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driveline flex? no one else has had this?

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by joe84bb, May 29, 2001.

  1. joe84bb

    joe84bb Registered Member

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    I have a problem with some kind of "slack" in my driveline somewhere. When I hit the gas hard all at once, it catches all at once, but not if you ease into it, like something isn't tight. But...this problem has been there since I bought the truck and has been there since the motor swap, then the tranny swap (auto to manual) and now the rear swap (10 to 14). Both driveshafts are new custom for my lift. If I replaced the think rubber trans mount with one of Summit's rigid mounts, would it help? This isn't a problem on gravel, if I gun it off the pavement it doesn't do it.

    I know just enough to know that I'll never know enough.<P ID="edit"><FONT SIZE=-1>Edited by joe84bb on 05/30/01 05:48 AM (server time).</FONT></P>
     
  2. '73 K5

    '73 K5 1/2 ton status

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    Re: driveline flex? pleeze read

    Are you using an NP203 'case with a manual tranny?

    '73 K5
    Chevy good...Ford bad
     
  3. joe84bb

    joe84bb Registered Member

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    Re: driveline flex? pleeze read

    pretty sure, if a 203 was stock on an 84 automatic K5, then that's what I've got

    I know just enough to know that I'll never know enough.
     
  4. newyorkin

    newyorkin 1 ton status

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    Re: driveline flex? pleeze read

    I get the same thing, feels almost like a motor mount is loose or wasted? I feel it in normal acceleration (not really hard accel.), and a little bit in turns.
    I have checked all the mounts, and everything is solid. I'm beginning to wonder if it's the frame flexing. I know my steering box is flexing at the frame.


    Ratch
    **Hmmm. Land or Mall? Land or Mall? Let's see. Lotsa SUV's around here... Let's build a mall.**
     
  5. thatK30guy

    thatK30guy 1 ton status Premium Member

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    Re: driveline flex? pleeze read

    If its a stock t-case, then its NOT the 203 for an '84 model year. 203's only ran up to '79. If your ride is an '84, you will have the 208 t-case.

    When In Doubt, Whip It Out!
     
  6. '73 K5

    '73 K5 1/2 ton status

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    Re: driveline flex? pleeze read

    K30 is right if you haven't switched out the stock 'case. I just know that a 203 with a manual is a bad combo, so thats what came to mind.
    Motor mounts maybe?

    '73 K5
    Chevy good...Ford bad
     
  7. Seventy4Blazer

    Seventy4Blazer 3/4 ton status

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    Re: driveline flex? pleeze read

    NP208 and NP 203 are both chain drive. you might need a new chain. nmy buddys burbon did that so we replaced the chain and new u-joints. problem solved....
    Grant.

    1974 Chevy Blazer Cheyanne. lots of plans for it....
    but it is on 33's now, with saggy old springs. i am in so cali if ya got any parts for me.
     
  8. joe84bb

    joe84bb Registered Member

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    Re: driveline flex? pleeze read

    I thought that also but, last year when the 700r4 died, I had the t-case dissassembled and checked professionally. He said it looked like new. And like I said this hasn't changed through all of the swaps she's gone thru. It was there when I had the auto, plus the bb was swapped in no more than 3 yrs. ago, and trust me I baby this thing. most of my wheeling is like going down a gravel road to a hardcore wheeler.

    I know just enough to know that I'll never know enough.<P ID="edit"><FONT SIZE=-1>Edited by joe84bb on 05/29/01 04:26 PM (server time).</FONT></P>
     
  9. Cliffy

    Cliffy Registered Member

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    Re: driveline flex? pleeze read

    Does it matter what X-fer case it is, if the problem isn't happening in 4WD. He didn't mention what range it happens in.

    Well.....

    Coil sprung 71 blazer.
     
  10. Seventy4Blazer

    Seventy4Blazer 3/4 ton status

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    Re: driveline flex? pleeze read

    its a sugestion. not a fix.

    1974 Chevy Blazer Cheyanne. lots of plans for it....
    but it is on 33's now, with saggy old springs. i am in so cali if ya got any parts for me.
     
  11. joe84bb

    joe84bb Registered Member

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    Re: driveline flex? pleeze read

    it happens in 2wd, I haven't checked in 4wd. The mount I had to use for the tranny is from an 89 & up. It has a fairly large (1 3/4" or so) rubber cushion. could this be it?

    I know just enough to know that I'll never know enough.
     
  12. joe84bb

    joe84bb Registered Member

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    Re: driveline flex? pleeze read

    ...anybody?

    I know just enough to know that I'll never know enough.
     
  13. Grim-Reaper

    Grim-Reaper 3/4 ton status Author

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    Your not helping us help you here. We need some more information.
    You need to give us full details on the truck and figure out what case you have. If it is the stock case then it should be a 208. But are you sure? Nothing else in your truck is stock if your bio is correct. 208's are notorius for the "Clunk" from slip yoke problems. This would be much more noticable with a manual. A auto kind of keeps it hidden most of the time.
    You bio says a 5 speed and 14 bolt. A 5 speed was never offered in the 73-91 body so most of us are not going to be familure with it.
    You got 14 bolt rear but what diff do you have? Could be a blown limited slip and flooring it gets it to lock but it has a slight left right slip so you percive it as driveline slop. Could also be excessive R&Pininon slop. Could be loose axle shaft to hub bolts, The lower the gear the more noticable this becomes. Could be worn splines on the yokes.
    Bad spud adaptor between the case and tranny. Most Manual cases have a course spline but if the 208 is original that has to be some rare or custom spud to mate the 208 set up for 28 spline to a manual tranny. Could be a whole lot of little areas of slop in the whole driveline that together seems excessive.
    Get back once your sure what you have and hopefully we can be more help

    Diging it in the dirt with my K5's
    Grim-Reaper
    <A target="_blank" HREF=http://grimsk5s.coloradok5.com/>http://grimsk5s.coloradok5.com/</A>
     
  14. Butch

    Butch 1/2 ton status

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    Re: driveline flex? pleeze read

    Are you running a detroit locker? If so that is where your slack is coming from. If not watch your gear shift when you stomp on it. If it goes way over to the right then you may have a broken left motor mount.

    I thought I was wrong once,
    but I was mistaken
     
  15. Grim-Reaper

    Grim-Reaper 3/4 ton status Author

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    Re: driveline flex? pleeze read

    Gear shift is not attached to the tranny on a 208 like our older 205 and 203 trucks. Shifter is bolted to the body. Lift the hood and stand on the brakes and watch the engine whent you ease into the throttle and see if the engine lifts is how he will have to do it.

    Diging it in the dirt with my K5's
    Grim-Reaper
    <A target="_blank" HREF=http://grimsk5s.coloradok5.com/>http://grimsk5s.coloradok5.com/</A>
     
  16. HarryH3

    HarryH3 1 ton status Author

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    Re: driveline flex? pleeze read

    The chain in chain drive cases is just dead weight until you engage 4WD. Then it drives the front output shaft. If the problem occurs in 2WD, then the chain isn't the culprit.

    <font color=black>HarryH3 - '75 K5</font color=black>
    <A target="_blank" HREF=http://ThunderTruck.ColoradoK5.com>http://ThunderTruck.ColoradoK5.com</A>
    It's a great day to be alive...
     
  17. BurbinOR

    BurbinOR 3/4 ton status

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    Re: driveline flex? pleeze read

    Joe, it could also be the following -

    Rear brakes - catching/not releasing
    Driveshaft spline engagement problems?
    U joints
    Axle wrap - do you have rear blocks?
    Transfer Case mount - ORD has nice ones for $45 to replace the rubber factory ones

    Keep us informed as to what you found.

    <font color=blue>'79 ONE TON TPI K5 - See it at---&gt;<A target="_blank" HREF=http://www.blazzinor.coloradok5.com>http://www.blazzinor.coloradok5.com</A>
     
  18. joe84bb

    joe84bb Registered Member

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    As far as what's in it...I'll start at the front. Fronm a bone stock 84 K5, (6.2 diesel, 700r4,np208-I asume-, 10 bolt front& back.) I went w/ a 2" suspension lift. Then, the diesel messed up and in went a 454 from a '77 wrecker. After that the 700 layed down on me, so I went with a rebuilt replacement 5 speed from a 1994. It's supposed to be a muncie getrag, I have LO, 1,2,3, and OD. the guy told me that he sold some to go in 3/4 and 1 tons. The crossmember brace for the tranny had to be changed from mine to one from an 87 3/4 ton I think (I forget why but it worked)-the mount is from a 88 up and has a very thick rubber bushing. Then came the 6" superlift (spring/block combo in back) to replace the 2". When I did this I had custom driveshafts made front & rear (cv joint added at front of rear shaft), w/ wedge shims as needed for better angles. Then I had the front & back regeared to a 4.56 w/a detroit locker in back-both with all new bearings. I'm now running 35x12.5 Pro Comp M/T's. The only thing left that hasn't been replaced is the t- case. It was dissassembled to install a new input gear to mate with the 5-speed and the mechanic told me it looked like brand new inside. All of these changes have been in the last 2 yrs with me putting less than 10k miles on the truck since. The shifter goes into the top of the tranny, no linkages on the side. As far as the transfer case brace. I don't think I have one unless you're talking about the trans crossmember brace that bolts to the bottom of the trans, my t-case just bolts to the back of the transmission. I appreciate the help, just bear with me guys.

    I know just enough to know that I'll never know enough.<P ID="edit"><FONT SIZE=-1>Edited by joe84bb on 05/30/01 04:23 PM (server time).</FONT></P>
     
  19. joe84bb

    joe84bb Registered Member

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    The whole time I've owned the girl she's had this problem. But, see if this is enough information to go with. Like before, any help is greatly appreciated.

    I know just enough to know that I'll never know enough.
     
  20. Grim-Reaper

    Grim-Reaper 3/4 ton status Author

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    WOW! Pretty killer set up!
    Ok well now that we know what you have lets look at a few things and see what we canfigure out. Ok you very last post says it has been here from the word go. Well the only thing left for the word go is the case. I have never played with the 208 but the few things I have heard is this. The rear bearing suport for the output shaft sometimes has problems. The Diesel then that 454 put a lot of torq out. Since this case is a slip yoke what may have and is happening is the bearing has been pushed hard. When you stomp it a few things happen that can explain why it goes away. The first and most important being that the ring climbs the pinion. If you were to look at your axle when you accelerate hard the pinion comes up. This lessens the angle that the CV is operating at and it pushed the yoke into the case. Understanding this I think that the yoke and the case splines are probably worn as is that tailshaft bearing. In my previous post I mentioned the 208 clunk. All related to wear and movement of that yoke. Do you get that clunk also?
    As for the mechanic saying it looked good, well he was paying attention to the input side and probably inspected your chain but he may have missed the yoke slop since he probably wasn't looking for it dirrectly. Honest mistake.
    Do you know if this was the original yoke for the case when you had the CV drive shaft made? Are you having problems keeping the rear seal from leaking?
    I would pull the yoke loose and put it into the case and check for up and down movement. Before removing it make a mental note of how much it is into the case. Yokes can and will wear one small area. In more or out more it gets into a less worn area so the wear at the area it rides can easily be missed. If you have a lot of up and down slop it may be time for a new yoke and possibly a new output shaft. The wear on the inside of the yoke will be hard to see. If you were to cut the yoke in half length wise the wear would be cone shapped. This means the point where the splines start in the yoke would be a larger diameter and taper down the deeper down into the splines you go. Not really noticeable to the eye. Might be able to check it with a pair of inside calipers but thats about it.
    Now get some pictures up of the truck and the drivetrain. It sounds killer and I'm not sure anybody else here has put a5 speed into one but now that your here and we have heard what you got there just might be a couple more show up [​IMG]

    Diging it in the dirt with my K5's
    Grim-Reaper
    <A target="_blank" HREF=http://grimsk5s.coloradok5.com/>http://grimsk5s.coloradok5.com/</A>
     

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