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Which Torque converter are you using?

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Cmoe, Jan 26, 2001.

  1. Cmoe

    Cmoe 1/2 ton status

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    As in the subject title I think my Torque converter is going out.... The truck is slipping...... I've already did a trany service to it and the trany was rebuilt a year ago (except the torque Converter)....What brand and what Stall rate? Anyone use one with a Clutch Lock?

    C'moe

    <font color=black>the blazer is "Back in Black"
     
  2. Grim-Reaper

    Grim-Reaper 3/4 ton status Author

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    I would use the stock stall speed. higher stall speeds are good if you drag race but for a truck they tend to build heat and not so great for feathering on the power when wheeling. Lower gets you into a problem with drag on the engine at idle. GM did a pretty good job when the selected the stall speed...stay with it. As for what cause the coverter to fail has me wondering. The only thing the wears out in a converter is the splines and hub. the rest is fluid drive and unless you break a vane in the converter there is not much to fail. If your feeling slipping I would be more inclined to blame the tranny not the converter. Now that's not to say that if I rebuild a tranny it ALWAYS gets a rebuilt converter.
    Several things can cause slipping. It's not uncommon for the splines to strip off on the stator shaft on the pump (this is what the converter rides on). If that happend it would cause a loss of power getting to the point that the truck wouldn't move. The real BIG killer of tranny's is heat. when they over heat not only does it bake the fluid causeing the fluid to break down it also hardens the seals and causes them not to seal. This drops the internal pressure of the pistons on the clutches and lets the clutch packs slip and that causes more heat and it gets in a real visious cylcle that eats the tranny. You got to have a BIG cooler to make a tranny survive in a 4x4 or a tow rig. the factory set up is not enough to keep the temp down.
    as for a clutch converter...if your still running that 78 TH350 you can't run one that I'm aware of. in 80 GM made the TH350c that did run a lock up converter. while a lock up converter is good for the hwy if your running large tires on wrong axle ratio (33's on 3.08's) you probably want to stay with a non lock up and just live with that little bit of top end slip when you get on the gas on those hills. This way you get that torq multiplication of the converter and good chance that little clutch wouldn't handle the load with a gear ratio problem.

    Diging it in the dirt with my K5's
    Grim-Reaper
    <A target="_blank" HREF=http://grimsk5s.coloradok5.com/>http://grimsk5s.coloradok5.com/</A>
     
  3. Waxer

    Waxer 1/2 ton status Author

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    I had the th350 in my 74 rebuilt a good 2-3 years ago now. I did have upgraded clutches put inside it and the torque converter is the stock t400. I have had NO slippage and have ran this thing hard. It just keeps going and going. As Grim said, heat is the most important factor in prolonging the life. I have an auxillary cooler ofcourse and it seems to have done magic for the tranny.
    p.s. Moe, hows the trailer I gave you workin? Still using it?
    You still in the area?

    <P ID="edit"><FONT SIZE=-1>Edited by waxer on 01/27/01 01:47 PM (server time).</FONT></P>
     
  4. djohnsn

    djohnsn 1/2 ton status

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    I needed a converter when I had my th350 built, so I thought that I might as well upgrade. I am using a B&M converter (Road and Tow/Traveler I think). This converter is has a slightly higher stall than stock and is advertised as good for towing. The higher stall is noticable. I am not sure that I would buy this converter again. I would probably stick with a stock stall speed converter.
     
  5. Blue85

    Blue85 Troll Premium Member

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    I use the Torque converter that was stock for '80's Corvettes that used the 700 R-4. It has a 1996 rpm stall. I think that stock (for the K-5) is 1700 rpm. The higher stall speed is bad for rockcrawling, but since I will be adding a bigger cam that will move the powerband up just a little (I will only have a little more off-idle torque than I do now), it is not too bad. I think that 1700-1800 is perfect for this kind of vehicle. With a higher stall speed, you definately want the lock up for highway driving, because the amount of heat from the converter is proportional to the amount of slip. Not only is the heat bad for the tranny, it is extra energy that has to come from the gas tank. I have a switch next to my tranny temperature gauge, so I can turn the lock-up on or off as I want to, except for top gear. In it's stock form, the 700 does not lock up in 4WD, except for top gear. It is not adviseable to disable the lockup on a converter that was designed for it: you will loose the tranny early. If you ever think that you will not want lockup, use a setup that is designed to be non-lockup.

    <font color=blue>"Anytime you tie the flyers, you are going to have a tight game." [/i]Buffalo captain Michael Peca</font color=blue>
     
  6. dyeager535

    dyeager535 1 ton status Premium Member

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    I'm not going to state that the converter is definitely not your problem, but if the converter fails, you aren't going to move (stripped splines, stipped pump tangs, etc) Maybe you can bust off a vane or three or four, but I would have to say that if anything breaks on teh converter, the whole thing is going to go. There is no room for the pieces to "hide" once they come out. Slipping is usually clutch wear or seals, but there are many more variables than just those. IMO

    Dorian
    My K5 and Chev/Olds tech/links page: <A target="_blank" HREF=http://yeagerd.home.mindspring.com/index2.html>http://yeagerd.home.mindspring.com/index2.html</A>
     
  7. Gopherkiller

    Gopherkiller 1/2 ton status

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    When I rebuilt the 700 in my diesel outfit, the two things that I looked for were heat operating range, and brazed fins. B&M didn't make a heavy enough convertor for my application. GOPHERKILLER
     

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