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'65 Daytona, Pinion Angle "Broken Back" configuration???

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  • Warren Webb
    replied
    On my 66 Daytona it bothered me that the fan was so close to the radiator at the bottom & how the engine sat low in the rear. When I replaced the 283 overdrive with a 327 4 speed I shimmed up the trans mount as high as I could but still had the low condition. I too used a junk yard driveshaft (from a Chevelle if I remember right) & thought it would work good being it was thicker than what was in the car originally. When all was said & done I drove it fine. No vibrations or issues. I'm sure the driveshaft isnt out of phase like the original but I'm not gonna worry about it.

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  • starliner62
    replied
    Cool video Jeff. Just about straight at the rear yoke under acceleration. I would imagine the spaghetti noodle springs on my lark twist my rear end up even higher.

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  • DEEPNHOCK
    replied
    This video, while drag race oriented, gives you an idea of how the pinion angle changes under accelleration/decelleration....

    http://www.flickr.com/photos/simpkinsfamily/7387713670/

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  • Dan Timberlake
    replied
    The non-constant velocity behavior of a pair of u-joints occurs at twice shaft speed, so it cancels out the same whether the transmission and pinion shafts are parallel or in the "broken back" configuration. The angle between the pinion shaft and driveshaft, and between the transmission main shaft and driveshaft must still be close to equal.

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  • wittsend
    replied
    Allan - Thanks for checking. At this point I think I'll just go forward with my setup (which is what Junior told me to do all along) and see what I have.

    rickhmn2 - That minimum I was able to get the transmission was 7 degrees down. Even at that the transmission was within 1/4" of the tunnel. BTW, the 7 degrees was relevant to the frame rail being at 0 (zero).

    My assumption is that Studebaker ('65 Lark type in my case) went with the "broken back" because the car has about the shallowest driveshaft tunnel I have ever seen. If both the the transmission and the differential point downward the driveshaft can be lower.

    ...

    It has been an interesting journey with this subject. Some adhere to the more conventional angle down (trans) / angle up (differential) of equal angles. The end result being the transmission and differential centerlines are parallel. With the minimum of 7 degrees down on the transmission I was able to achieve I'm not too sure this is viable - at least on this particular car. My understanding is 1-3 degress is desirable.

    While one could do the math and get the right measurement (regardless of the cars inclination) having a zero reference is helpful to the novice. This method also rules out the angle of the driveshaft as relevant.

    ...

    At least as I understand it with the broken back configuration the driveshaft angle does factor in. I was getting what I thought were strange numbers (T=8, DS=4, Dif=0) until I factored all three.

    ...

    The U-joint offset is a mystery to me. I understand about harmonics, but it would seen a compromise at best. Other manufactures don't resort to this method with similar set ups. Studebaker owners have stated to have had driveshafts made up without the offset and without issue.

    Again, thank you to EVERYONE for your help. It was greatly appreciated.

    Tom

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  • alpayed
    replied
    Hi Tom
    I checked my tailshaft today and it has no offset on the yolks. As I said earlier I forgot all about it when I had the shaft made. On my Hawk it does not appear to make any difference.
    Allan

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  • rickhmn2
    replied
    I have a lark with a chevy V8 and I was able to get the engine to about 4 degrees down and set the diff at 4 and a little more up. As others have said the angle of the shaft is completely irrelevant. I have no idea if the broke back configuration will work without the yoke offset but manufactures have all gone to the more conventional arrangement for a reason I presume. As long as you are fabbing things up I'd get conventional angles on it.

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  • alpayed
    replied
    Hi Tom.
    I have been away for a couple of days.
    What you have measured is about where it should be. The 1/2deg probably won't matter. Test drive the car and see if the tailshaft vibrates. You can tell if the 1/2deg is of any concequence by gas on gas off at 60mph. If there is any vibration with gas on (diff wind up) shim the rear engine mounts up a little bit. that will lessen the front angle and increase the rear angle.
    good luck
    Allan

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  • wittsend
    replied
    "you will find that they are out of phase by some 11-13 degrees," / "and most driveline shops would not have a clue to the original Stude OE spec for that any more."

    Apparently few if any. A 100 link per page Google search of "Studebaker drive shaft phase rotation"... and this post is the only relevant thing that showed up.

    No, I have not applied the phase rotation to the Buick shaft. Strange that other cars run the same configuration and don't use it. Is it because of the broken back configuration??? I don't see it mentioned in the other cars that run a "broken back." This is a hobby car that will see a few hundred miles a year unless something is blatantly disruptive I'll live with it.

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  • DEEPNHOCK
    replied
    IIRC, it was a lot less than 11 degree's.. More like 4 or 5 degree's....or less.
    And 'out of phase' is the rotational position of the trunnion position on the driveshaft tube, front to rear.
    I don't think he cut and rewelded his driveshaft tube, and most driveline shops would not have a clue to the original Stude OE spec for that any more.
    IIRC, there was an oscillation frequency issue that was solved by a shift in the phase of the u-joints in relation to each other.
    A cheap band-aid cure for a harmonic issue, which occasionally plagues vehicle manufacturers (think Lark convertible weights by the front end).
    Solutions have to be cheap per unit....

    Originally posted by WCP View Post
    Wittsend, what you observed is the way Studebaker built them - right or wrong. Also if you remove the driveshaft, and eyeball the universal joints, you will find that they are out of phase by some 11-13 degrees, as I recall. Apparently they had their reasons for that setup.

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  • DEEPNHOCK
    replied
    Again...
    The 'plane' that the crankshaft is whatever it is.
    The angle that the driveshaft is at in relation to the crankshaft is what counts.
    If that angle is, say 4 degree's, then the angle between the pinion shaft 'plane' should be -4 degree's in relation to the driveshaft.
    Whatever you have in front you take out in back. It should be as close to zero as possible.
    You could stand the car in it's nose and that relationship would not change.
    You do want the suspension at ride height, so jacking the side of the car up and measuring things from the side is kind of futile.
    You can jack the rear of the car up, and put the rear axle on jackstands and measure it with the front wheels on the ground.
    The crankshaft angle to driveshaft and the driveshaft angle to pinion angle will be the same as if it was on all fours.
    It is not rocket science.
    The reason for needing some angle is to oscillate the u-joint rollers in the caps and on the trunnions, or you will brinnel the rollers into the cap and trunnion and have a short u-joint life.
    Big differences in u-joint angle 'differences front to rear' will cause vibrations.
    The same rules apply for side to side.
    These specs are almost always from the driveline people (Spicer/Dana, etc) and not from the vehicle manufacturer.
    Studebaker bought from vendors and relied on their recommendations and engineering expertise.

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  • wittsend
    replied
    Ok, I spent some more time with the measurements. To insure consistency I made sure I was using a common side of the angle gauge - regardless of the contortions it took to read it.

    I got 8 degrees on the machined end of the output shaft.

    I got 4 degrees on the driveshaft.

    I got 0 (zero) degrees on the pinion yoke (using a long socket on the cap seats).

    So if I do the math (that I still struggle to grasp) I get:

    Output shaft 8 minus driveshaft 4 = 4 degrees

    Pinion yoke 0 (zero) plus driveshaft 4 = 4 Degrees

    For the moment (I'll get to it eventually) I won't sweat the 1/2 degree. I just feel content to be ... that close for now.

    Thank you all for your patience (WCP especially). Hopefully I'm moving forward. I've done all kinds of swaps, rebuilds etc., but this is the first time that I have ever had to deal with driveshafts and pinion angles. I've done two other transmission swaps and the original driveshaft just fit right in. Not this time. Still I'm happy I found an appropriate length shaft with the correct trans yoke and correct rear U-joint for $20!

    Tom

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  • WCP
    replied
    It is all about the driveshaft. The engine angle to the driveshaft should match the angle of the driveshaft to the axle. The angles are measured relative to a level driveshaft. In the so-called "broken back" configuration, Studebaker specifies that the rear angle be 0.5 degrees greater. Measuring the angle of the driveshaft and adjusting the other two angles accordingly, is easier than levelling the driveshaft physically.

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  • wittsend
    replied
    WCP,

    Thank you for replying.

    I have, however, become even more confused - now. I was under the assumption that the angle of the driveshaft is irrelevant. A large number of reputable web sites never factor the driveshaft angle. The only angles they say that matter are that the angle of the engine/trans centerline matched that of of the differential (pinion) centerline. In essence the angle of the driveshaft becomes an irrelevant consequence of the other two angles. In example:

    1. In a "broken back" like the Studebaker if the engine/trans was down -6 degrees (from "level") the differential (pinion) was also to be down -6 degrees (from "level"). Thus making the engine/trans and differential (pinion) centerlines merge (at a point in space) relative to the center of the driveshaft length.

    OR

    2. In a more conventional setup if the engine/trans were down -6 degrees (from "level") the differential was up +6 degrees (from "level"). Thus making the engine/trans and differential (pinion) centerlines parallel to each other and in theory the lines never merging.

    The numbers you give me are as you states from "the manual." So, it is difficult to dispute Studebaker, - but my brain just isn't getting "it."

    I still can't get past the fact that the angle of the engine trans centerline - to the driveshaft, and the angle of the differential (pinion) - to the driveshaft are different. Shifting the numbers across a "zero-ed" driveshaft doesn't alter their relative angles being different even if numerically the become equal through this "zeroing" driveshaft process.

    I'm not trying to be argumentative, I'm just confused. All this being said my angles are very close to those (factory) you listed - even if I'm not understanding them and maybe I'll just leave things were they are - maybe..., until my brain wrestles with me again.

    Thanks, Tom
    Last edited by wittsend; 06-06-2012, 03:07 PM.

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  • WCP
    replied
    I overlooked the fact that you have a GM engine rather that a Studebaker V8. So the engine angle may be a bit different as well as the preferred measurement location. However, the measurement and setup procedure remains the same with final angles less than 5, and 1/2 degree more at the rear.
    My experience is with Stude powered drivetrains.

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