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Tansmission 700 -88

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by xswede, Aug 10, 2003.

  1. xswede

    xswede Registered Member

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    I have the 700 tranny on my -88 Blazer. In the shifter display I have both the D and the (D). Somebody here in Sweden told me that I should only put it in (D) when driving on the highway because it then utilizes the overdrive... What are your thoughts on this? When should I use D and when should I use (D)? /forums/images/graemlins/ears.gif
    Thanks,
    Dan
     
  2. Confedneck

    Confedneck 3/4 ton status

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    driving in (D) or overdrive is the norm for daily driving, use D for towing heavy loads so it doesnt kick in and out of overdrive all the time..
     
  3. xswede

    xswede Registered Member

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    That's what I thought! Good, now I know I was right. Thanks!
    Dan
     
  4. Bubba Ray Boudreaux

    Bubba Ray Boudreaux 1 ton status

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    Use Drive when you are under 45 mph and Overdrive when going faster, unless you are towing.
     
  5. xswede

    xswede Registered Member

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    Ok guys! Now I'm uncertain again... Why should I use D only when going under 45MPH? The overdrive wont jump in untill it's necessary anyway will it?
     
  6. Bubba Ray Boudreaux

    Bubba Ray Boudreaux 1 ton status

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    You have to manually shift the tranny into Overdrive, it doesn't automatically do it.

    Furthermore, 45 is the general rule of thumb between Drive and Overdrive.

    Drive is a 1:1 gear ratio, while Overdrive is something like .71:1.

    What happens if you are driving in let's say city traffic with a lot of stop and go, you will be undergeared, forcing the transmission to work harder in Overdrive and that will lead to early failure cause it builds heat.
     
  7. MTBLAZER89

    MTBLAZER89 3/4 ton status Premium Member GMOTM Winner

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    Yeah it will still shift when it doesnt "need" to. If you maintain a certain speed it will shift into OD. It is just hard on the tranny to constantly be shifting. I would just pay attention to your engine rpm's if it sounds like it's revving to hi throw it in OD /forums/images/graemlins/thumb.gif
     
  8. MTBLAZER89

    MTBLAZER89 3/4 ton status Premium Member GMOTM Winner

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    Ok Dan I didnt know this was you /forums/images/graemlins/thumb.gif You are on 35's right? and have not changed the gears? If so I would reccomend not using OD at all unless you are going pretty fast. I know before I re geared I couldnt use OD cause the truck would lose speed when it shifted into OD. It will prolong the life of your tranny too.
     
  9. SUBFAN

    SUBFAN 1/2 ton status

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    Since you are running 33" tires, you didn't state what gear ratio you are running. If you are running a ratio that is to high, then I wouldn't use OD unless going really fast down the flat highway.

    Presently I have a 3.42 ratio turning 35's, and I don't even put it in OD, ever.
     
  10. xswede

    xswede Registered Member

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    Ok guys, this might sound really dumb, but how do you know what ratio you're running? I think everything is stock on this baby except the lift and wheels...
    Dan /forums/images/graemlins/confused.gif
     
  11. MTBLAZER89

    MTBLAZER89 3/4 ton status Premium Member GMOTM Winner

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    Need to pull the cover then rotate the ring gear till you find some small numbers stamped in it. Get those numbers and post them here /forums/images/graemlins/thumb.gif Prolly somewhere between 3.08-3.73 I am pretty sure most Blazers cam with that gearing range.
     
  12. dyeager535

    dyeager535 1 ton status Premium Member

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    [ QUOTE ]
    Ok guys, this might sound really dumb, but how do you know what ratio you're running? I think everything is stock on this baby except the lift and wheels...

    [/ QUOTE ]

    If it's *truly* stock, look at the codes in the glovebox. All codes starting with "G" are axle related codes. G80 for instance is some form of traction device on just about all GM vehicles. (gov-lock for most trucks, limited slip/posi for cars) Any other code should be the axle ratio.
     
  13. zach78k5

    zach78k5 1/2 ton status

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    If you dont want to pull the cover off. just jack up the rear end and spin both tires one time. count how many times your driveline spins. if it is almost an even 3 than your ratio is 3.08:1 if it spins almost four 3.73:1. I find this to be the easiest. You need to spin both tires or just spin one tire twice. (i think that is right????)
     

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