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What MPH does yor 6.2-TH400 shift??

Discussion in '1982-Present GM Diesel' started by Rob 85K5, Jan 3, 2007.

  1. Rob 85K5

    Rob 85K5 1/2 ton status GMOTM Winner

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    I am wondering about the 2 to 3 shift. If I am on it steady, it doesn't want to shift to 50-55. This is with 4.10 gears. Where does you 2 to 3 shift happen?
     
  2. 86dieselburb

    86dieselburb 1/2 ton status

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    Shifts about the same place mine does, but mine is a TH400 set up for a gas engine.
     
  3. protechk5

    protechk5 1/2 ton status

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    ha my 6.2/400 with 4.56 and 33s shift from 1st to 2nd at around 10, then 2nd to 3rd around 20-25.
     
  4. diesel4me

    diesel4me 1 ton status Premium Member

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    early...

    My Th400 in the 82 K20 shifts into second almost immediately,at about 10 mph I'd guess--then into third at 15-20 mph,under light throttle..

    My VRV valve that controls the vacuum to the modulator was not working right,so I just put the vacuum hose direct to the modulator from the vacuum pump,and screwed in the adjustment screw in the modulator hose nipple all the way until it just hit bottom-(as instructed by a local tranny rebuilder/guru)..seems to work ok,but I hope I'm not harming the clutches in the tranny..should have died by now if that was the case,I've beaten the truck badly plowing a lot of 2' storms in the winter of '03-04,so far its still going strong!..

    Before when I first got the truck and tried running it with that vacuum regulator valve ,no matter where I adjusted it,the tranny refused to upshift until the motor was redlining,would not go into second until 35 mph,and third until at least 50!..and it would SLAM into the next gear,like it had a super shift kit..I'd prefer a firm shift (now its a bit "soft",you can hardly feel it change gears),but I hated the delayed shifts,that was hard on the motor and fuel economy...

    I remember B+M selling a modulator vacuum control you could mount in the cab,and control the shift points and firmness by turning a knob,it increased or decreased the amount of vacuum to the modulator..wish I could find one,that is what the stock VRV valve does in a way..would be nice to firm up the shifts a bit,and make it shift at the speed you want it to..:crazy:
     

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