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Turbo 400

Discussion in 'Chevy Trucks' started by kingriver, Mar 27, 2006.

  1. kingriver

    kingriver Senior Member
    from alaska
    Messages: 216

    On our sand truck 1990 Chevy Silverado 1T, duelly, airbags rear, timbrens front, :cool: :cool: we have a TURBO 400 Transmission. I have heard that these things are pretty much bullet proof, is this true ? :cool: :cool:
  2. wheeler4x4

    wheeler4x4 Member
    Messages: 38

    T-400 by far the best trans GM ever made. About the only way to destroy one, is to severely beat on it(neutral drops @ high rpm, reverse from drve @ 40 mph etc...). Don't forget a cooler, other than a factory one. I use old A/C cooler coils. They work great! Extra oil capacity & cooling.
  3. Makndust

    Makndust Senior Member
    Messages: 324

    I have a TH-400 in an 87 chevy with a 9'2" Boss poly V. Long story short. I had some money that my snow removal company had to spend about 3 years ago. I took it to the GM dealer. They instaled a shift kit, extra clutch pacs, and an Allison Tourque converter. All to the tune of about 2800.00. We installed a temp guage. I don't like were the sending unit is (in the bottom of the pan) but o - well. Since the temp guage was put in, it has scared the hell out of me. It will run up to 210 in a heartbeat. By the way we put a brand new HD tranny cooler in also. Since then I have had the old 454 replaced with a new GM crate 454 with a 427 truck cam for low end torque. 1 year ago last Decmeber, reverse went out. This year (431 miles later) reverse went out again. I am very confident about the forward mechanism being "bulletproof", but I have had the heaviest reverse springs (parts etc.) put in this tranny that money can buy and am a little worried about it. I notice that I can plow forward all day and the tranny will never go over about 185, but the minute that I start pushing forward and backing up verymuch at all the temperature guage starts to climb. It isn't as bad when its cold (of course) but it still climbs. I am going to go get a second opinion about this temperature thing. I would have a regular GM tranny put in the next time that Reverse goes out, but I already have so much money into this one I hate to give up on it.
  4. ljrce

    ljrce Senior Member
    Messages: 181

    turbo 400 are bulletproof had one in my s10 with a 350 in it and they are unstopable
  5. PDQ Pete

    PDQ Pete Senior Member
    Messages: 139

    I do not think any trans is bulletproof.
  6. MrBigStuff

    MrBigStuff Senior Member
    from Boston
    Messages: 140


    Well, they're pretty tough "out of the box" compared to many of today's trannies.

    With some fairly minor upgrades, they can be made virtually bulletproof. I know a guy who runs one in a 1200 hp drag car and has gone an entire season without a major teardown. I've got a heavily modified twin-turbo 400 in my 71 Chevelle that sits behind a 600 hp BB.

    It's essentially two, TH400 transmissions connected in series. That gives me 5 forward gears and 3 reverse. With 2.73 rear gears, total gearing in first is something like 22:1 if I recall correctly (been awhile and I'm not getting any younger). With slicks, that's alot of torque being transferred through the driveline on launch. I went through a few hubs in the beginning because I couldn't resist laying rubber and chirping the tires at 40mph. I upgraded to better hubs and clutches and no worries since. I'm alot harder on that car than I ever was in any of my trucks.

    Count me among the fans of the 'ol TH400.
  7. kingriver

    kingriver Senior Member
    from alaska
    Messages: 216

    Hey thanks. Im going to ask my transmission guy about installing a cooler on one we have in a 90 Suburban 3/4T HD--maybe will make it last alittle longer. Where do you think a temp sending unit should be installed on this tranny.

    :cool: :cool:
  8. crete5245

    crete5245 Member
    Messages: 61

    The reason it gets hotter in reverse is that the fluid pressure in reverse is at its max,which heats the fluid up.
  9. crete5245

    crete5245 Member
    Messages: 61

    The fluid will heat up in reverse, because the line pressure go to the max and that is what heats the fluid up in reverse.