1. Welcome to PlowSite. Notice a fresh look and new features? It’s now easier to share photos and videos, find popular topics fast, and enjoy expanded user profiles. If you have any questions, click HELP at the top or bottom of any page, or send an email to help@plowsite.com. We welcome your feedback.

    Dismiss Notice

Turbo 400

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

  1. kingriver

    kingriver Senior Member
    from alaska
    Messages: 217

    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: 182

    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: 217

    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: 59

    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: 59

    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.