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Thread: Rear Axle 53 Champion

  1. #41
    Champion Member
    Join Date
    Jun 2017
    Well according to the Spicer article Junior referenced I was calculating the drive line angle all wrong. You have to calculate the "True" universal joint angle when its a compound angle. Compound meaning both vertical and horizontal.
    If I did my math right (and it gets harry) here is what I have. by using their chart on page 8 I have identified the horizontal angle as 4.5 degrees.

    The formula from spicer is; the square root of the horizontal angle identified by their chart squared + the trans output shaft verticle Ujoint angle squared.
    So for the transmission output shaft compound angle = Horizontal 4.5 degrees squared = 20.25. plus vertical = 0.3 squared = .09. That sum is 20.34 and the square root of that = 4.5

    And now at the pinion end
    Horizontal angle 4.5 squared = 20.25 plus vertical pinion ujoint angle 1.0 squared = 1. So 20.25 + 1 = 21.25 and the square root of that = 4.6

    So according to their article and if I did it right, the total driveline angle = 0.1 They say the minimum should be at least 1 in order to allow the needle bearings in the U joints to work. But in any case the individual angles should not be higher than 3.

    It would be easier and less painful just to go beat my head against a wall! :-0

  2. #42
    President Member r1lark's Avatar
    Join Date
    Oct 2004
    Winston-Salem, NC, USA.
    Blog Entries
    Couple of ideas, hopefully you have all these bases covered already.

    Have you been able to determine the vibration frequency? If you assume a 1 X rpm frequency (which is not always the case but a good place to start) you can use a simple Briggs&Stratton tachometer - technically a sirometer ( This should give you a good idea of whether the vibration is coming from the driveshaft or the wheels/drums/etc. Quick and dirty.

    Measure where the vibration is the most pronounced (maybe the floor pan in the rear of the car?) and have someone hold the tach in that area while the car is being driven and record the results.

    if a measurement and calculation is made that doesn’t exactly fit any component that would be at 1 X rpm frequency, it will be necessary to start looking at components that could have vibrations of 2 X rpm frequency, and so on. You can buy more expensive vibration equipment that will allow direct reading of the frequency, but I have not had to do that in the past.

    Engine vibrations have a specific frequency based on the number of cylinders - can't remember for sure but think it's 1/2 the number of cylinders. So a 4 cylinder would have a 2 X rpm frequency, etc. Check that however, I may be remembering wrong.

    Another simple check - driveshaft runnout with it installed in the car. For example, I have seen worn rear axle yokes that the U-joint caps didn't fit tightly into (ie, side-to-side movement), and so the driveshaft was not concentric with the pinion..........and caused a vibration that took a while to find.

    Is there a possibility that the rear axle housing was warped when the 4-bar brackets were welded on? If so, could that possibly cause some hard to find vibration?

    I know these are some off the wall items, but sounds like you have covered all the 'normal' bases already (at least once or more).
    Winston-Salem, NC
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  3. #43
    Champion Member
    Join Date
    Jun 2017
    I don't have anything to sample vibration frequency or a chart to compare the results of what a tool of this nature might give you.
    When I took the driveshaft in to a driveline shop for balancing, new Ujoints were installed as well as a new ford rear mounting flange. since the driveshaft balanced out fine, I wouldn't think there would be any loose fitting components.

    Rear axle housing warped? Possibly - since it was a hack job anyway. If my math calculations were right on the compound angles the driveline angles are too high anyway at 4. something. I would have to tighten both the upper and lower 4 link bars on the passengers side only to narrow the horizontal angle to get the driveline angle down to 3 or below, but then the pinion to trans output shaft wouldn't exactly be parallel anymore.

    Found Barry Hackney out of Houston that says he is the biggest Studebaker parts supplier in Texas and has several rear axles. Only an hour of so from Austin. I can get an original Dana 44, drop in a set of leaf springs and get rid of all the whole rear end mess. Of course that means probably modifications to the drive shaft.

  4. #44
    President Member
    Join Date
    May 2012
    Oklahoma City
    I think that before you start disassembling the rear axle set up you should put four good tires and wheels that have been properly balanced on it and take it for a 70 mph ride.

    Now mind you, this is just a rule of thumb, but NORMALLY driveline vibration comes on 45 to 50 mph, and even lower speeds with a shorter gear, so with that 4.11 screw, I would expect 40 - 45 mph.

    Wheel and tire vibrations normally start over 60. There are exceptions. For instance out of round or belt separated tires or bent wheels can be felt at much slower speeds.

    I don't like most aftermarket wheels. Find someone with a nice smooth driving Studebaker or Ford and borrow all four wheels and tires (assuming the tires and wheels fit this car).

    As a last resort, I have an EVA (electronic vibration analyzer) bought from one of the car dealers who went out of business in 2008-9. You plug in all the parameters: engine type, number of cyl, tire size, rear gear, etc. and take it for a drive. The EVA will tell you what is vibrating. Only down side is you will have to pay shipping to Austin, and back to Guthrie, OK.

    But first, I would try different tires and wheels.

    Just my 2 cents. Good luck.


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