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6 bolt diff input on e30

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    6 bolt diff input on e30

    Has everyone ever put a 6 bolt e36 diff input flange onto an e30 diff? and then run an e36 or similar CV driveshaft back section?

    Curious if this would work with a single piece driveshaft to help out since the length adjustment in the stock e30 shaft would be lost. The CV joint can take up a little slack for tolerance issues that a ujoint cant.
    e30sport.net
    '15 Porsche GT3 - 7-speed PDK - Daily Driver
    '86 325es - s54b32tu - 6-speed - Mtech 1
    '89 325is - m20b25 - 5-speed - Individual

    #2
    For what purpose?

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      #3
      Originally posted by e30davie View Post
      For what purpose?
      Originally posted by BeirBrennerE30 View Post
      to help out since the length adjustment in the stock e30 shaft would be lost. The CV joint can take up a little slack for tolerance issues that a ujoint cant.
      Byron

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        #4
        Originally posted by e30davie View Post
        For what purpose?
        Using a 1 piece driveshaft essentially. A CV joint allows for a little bit of slack to be taken up where a uJoint that the e30 has is pretty solid. a 1 piece driveshaft would not have the adjustable section a 2 piece DS has.

        I am pretty sure that you can install the large 6 bolt input on an e30 188 case diff. i.e. I think that a 6 bolt input for an e36 M3/e46 M3 CV input exists for the 188 diff. But that input is longer and larger in diameter than a normal 4 bolt input. Does this interfere with the subframe of the e30 or have any other unforeseen consequences I am not thinking of.
        Last edited by BeirBrennerE30; 04-12-2019, 10:17 AM.
        e30sport.net
        '15 Porsche GT3 - 7-speed PDK - Daily Driver
        '86 325es - s54b32tu - 6-speed - Mtech 1
        '89 325is - m20b25 - 5-speed - Individual

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          #5
          You would have to reset the preload on the pinion gear and get the gear mesh correct if you pull the input flange. Not as simple as just unbolting and bolting back on.
          sigpic

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            #6
            The 325ix comes standard with a 6 bolt driveshaft / diff flange with a CV joint instead of a regular U joint.
            1990 325iX Touring - November 2018 R3V Car Of The Month

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            1974 BMW 2002 Touring

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              #7
              Originally posted by BeirBrennerE30 View Post

              I am pretty sure that you can install the large 6 bolt input on an e30 188 case diff. i.e. I think that a 6 bolt input for an e36 M3/e46 M3 CV input exists for the 188 diff. But that input is longer and larger in diameter than a normal 4 bolt input. Does this interfere with the subframe of the e30 or have any other unforeseen consequences I am not thinking of.
              (Some?) E34's had 6 bolt flanges... I just took a glance but couldn't find the part number.


              Originally posted by D.Martijn View Post
              The 325ix comes standard with a 6 bolt driveshaft / diff flange with a CV joint instead of a regular U joint.
              It does not.

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                #8
                Originally posted by AndrewBird View Post
                You would have to reset the preload on the pinion gear and get the gear mesh correct if you pull the input flange. Not as simple as just unbolting and bolting back on.
                Input flange doesn’t set gear mesh at all, the preload is the only thing you have to worry about. The crush sleeve is so stiff on these diffs though that you can basically blast the nut back on with an impact and not have it get too tight.
                Byron

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                  #9
                  Originally posted by The Dark Side of Will View Post



                  It does not.


                  Umh.. It does. check realoem. + it's fitted on my iX Touring lol
                  http://www.realoem.com/bmw/enUS/show...diagId=26_0057

                  edit. I looked at my original post and I forgot to add iX Touring..
                  1990 325iX Touring - November 2018 R3V Car Of The Month

                  1980 Volkswagen Golf mk1 1.1
                  1974 BMW 2002 Touring

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                    #10
                    What is the reasoning for wanting to go a 1 piece drive shaft?

                    1 piece shaft is going to be custom made so I would be tempted to see what industrial/aftermarket options are available for a slip joint to be built into a 1 piece tail shaft (with fixed ends to bolt up to e30 transmission and diff). google suggests that a slip joint in a 1 piece drift shaft is a thing.

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                      #11
                      Originally posted by D.Martijn View Post
                      Umh.. It does. check realoem. + it's fitted on my iX Touring lol
                      http://www.realoem.com/bmw/enUS/show...diagId=26_0057

                      edit. I looked at my original post and I forgot to add iX Touring..
                      Well aren't you the happy little unicorn? :p

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                        #12
                        BMW used a two piece driveshaft to increase the critical speed of the driveshaft above the RPM it would see during extended driving at maximum speed on the autobahn. A one piece driveshaft *of the same diameter* would have too low a critical speed and resonate.

                        In order to be stiff enough to push the critical speed higher, a one piece driveshaft would have to be larger in diameter, which makes it harder to fit in the tunnel with exhaust and everything else.

                        I think OP was looking for a way to use an E36 driveshaft whole instead of having to frankenstein one together from E30 & E36 parts.

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                          #13
                          Originally posted by The Dark Side of Will View Post

                          I think OP was looking for a way to use an E36 driveshaft whole instead of having to frankenstein one together from E30 & E36 parts.
                          Actually no. I was thinking of getting a custom s54/e30 carbon fiber one-piece driveshaft made. Since there is like 0 interest of anyone else, doing this group buys for e30/s54 carbon driveshafts are out the window. Hopefully I can use an e36/e46 M3 CV joint at the diff input I can ask one of the e46 M3 carbon driveshaft suppliers to build me a e46 M3 drive shaft but with a X.XX" shorter tube.

                          In the e46 swapping steel for carbon and slightly increasing the diameter seems to be enough to push the critical speed higher for a 1-piece since everyone on M3forum seems to have positive reviews of their carbon 1-piece. With the e30/s54 shaft being even shorter it should be even better. Ultimately I am leaving it up to the experts designing the thing to tell me if it wont work because of diameter or length, but its up to me to make sure it will fit.

                          Interesting that the ix uses a CV. I know the e34 does too. I think the correct input is available:



                          A in the above image. All of these are inputs for a medium case diff. Swapping the input is no issue though I am concerned that the slightly larger in diameter input is going to interfere with the subframe, or if the shaft itself will interfere with the subframe where it passes through it.
                          e30sport.net
                          '15 Porsche GT3 - 7-speed PDK - Daily Driver
                          '86 325es - s54b32tu - 6-speed - Mtech 1
                          '89 325is - m20b25 - 5-speed - Individual

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                            #14
                            I have an E30 iX touring with the CV as well. It is a similar CV to the E34 unit, but it is stepped down to clear the subframe.

                            With either a tiny bit of spacer or some modifications to the CV boot, you can run an E34 CV and it'll clear. Info here - https://r3vlimited.com/board/showpos...&postcount=106

                            edit: you'll want diff input flange B
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                              #15
                              Originally posted by kronus View Post
                              I have an E30 iX touring with the CV as well. It is a similar CV to the E34 unit, but it is stepped down to clear the subframe.

                              With either a tiny bit of spacer or some modifications to the CV boot, you can run an E34 CV and it'll clear. Info here - https://r3vlimited.com/board/showpos...&postcount=106

                              edit: you'll want diff input flange B
                              So thats an e34 CV on an e30ix driveshaft in the link you sent? the B input flage is on the right below:



                              The difference be tween the diameters of A and B flanges is 6mm so just 3mm radius. Do you think that would clip the subframe? The e46m3 CV looks like it wouldnt extend outside of the lip of the input flange. Also the larger input is slightly longer so maybe it would stick through the subframe more, not sure if that would help or hurt:

                              Last edited by BeirBrennerE30; 04-16-2019, 03:10 PM.
                              e30sport.net
                              '15 Porsche GT3 - 7-speed PDK - Daily Driver
                              '86 325es - s54b32tu - 6-speed - Mtech 1
                              '89 325is - m20b25 - 5-speed - Individual

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