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2-Piece Driveshaft, Phasing and Angles

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  • Drive Shaft: 2-Piece Driveshaft, Phasing and Angles

    I am convinced, of all 57 and earlier Studebakers with 2-piece driveshaft, the worst vibration occurs in 56J (and maybe SkyHawk). The reason is their fiberboard headliner, which reverberates the driveshaft vibration throughout the car. I have owned, worked on and test driven driven probably 10-12 of the 56Js, and the only ones that did not have this noise were those with 1-piece driveshafts and/or cloth headliner. I test drove a 56J with Torqueflight transmission, 1-piece driveshaft and cloth headliner; though the adapter spool was misaligned, there was no driveshaft vibration/reverberation noise. I also drove a 56J with TH400, OEM headliner and 1-piece driveshaft for 41,000 miles, and it had no drive shaft vibration. I also drove a 56J with original 3 speed/OD transmission, 2-piece driveshaft and cloth headliner, and its reverberation was minimal. All others, Ultra and OD, had the vibration and reverberation. The reverberation is the worse than the vibration, since it sounds like a deep base drum coming from overhead.

    I have learned to live with the noise, but recently doing small jobs on the Studes, decided to attempt reduce it in the blue & white 56J. In preparation, I watched several YT videos on driveshaft phasing and angles. I first plan to inspect all as is, for a baseline read. Then install new: rubber between the carrier crossmember and car floor; transmission mount; drive shaft carrier bearing & bushings, and u'joints. (A good idea anyway, because it's been at least 100,000 miles since any of the above were replaced.) I plan to measure angles on the transmission yoke, jackshaft, drive shaft, and differential yoke. If not within spec, will shim the T85 rear up or down; adjust carrier bearing height, and/or install degreed wedges under the rear differential perches. After done, I will continue living with it as, "just a 56J thing". But hope to reduce it at least a bit.
    Last edited by JoeHall; 05-14-2020, 06:49 AM.

  • #2
    I hope you will document your efforts and post pictures if possible. I have found it difficult to find out
    how to determine what the proper angles are. So looking forward to future posts. thanks

    Comment


    • #3
      Originally posted by 5brown1 View Post
      I hope you will document your efforts and post pictures if possible. I have found it difficult to find out
      how to determine what the proper angles are. So looking forward to future posts. thanks
      I believe the vibration is inherent with design. Modern, "constant velocity" joints maintain constant velocity of rotation, while center u'joints, if out of phase, have elliptical (pulsating) rotation in the center. Vibration can be dampened by rubber, i.e. between crossmember and floor, transmission mount, and carrier bearing mount, but will still be present, especially if out of phase. Two-piece shafts with u'joints are also more sensitive to changes in angle due to sags in the above rubber components.

      Agree, phasing for Studes is a mystery. Phasing theory says all bearing surfaces must be in line, front to rear, within 1/2 degree. All 1-piece driveshafts are properly phased at the factory and are non-adjustable. But 2-piece shafts are adjustable (instead of having a blind spline to make them non-adjustable) and there's likely a reason why, but any adjusted variance would violate phasing theory. I found a note I made in the Shop Manual (unsure when, or what my reference was), that the 56J shaft is out of phase 12 degree CCW, viewed from front. I also found a pic of a 2-piece Stude shaft on-line, and it appears about 12 degrees out of phase. But the only way that could be accurate is if the engine and transmission driveline is not centered, front to rear in the car. Also, unsure if it's even possible to offset phasing by 12 degrees, since there'd have to be 30 splines in the junction. Not sure how many splines there are, but believe less than 30. There's no pic of the entire shaft in the Shop Manual, and it only says to mark it before disassembly to maintain phasing and balance.

      Rear height of the car should not matter since the rear spring shackle keeps the rear differential/yoke from tilting excessively, and would only affect driveshaft front/rear angle, not phasing.

      Before buying parts recently, I coulda used the $ toward a custom made 1-piece driveshaft with floating front yoke, to eliminate the 2-piece shaft. That's what I did when I installed a fixed yoke T85 in the 62GT, and there's not even a hint of driveshaft vibration. I noticed it's a fairly popular conversion for some older pickup trucks too, probably for same reasons. Anyway, gonna give it my best shot, and will post results here.
      Last edited by JoeHall; 05-13-2020, 10:16 AM.

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      • #4
        JOE - I chased around a severe vibration in my Sky Hawk drive line for MONTHS. I did EVERYTHING humanly possible to find/cure it...new parts, from the output yolk of the transmission (2004-R) to the pinion gear. We finally nailed it down at a Driveline Shop. Car was on the lift, running, in gear, rear wheels turning at an idle. The brand new carrier bearing rubber mounts were dancing up and down about an 1/8th of an inch. Driveline was in phase, universals were new, the entire Carrier assembly was new. We removed the carrier assembly, the 2 piece drive shaft, installed a new one piece drive shaft(phased the U-joints), and totally cured the problem....AND the reverberation, making the Hawk a pleasure to drive...

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        • #5
          Originally posted by 345 DeSoto View Post
          JOE - I chased around a severe vibration in my Sky Hawk drive line for MONTHS. I did EVERYTHING humanly possible to find/cure it...new parts, from the output yolk of the transmission (2004-R) to the pinion gear. We finally nailed it down at a Driveline Shop. Car was on the lift, running, in gear, rear wheels turning at an idle. The brand new carrier bearing rubber mounts were dancing up and down about an 1/8th of an inch. Driveline was in phase, universals were new, the entire Carrier assembly was new. We removed the carrier assembly, the 2 piece drive shaft, installed a new one piece drive shaft(phased the U-joints), and totally cured the problem....AND the reverberation, making the Hawk a pleasure to drive...
          Yours matches my experience. As mentioned, every 56J with 1-piece driveshaft did not have the problem, and in those with 2-piece driveshaft but cloth headliner, the vibration was less. The worst is 2-piece driveshaft and fiberboard headliner combined, since the floor vibration from the carrier bearing reverberates with the headliner. That's why I suspected Sky Hawks have the same problem.

          But I'm not ready to give up on this 56J's OEM shaft. As you, I tried everything I could think of, to no avail, over 30 years ago, so never bothered to even try with other 56Js later. I've been reading a lot lately; there's the, "Toyota method" of setting up a 2-piece driveshaft, and the, "Spicer method" which is (of course) what Studebaker used. I may need to be creative, i.e. drill additional holes to position the carrier bearing to align the jackshaft with T85 output shaft within 1/2 - 1 degree, and/or install wedges below the differential perches to make the pinion and jackshaft angles parallel within 3 degrees. Biggest problem may be horizontal realignment, if needed.

          From your experience, I know we are both on the same sheet with this confounding vibration, which many do not even believe exists. Stay tuned. LOL

          Thanks for your input.
          Last edited by JoeHall; 05-13-2020, 02:53 PM.

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          • #6
            The most common reasons for driveline vibration are out of phase, runout of shaft or yokes, operating angles, pretty much in that order. In 1952-53 Studebaker began assembling their two piece shafts differently than what is generally considered correct.
            I don't know about a 12ยบ out of phase on a two piece shaft, but Stude certainly did that with most of the one-piece shafts. The specific amount is shown in the specs for each year.
            Sometimes mounting the center support in a set of holes different than what the shop manual shows will help. And as you say, shimming/wedging may be necessary.Click image for larger version

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            If it comes down to a point where you have exhausted all options, try to find a shop that does NVH testing. They often use a tool called 'Chassis Ears'.

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            • #7
              Dwain,
              Thanks for the info, which documents a problem back to 52, but I seriously doubt the factory fix was sufficient to, "eliminate" it. It may have reduced vibration, but likely did not eliminate it. I am half way through a 47 page thread on a Toyota 4-runner forum, and those folks have written volumes on attempts to eliminate their 2-piece driveshaft vibration. A few have been successful, some with expensive fixes, and some with $5 fixes. Others have spent big $, and still have the problem. More than anything, they voice frustration. I am not expecting to eliminate the 56J's vibration either, but will have done the best I can to reduce it.

              The 56J's vibration begins around 20-25 MPH, and becomes a deep base sound by 50, then all but goes away by 60-70, and returns as an oscillating pitch at 75-80. It has been there as long as I can recall. I even advanced the jackshaft forward, one spline at a time till 90 degrees out of phase, where it seemed a bit less. I also experimented with various carrier bearing mount holes, the Shop Manual said were for other models, which did not help. I left it 90 degrees out of phase about 30 years and 150,000 miles ago, where it remains today.

              The Spicer method is to align the jackshaft to near zero angle deviance from the transmission output shaft, as if it were an extension of the output shaft (need 1/2 to 1 degree for u'joint bearing rotation). Next align the jackshaft and pinion shaft within 3 degrees of parallel, and set the driveshaft up with all three u'joints phased. I believe this is the principle Studebaker used, but with a mass production, one size fits all approach. I plan to dial mine in so every angle is per spec. To do so will likely require new holes into crossmember that mounts the carrier bearing, and tilting the pinion yoke a bit. I will also check for horizontal misalignment. Whatever vibration is left then, I will continue to live with. Unless I get tired of it someday and install a 1-piece, with floating front yoke.

              Thanks Again

              Comment


              • #8
                I really don't know if this could apply here, but I have heard of transmission shafts that were "silenced" by drilling a little hole and fill them with polyurethane expansible foam. Did you have a look at the 1961 Lincoln Continental setup? It seems they went to great lengths to eliminate any vibration. You might be able to use some parts from their arrangement.
                Best of luck on this one and nice day to all.
                sigpic

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                • #9
                  Originally posted by christophe View Post
                  I really don't know if this could apply here, but I have heard of transmission shafts that were "silenced" by drilling a little hole and fill them with polyurethane expansible foam. Did you have a look at the 1961 Lincoln Continental setup? It seems they went to great lengths to eliminate any vibration. You might be able to use some parts from their arrangement.
                  Best of luck on this one and nice day to all.
                  The 2-piece design has problems which is likely why Studebaker went to 1-piece in 1958. For sure they did not fix it by 1956, as every 56J I have driven had the problem. The good news, it's only annoying and will not self destruct, since mine currently has the same u'joints for around 150,000 miles. I'am sure a basic rebuild, dialing in all angles as best I can will help, but doubt it will go away. With 57 and earlier Stude it is a PITA to install a 1-piece, but it does fix the problem. I recall my local driveline specialty shop suggests a 3.25" OD shaft, which requires bending the floor a bit. I will probably just continue to live with mine's OEM. I have discovered over the decades, it helps to keep the slip joint well greased, and have always done so. I'd like to try the foam idea, but don't have a spare 56J driveshaft (they are unique), so probably won't. I read about 58-64 Chevy's 2-piece shaft used with their 'x' member frame. They did not have many problems, as long as the system was left alone, but even different style motor mounts often triggers vibration.

                  I am now on page 30 of 47 pages of a Toyota truck forum, that began in 2012 and continues today about their problems with a similar design. It is educational to read their historical fix attempts, some of which have been successful, but many have not. Some successful fixes have even stood phasing theory on its head! Mysteriously, some trucks never have the problem, but many do. Toyota has redesigned it a few times but most owners have fixed it with 1-piece driveshaft and in-line double Cardan joint.
                  Toyota denies the problem exists, but has been successfully (and unsuccessfully) sued via the Lemon Law, and has replaced many trucks, or took them back in trade, etc.. Their problem is well documented, even in stock trucks after only 50 miles. They have enough lawyers to avoid mass recall though. Many owners have replaced tires, wheels, bearings, etc., in vain. Finally, with a custom made 1-piece driveshaft the truck usually transforms into a smooth operating vehicle, relieved of all its mysterious vibration maladies. I have driven enough 56Js to know they have the same problem.

                  Thanks for your input. Stay safe over there Christophe, as we are trying to do here.

                  Joe H
                  Last edited by JoeHall; 05-14-2020, 06:54 AM.

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                  • #10
                    I don't understand why Studebaker used a 2 piece shaft in the FIRST place...and then tried to put a band-aid on it, rather than throwing in the towel and installing 1 piece shafts...

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                    • #11
                      Originally posted by 345 DeSoto View Post
                      I don't understand why Studebaker used a 2 piece shaft in the FIRST place...and then tried to put a band-aid on it, rather than throwing in the towel and installing 1 piece shafts...
                      They did, in 1958. LOL

                      Comment


                      • #12
                        Long one-piece driveshafts bring their own set of problems.

                        Two-piece driveshafts have been a design feature in longer wheelbase cars for a hundred years. Long-wheelbase trucks have three-piece driveshafts and with their low-rear-gear ratios, the shaft system is spinning very high RPM. Mostly, two-piece driveshafts bring more packaging benefits than they cause vibration problems. You can bet CASO Studebaker Engineering wouldn't have spent the money for the extra parts in the two-piece system unless the benefits were there.

                        There are so many factors which go into producing a vibration or eliminating a vibration, sometimes it's almost impossible to pinpoint. As Joe states, if Toyota, with all of today's computer engineering and testing resources, has a continuing problem, Studebaker can be given some slack.

                        jack vines
                        PackardV8

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                        • #13
                          Then too, the ole 56J has good and bad days with the vibration. My son and I just returned from a 30 miles drive and, for the most part I thought vibration, what vibration? It was minimal today, but still several opportunities presented to point it out to my son, who has grown up in Stude Hawks. I also had my son video some of today's drive, which I will post in another thread. I can definitely live with it, and only ever swapped a 56J over to 1-piece driveshaft in coordination with installing a Th400 transmission. But have noted the problem, and variances over the years, as noted above. Also will add that I have never seen a 56J anywhere near as bad as is described in the above Service Letter. It's more an annoyance than anything. Not sure I'd ever use the word, "shudder" to describe it in a 56J. More a reverberation magnified by bouncing off the fiberboard headliner, as I described already.

                          As mentioned above, pretty sure S-P Corp used a mass production approach, and did not dial each car's driveline harmonics in. But I plan to do so on this 56J, and will see if it makes any improvement. No matter what I will love the old 56J just the same, but just hope my attempt to improve it doesn't make it any worse. LOL
                          Last edited by JoeHall; 05-14-2020, 11:06 AM.

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                          • #14
                            Joe is to be commended for putting in the work to find and fix the problems with what he's got.

                            Back in my CASO days, I, too, put in the time before any money. Today, time is shorter than money; for this problem, it would get all new U-joints, both driveshaft sections balanced, new carrier bearing and new rubber mount, new transmission mount and new rubber bushings in the rear springs. BTW, I'd also probably replace the front motor mounts as well. The Packard V8 design with 45-degree motor mounts start getting in a strain from Day One.

                            jack vines
                            PackardV8

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                            • #15
                              Two thoughts just occured to me.
                              Did you ever try to put the car in neutral while the vibration was there? If it ceases, this is likely to come from the engine area.
                              Assuming this vibration is not related to road surface or wheel balancing, did you try to have the rear wheels balanced on the car? You might have one or two unbalanced rear brake drums that only enter in conflict when in a certain position.
                              Thanks for your concern, Joe; and stay safe on your side of the pond too!
                              Nice day to all.
                              sigpic

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