Class 8 driveline build/ assembling - Page 2
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  1. #21
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    Quote Originally Posted by Garwood View Post
    You want the tube centered about the axis of rotation right? on the road, at freeway speeds you will feel the difference between under 5 thou runout and 10 thou+ if it's not balanced. This is exagerated the bigger the tube. 3" .100 tube is not as bad as 4" .200 wall tube. I'm sure you get the idea.

    If you take a cut on the ID of the tube it won't result in a uniform wall thickness. That fucks up your ability to indicate the tube where it matters most.

    This is how it works in my head anyway. I hillbilly'd a lot of drivelines together before I ever had a machine shop and most of them worked pretty OK. A few years ago a guy brought me one to fix from an old truck he had. It was twisted right off and it was made from the thinnest shittiest tubing, like .040" 3.5". I couldn't believe somebody would do something like that. Then I remembered building a driveline like that for a truck I built and sold many years earlier. It was mine.

    I think sometimes machinist thought process can overthink the hell out of stuff. I'm sure there's millions of half assed drivelines out there doing great. I know I made some of them.


    I agree the weld was cold on that broken tube.
    Are you going to turn the complete OD ? of course not, as your not turning the ID completely either.

    Alignment requires turning the OD, Why ????

    At present, your ramming them together, and the tube & end piece float into some kind of equilibrium. Wether that's concentric with the center axis or not is a crap shoot.

    You are not dynamic balancing these afterwards ?

  2. #22
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    I don't see a lot of class 8 stuff but find them a lot easier than dealing with GM Saginaw crap from the 60's and 70's that had non-machined butts on the yokes. Can't say if I ever had one that was reasonably straight either. .05 to .12 runout in the middle is the usual.

    Had a two piece shaft come in a couple of weeks ago off an early 2000's F150 truck. Not welded. Some sort of crimping wire ring that squeezes tube into groove in the butt. How the fuck does that work out???

  3. #23
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    Years ago I done 1000s of drive lines, never just pushed the tube on and made straight, I would machine the end flat and bore the tube to press fit size, heat and push the end in with the tail stock, never had any problems and never had many i had to bal...Phil

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    Quote Originally Posted by Street View Post
    They are not the heaviest the heavy ones are Mack drivelines with heavy wall tubes and earthmoving shafts.
    when i was a apprentice ( then tradesperson ) the shop did these and many others as well as other work.
    We assembled them by hitting the yoke in with a large hammer ( hefty pounder ) and drift typically the smaller shafts has about 0.002 interference the bigger ones you can go a little more but not too much.
    Tube is sometimes not round but is pretty good, all you do for that is average it and add some interference fit.
    To align we just sat it up in a vice and knocked a end to align with the other...we used straight edges sitting on the cap ends or caps ( machined surfaces ) and sighted along the edges...nothing too fancy. The vice we had did not crush the tube so be careful what vice you use we grabbed it on the throat of the vice not by the jaws.
    Some shafts had missalignment on purpose some 2 piece cv joint ones on cars about 15 degrees out.
    generally most if not the majority align the yokes.
    We welded the larger shafts in a lathe and knocked them straight before welding. for welding it was tacked first then welded in one go with a mig.

    If it had a small amount of runout we shrink one side of the tube by spotting it with a torch then quenching it ...but be warned doing this on excessive runout if not advised and it is better to break the weld and start again.

    Balancing was done in a schenk balancer ...some shafts come out fine without the need of added weight but that maybe 1 in 10 most require balancing.
    Runout being low is important for balancing and also where you add the weight or take it off for small amounts.


    Never did we have the need to shrink fit the tube yokes i cannot see why you need to do this step or have so much interference to require it.

    Most of the parts are made by Hardy spicer ...well the good ones are
    How long ago was this? Sure doesn't sound like you've been around drivelines in the last 30 years.

  5. #25
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    Quote Originally Posted by digger doug View Post
    Are you going to turn the complete OD ? of course not, as your not turning the ID completely either.

    Alignment requires turning the OD, Why ????

    At present, your ramming them together, and the tube & end piece float into some kind of equilibrium. Wether that's concentric with the center axis or not is a crap shoot.

    You are not dynamic balancing these afterwards ?
    No, that's not how it works at all. I don't know how to explain this any better.

    The fucking joints are held in yokes on center, driveline is mounted and made to run true by the OD of the tube where the yoke is installed.

    If you turn tube ID the wall thickness is not consistent and you can't indicate it. If you turn a reference on the OD atleast you can get the yoke concentric, but your tube is still fucked. It's the same fucking thing when you steady up a tube or shaft that's not round.

    You don't get that? I don't know how to help you if that doesn't make sense to you.

  6. #26
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    Quote Originally Posted by Garwood View Post
    No, that's not how it works at all. I don't know how to explain this any better.

    The fucking joints are held in yokes on center, driveline is mounted and made to run true by the OD of the tube where the yoke is installed.

    If you turn tube ID the wall thickness is not consistent and you can't indicate it. If you turn a reference on the OD atleast you can get the yoke concentric, but your tube is still fucked. It's the same fucking thing when you steady up a tube or shaft that's not round.

    You don't get that? I don't know how to help you if that doesn't make sense to you.

    I'm guessing that Digger has never done a driveshaft. He may not be aware that nearly all tubing is not round, not even DOM. It ain't straight either. I have only been doing drivelines since 1976 so I don't know much about them.

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  8. #27
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    Quote Originally Posted by Garwood View Post
    No, that's not how it works at all. I don't know how to explain this any better.

    The fucking joints are held in yokes on center, driveline is mounted and made to run true by the OD of the tube where the yoke is installed.

    If you turn tube ID the wall thickness is not consistent and you can't indicate it. If you turn a reference on the OD atleast you can get the yoke concentric, but your tube is still fucked. It's the same fucking thing when you steady up a tube or shaft that's not round.

    You don't get that? I don't know how to help you if that doesn't make sense to you.
    No need to get hostile, I was trying to help you.

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    Quote Originally Posted by digger doug View Post
    No need to get hostile, I was trying to help you.
    Fair enough, but I fail to see how suggesting I need to bore the ends of tubes solves anything. I don't have nor want a machine that can swallow a big tube to bore the ends so it would be in a steady. I can't think of any way that is more efficient or a better result than heating the tube ends.

    I started the thread looking for ideas to build efficient driveline assembly fixtures/tooling. Instead I got "just use a sledge hammer and bore the tube ends".

    Explain to me how boring tube ends helps. I can't see it so open my eyes, convince me otherwise.

  10. #29
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    Not quite 30 years but damm close to ....its been a while the series you mention is what i worked on as well as others. the schenk balancer had analog gauges then now their all digital and even tell you how much weight to add or remove.
    back then it was experience by how far the gauge moved and weight of the shaft. Weights are only tacked on not welded on.

    They worked then with all sorts from racing applications ( 7k rpm ) for sports nuts to normal production applications doing 3k ( mack truck)

    Only trouble we had was a one off when someone shrunk the tube too many times and it weakened it and failed at the shrink point. One or two spots is ok. if its bent too far and cannot be done with two small spots replace the tube is all i say. That is if the ends are ok and the tube is bent like a banana.

    Tube is made a standard size ends are too so you just fit them up just vee the tube ends for weld prep and check length and alignment.

    One other thing if you make the sleeves too long ( mods ) it is harder to move the joint to get it to run central so don't do that too long or it won't move.

    Basic premise is centroid of mass is to rotate about the centre of rotation if they don't match then you have a imbalance.
    Forgings can be slightly out.



    back then the boss was old school and taught us how to use a surface gauge to set it straight after a while you get quite good at using a surface gauge and no need for a dial indicator although at the time we did occasionally check to see how good we could do it. A surface gauge can be surprisingly good and quick way to do it.


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