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Technical rear end angle

Discussion in 'Traditional Hot Rods' started by jeff020571, Feb 7, 2020.

  1. buick bill
    Joined: Dec 18, 2008
    Posts: 420

    buick bill
    Member
    from yreka;ca

    I have seen people say that when you lift a 4x4 , 6 - 8+ inches you should point the pinion at the trans. tail housing .cant see u joints lasting long ! . I think they do it because otherwise the shaft needs to be lengthened . but sure cant be vibration free !!
     
  2. anthony myrick
    Joined: Sep 4, 2009
    Posts: 5,930

    anthony myrick
    Member

    as far as the steering shaft out of phase, it doesn't turn fast enough to have any issues with vibration and shouldn't bind. It does have a slip yoke
    our diesel instructor is also trying to figure why the drive shaft would be.
     
    gimpyshotrods likes this.
  3. gimpyshotrods
    Joined: May 20, 2009
    Posts: 17,384

    gimpyshotrods
    ALLIANCE MEMBER

    No.

    Totally different kind of driveshaft, using a double-cardan joint on the transfer case end.

    No relationship to a two-joint shaft.
     
    Last edited: Feb 13, 2020
    trollst and anthony myrick like this.
  4. HotRodWorks
    Joined: Dec 6, 2005
    Posts: 258

    HotRodWorks
    Alliance Vendor

  5. The Shift Wizard
    Joined: Jan 10, 2017
    Posts: 2,007

    The Shift Wizard
    ALLIANCE MEMBER

    Let's agree that you have to know and follow the rules to get a passing grade in the classroom. The problem is there are a lot of guys building rods who never took the class or saw the textbook. But they have real-world knowledge of what works and what doesn't. They know that when they launch their racecar the pinion nose wants to rotate"up" into the tunnel or floor pan unless they install a snubber. On their street car, when they punch the throttle, the center of the differential stays centered on the axle but the springs wrap, the diff torques and the "nose" swings higher up. The rule would call that greater down slope, however. It's not that hard to understand why so many don't speak and write it the way it's done in the textbook.
    When a rule is at odds with popular usage, away from the academic world, the book often loses. If following the rule with those who don't know the rule is confusing and counter-communicating so often to so many, something has to give to get the correct info across. It could be as simple as saying...... "I go from left to right, so.....".

    I'm bi-lingual so I can understand and talk to both factions. :rolleyes:
     
    Last edited: Feb 13, 2020
    31Vicky with a hemi likes this.
  6. I get it, really I do.

    I’ve been a technical fabricator my entire adult life, before that I was just a mechanically inclined asshole kid. I’ve done nicely for myself and retained the better parts of being an asshole. Mixing in a decade of construction work
    I’ve worked from verbal descriptions, bar napkins, envelopes, photographs, isometric sketches, artistic rendering, blue prints that were hand drawn, and CAD drawings, some bare minimum and some highly detailed. Worked on extremely small stuff ( 700 plus parts in the size of lunch box the smallest) to huge massive big stuff. I’ve built for those demanding the highest standards and the lowly homeless crackhead guys who needed a dofuckinghicky welded on there shopping cart. Prototype MRI machine or neighbors mower deck don’t really matter.

    Now, here on the Hamb in this thread (as well as most other driveline angle threads) we have got very highly descriptive terms being. Apparently I was unaware that the way to achieve parallel is to go with opposing angles. Positive and negative +,- being reversed ANY PLACE ELSE in your life will result in really bad things: bounced checks, overpayments, shorted electrical systems, incorrect dimension stack ups the list is endless. Not here in a drive line angles thread NOPE mixing them up it’s all good fuck yeah just make up a word.
    Give instructions using left and right without the direction (north south) is a recipe for disaster. Up & down , ahhh yeah you know same same.
    So let’s fall back on a picture is worth a 1000 words saying. Ahhh well the picture is wrong. I proved that earlier . How about a useful online calculator,,, oh that works and quite well at doing the trigonometry but not if you don’t know the difference between up and down in a slope,, I proved that earlier too.

    It’s no wonder all the confusion on driveline angles conversations on every place it’s discussed. That evidence is out there. People build some goofy looking stuff and that evidence is out there as well. People build drive angles that are completely wrong,,, is it because of the counter communication they were exposed to or is it because they are completely oblivious or are they trying to follow some senseless rules and compromise in the wrong place.

    Regardless it’s degraded to lunacy and complete nincompoopery.
     
  7. Budget36
    Joined: Nov 29, 2014
    Posts: 3,613

    Budget36
    Member

    So trans down 2 degrees and pinion up 2 degrees, is still good?- assuming the tail of the tranny is higher than the yoke on the rear.

    I mean I'm totally fucking confused now.

    No worries, I don't work tomorrow, I can have another Silver Bullet.
     
  8. anthony myrick
    Joined: Sep 4, 2009
    Posts: 5,930

    anthony myrick
    Member

    What’s the driveshaft angle?
    Position higher or lower is irrelevant.
     
  9. Budget36
    Joined: Nov 29, 2014
    Posts: 3,613

    Budget36
    Member


    Well in most vehicles, except extreme builds, that question is irrelevant, right?

    So say I have a '53 Chevy that had a 6 in it, and I wanted to put a V8 and a upgraded rear in it.

    Kinda covers 90%+ on this site, right?

    So tranny down 2, pinion up 2, works.

    Am I right, or am I wrong?
     
  10. gimpyshotrods
    Joined: May 20, 2009
    Posts: 17,384

    gimpyshotrods
    ALLIANCE MEMBER

    This is the drive shaft found under most 4x4 rigs.
    [​IMG]
    Note that it has three u-joints. Two are in an articulated arrangement (linked to each other, with a ball socket). The movement of those two is relational to each other. They do not move independently.

    I used to drive an XJ Cherokee, with two of these, and 12" of lift, and no vibrations.

    A driveshaft such as this is unlikely to be needed in a hot rod, unless it has a very short wheelbase, with a large difference in tail shaft and pinion heights.
     
  11. Of course ,,,, it’s irrelevant all of it.
    Draw a measured picture and post that. Your best bet.

    If a guy knows drivelines ,,, even if he don’t know up from down or parallel from opposing or when to add nor when to subtract ,,,he can tell you if it will work
     
  12. anthony myrick
    Joined: Sep 4, 2009
    Posts: 5,930

    anthony myrick
    Member

    The drive shaft angle is missing.
    You have to have a trans, driveshaft and pinion angle to determine if it’s good to go.
     
  13. Budget36
    Joined: Nov 29, 2014
    Posts: 3,613

    Budget36
    Member


    No, not in the majority of things built.

    Say I take a closed driveline '35 Ford PU and want to put in a '65 Mustang rearend in it. After I either convert or change the transmission, I'm left with installing the rearend, and possibly adjusting the engine/tranny.

    I'll set the tranny down 2 degrees, and pinion up 2 degrees.

    Works for me, but I've never built a "in the weeds", etc, type of vehicle. Lowered some, raked some, etc, but never went for a head turner.
     
  14. anthony myrick
    Joined: Sep 4, 2009
    Posts: 5,930

    anthony myrick
    Member

    Thanks for that explanation
     
    Cosmo49 likes this.
  15. anthony myrick
    Joined: Sep 4, 2009
    Posts: 5,930

    anthony myrick
    Member

    Yep. But to calculate the operating angles of the u joints a drive shaft angle is needed.
    I severely lower stuff so I have to use this.
     
  16. anthony myrick
    Joined: Sep 4, 2009
    Posts: 5,930

    anthony myrick
    Member

  17. kevinrevin
    Joined: Jul 1, 2018
    Posts: 53

    kevinrevin
    Member
    from East Texas

    Just to stir things up a bit, how does driveshaft length play into the mix?
     
  18. Budget36
    Joined: Nov 29, 2014
    Posts: 3,613

    Budget36
    Member


    I see where you're coming from now.

    Back to our regularly scheduled program;)
     
  19. Thanks but That thing only works if the operator knows not to turn themselves around and not reverse up from down.
     
  20. anthony myrick
    Joined: Sep 4, 2009
    Posts: 5,930

    anthony myrick
    Member

    I banged my head against the wall a few times.
    Wish this thread was around when doing it.
    21A0F24C-16BD-438B-9D02-A106F48068A8.jpeg
    This was the last one I set up.
     
  21. anthony myrick
    Joined: Sep 4, 2009
    Posts: 5,930

    anthony myrick
    Member

    I think your explanation clarified that well.
    It will be used the next time it comes up in class.
     
    Last edited: Feb 13, 2020
    31Vicky with a hemi likes this.
  22. Trigonometry,,,,
    First is the elevation difference between trans and diff then the distance between them.
     
  23. anthony myrick
    Joined: Sep 4, 2009
    Posts: 5,930

    anthony myrick
    Member

    The school bus got a 2 piece.
    It helped with how low it is.
    I set up a 944 with a blown sbc for my old boss.
    An old school drag guy built the chassis. He set the pinion up,(yoke end pointing downward towards the floor) and the engine with a slight angle downward. It had a very bad angle on the rear, like 7 or 8 degrees. I was told it was set that way to maximize launch at the track. Hmmmm
    The boss wanted it set up for the street. This meant reworking the 4 bar to get a usable driveline angle. I also changed engine height. Like to never got my boss to understand why I needed him to clarify ride height before I moved anything due to how extremely low he wanted it.
     
  24. The Shift Wizard
    Joined: Jan 10, 2017
    Posts: 2,007

    The Shift Wizard
    ALLIANCE MEMBER

    I know that you know what you're talking about. Consider it a compliment when I say, I don't skim your posts. I have no problem if you were made Moderator For A Day so you could clean up the too many pinion angle threads and the too much misinformation posts.
    I see the misinformation posters as falling into two categories. My earlier post was not meant to extend any grace to the first category of mouth breathers who don't have a clue. Thirty days in the electric chair seems about right.
    But the other category of perps who seem to have it figured out and are only guilty of going left to right for the front angle but then switch backwards to right to left for the back, pinion angle; those in that category I was suggesting letting them off with a pistol-whipping and a warning. They probably have enough human DNA to be allowed to reproduce.
     
  25. V8 Bob
    Joined: Feb 6, 2007
    Posts: 2,640

    V8 Bob
    ALLIANCE MEMBER

    I've read that "broke back" drivelines (tranny and pinion down) place the joints out of phase, just don't know the details. Some late model Studebakers are one early example.
     
  26. Great post shift wizard.
    Nicely worded and great points.

    3 categories figuratively seems like this
    B7565DC1-E181-47DA-81AC-DFCFBA6D5805.jpeg

    Here’s the results in reality

    889C5DD6-5082-49CF-B1E7-786B0D44E325.jpeg

    I’d really like to comment on V8 bobs post,
    But I’m not going to ask him which side of the car he’s standing on or if he’s following the rules for reading a slope, because one really needs that information. “Broke back” seems to imply opposing with the trans down towards the rear and pinion up towards the rear,,, but he said trans down pinion pinion down and that expressly describes parallel.

    The trigonometry calculator won’t give correct information if the slopes are messed up.
    I understand that math isn’t everyone’s strongest suit, but this driveline angle stuff is nothing more than a simple trigonometry problem.
     
    Last edited: Feb 14, 2020
  27. lake_harley
    Joined: Jun 4, 2017
    Posts: 1,017

    lake_harley
    Member

    Boy oh boy....have I ever heard my share of that BS in my shop. I had a pretty good race parts business going for a number of years and guys were always talking about setting pinion angle (downward at the yoke end of the pinion) for forward bite. Lot's of "discussion" about that on many occasions! No one seemed to grasp that from a traction standpoint that it didn't matter if the pinion came into the rearend from the top, front or back it didn't make any difference to the relationship between the pinion and ring gears.

    Lynn
     
  28. anthony myrick
    Joined: Sep 4, 2009
    Posts: 5,930

    anthony myrick
    Member

    And there wasn’t enough adjustment in the 4 link to correct it.
    We had to shorten 2 bars and make 2 longer bars to fix it.
     
    31Vicky with a hemi likes this.
  29. jaw22w
    Joined: Mar 2, 2013
    Posts: 1,037

    jaw22w
    Member
    from Indiana

    I had all the geometry, trig, calculus, etc. courses in high school and college. Made good grades, too. I never used any of it. As a result, 50 years later, I remember very little trig and no calculus, but I can set up a driveline. As 31 Vicky states, it can be solved with trig, but remembering your trig is not necessary to setting up driveline angles. Don't let your lack of trigonometry scare you away from solving this problem. Understanding of positive and negative angles and a little simple addition and subtraction will get you there.
     
    31Vicky with a hemi likes this.

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