Possibly buying 90 Suburban late 1-2 shift

Discussion in 'GM Powertrain' started by Falconer, Sep 8, 2009.

  1. Falconer

    Falconer New Member

    Hi folks. New to the forums. Like what I see so far...
    I'm a retired auto tech; been out of the business for about 10 years. Still know a few things, though...
    Looking at buying a 90 suburban 5.7 4wd. 153K miles. Stopped and looked at it briefly today. Body/interior very good considering the age.
    Started it up, small-med amount of blue smoke, probably valve seals. No big dieal, I don't think, but I'll be checking compression anyway.. Seemed to run OK; maybe a slight miss. Didn't do any hard-core diags yet.
    Dealer (this is from a small used car lot; I'm in a small town in the desert) is a decent enough guy; didn't try to BS me much once he realized I know my stuff about cars. He says the 1-2 shift is late. Always shifts, it's just late; not sure how late, though. 4L60 trans.
    I haven't driven it at all; didn't have time today. Vehicle came from a wholesale auction, so no previous history.
    Curious what might cause a late 1-2 shift. He says one of his guys has one just like it, does the same thing. Might it be normal? I've been driving a 93 Toyota MT PU for the past 12 years, so getting back into a GM AT will be different.
    I have no idea if it has a shift kit installed, or how to tell.
    Any ideas as to what I should be looking for? Fluid looks/smells OK.
    I'm probably going to go back later this week to look at it...

  2. Jimmiee

    Jimmiee Epic Member 5+ Years 1000 Posts

    The shifts are controlled by the TV cable. Get the truck off the lot and try to adjust the cable. Pop the tab and note where the position of the cable is. Move the cable housing toward the front of the truck which makes the cable longer. If you get it too long the trans will slip so the trick is to get it as long as possible while still being able to make a 2-1 downshift as soon as it upshifts to 2nd at light throttle. Take a good look at the pan and beware if it looks like it was just serviced. Also, if you can't make the shift earlier then it probably has a stuck valve in the valve body. Good Luck!

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