which is connected to the impeller.  The transmission and the engine are now mechanically connected resulting in no slippage.

I THINK I JUST GOT IT!!!!

The stall speed only comes into play when accelerating, and more so from a stop.  This allows the engine to get into its rpm range before attempting to move a large chunk of metal that is my car.  The lockup will only kick in when the car is near cruising speeds and not needing the slippage to get the car moving.  Now the transmission can be locked up at any rpm to further reduce any slippage in the transmission.  As the car slows, the lockup is released.  Then starts all over again as the car starts to move.

 I hope I got this right as I feel like such an A&&.  I know all these principles, I just had to put them together.

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Re: transmissions and stall speed ; again

Post by marks454ss on Wed Dec 31, 2014 7:52 am

Don't feel like your alone on this. It's without a doubt the most misunderstood part of a driveline. These guys did a great job explaining it.
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Re: transmissions and stall speed ; again

Post by bitterfitter on Wed Dec 31, 2014 8:02 am

I think I got it now. Now I am not sure if I should have my trans built by a local shop or by a finished one. And if I get a new one; from who? So many builders online think theirs are the best.

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Re: transmissions and stall speed ; again

Post by thatfnthing on Wed Dec 31, 2014 9:44 am

I got my 200-4R and lockup converter from PATC and it's been nothing short of excellent. Firm shifts, high-pressure valve body to eliminate TV cable adjustment worries, and good to 450hp. Just shy of 2k all in. The only place they goofed up was in the speedometer sending unit, so I had Buchholtz Transmission on Sheridan take care of it. They also seem to know what they're doing, but I don't know if that's too much of a hike for you to haul it.

FWIW, PATC has great knowledge about transmissions, but not so much about web design -- their site is one of the worst I have ever seen. Smile
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