Announcement

Collapse
No announcement yet.

'53 Commander Coupe - driveshaft is not the Beach Boys "Good Vibrations"

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • #31
    Originally posted by Dwain G. View Post
    I don't think there is an official 'as-built' specification published for those angles. The V8 engine does sit at a steep angle, and 7 1/2 degrees doesn't appear to be too far off. Still, I'd probably try to raise the rear of the engine to reduce that a bit.
    After the first 6,000 or so cars, the rear axle pinion angle was lowered 4 degrees. The memo I have does not say what the old or new angles were, but it probably did end up at or near the -1 degree you read.
    I'm not sure I understand what you meant when you said "Horizontally, the engine and pinion are parallel?
    Sorry that I had not replied to the last question. I meant that I confirmed that the engine and rear axle are at exactly 90 degrees to one another, or that the pinion and engine are parallel with the center line of the car.
    sigpic
    Old Car Guy....New Stude Guy

    Comment


    • #32
      Update:

      Tires and wheels are now all round, true, and in balance.
      No launch shudder from driveshaft.
      Vibration persists above about 30 mph and is constant, whether accelerating, decelerating, or holding speed steady. It is not as severe at 55 to 60 mph.
      Frustration also persists, although I feel that I am getting closer (much improved from first drive).

      Next, I will play with phasing of the shaft, as I feel that, not balance, is a significant part of the problem.
      I am fortunate in that when the shaft was balanced, the factory weight was removed from the rear shaft and no weights needed to be added. This should at least allow me to try the different positions without too much concern for balance. If changing the phasing (I hope back to in-phase) improves things immensly, I will probably have it rebalanced in the new phasing, just to be safe.
      sigpic
      Old Car Guy....New Stude Guy

      Comment


      • #33
        Something way way back in my memory says that some C/K Studebakers had the yokes welded 8 degrees out of phase on one of the two driveshafts to combat vibration. Might give you something to ponder..now I really can't remember if I read it, or was told it, or if it's an Studefied urban legend...just remembered it. Really hoping you get to the bottom of your bad vibes as I'm sure a lot of us can benefit from the solution. Good luck, keep at it. Junior
        sigpic
        1954 C5 Hamilton car.

        Comment


        • #34
          I was wondering ,what do you have to do phase the driveshaft? ?

          Comment


          • #35
            Originally posted by 14x7 View Post
            I was wondering ,what do you have to do phase the driveshaft? ?
            Phasing involves rotating the sliding spline to align the yokes of the universal joints. When a pair of shafts are "in phase", all three yokes pointed toward the pinion (rear of transmission, sliding yoke at front of second shaft and rear of second shaft are in line. Right now mine has yoke at the rear of transmission 90 degrees to the other two (as it supposedly was from the factory).

            To put them in phase, I need to slide the spline out and re-insert it in "in-phase" alignment. The spline is held from sliding out by a large nut just behind the carrier bearing. The corners of a square plate are bent over to lock the nut. I will mark the yoke's present position relative to the front shaft yoke, remove the rear shaft by loosening the nut and the u-joint at the pinion, slide it out and reposition. For now, I will leave the tabs unbent so I can try it in different positions as might be necessary. I can put it in phase or out of phase in increments dependent on the number of teeth on the spline. I believe it amy be a twelve-tooth spline, so it can be phase in 30 degree increments, if that proves necessary.

            I hope that explanes it.
            sigpic
            Old Car Guy....New Stude Guy

            Comment


            • #36
              Is the "vibration" something you hear ( booming, shift linkage buzz, ), something you see (mirror vibration/motion, seat back quiver) or something you feel? If you feel it, is it just in the steering wheel, or the seat? Does it seem to be in the centter of the car, the front, or the rear?

              Comment


              • #37
                It is a shudder at driveshaft speed. It does not seem to be balance related, and is there even as I coast with the clutch disengaged. It shakes the whole car, probably at the center. I do not feel it in the front end (steering wheel).
                Last edited by irishjr; 04-10-2011, 04:00 AM.
                sigpic
                Old Car Guy....New Stude Guy

                Comment


                • #38
                  SUCCESS!

                  With the driveshafts in phase with one another, the car goes smoothly down the road!

                  There is a launch shudder, for which I intend to make traction bars or a slapper of some sort. That is minor compared to my issues with the "at-speed" vibration.

                  BTW, I read on another thread about the vibration problems where the owner was so frustrated he tried a shaft out of another Studebaker and, GUESS WHAT, the vibration went away. Could it be that he did not understand the phasing issue and the replacement was a correctly-phased shaft?

                  I'm feelin' GOOD! Now back to working on the '40 Ford.
                  Last edited by irishjr; 04-10-2011, 06:16 PM.
                  sigpic
                  Old Car Guy....New Stude Guy

                  Comment


                  • #39
                    Glad you got it figured.

                    Comment


                    • #40
                      Attached is the service letter that describes the change in driveshaft assembly. It was written in 1952 specifically for cars with automatic transmission, but it appears that Studebaker began assembling all the two-piece car driveshafts this way.
                      I have found that in many cases one has to ignore the manual and experiment with the location of the center support mount and the driveshaft assembly.



                      "Burning Bridges...Lost Forevermore"......

                      Comment


                      • #41
                        Thanks, Dwain G.-

                        I appreciate seeing the service bulletin, but still wonder at what the engineers were thinking.

                        Obviously my driveshaft was assembled out of phase 90 degrees from the factory and that eliminated the launch shudder. Unfortunately, it also caused the cruising speed shudder. I thought of trying a partial phase change, i.e., 22-1/2 degrees that would be easy by moving the spline one tooth (16-tooth spline) and see what happens. It only takes about 15 minutes on a lift and would be easier than building traction bars, especially if it works.
                        sigpic
                        Old Car Guy....New Stude Guy

                        Comment


                        • #42
                          The symptoms in the factory bulletin are consistent with "secondary couple" issues that result from U-joints transmitting high torque (low gear) while operating at an angle. Note they say easing off the throttle will cause the car to " not remain in the vibration state." I'm aware Rotating the driveshaft yoke "out of phase" has been used at times to reduce the "secondary couple" shudder under load, but it has to applied carefully since it brings on the generally undesirable effect of passing "non constant velocity" to the next component down stream.

                          I'm confused.
                          On April 6 you said the tire work improved "the vibration." And there was no "launch" (starting from rest, related to torque?) shudder.
                          Now after standard phasing there is "launch shudder" (although fairly minor) and some much more noticeable "at speed" vibration that is not load or engine speed related.
                          Driveshaft balance or stiff u-joints exert their evil based on driveshaft speed. Load does not change them. If the frequency of vibration is indeed now at 1X driveshaft rpm (that would need to be measured to be sure) I'd be measuring dirveshaft runout (front rear and middle on every tube) on the car, asking the balance shop how they fixtured the driveshafts for balancing and how much runout the tubes had when fixtured that way, and confirming every u-joint operates smoothly in both directions.

                          Comment


                          • #43
                            Originally posted by Dan Timberlake View Post
                            The symptoms in the factory bulletin are consistent with "secondary couple" issues that result from U-joints transmitting high torque (low gear) while operating at an angle. Note they say easing off the throttle will cause the car to " not remain in the vibration state." I'm aware Rotating the driveshaft yoke "out of phase" has been used at times to reduce the "secondary couple" shudder under load, but it has to applied carefully since it brings on the generally undesirable effect of passing "non constant velocity" to the next component down stream.

                            I'm confused.
                            On April 6 you said the tire work improved "the vibration." And there was no "launch" (starting from rest, related to torque?) shudder.
                            Now after standard phasing there is "launch shudder" (although fairly minor) and some much more noticeable "at speed" vibration that is not load or engine speed related.
                            Driveshaft balance or stiff u-joints exert their evil based on driveshaft speed. Load does not change them. If the frequency of vibration is indeed now at 1X driveshaft rpm (that would need to be measured to be sure) I'd be measuring dirveshaft runout (front rear and middle on every tube) on the car, asking the balance shop how they fixtured the driveshafts for balancing and how much runout the tubes had when fixtured that way, and confirming every u-joint operates smoothly in both directions.
                            I didn't realize how bad the wheels and one tire were until it was up on a lift and running in gear. In order to eliminate possibilities as a vibration source, I decied to get the tires fixed first before doing anything else with the shaft. (Scientific Method - CHANGE ONE THING AT A TIME) Once that was taken care of, and with the shaft in stock configuration (90 degrees out of phase and carrier in hole position No. 1), the car shuddered at cruising speed but had no noticeable launch shudder (standing start shudder probably due to pinion slap). Today, I put the shaft "in phase" and the cruising shudder went away, but the launch shudder is now evident. While this is bothersome, it is not as bad as having the shudder at cruising speed.

                            As to the driveshaft runout, I may need to have the shaft re-tuned by the shop. Per my instructions, they balanced it with the two shafts 90 degrees out of phase. At that time, they had to straighten the back shaft (a little heat in two places and there are no weights. When putting it back into phase, there may indeed be some runout or imbalance, but with no cruising shudder, I think it would be very minor.
                            sigpic
                            Old Car Guy....New Stude Guy

                            Comment


                            • #44
                              Here is a vibration measurement I made on my old RWD Volvo's steering wheel running on the highway.
                              I can "feel" vibration in the steering wheel at that speed.
                              Because there is a "spike" visible at ~ 900 rpm ( the wheel/tire rotating speed) I will be checking the tires for runout, and if that is OK getting them balanced.
                              I will not have any work done on the driveshaft since the vibration is not at it's running speed of ~ 3400 rpm.
                              Attached Files
                              Last edited by Dan Timberlake; 04-15-2011, 08:44 AM. Reason: left off attachement

                              Comment


                              • #45
                                Think of it this way.
                                The crankshaft and the pinion need to be parallel.
                                not 'in line', but parallel.
                                If your pinion is down 4 degree's (from level), then your crank needs to be the same.
                                The reason is to make the rollers in the u-joint oscillate.
                                If they don't, the rollers will 'brinell' and groove the u-joint trunions and cups and wear out prematurely.

                                Originally posted by junior View Post
                                I read the paper that Pat Dilling posted a link to, and I'm having a huge mental block here. You know how you've been told something your whole life, and then someone tells you something completely opposite your brain just flat-out tells you it's all wrong. If I understand the artical, and what Sals54 is saying, if my engine/trans points down 4 degrees, then I could set my pinion angle to point up 4 degrees (this seems right), or I could set the pinion angle to point down 4 degrees (this seems totally wrong). If I set it to point down 4 degrees this would allow me to run a single driveshaft without tunnel mods? This just seems so backwards. Any thoughts? Sorry for the tangent on this post, but its kinda all sorta related isn't it? Thanks, Junior.

                                http://www.airridetalk.com/articles/...-enigma_2.html
                                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

                                Working...
                                X