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205 - Slip v fixed ***POLL***

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by KRAZIE87K5, Nov 12, 2001.

  1. KRAZIE87K5

    KRAZIE87K5 1/2 ton status

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    I am acquiring a SM465/NP205 setup in the near future, and need to decide which route to take. I have heard a lot of talk on the subject, but never really understood the advantage" of a fixed yoke.

    I currently have a slip yoke 205 under the truck now, and have had custom shafts made to fit SO:

    Since I have never had a (rear) fixed yoke xfer case, what are the advantages? I will prolly have to get the drive shaft's length changed anyways.

    Is fixed all that its cracked up to be? (HOPEFULLY ITS NOT REALLY CRACKED AT ALL[​IMG]!!!) What does one gain from going to fixed vs slip? The then has to have a slip joint installed right? This damn thing is soooo much freaking work! Can't believe how much I have learned about 4x4's from you and all the other folks on CK5 though...

    <font color=red>GOT MUD???</font color=red>
    My license plate reads:<font color=blue> 8 YR SUV</font color=blue>
    <a target="_blank" href=http://24.10.209.54/bigolk5.htm>http://24.10.209.54/bigolk5.htm</a>
    454/TH400/NP205 - 14BFF/D60/w/ 4.10s
     
  2. Chris Demartini

    Chris Demartini 1/2 ton status

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    <font color=blue>Go solid. Its an easy conversion (except you would need a new shaft) and you can acutally drive without a rear driveshaft.
     
  3. wayne

    wayne 3/4 ton status

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    IMHO the fixed is worth it. If you brake a rear shaft you can still drive the truck on the front to get home. Plus the fixed gives you a little longer rear shaft and is less likely to bust an output housing like I did on my 241.

    See <a target="_blank" href=http://coloradok5.com/gallery/Waynes-Toy>Project Mighty Mouse</a> here.
    <font color=blue>Wayne<font color=blue>
    <font color=blue>Happy Trails<font color=blue>
     
  4. Boss

    Boss 1/2 ton status Author

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    yeah, fixed is the way to go. The advantages are listed already.
    Boss

    Pic of my truck Before N' After
    <a target="_blank" href=http://coloradok5.com/gallery/BeforeNAfter>http://coloradok5.com/gallery/BeforeNAfter</a>
     
  5. KRAZIE87K5

    KRAZIE87K5 1/2 ton status

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    Why would it allow you to drive with only the front shaft? Is there an internal difference in the fixed 205 v the slip 205? I just don't understand how it would be any different... [​IMG]

    Thanks guys for the responses.

    <font color=red>GOT MUD???</font color=red>
    My license plate reads:<font color=blue> 8 YR SUV</font color=blue>
    <a target="_blank" href=http://24.10.209.54/bigolk5.htm>http://24.10.209.54/bigolk5.htm</a>
    454/TH400/NP205 - 14BFF/D60/w/ 4.10s
     
  6. Boss

    Boss 1/2 ton status Author

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    B/c if you bust the rear shaft, with a Slip yoke, you would have to remove it to drive in 2WD front only, but then you risk of losing fluid. You could alwasy cap it somehow, but that's a Pain right there. With the fixed yoke, you would remove the shaft from the yoke and drive in 2wd. No loss of fluid.
    Have you ever removed a slip yoke shaft before? You'll know what I mean if you have. Take care
    Boss

    Pic of my truck Before N' After
    <a target="_blank" href=http://coloradok5.com/gallery/BeforeNAfter>http://coloradok5.com/gallery/BeforeNAfter</a>
     
  7. Blazer1970

    Blazer1970 1/2 ton status

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    Slip yokes and lifted trucks do not mix. A severe driveshaft angle is the enemy of the slip yoke. The reason is that the force to extend and retract the slip yoke is not in line with the extend / retract motion. The driveshaft imparts the force, but the bigger the angle, the smaller the component of the force is available to extend / retract the yoke. Worse yet, the vertical component of the force from the shaft acts as a destructive force against the t-case output. This link is to a picture that I drew that tries to illustrate this concept.

    <a target="_blank" href=http://wsphotofews.excite.com/021/LU/dn/Lv/5a79483.jpg>http://wsphotofews.excite.com/021/LU/dn/Lv/5a79483.jpg</a>

    If you have a severe driveshaft angle with a slip yoke, and say you jump the truck, when you come down you are as likely to grenade the t-case output housing as you are to stuff the slip yoke back in the case like it is supposed to. If you look at factory slip yoke set-ups, you will see that they are used with very little angle on the drive shaft. The shorter the wheelbase of the truck, the more driveshaft angle you get for a given amount of lift - this makes the problem even worse on Blazers.

    Tim

    70 Blazer CST 4X4 350 SM465 NP205
    87 Burb 4X4 350
    01 GMC 2500HD 4X4 Duramax/Allison
     
  8. Sparky

    Sparky 1/2 ton status

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    From an engineering perspective (sorry i'm an engineering student) the fixed yoke is a much better design, and assuming the same material selection and what not it will be stronger. This is especialy true for a lifted vehicle such as a blazer with a high angle driveline. This is why...

    With a slip yoke the splines going into the transfercase have to move as the axle does only the axle moves in an up and down direction while the slip yoke has to move in and out in a horizontal horizontal direction. This causes a torque to be created on the splines as the axle pushes the driveshaft up. (you have to picture it to understand). It will be harder on U-joints too. On the other hand, the fixed yoke has the splines in the driveshaft which is at an agle that is much closer to being parallel to the axles motion. This allows for less stress on the splines. Not only that, but the slip joint in the driveshaft absorbs alot of the torque and force that would otherwise be translated through the upper u-joint. Hope this makes sense. If not, just trust me, its true. Also, like everyone else said, if you have to remove your reard driveshaft on a trail or something you wont loose all your fluid. I have had to make my truck front wheel drive on more than one occasion and been glad I had a fixed yoke.


    Sparky

    When all else fails... Check the blinker fluid.
    78 K-5
     
  9. Blazer1970

    Blazer1970 1/2 ton status

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    Beat ya to that one by a couple minutes.

    Tim

    70 Blazer CST 4X4 350 SM465 NP205
    87 Burb 4X4 350
    01 GMC 2500HD 4X4 Duramax/Allison
     
  10. thatK30guy

    thatK30guy 1 ton status Premium Member

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    Dan, you have two scenarios to look at:

    One, would be that you run the slip yoke t-case, and say a driveshaft loses or breaks a u-joint at either end. If it breaks at the pinion end, the shaft will fall out from the spinning revolutions from the motor/tranny/t-case. Fluid in the t-case will fly out of the tailshaft housing on the t-case.
    If the shaft joint breaks at the t-case end, the shaft will fall down and flop like crazy as long as its still hooked to the pinion. This may result in shaft damage from banging around, or if the tires make contact with it, bend the shaft and ruin it for good. The remaining piece of the slip yoke in the t-case will fly out at the same time and fluid start to spew out.
    The slip yoke can be a 'bad' thing.

    Two, is you are running the fixed yoke and the u-joint breaks at either end, the damage will be on the shaft, if this occurs at higher speeds. With a fixed yoke, there is no long tailshaft like the slip yoke. The fixed yoke is bolted to the output shaft and oil is retained by a seal on the output shaft and yoke.
    Using a fixed yoke allows the shaft to be 'longer' somewhat. Not much, due to the slip yoke tailshaft housing being longer than the fixed yoke. This will decrease shaft angles too.
    Thats why if the rear shaft goes, you can power around with the front shaft. You have no loss of fluid spewing out the rear, as you would on the slip yoke.

    Many owners are converting over to fixed yokes. Especially those who have the slip yokes and don't want to take the risks of damaging their shafts or losing fluid all over the place. This holds true when they are out in the backwoods and are miles from home or the nearest service station, etc. With the slip yoke, driving XX-amount of miles to the next service station, or town, will result in loss of fluid and no lubrication to the internal parts in the slip yoke case will heat parts up quickly and therefore explode or break major internal parts. This can also damage your transmission if the t-case shall explode. [​IMG] More $$$$ to repair when running the slip yoke.

    These are just some of my personal ideas and experiences. What you need to ask yourself is the type of driving you do. If you do mainly street driving, you will be ok with the slip yoke. But rock crawling will and should require anybody to upgrade to fixed yoke. Its also safer with the fixed yoke. [​IMG]


    I'm not picking my nose...I'm just pointing at my brain!! [​IMG]

    <a target="_blank" href=http://coloradok5.com/gallery/thatK30guy>The K30 Collection</a>
     
  11. mudhog

    mudhog THEGAME Staff Member Super Moderator

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    the reason to have a fixed yoke? well when i anialated my 12bolt last weekend if i had a slip yoke i would have to had it towed over 150 miles home very big tow bill$$$ ouch but since i had a fixed yoke i was able to unbolt my rear drive line and drive home in front wheel drive and did not have to pay a huge tow bill[​IMG]

    wheeling videoshttp://community.webshots.com/user/ssmith6333
     
  12. TX Mudder

    TX Mudder 1/2 ton status

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    My rear drive shaft tosted on me once and if I had a slip yoke I would have been SOL. Thanks to a fixed yoke on the 205, I just unbolted it and drove it on the front axle.
    You really don;t want to drive your 205 with an empty case in the middle of the woods, but you may end up having to and you will be pissed when the inside of the tcase is trashed.
    -- Mike

    <font color=blue> The mud's on it to hide that it's more than one color.[​IMG]
     
  13. KRAZIE87K5

    KRAZIE87K5 1/2 ton status

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    Boss - I have removed so many slip yoke before, that I am imbarrased to say that I didn't even think of loosing fluid [​IMG]..... but thanks for pointing out the obvious! [​IMG]

    <font color=red>GOT MUD???</font color=red>
    My license plate reads:<font color=blue> 8 YR SUV</font color=blue>
    <a target="_blank" href=http://24.10.209.54/bigolk5.htm>http://24.10.209.54/bigolk5.htm</a>
    454/TH400/NP205 - 14BFF/D60/w/ 4.10s
     
  14. KRAZIE87K5

    KRAZIE87K5 1/2 ton status

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    Wow! You guys have the sh!t on the fixed yoke I guess! Thanks for all the info! I would gladly take the fixed yoke given the chance now after having all this info at my disposal! Of course, thanks for all the fast and incredibly informative resopnses!

    You fellas ROCK!

    <font color=red>GOT MUD???</font color=red>
    My license plate reads:<font color=blue> 8 YR SUV</font color=blue>
    <a target="_blank" href=http://24.10.209.54/bigolk5.htm>http://24.10.209.54/bigolk5.htm</a>
    454/TH400/NP205 - 14BFF/D60/w/ 4.10s
     
  15. kpanza

    kpanza 1/2 ton status

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    I agree with all points (and wish I had the fixed yoke already), but you CAN cap the case to prevent fluid loss when removing the driveshaft. I have personally had to do it twice. I bring along some spare paint can tops that I measured on an old tailshaft housing (which cracked due to the reasons above!), and with a bunch of duct tape you CAN seal the rear of the case well enough to get home. Desperate times call for desperate measures!! [​IMG]

    As soon as I decide which case to go to next, and get the $$, I will finally be able to throw those paint can tops away and be a fixed yoke guy! ha,ha
     
  16. Boss

    Boss 1/2 ton status Author

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    Krazie,

    Wasn't questioning your intelligence, just saying [​IMG]. But atleast you know what I mean.
    Kpanza, definately there are ways to cap it (like I mentioned above [​IMG]), but boy is that a pain to do.

    Well, I have an NP205 (SM465 version) with a fixed yoke forsale if anyone is interested [​IMG][​IMG]

    Boss

    Pic of my truck Before N' After
    <a target="_blank" href=http://coloradok5.com/gallery/BeforeNAfter>http://coloradok5.com/gallery/BeforeNAfter</a>
     
  17. Sparky

    Sparky 1/2 ton status

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    Oops! Ya did beat me Tim. Couldnt have said it better myself either. I like the pic too.

    Sparky

    When all else fails... Check the blinker fluid.
    78 K-5
     

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