Beefier TH-350?

Discussion in '1969-1972 K5 Blazer | Truck | Suburban' started by Ryan_B, Apr 27, 2001.

  1. Ryan_B

    Ryan_B Registered Member

    Apr 22, 2001
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    I was just curious, has anyone had their TH-350 tranny rebuilt and beefed up with more clutches, stronger bands, hardened input/ output shafts etc..?
    Anyone tried the JET 350 transmission?
    The reason I ask is I want to build up a 500HP 470Ft LBS+
    bored & stroked 400 smallblock, but the only thing I have to worry about is the tranny not being strong enough. I don't want to spend lots of money on my engine only to have to rebuild the tranny several times because it can't handle so much torque and power!?
    I don't want to go to a TH 400 either because crossmembers will have to be moved or drivelines will have to be shortened/ lengthened , I think.

    Anyone have any suggestions?
  2. Steve_Chin

    Steve_Chin 1/2 ton status

    Mar 6, 2001
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    Foster City, CA, USA
    Horsepower isn't waht kills drivetrain parts. Troque kills 'em. A TH350 can be built up fairly strong, but if you've got big tires, high gears (low numerical ratio), and a really torquey engine, you're asking for the tranny to get killed. A loose torque converter will increase the amount of beating on the tranny. I put a lot of hop-up parts into the M38 in my Trans Am and killed it with torque (560 lbs*ft torque (measured), 2.56:1 gears, 27" tires, very tight converter), and I don't bash on that car all that hard most of the time.

    That said, I think if you keep the gears at a reasonable level with your tire setup (say 4.10:1 or 4.33:1 gears with 35s or 36s) and you don't run a really radical converter, you will probably be able to build a TH350 to live a good long time. The guys at Continental Converters can probably advise you on converter selection and transmission hop-up options. Continental makes a lot of custom converters for guys who have some pretty bad cars, so I think they can probalby help you out. I'll ahve to find contact information...

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