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Tailshaft vibrations- VE T56 in FD RX7

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    Tailshaft vibrations- VE T56 in FD RX7

    So I have a car with an engine and this also came with a gearbox. -> http://www.performanceforums.com/for...#post842889164

    Said gearbox is a T56 from a VE V8 which has a flanged output. Upon driving the car it has vibrations at about 105-110kph and I donít like it. So here are the deets:

    I think the OE Commodore setup is: Gearbox Flange > Rubber doughnut coupler > 2 piece tailshaft (Flange-Uni-centre bearing/CV-Uni-Flange) > Rubber Dougnut coupler > Diff Flange

    Rubber coupler:




    VE Tailshaft




    My setup is: Gearbox Flange > Billet steel coupler > Single piece tailshaft (Flange-Uni- Slip joint spline- Uni-Flange) > Diff Flange

    I have about 2 degrees angle at both joints (box and diff axes are parallel and offset) as per normal tailshaft requirements. Like this diagram but in the opposite direction




    Iíve also had the tailshaft rebalanced and I have 2 sets of wheels so pretty confident itís not either of those things.

    So investigating with internet and also Mal Wood suggests that itís fucked and canít be fixed because itís not a slip yoke. I thought my slip joint would fix it but it obviously has not.

    So why is it fucked? I am thinking the flange faces donít like to be pointing anywhere other than true so maybe my uni on the back of it is making it upset so I have a few options to ponder.

    1- Install a rubber doughnut Ė Iíve been told a numerous people including Mal Wood this will result in disaster because I have a slip joint too

    2- Install one of those aftermarket performance adaptors with urethane sleeves like this:


    3- Shim the gearbox so it points right at the diff so I get no relative angle on the flange end and 2-3 deg on the diff end. My understanding is that unis like to work in pairs and opposite each other though but this is the easiest to do

    4- Get a commodore tailshaft and modify it so I have a two piece in there. The whole shaft is like 1070mm long so it would be short!

    5- Convert to a slip yoke rear (this is expensive- box rebuild or new box plus new tailshaft so not super keen just yet)

    Come to me driveline nerds

    #2
    What is this billet steel coupler?

    Do you have this:

    Gearbox output flange --> Flange-to-yoke adaptor --> U-joint --> slip yoke --> driveshaft main tube --> U-joint ->> Pinion flange

    If so, that slip yoke may be the problem. I've never seen a slip yoke used without a carrier bearing right close to/on it in OEM stuff. I see it done in aftermarket/conversion stuff but you never know what kind of vibration issues might crop up just from seeing a photo.

    Comment


      #3
      The billet adaptor is just to connect the 3 bolt GM output flange to the Dana style 4 bolt flange on the Uni.





      The slip joint is a teflon coated spline thing like whats at the bottom of this page

      Comment


        #4
        I reckon you need to change the rear uni joint to a cv joint
        you cant spell advertisements without semen between the tits

        Comment


          #5
          Ive jsut been working through all the same shit on my setup.

          I had a custom 2 piece shaft in my IS200 (with VE tr6060) and it killed 2 center bearings in quick time. I corrected the angles a bit by dropping the motor in the bay and making custom mounts for the diff cradle. Angles are within 0.5 deg now.

          Im making a single piece shaft same config as yours from some Strange 3.5" chromoly tube and 1350 yokes, coupled to the gearbox with one of these...

          https://www.sonnax.com/parts/3868-3-...er-flange-yoke

          Im hoping that vibration goes away now that the angles are good and no center bearings to fail.

          Comment


            #6
            So what angles are you running? Iím at 2.0 deg by memory (maybe a touch under) but same front and rear. But all info Iím receiving is the flange output doesnít like this setup. Iím beginning to think to run this you need zero angle on the flange joints with rubber isolators and a cv in the middle. Ie as per factory holden

            Comment


              #7
              Having inverted angle at the rear likely means the angle gets steeper (e.g. more like 2.5-3) at speed when you get more downforce happening (assuming you have a spoiler).

              Try dialing in 1/2 a degree less at the rear so you might get 1.5 static and 2.0 at speed to see if it goes away.
              302 Ford Windsor Technical Forums

              Originally posted by rollin7
              but I'm seriously in love with this thing ...the pure uselessness and dickheadness of this mustang makes it the most enjoyable car I've ever driven, its fucking STUPIDLY loud for no reason, it gos real fast but wont slow down, they have made the suspension real hard and yet and it wont corner worth a shit. theres something very Aussie about it, like the drunk guy who makes a hat out of watermelon.

              Comment


                #8
                Tailshaft vibrations- VE T56 in FD RX7

                Originally posted by C0V3R View Post
                Having inverted angle at the rear likely means the angle gets steeper (e.g. more like 2.5-3) at speed when you get more downforce happening (assuming you have a spoiler).

                Try dialing in 1/2 a degree less at the rear so you might get 1.5 static and 2.0 at speed to see if it goes away.
                There is 0.5 degree angle between front and rear flange, virtually no angle from the uni to the shaft. Now that we have shimmed, the shaft is nearly too straight from the box to the diff flange.


                Sent from my iPhone using Tapatalk

                Comment


                  #9
                  Itís in an FD RX7 so should be fairly stable being IRS

                  Comment


                    #10
                    Tremec boxes supposedly like the operating angles fairly precise, as I recall with a working angle under 3 deg.

                    I had all sorts of dealings with them when I was warrantying a box, and they gave me all sorts of grief about angles (when I didnt have any vibration issues).

                    Youd probably do well to use something like this to work through the angles you have
                    http://spicerparts.com/calculators/d...gle-calculator
                    http://spicerparts.com/calculators/d...rpm-calculator
                    http://www.tremec.com/menu/tremec-toolbox-app/

                    http://www.superchevy.com/how-to/tra...le-finder-app/
                    302 Ford Windsor Technical Forums

                    Originally posted by rollin7
                    but I'm seriously in love with this thing ...the pure uselessness and dickheadness of this mustang makes it the most enjoyable car I've ever driven, its fucking STUPIDLY loud for no reason, it gos real fast but wont slow down, they have made the suspension real hard and yet and it wont corner worth a shit. theres something very Aussie about it, like the drunk guy who makes a hat out of watermelon.

                    Comment


                      #11
                      Originally posted by lukevl View Post
                      Itís in an FD RX7 so should be fairly stable being IRS
                      Fair enough, wasnt sure what rear was in it due to the conversion.
                      302 Ford Windsor Technical Forums

                      Originally posted by rollin7
                      but I'm seriously in love with this thing ...the pure uselessness and dickheadness of this mustang makes it the most enjoyable car I've ever driven, its fucking STUPIDLY loud for no reason, it gos real fast but wont slow down, they have made the suspension real hard and yet and it wont corner worth a shit. theres something very Aussie about it, like the drunk guy who makes a hat out of watermelon.

                      Comment


                        #12
                        i'd be pretty tempted to do

                        4- Get a commodore tailshaft and modify it so I have a two piece in there. The whole shaft is like 1070mm long so it would be short!
                        what do they do in the USA? aren't there millions of LSRX7s over there?

                        Comment


                          #13
                          Iím pretty happy with the angle calcs. I used a laser pointer and spun the flange and then did trig. Should be ok. Can always get it closer though so Iíll revisit it

                          Comment


                            #14
                            Originally posted by Roadsailing View Post
                            i'd be pretty tempted to do

                            what do they do in the USA? aren't there millions of LSRX7s over there?
                            They mostly use the slip yoke style I think. But I have a lot more searching to do on norotors.com.

                            Does anyone know why the slip yoke is meant to be better than the flange?

                            Comment


                              #15
                              How much of a vibration are we talking?

                              Comment

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