Torque converter questions and selection help.

Discussion in 'Gasoline Engines' started by Lonesome7.3, Oct 17, 2011.

  1. Lonesome7.3

    Lonesome7.3 CSA

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    I think I have narrowed down the transmission I want for my 72 D200 with a 318. Because it is a ¾ ton truck and we do plan to use it as such I want a good transmission in it that will not fail on me like the tired stock one. Now my attention is on the torque converter. I know very little about automatics and even less about Mopar anything. So first question:
    What does lock up mean when dealing with torque converters?
    What is stall speed and how do I know what mine is?
    This truck has a 318 with 4:10 gears stuffed in the rear D60 what role does that information play in selecting the torque converter?
    This is the link to the trans I am 90% certain I am getting.
    http://www.summitracing.com/parts/TCI-111101/Application/?prefilter=1
    This is the torque converter TCI said I need.
    http://www.summitracing.com/parts/TCI-142240/
    What would happen if I used my stock original Torque converter? Other than voiding the warranty from TCI could I hurt anything else? Also, how do I know if anything is wrong with it to begin with?
    If the new Torque Convert does not have a drain plug, can I simply drill and tap the house to install one?
    Any input on what I have put out there so far?
     
  2. FORDMAN41291

    FORDMAN41291 PUNCH IT!!!!!!!!!

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    Lock-up is a feature found primarily in Chrysler automatic transmissions ( i say primarily chrysler because I havent seen it in any other auto maker) it is where an electronic solenoid in the case of a 46RH RE transmission opens a valve and uses hydraulic to push 2 discs inside the torque converter together to create a lock. kinda of like how a clutch is. it rarely moves except under extreme stress and heat (for a clutch) in the case of a lockup TC. it reduces engine speed again after OD has engaged. and the transmission matches the speed of the engine.


    Efficiency and torque multiplication[edit source | editbeta]
    A torque converter cannot achieve 100 percent coupling efficiency. The classic three element torque converter has an efficiency curve that resembles ∩: zero efficiency at stall, generally increasing efficiency during the acceleration phase and low efficiency in the coupling phase. The loss of efficiency as the converter enters the coupling phase is a result of the turbulence and fluid flow interference generated by the stator, and as previously mentioned, is commonly overcome by mounting the stator on a one-way clutch.
    Even with the benefit of the one-way stator clutch, a converter cannot achieve the same level of efficiency in the coupling phase as an equivalently sized fluid coupling. Some loss is due to the presence of the stator (even though rotating as part of the assembly), as it always generates some power-absorbing turbulence. Most of the loss, however, is caused by the curved and angled turbine blades, which do not absorb kinetic energy from the fluid mass as well as radially straight blades. Since the turbine blade geometry is a crucial factor in the converter's ability to multiply torque, trade-offs between torque multiplication and coupling efficiency are inevitable. In automotive applications, where steady improvements in fuel economy have been mandated by market forces and government edict, the nearly universal use of a lock-up clutch has helped to eliminate the converter from the efficiency equation during cruising operation.
    The maximum amount of torque multiplication produced by a converter is highly dependent on the size and geometry of the turbine and stator blades, and is generated only when the converter is at or near the stall phase of operation. Typical stall torque multiplication ratios range from 1.8:1 to 2.5:1 for most automotive applications (although multi-element designs as used in the Buick Dynaflow and Chevrolet Turboglide could produce more). Specialized converters designed for industrial, rail, or heavy marine power transmission systems are capable of as much as 5.0:1 multiplication. Generally speaking, there is a trade-off between maximum torque multiplication and efficiency—high stall ratio converters tend to be relatively inefficient below the coupling speed, whereas low stall ratio converters tend to provide less possible torque multiplication.
    While torque multiplication increases the torque delivered to the turbine output shaft, it also increases the slippage within the converter, raising the temperature of the fluid and reducing overall efficiency. For this reason, the characteristics of the torque converter must be carefully matched to the torque curve of the power source and the intended application. Changing the blade geometry of the stator and/or turbine will change the torque-stall characteristics, as well as the overall efficiency of the unit. For example, drag racing automatic transmissions often use converters modified to produce high stall speeds to improve off-the-line torque, and to get into the power band of the engine more quickly. Highway vehicles generally use lower stall torque converters to limit heat production, and provide a more firm feeling to the vehicle's characteristics.
    A design feature once found in some General Motors automatic transmissions was the variable-pitch stator, in which the blades' angle of attack could be varied in response to changes in engine speed and load. The effect of this was to vary the amount of torque multiplication produced by the converter. At the normal angle of attack, the stator caused the converter to produce a moderate amount of multiplication but with a higher level of efficiency. If the driver abruptly opened the throttle, a valve would switch the stator pitch to a different angle of attack, increasing torque multiplication at the expense of efficiency.
    Some torque converters use multiple stators and/or multiple turbines to provide a wider range of torque multiplication. Such multiple-element converters are more common in industrial environments than in automotive transmissions, but automotive applications such as Buick's Triple Turbine Dynaflow and Chevrolet's Turboglide also existed. The Buick Dyna flow utilized the torque-multiplying characteristics of its planetary gear set in conjunction with the torque converter for low gear and bypassed the first turbine, using only the second turbine as vehicle speed increased. The unavoidable trade-off with this arrangement was low efficiency and eventually these transmissions were discontinued in favor of the more efficient three speed units with a conventional three element torque converter.
    Lock-up torque converters[edit source | editbeta]
    As described above, impelling losses within the torque converter reduce efficiency and generate waste heat. In modern automotive applications, this problem is commonly avoided by use of a lock-up clutch that physically links the impeller and turbine, effectively changing the converter into a purely mechanical coupling. The result is no slippage, and virtually no power loss.
    The first automotive application of the lock-up principle was Packard's Ultramatic transmission, introduced in 1949, which locked up the converter at cruising speeds, unlocking when the throttle was floored for quick acceleration or as the vehicle slowed down. This feature was also present in some Borg-Warner transmissions produced during the 1950s. It fell out of favor in subsequent years due to its extra complexity and cost. In the late 1970s lock-up clutches started to reappear in response to demands for improved fuel economy, and are now nearly universal in automotive applications.

    Chrysler does make good transmissions just people don't know how to take care of them. like everything else in this world it has a breaking point, for more information on lock up torque converter look it up on wikipedia
     
  3. aofarrell2

    aofarrell2 Turbo Desirous

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    Any modern torque converter has a lockup clutch in it, Dodge, Ford, Chevy. Without it it would kill fuel economy. I only say that because your post was a little confusing from that first statement.

    The torque converter lockup clutch, on most 4spd autos in trucks, is always locked in 3rd and 4th (OD) gears, and sometimes locked in second.

    You will want a locking torque converter, and if you replace the trans, ALWAYS replace the T/C. There's a reason that warranty hinges on that...

    Now how to properly setup to avoid trans failure (this applies to ALL automatics, regardless of brand or how well they are built). It's as easy as 1-2-3:

    - NUMBER 1: The most important of all. Keeping that fluid cool. When towing, almost no manufacturers tranny cooler built into the radiator is sufficient. Sometimes, even a factory aux cooler isn't good enough. Make sure you have plenty of cooling capacity! Part of this is to make sure you have a temp gauge installed on the trans. That way you can monitor it's temperature and make sure it doesn't get too hot while you are driving.

    - NUMBER 2: This is basically just as important as above. KEEP THE FLUID CLEAN and use high-quality fluid. The internal filters are great, but ALWAYS add a external filter to the cooling lines. It's cheap insurance, and no one should try to avoid it. http://www.tdperformance.com/Single-Filter-Relocation-Brackets This also means to change the fluid frequently, as a general rule, every three oil changes. Even if the fluid smells fine, and looks fine, it's got tiny particles that the filter can't filter, and you can't see. Also, the chemicals in ATF "wear out", and as heat goes up life of those chemicals go down. This also means to use the right type of fluid, for 46RE/RH this means ATF4. The brand also has to do with quality of fluid, AMSOIL and NAPA Performance are the best two I have found aftermarket, and OEM is good to, but AMSOIL is better (I am NOT related to amsoil in any way)

    - NUMBER 3: NEVER EVER TOW IN O/D FOR ANY REASON AT ALL. If it has a O/D off button, or a non-overdrive position on the shift lever, there's a reason for it. Knock it out of overdrive if you want your transmission to last, if you've got plenty of money to rebuild it, then hell, leave it on O/D. But most of us don't have that sort of money.

    Hope this helps, if you have any questions just reply back.
     
  4. Lonesome7.3

    Lonesome7.3 CSA

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    Great reads, thanks.
     

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