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  1. #1

    Default Late Shifting 1990 Suburban

    Hello

    This is a problem on my 1990 6.2D 2500 Suburban 100K miles Travelled.

    Recently my Transmission has begun to shift late,it shift's into 2nd at about 25mph and will not shift into 3rd untill 50mph.

    I can maually shiff the transmission by moving the shifter from Drive into 2nd and back to Drive at 40mph to make it shift to 3rd.Also the Transmission wants to down shift at 40mph.

    I replaced the Filter and Fluid,there was only a tiny ammount of metal stuck to the Magnet in the Pan.

    Replaced Speed Sensor on Transmission.

    Took a sample of the Fluid to a Transmission shop,they said it wasn't "Burned".

    I have learned that the AutoXray Scanners won't diognose Transmission Faults.I cannot get any Fault Codes to Flash up in my Car.Perhaps as stated its because it is an export version (I live in Norway).

    Any help is appreciated,thanks in advance.

    Mike Hill
    Last edited by Mike Hill; 03-20-2011 at 07:45 AM. Reason: forgot somthing

  2. #2

    Default

    Bump.

    If I can't find the problem,I will have to order a new Transmission from the States.Gulp.

  3. #3
    Jr. Engineer racekid91's Avatar
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    Default

    Sounds like your clutch packs are wearing out. What did the fluid look like and smell when you dropped the pan? Was it a dark color, almost black in color?

    1995 Chevy Tahoe

  4. #4
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    Mike, is this the 700R4 trans with the TV cable? If it is, you might try loosening the cable a couple of clicks. A tight cable causes late hard shifts, a loose cable allows earlier softer shifts. Look for this cable on the bottom of your TBI bellcrank. It works opposite of the throttle cable. Mark it before you adjust it. Depress the detent on the side of the cable housing holder & slide the cable foreward 1 or 2 clicks then drive it & see if this helps.
    1988 Chevy C-3500 2wd (no pic)
    350 c.i. 5.7 L Stock Block, 4 Bolt Mains
    L-31 Vortec Heads, Edelbrock Cam & Intake,
    Holley 650, Flowtech Headers, Magnaflow exh.
    Jet Trans 700R4, B&M Ratchet, 4:10 gears,
    3" susp. lift kit "shadetree"
    No rev limiter, No speed limiter lol


  5. #5

    Default

    Quote Originally Posted by stephan View Post
    Mike, is this the 700R4 trans with the TV cable? If it is, you might try loosening the cable a couple of clicks. A tight cable causes late hard shifts, a loose cable allows earlier softer shifts. Look for this cable on the bottom of your TBI bellcrank. It works opposite of the throttle cable. Mark it before you adjust it. Depress the detent on the side of the cable housing holder & slide the cable foreward 1 or 2 clicks then drive it & see if this helps.
    Thanks,I will get underneath and have a Look.

    To answer the earlier post regarding the Clutch Packs.The Fluid was not dirty or "Burnt", I took a Sample to a Transmission Shop who beleived it was an Electrical Problem.However no one has the diognostic Tools required in this Town.

  6. #6
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    Mike, the adjustment for the cable (if it's the 700R4) is up top on the engine, not underneath. The trans tv cable is operated by the TBI bellcrank opposite the throttle cable. As your throttle cable pulls the bellcrank, the tv cable gets pulled the opposite direction by the opposite side of the bellcrank. Look for a cable coming off the bottom of the bellcrank & follow it back to the cable housing mounting point. This is where you adjust it. You depress the spring loaded detent in the side of the cable boss & this releases the housing so you can adjust it by sliding the cable housing/sleeve foreward or back. The inner cable is adjusted by moving the outer cable housing/sleeve. Be sure & mark it first, or you can count the number of slots/grooves in the plastic slide of the cable that are on the front side of the mount. Try moving it foreward 1 or 2 clicks (this will loosen the inner cable & allow it to shift earlier).
    Last edited by stephan; 03-26-2011 at 04:11 AM.

  7. #7

    Default

    Stephen

    I don't think the Transmission I have is the one you descibed.I could not find any Cables,only Vacume Hoses and one Rigid line.

    One of the Hoses was not attached to anything,its the last Hose in the Pictures.I found it hanging alone by the Master Cylinder.Curiously the Shift problem started after I had the Master Cylinder replaced?The Hose ran back to a "T" connector that sat atop the Bell housing with a "Vacume device" and all the way around to the Throttle mechanisim?I replaced all the Hoses I could find.
    As well as replacing the worn wire pictured and cleaning up the Earths.
    I have ordered a replacement Transmission.however I fear that if this is an Electrical problem,I may not be Cure it by installing another Tranny.
    Attached Thumbnails Attached Thumbnails 026.jpg   024.jpg   028.jpg  

  8. #8

    Default

    sounds like the piston is sticking in your valve body

  9. #9

    Default

    I believe you have the TH-400, which is a non-overdrive tranny, correct? If so, the kick down adjustment is on the pedal itself. It is just a slider attached to the top of your gas pedal, in the cab. I don't know how to adjust it, but maybe somebody else will...
    Jess

    1991 Suburban


  10. #10
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    Mike, have you determined which trans you have yet? If Jess is correct & it is the Turbo 400, there is a vacuum modulator valve on the right rear corner of the trans (passenger side rear corner) Slide under there & see if you have this valve on it. If so pull the vacuum hose off it & see if trans fluid runs out of the hose. If so the diaphram is leaking & a new mod valve may fix your problem. It's an easy replacement. Also check & see that this hose is not cracked/leaking along it's entire length, & that it is hooked up on the other end.

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