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Hard shift from 1st to 2nd

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by 8_YOUR_H2, Jun 5, 2000.

  1. 8_YOUR_H2

    8_YOUR_H2 1/2 ton status

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    My 700R4 shifts quick from 1st to 2nd. It seems too quick, it bangs into 2nd gear. If I gun it from a dead stop and keep it full throttle it wont do it, it wont do it in 4X4 eaither. Some local yahoo told me its good, it means the clutch plates are tight? I have serviced the tranny every 40k and I have replaced the rear U-Joints. I dont know what to think....what do you think?
     
  2. Blazer1970

    Blazer1970 1/2 ton status

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    How many miles on the tranny? That hard 1-2 shift is a sign that it is wearing out.

    Tim

    1970 Blazer CST 4X4 350 SM465 NP205
    1987 Suburban 4X4 350
    1988 Chevy Pickup 4X4 350
     
  3. 8_YOUR_H2

    8_YOUR_H2 1/2 ton status

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    120k miles on the 700R4
     
  4. 8_YOUR_H2

    8_YOUR_H2 1/2 ton status

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    I was thinking, It has always shifted hard. I bought it with 80k miles 4 years ago. I have never had any other problems with the tranny...
     
  5. BurbinOR

    BurbinOR 3/4 ton status

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    A good, firm snap shift is a sign of a GOOD shift kit. If it is shifting too SOON, that is a different issue. My father in law has a T350 in his 3/4 Ton pickup that will flat out snap your head into the window if you aren't paying attention at low speeds. I personally love it!

    <font color=blue>'79 K5 - 406 w/IROC TPI -<font color=orange> K5#5 - <font color=black>http:// www.blazzinor.coloradok5.com
     
  6. Grim-Reaper

    Grim-Reaper 3/4 ton status Author

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    A hard shift is better than a very soft shift because of less wear on the clutch packs. Now I haven't played with a 700 but on a TH350 I would say that a shift kit has been put in the case. If you didn't own this truck from new I would also say it has been rebuilt as a guess. Thats an early 700 and they were very prone to failure back then. The fact that it shifts hard leads me to belive when it was rebuilt that whomever did the work, did all they could to beef the tranny to try to prevent it from failing. Usualy this means a shift kit and beefing up the acumulators to bring up the line pressure.
    Now you may be able to swap the Modulator and get the shift softer. Some modulators are adjustable and you may be able to do that. Also adjust the down shift cable. I belive on the 700 they use the down shift as a sort of Throttle posistion sensor. If the carb is ever pulled you ar supose to readjust the cable. On a TH350 you can also put a lighter spring in the 1-2 acumulator.
    All of the above is ways of trying to get the shift soften without having to open the tranny. Now I havn't drove your truck so I don't know how hard it is shifting but there is hard and too hard. Too hard will do things like blast the foward sprag, strip the splines off the stator shaft and various other nasty expensive things.
    The problem here is the age of the tranny. If indeed this is the original miles on it then there is a chance if you go into the tranny and mess with the valve body (changing to a stock or different shift kit) it may be the "straw that breaks the cammels back" so to say. Trannys like being left alone and if they are run long periods without servicing sometimes just the difference of clean fluid will kill them.

    Diging it in the dirt with my K5's
    Grim-Reaper
     
  7. 8_YOUR_H2

    8_YOUR_H2 1/2 ton status

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    No not shifting too soon, the shift points are good. The fluid was a little burnt when I got it but I have kept it up.
     
  8. Blazer1970

    Blazer1970 1/2 ton status

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    I am talking about a CLUNK from 1st to 2nd, not just a firm shift, that is how I read your post. At any rate, I would just keep the fluid clean, and keep driving it. The 700R4 in my '88 pickup clunked hard on the 1-2 when I got it, and it kept working until the torque converter clutch went out, and I decided to rebuild the tranny while it was out.

    Tim

    1970 Blazer CST 4X4 350 SM465 NP205
    1987 Suburban 4X4 350
    1988 Chevy Pickup 4X4 350
     
  9. Bone85K5

    Bone85K5 1/2 ton status

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    I have rebuilt 700R4 that has been in my 85 K5 for about 4 months, with a new 350 (prev a 305) and I have also noticed a harder shift from1st to 2nd. The old tranny was smooth from 1st to 2nd and hard into the higher gears. Afetr the tranny and engine though it completely opposite, which I like. Simply letting off the gas a hair makes it a little smoother while keeping it down nails it hard and then on to 3rd which is nice too... doesnt seem to be a bad thing doesnt't Our other 2 suburbans (95 and 91) both 4Wd also do similar things.


    www.benjaminbone.coloradok5.com

    BBone 85'K5
    Wilderness Roof Rack in the winter, Skyler in the summer...
     
  10. hpfire7227

    hpfire7227 Registered Member

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    My brother's '85 Blazer and his '85 Suburban, as well as my '89 Blazer all have TH700R4's and they all have had a rather hard 1-2 shift from day one. They are all well maintained. The 85's have well over 150k on them and my 89 has 75k, still no problems.

    10 BOLTS O' FUN
     

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