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Old 11-04-2012, 01:49 PM
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Lock up or non lock up transmission?

I am skeptical of the lock up transmissions. Ive seen lock up transmissions go out pretty quick like 700r4s. I believe this is because the lock up. I read once that torque multiplication was cause by the spinning of the torque convertor, pushing the other half with fluid forcing it to spin like a clutch, and twisting the imput shaft producing torque to move a car with a non lock up. I dont know much about trannys, and i dont know much about torque multiplication but i think i have an idea of it. Can anyone tell me the difference between clutch actions? The pros and cons of both types?

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Old 11-04-2012, 06:56 PM
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I don't know a whole lot, but here is what I do know. It's the torque converter that locks, not the trannie. It only locks in the high gear - which is 4th on a 700-R4, a .70 overdrive. The purpose of locking the torque converter then is to reduce the heat generated by the torque converter turning below it's stall speed. The operation of the transmission and torque converter in the first 3 gears is identical for lock-up and non-locking torque converters. A large percentage of problems with 700-R4 transmissions is due to the mis-adjustment of the TV cable (sometimes wrongly referred to as the kickdown cable). Hope this helps.
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Old 11-07-2012, 05:12 AM
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Many 4-speed OD Trans can Lockup the TC in 2nd, 3rd & 4th gears, the newer Trans with 6-8 gears also do this. It does cut down on heat but, more importantly helps with MPG.
Lockup Lowdown, PDf file >> Phoenix Transmission Products | 700R4 - TH-2004R - TH-350 - 4L80E - High Performance Transmission Products
TC explained >> Torque Converters Explained - TCIŽ Auto
More >> http://www.sonnax.com/system/pdfs/12...pdf?1289926057
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Old 11-07-2012, 11:20 AM
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This is also from that same Phoenix Transmission web page: "Why do I need a “Lock-Up” torque converter?

The greatest source of heat in an automatic transmission is the torque converter. This is because there is a constant source of friction within a converter and as we know, friction creates heat. Even the most efficient low stall torque converter will never stop slipping so you will always have that source of heat generation in a non locking converter. When you add stall speed to a converter you are raising the RPM that the converter must attain before it transmits full engine power back to the transmission. While this is great for performance, it creates an even greater heat and efficiency problem. To make matters worse, in an overdrive transmission, even with steep gears, the engine rpm’s at cruise may be substantially less than the stall speed of the converter, a recipe for disaster. By applying a Converter Clutch you eliminate this slippage and heat source, allowing you to have the benefits of a performance oriented stall speed, plus economy, efficiency and lower operating temperature."

The 700-R4 locks up in 4th gear, where there is the greatest chance you will be cruising at or below the stall speed of your converter, causing the most slippage and most heat. The lockup converter eliminates the slippage.
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Old 11-07-2012, 10:53 PM
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X2 ^^ SedanBob

Lockup TCs with high stall ratings are very inefficient when ran unlocked = much more slippage @cruise & up top than a Non-Lockup TC with high stall.
Lockups running unlocked will see 20-25% slippage up top compared to as low as 3-5% slippage with a quality Non-Lock TC up top or thru the Traps.
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Old 11-08-2012, 04:56 PM
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The setup for a strong quarter mile is different than the setup for cruising on the street/highway - I suppose we should have asked the OP what he is planning. So, Chevy302Builder18, what are your plans for this car?
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Old 11-08-2012, 07:28 PM
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Quote:
Originally Posted by sedanbob View Post
The setup for a strong quarter mile is different than the setup for cruising on the street/highway - I suppose we should have asked the OP what he is planning. So, Chevy302Builder18, what are your plans for this car?
its a truck, sorry about that. i was just curious cause my th350 i believe is locking up at idle at stop lights and stalling the engine. this makes it die and i cant help but notice a vacuum operates the stall on these. i did have a three way vacuum manifold tree break on me, cause the engine wasnt running right. so i fixed the vacuum leak with a good plug and screwed the thing back in. the vacuum lead going to the trans is connected to a plastic t connector, and then hooked to the vacuum ball i recently installed. i have a another t running to the vacuum advance.
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Old 11-08-2012, 07:33 PM
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im also ditching the idea of automatic transmission and putting in a 3 speed saginaw. ive heard horrible things but its the 4 speed saginaws that went out the most. given the saginaw a bad name. i have two in my area being sold for $150
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Old 11-08-2012, 11:41 PM
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Quote:
Originally Posted by chevy302builder18 View Post
im also ditching the idea of automatic transmission and putting in a 3 speed saginaw. ive heard horrible things but its the 4 speed saginaws that went out the most. given the saginaw a bad name. i have two in my area being sold for $150
Back to basics. Cool.
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Old 11-25-2012, 06:17 PM
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Back to basics. Cool.
i figured out the problem, it was the carb? i just rebuilt a quad and i guess i didnt do most of it right because it doesnt like running with the dang choke. i had to literatly get rid of the choke plates. its 30 degrees out, and itll still start?
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