Torque Converters and trannys - The 1947 - Present Chevrolet & GMC Truck Message Board Network

bbchevy · 07-27-2005, 05:04 PM

I have a question about torque converter stall speeds, and one about a TH350.

first off i'm a little confused about stall speeds. in the simplest way possible, can someone please describe to me what a stall speed is and what the benefit is to a higher and a lower stall speed. why do hot rodders want a higher stall speed. what would happen if i installed a 1200 or 1500 in a th350 as apposed to a 2000 or 2500?

and about the th350. i have one that looks like it was kept up well, its very clean, has an aluminum pan, and is mated to an np205... or was it a 203.(its the part time not the full time) i was wondering if there was a way to tell if it was any good before i install it. probably isnt but i figured i'd ask.

thank you guys so much in advance. im doin an engine swap this weekend so i would really appreciate the responces before.

-Scott

FLAGG · 07-27-2005, 05:35 PM

Stall speed is just the speed at which the torque converter "grabs" (for lack of a better term) or starts transmitting torque from the engine to the transmission. Racers and such like a higher stall because it puts the engine into the power band before it starts loading through the transmission. If you've driven a standard transmission, it's like reving the engine to 3000RPM and then dumping the clutch to take off like a bat out of hell.

There are some pros and cons of high and low stalls, and I'm hardly the person to speak from experience. I do have a story from a friend. Seems his buddy bought some form of old muscle car (forget what it was) and was quite excited when he found out it had a high stall torque converter on it because he could imagine all the fun he was going to have with it. So he gets the car, brings it home, and proceeds to try and put it into the garage. Problem was, he has a bit of a steep driveway. So he's on the driveway trying to roll up carefully, but with the high stall converter he's having some issues. When he finally gets the converter to catch, the car lays two black strips of rubber up the driveway. Apparently he just got the brakes on the car in time to keep coming out the back end of the garage.

He had the torque converter changed to a lower stall model later that week.

jermasaurus · 07-27-2005, 10:00 PM

As far as stall speeds, read this and you will know more than most do http://www.hardtail.com/techtips/sel...converter.html

75sierraclassic · 07-28-2005, 08:40 AM

The only way would be to drop the oil pan and look for debris, metal, water or any thing else foreign that shouldn't be there. You can take out the filter and cut it up to see if there is a lot of metal or clutch material in it. This may be a little too invasive for you, but it doesn't take long to do.
Good Luck

07-27-2005, 05:04 PM	#1
bbchevy 87 Wanna Be K30 Join Date: May 2003 Location: long island, new york Posts: 218	Torque Converters and trannys I have a question about torque converter stall speeds, and one about a TH350. first off i'm a little confused about stall speeds. in the simplest way possible, can someone please describe to me what a stall speed is and what the benefit is to a higher and a lower stall speed. why do hot rodders want a higher stall speed. what would happen if i installed a 1200 or 1500 in a th350 as apposed to a 2000 or 2500? and about the th350. i have one that looks like it was kept up well, its very clean, has an aluminum pan, and is mated to an np205... or was it a 203.(its the part time not the full time) i was wondering if there was a way to tell if it was any good before i install it. probably isnt but i figured i'd ask. thank you guys so much in advance. im doin an engine swap this weekend so i would really appreciate the responces before. -Scott

07-27-2005, 05:35 PM	#2
FLAGG Registered User Join Date: Feb 2004 Location: St. Albert, Alberta, Canada Posts: 89	Stall speed is just the speed at which the torque converter "grabs" (for lack of a better term) or starts transmitting torque from the engine to the transmission. Racers and such like a higher stall because it puts the engine into the power band before it starts loading through the transmission. If you've driven a standard transmission, it's like reving the engine to 3000RPM and then dumping the clutch to take off like a bat out of hell. There are some pros and cons of high and low stalls, and I'm hardly the person to speak from experience. I do have a story from a friend. Seems his buddy bought some form of old muscle car (forget what it was) and was quite excited when he found out it had a high stall torque converter on it because he could imagine all the fun he was going to have with it. So he gets the car, brings it home, and proceeds to try and put it into the garage. Problem was, he has a bit of a steep driveway. So he's on the driveway trying to roll up carefully, but with the high stall converter he's having some issues. When he finally gets the converter to catch, the car lays two black strips of rubber up the driveway. Apparently he just got the brakes on the car in time to keep coming out the back end of the garage. He had the torque converter changed to a lower stall model later that week.

07-27-2005, 10:00 PM	#3
jermasaurus Registered User Join Date: Dec 2004 Location: New Lenox, IL Posts: 442	As far as stall speeds, read this and you will know more than most do http://www.hardtail.com/techtips/sel...converter.html

07-28-2005, 08:40 AM	#4
75sierraclassic Registered User Join Date: Jun 2002 Location: Kansas City, MO Posts: 186	The only way would be to drop the oil pan and look for debris, metal, water or any thing else foreign that shouldn't be there. You can take out the filter and cut it up to see if there is a lot of metal or clutch material in it. This may be a little too invasive for you, but it doesn't take long to do. Good Luck



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