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Hey Tranny Guys!

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by CarolinaBogger, Jun 12, 2001.

  1. CarolinaBogger

    CarolinaBogger Registered Member

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    Ok guys, I think i have some tranny problems, but I'm not sure. Just recently I put in a 12 bolt so I'm not sure if this problem could be related to the bearings on the carrier, but i don't think so. Anyway, I have a 700-R4 and when I'm stoped and press the gas moderatly, I can feel a little slipping in the drivetrain. I don't know a lot about tansmissions but I'm thinking it could possibly be the torque converter wearing outand it is causing the slipping. Also, when driving about 40+ mph, there is a vibration that lets up when I let off the gas. And it also feels as if i have to use more than normal throtle to keep the truck moving, like the brakes are on a little bit or something. I just replaced the u-joint so i don't think that is it. I checked the tranny fluid and there are little bubbles on the dipstick -- what does this mean? The tranny is a crate tranny that has only 22,000 miles on it. Any advice you guys have would be appreciated
    Thanks yall
    CB
     
  2. newyorkin

    newyorkin 1 ton status

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    Sounds to me like something is too tight in the rear. Can you roll the truck easy in nuetral? If not, I'd say tear apart the rear again... If you put in a whole new rear, housing and all, make sure there's no binding in the brakes. Maybe the parking brake cable got hitched up on something during the install.
    Bubbles in the tranny fluid are usually a sign of airation, from it being overfilled or overworked. It loses a lot of it's cooling properties when it's airated (mentally compare foam versus liquid for cooling purposes). You could end up toasting the tranny with the constant load simulation and airated fluid...
    If your tranny was good before the change in the rear, I'd doubt your tranny is the source of the problem.
    Good Luck!!!

    Ratch
    **<A target="_blank" HREF=http://k5.8m.com>http://k5.8m.com</A> What more is there to life?**<P ID="edit"><FONT SIZE=-1>Edited by newyorkin on 06/12/01 10:30 AM (server time).</FONT></P>
     
  3. Blue85

    Blue85 Troll Premium Member

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    Newyorkin is right, bubles usually mean underfilled or overfilled. Make sure you check the fluid level with a warm tranny and the engine running. With the engine off, the pump stops and the fluid in the pan is higher. If you are underfilled, that could mean that your torque converter isn't completely filled and that would explain the slipping feeling. If there really is something slipping, it can only be in the transmission.

    But here's my first guess as to what the problem is. I would say that something is too tight in the driveshaft or rearend. That would make the tranny work harder, maybe causing the bubbles, and explain the need for more gas pedal. This would also explain the slipping feeling, because with a higher torque load through the transmission, the torque converter will slip more. I would put the rearend on jackstands and the drivetrain in nuetral and turn everything by hand to make sure it works good. Also measure the angles that the U-joints are operating at.

    I also want to say that it is always a good idea to have a temp gauge for the tranny. They are like $50 and an overall is like $1200. Which one is better?

    My second guess is a worn out clutch in the torque converter. I am talking about the clutch that only lets the rotor turn in one direction. There are two failure modes, one of which will give you an effectively higher gear ratio at take off and will make it accelerate like crap. The other one will give you decent acceleration, but will make the engine rev too high for cruising, plus run hot and suck too much gas. Other than that, the only things that can go wrong with a torque converter are for the lockup clutch to fail (no lockup) or for it to blow chunks, which usually causes cascading failures throughout the transmission. Was the converter replaced when that tranny went in? It always should be unless it is already pretty new.

    <font color=green>If a K-5 is "Built not Bought", why does this stuff cost me so much money? [​IMG] </font color=green>
     
  4. CarolinaBogger

    CarolinaBogger Registered Member

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    hey guys, i really appreciate you're input. I'm gonna go jack the back end up and check the motion of everything. Hopefully it might be something like i just put the u-joint in too tight. Also, I have never had to put any fluid in the tranny before (it's only 22k miles old). Every time I take the driveshaft out and fluid comes out the tailshaft housing, i check the fluid from the dipstick after i get it running and warm again. When I check it, it seems to be ok. But, now since you guys tell me what the air bubbles mean, I could be getting a false reading like maybe the dipstick tube wasn't installed fully. At least I have some more leads now. Thanks again guys! It's great to have free consultants.
    CB
     
  5. Executioner

    Executioner 1/2 ton status

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    Check your T-case, the fluid came from where ?
     
  6. newyorkin

    newyorkin 1 ton status

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    Is your truck 2x4 or 4x4? If it's a 4x4, you lose fluid from the transfer case when you take out the driveshaft, the tranny shouldn't lose any that way. Check your transfer case level if you haven't yet! If it's a 208, there's a big bolt at the top of the case. Take that out, and fill it until some fluid spills back out at you (do this slowly!).

    Good luck!!

    Ratch
    **<A target="_blank" HREF=http://k5.8m.com>http://k5.8m.com</A> What more is there to life?**
     
  7. rampage

    rampage 1/2 ton status

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    Just a thought, but I think I recall that if the rear drum brakes are installed backwards then they will 'adjust' themsleves and tighten up. They are only suppose to adjust when you go in reverse. Someone please correct me if I'm wrong.
     
  8. CarolinaBogger

    CarolinaBogger Registered Member

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    damn! what was i thinking about loosing tranny fluid when I take out the driveshaft? Thanks for reminding me about that one! When I did the axel swap about a month ago, i used my original brake baking plates and components from my 10 bolt since they mount up to the 12 bolt, so I know they are not backwards. I jacked up the truck and in neutral, I spun the rear driveshaft by hand and everything was smooth, so thats good. However, I did find that there is play in the driveshaft around the front u-joint, so that probably is the culprit for the vibration. Thanks yall for the tips!
    CB
     
  9. newyorkin

    newyorkin 1 ton status

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    Hey carolina, I think I'd drop that tranny pan and swap out that fluid and filter quick if it's airating, especially if it hasn't been done in 22k. What color was the fluid, BTW? It's supposed to be red, brown if overheating and burning up. NP208 transfer case will also take ATF, so that IS what you had spilling out if you have a 208.
    Was it rebuilt or new? Did you follow a break-in? Get that sucka looked at under warrantee if you can...
    I was also thinking... If you changed the ratio in the rear, but not the front, that would seriously mess things up when you're in 4 or have the front hubs locked. I've never experienced it, but I'd guess it would feel like you're describing just before the transfer case grenaded...
    Just an extreme thought, though, probably not applicable...


    Ratch
    **<A target="_blank" HREF=http://k5.8m.com>http://k5.8m.com</A> What more is there to life?**
     

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