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Driveshaft setup

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  • Driveshaft setup

    finally got an opportunity to check the driveline angles on my '55 coupe; I'm using pretty much all the driveline parts from a '63 C-K. I believe that I have all the correct mounts, spacers, etc. for the car. Here's my angles:

    tailshaft of transmission, 9 degrees down

    driveshaft, 4 degrees down (towards rear of car)

    rear axle pinion, 4 degrees down

    this means that I have an angle of 5 degrees through the front U-joint and *8* degrees through the rear one! Can this possibly be right? I thought that a good rule of thumb was to aim for an equal angle between 0 and 3 degrees at both ends.

    I could try a thicker spacer between the trans. mount and bellhousing, and it's clear that I will have to rotate the pinion up significantly... I'm just curious if, say, a stock '63 Hawk would have similar angles, as I have not heard of an unusual problem with them vibrating badly or spitting U-joints on the ground.

    nate

    --
    55 Commander Starlight
    http://members.cox.net/njnagel
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    55 Commander Starlight
    http://members.cox.net/njnagel

  • #2
    Ignore the driveshaft angle measurement.
    Couple questions...
    1) Is the car setting on all fours?
    It should be.
    You can do this with jackstands if you set all four jackstands at the same height and set
    the rear end on two and the a-arms on two.
    The floor should be flat, but doesn't have to be perfectly level.
    What you want is the car setting at ride height with all the weight on
    the suspension.

    If your trans is indeed nine degree's down, then the pinion should be
    nine degree's up.
    (A lot of guys take two degree's out (down) for spring wrap up, but
    that's drag racer stuff)...


    The front angle should be zero'd out by the back angle.
    (and technically the side angle of the trans to the side angle of the
    pinion).


    If your numbers are accurate, then the diff needs to be rotated up.
    Ignore the driveshaft angle.
    Hope the info helps.
    Jeff [8D]



    HTIH (Hope The Info Helps)

    Jeff


    Get your facts first, and then you can distort them as much as you please. Mark Twain



    Note: SDC# 070190 (and earlier...)

    Comment


    • #3
      Jeff,

      the end of the trans and the axle pinion are *both* pointing down... therefore this isn't like a normal driveshaft setup, I think they call this a "broken back" arrangement, where both the U-joints are bent the same way (as opposed to the normal way which is equally and in opposite directions) that is why I'm taking the driveshaft angle into account. Yes, the car was sitting on all fours on the ground when I made these measurements.

      I guess I'm curious if the pinion angle changed when they went to the one piece driveshaft, by means of moving the springs... I guess there's nothing for it but I do need to just shim the pinion up and remeasure. Also curious if the stock driveshaft angles for, say, a GT Hawk were similar - i.e. they really did have 5 degrees or more angle on the U-joints from the factory?

      nate

      --
      55 Commander Starlight
      http://members.cox.net/njnagel
      --
      55 Commander Starlight
      http://members.cox.net/njnagel

      Comment


      • #4
        If you have a one piece driveshaft, the info I gave you is correct.
        If you are down on both the pinion and the trans (crankshaft centerline) there will be a bad vibration because the ujoints will be fighting each other.

        You should look like this, even if the numbers are different.
        (If your trans is 'down' then the pinion should be 'up', as long as the numbers are close to zero when combined. You can run a degree (or two) 'down' at the pinion and it will zero itself out under acceleration. But you aren't accellerating a street car all the time like a drag car, so setting it as close to zero is best for street cruising)

        2 piece, and three piece driveshafts are a bit different, but the concept is the same. On a 2 piece driveshaft, all three working angles should add up to zero.
        One thing you don't want is a straight line shot.
        You need some misalignment of the driveshaft to the yoke (and pinion) to oscillate the u-joint, otherwise the rollers will brinell into the cross and wear out prematurely.
        Jeff



        quote:Originally posted by N8N

        Jeff,

        the end of the trans and the axle pinion are *both* pointing down... therefore this isn't like a normal driveshaft setup, I think they call this a "broken back" arrangement, where both the U-joints are bent the same way (as opposed to the normal way which is equally and in opposite directions) that is why I'm taking the driveshaft angle into account. Yes, the car was sitting on all fours on the ground when I made these measurements.

        I guess I'm curious if the pinion angle changed when they went to the one piece driveshaft, by means of moving the springs... I guess there's nothing for it but I do need to just shim the pinion up and remeasure. Also curious if the stock driveshaft angles for, say, a GT Hawk were similar - i.e. they really did have 5 degrees or more angle on the U-joints from the factory?

        nate

        --
        55 Commander Starlight
        http://members.cox.net/njnagel
        HTIH (Hope The Info Helps)

        Jeff


        Get your facts first, and then you can distort them as much as you please. Mark Twain



        Note: SDC# 070190 (and earlier...)

        Comment


        • #5
          Just a comment for the younger guys trying to "rotate" the rear end angle up or down.

          In the old days with leaf spring front axles it was common to use wedge shaped shims between the spring main leaf and axle mounting flange to adjust caster angle to stop shimmy when springs fatigued with age. These wedges came in 1/2 degree increments so you could get a 2-1/2 degree or 3 or 4 degree shim depending on the amount of angle you wanted to obtain.

          They are "U" shaped so you just loosen the axle U bolts and drive the shim in around the center pin and torque the U bolts back up snug again.

          A truck spring shop would be a good place to visit to get a selection to try out in adjusting your rear end attitude. Stude8

          Comment


          • #6
            Nate ... you got that spacer on the drivers side only? Or is this an
            automatic trans? The manual doesnt have it.

            I know that my Avanti looks to be down in the rear with the T86 trans.
            I sometimes think I am missing something at the rear mount under the
            bellhousing. Hmmmmm.

            Tom

            '63 Avanti, zinc plated drilled & slotted 03 Mustang Cobra 13" front disc/98 GT rear brakes, 03 Cobra 17" wheels, GM alt, 97 Z28 leather seats, soon: 97 Z28 T-56 6-spd, Ported heads w/SST full flow valves, 'R3' 276 cam, Edelbrock AFB Carb, GM HEI distributor, 8.8mm plug wires
            '63 Avanti R1, '03 Mustang Cobra 13" front disc/98 GT rear brakes, 03 Cobra 17" wheels, GM alt, 97 Z28 leather seats, TKO 5-spd, Ported heads w/SST full flow valves.
            Check out my disc brake adapters to install 1994-2004 Mustang disc brakes on your Studebaker!!
            http://forum.studebakerdriversclub.c...bracket-update
            I have also written many TECH how to articles, do a search for my Forum name to find them

            Comment


            • #7
              No single spacer - you are thinking of the automatic. The 4-speed cars *only* had a spacer between the single rear mount and the bellhousing, for some reason the 3-speed cars did not have this. I did put some spacers in there; they were the thinner of the two variants which I was told were correct for a C-K (the thicker ones were apparently for a Lark.)

              I'm going to try to measure JP's R2 '63 tomorrow and see what if anything is different there. I suspect that much of the adjustment needs to be done at the rear axle as I'm using a TT rear from a later car on the '55 springs, but with a single piece driveshaft, so who knows what changes with the springs or the position of the spring pads between '57 and '58.

              nate

              --
              55 Commander Starlight
              http://members.cox.net/njnagel
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              55 Commander Starlight
              http://members.cox.net/njnagel

              Comment


              • #8
                Nate,
                Don't make it harder than it needs to be.
                Just add a couple of wedge shim plates and be done with it.
                http://store.summitracing.com/partde...5&autoview=sku

                A 4WD shop will have these in all sorts of degree's, as the truck guys raise their stuff so much the diff's (both front and rear) need to be rotated to keep the alignment within reason.
                Jeff[8D]




                DEEPNHOCK at Gmail.com
                Brooklet, Georgia
                '37 Coupe Express (never ending project)
                '37 Coupe Express Trailer (project)
                '61 Hawk (project)
                http://community.webshots.com/user/deepnhock

                HTIH (Hope The Info Helps)

                Jeff


                Get your facts first, and then you can distort them as much as you please. Mark Twain



                Note: SDC# 070190 (and earlier...)

                Comment


                • #9

                  Comment


                  • #10
                    Just measured JP's R2... angles are all identical to the ones I measured on my car with the exception of the pinion. A web site recommended measuring the tailshaft angle by using the starter motor body, makes sense to me and I didn't have to drop the driveshaft then. When I did it that way both cars measured 8 degrees down. driveshaft remains 4 degrees down, my pinion is 4 degrees down but JP's is pretty close to dead level. So the factory did use the "broken back" driveshaft layout, but apparently something changed WRT the rear springs. Good news is I have a set of wedges that measure out at about 4 or 5 degrees - I thought they were 2 degree wedges but the angle finder says otherwise. Break out the air tools!

                    It would appear that with everything factory, the U-joints run about 4 degrees. Not ideal, but...

                    nate

                    --
                    55 Commander Starlight
                    http://members.cox.net/njnagel
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                    55 Commander Starlight
                    http://members.cox.net/njnagel

                    Comment


                    • #11
                      While it's certainly desirable to have both U joints running at the same angle to cancel out speed variations, you must keep in mind that no matter how carefully you align the two, under use the two joints (especially the rear) are always changing angles. Things such as a full tank or nearly empty gas tank, passengers or none, acceleration or decelleration, braking, loads in the trunk or bumps are all going to change the angle. The average U joint is functional up to around 45 degrees and the rotational differential is fairly minimal under 20 degrees. I've put many years and plenty of hours of use on farm implements that had grossly unequal angles on the power take off shafts with no ill effects. I have a rotary mower with a 5' long pto shaft and the pivot point of the hitch is 18 inches from one end. When making a 45 degree turn, the front U joint is at a 32 degree angle and the rear at 13 degrees which is quite unequal. Also throw in the fact that vertically, the rear joint runs at 7 degrees and the front at 10 degrees when on a prefectly flat surface. Throw in rough ground with humps and dips, and those angles are also going to change with most of the change being at the front joint. It's ran that way for decades and promises to continue doing so.

                      The point I'm trying to make is that while having both joints at equal angles is certainly desirable, they aren't going to stay that way when in use. Unequal angles isn't the end of the world and therefore I don't lose sleep over it. Nor do I bother to make such adjustments because the rewards of alignment won't offset the effort I'd put into it. If I'm going to spend time busting my knuckles, I want to be doing something that will at least be noticable afterwards. Now if I didn't have anything else to do with my life or had a pickup jacked up 4 feet in the air, that'd be a different story.

                      Comment


                      • #12
                        Can't beat experience...
                        But PTO's don't usually run at the same RPM a car driveshaft runs at speed.
                        And you do notice the increase in vibration on your PTO when you kink it over like that.
                        The increase in the angle (even if the other angle cancels out the difference...which it should) increases the accelleration and decelleration of the rollers as the angle increases. You don't want zero, and you also don't want 45 degree's. And that accelleration and decelleration happens twice per revolution. The amount of degree's of change on a Stude between empty and full isn't more than a few degree's anyways, so if you can get it close, you should see a minimum of vibration. And that's not counting a balance vibration.
                        A lot of things can affect balance vibration. Things like U-joint 'stack up' tolerances, age (and RPM) of balancing equipment, etc. Stude used to also rotate the front yoke (on the tube) one degree to prevent sympathetic harominics.
                        Driveline theory is a wierd realm all unto itself, and a Stude is a simple machine. We shouldn't overcomplicate things. And tossing theorums out to an engineer is like taunting a yappy lil' dog..
                        Nate'll get it sorted out OK... After a couple hundred pages of reading.
                        (JP'd just jam it in there and run the snot out of it[])..
                        They both work pretty well..
                        Jeff[8D]



                        quote:Originally posted by John Kirchhoff

                        While it's certainly desirable to have both U joints running at the same angle to cancel out speed variations, you must keep in mind that no matter how carefully you align the two, under use the two joints (especially the rear) are always changing angles. Things such as a full tank or nearly empty gas tank, passengers or none, acceleration or decelleration, braking, loads in the trunk or bumps are all going to change the angle. The average U joint is functional up to around 45 degrees and the rotational differential is fairly minimal under 20 degrees. I've put many years and plenty of hours of use on farm implements that had grossly unequal angles on the power take off shafts with no ill effects. I have a rotary mower with a 5' long pto shaft and the pivot point of the hitch is 18 inches from one end. When making a 45 degree turn, the front U joint is at a 32 degree angle and the rear at 13 degrees which is quite unequal. Also throw in the fact that vertically, the rear joint runs at 7 degrees and the front at 10 degrees when on a prefectly flat surface. Throw in rough ground with humps and dips, and those angles are also going to change with most of the change being at the front joint. It's ran that way for decades and promises to continue doing so.

                        The point I'm trying to make is that while having both joints at equal angles is certainly desirable, they aren't going to stay that way when in use. Unequal angles isn't the end of the world and therefore I don't lose sleep over it. Nor do I bother to make such adjustments because the rewards of alignment won't offset the effort I'd put into it. If I'm going to spend time busting my knuckles, I want to be doing something that will at least be noticable afterwards. Now if I didn't have anything else to do with my life or had a pickup jacked up 4 feet in the air, that'd be a different story.
                        HTIH (Hope The Info Helps)

                        Jeff


                        Get your facts first, and then you can distort them as much as you please. Mark Twain



                        Note: SDC# 070190 (and earlier...)

                        Comment


                        • #13
                          That's what I did with the Caddy into the truck, just bolted the engine in where it would sit and called it done. Having N8 around made me want him to check the angle and he did. I'm running about 6 degrees down in front and 3 in the rear and I'll live with that.

                          JDP/Maryland

                          64 Daytona HT/R2 clone
                          63 GT R2
                          63 Lark 2 door
                          62 Lark 2 door
                          60 Lark HT-60Hawk
                          59 3E truck
                          58 Starlight
                          52 & 53 Starliner
                          51 Commander

                          JDP Maryland

                          Comment


                          • #14
                            For what it's worth...I agree with what Jeff is saying.

                            The driveshaft doesn't even know it's own name why would it know what angle it should be set at. Measuring two cars as old as these suckers are means very little as to the real dynamics the u-joints go thru.
                            I believe I read somewhere in the Stude manual that the u-joints (per tube) should be seperated rotationally by 12 degrees...."no" one does that anymore either.

                            Mike

                            Comment


                            • #15
                              See... I know you only too well
                              Jeff[8D]


                              quote:Originally posted by JDP

                              That's what I did with the Caddy into the truck, just bolted the engine in where it would sit and called it done. Having N8 around made me want him to check the angle and he did. I'm running about 6 degrees down in front and 3 in the rear and I'll live with that.
                              HTIH (Hope The Info Helps)

                              Jeff


                              Get your facts first, and then you can distort them as much as you please. Mark Twain



                              Note: SDC# 070190 (and earlier...)

                              Comment

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