Help! Crusing @ 60mph 5th gear 4000 revs

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  • supkev
    E30 Modder
    • Nov 2010
    • 912

    #1

    Help! Crusing @ 60mph 5th gear 4000 revs

    I have a euro cluster and I have a 3.73 lsd, anyone know what might be the problem? everyone thinks I got a 4.10 but thats not the case I went underneath my car and it says 3.73? anyone know what could be the problem?
    Last edited by supkev; 05-10-2011, 03:38 PM.


  • Kershaw
    R3V OG
    • Feb 2010
    • 11822

    #2
    coding plug issue?
    AWD > RWD

    Comment

    • supkev
      E30 Modder
      • Nov 2010
      • 912

      #3
      Hmm I'll check that out but I highly doubt its that. I lined up with my friends car at 60 mph and it sounds like my car is at 4000 revs.


      Comment

      • A Sucked Orange
        Mod Crazy
        • Mar 2011
        • 707

        #4
        Its either not 4k, or its tiny wheels, or its your diff.

        Comment

        • supkev
          E30 Modder
          • Nov 2010
          • 912

          #5
          I'm thinking might be my diff, I have stock weaves.


          Comment

          • nando
            Moderator
            • Nov 2003
            • 34827

            #6
            there is no diff ratio that would result in 4krpm at 60mph, even with slightly undersized tires.

            something else is wrong.
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            • e30loverSC
              E30 Addict
              • Jun 2009
              • 575

              #7
              what should it be?

              Comment

              • supkev
                E30 Modder
                • Nov 2010
                • 912

                #8
                Yea thats what I thought even a 4.10 is like at 3500-3700 I can barely keep up though my car is a stroker I can hit 110 mph but I'd be at 7k or beyond (I have no redline) but the only other thing I can think of is transmission gearing? I'mma change the diff fluid soon see if it helps


                Comment

                • supkev
                  E30 Modder
                  • Nov 2010
                  • 912

                  #9
                  Now if I had a 4 banger 318 I would understand but in my I6 hmm I get like 22mpg combined 16-17 city but I know other people with 3.73 are getting better than what I get.


                  Comment

                  • nando
                    Moderator
                    • Nov 2003
                    • 34827

                    #10
                    a 4.10 is about 3000rpm at 60mph, not 3500-3700. 80mph is about 3750.
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                    • supkev
                      E30 Modder
                      • Nov 2010
                      • 912

                      #11
                      Damn what could be the possibilities for my high rev on freeway's :/


                      Comment

                      • nando
                        Moderator
                        • Nov 2003
                        • 34827

                        #12
                        your tach is probably not reading correctly
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                        • zxert
                          E30 Addict
                          • Jan 2011
                          • 444

                          #13
                          I don't think that fluid will have anything to do with it, though changing it is always good. Think about it, a differential is either engaged or it isn't. Fluid or lack of fluid doesn't play a part in RPMs. I honestly think there isn't a problem. It sounds like you have a 4.10 diff with a 3.73 cover. What year and model E30 do you have.



                          Here are the gear ratios for different models (SEE ATTACHMENT)

                          Heres a calculator that will tell you RPM. Just input the data for your model and BAM! You're pregnant. I mean, your RPM.
                          http://www.f-body.org/gears/

                          I put in the numbers for a 325i 5 speed w/ a 4.10 and got 60mph @ 3100rpm just as nando says.

                          Post what transmission you have and we can help you.

                          Also post which differential you had before and RPM at speed with that diff.
                          Attached Files

                          Originally posted by StewStewIloveyouyou
                          hahahahahahahahahahahahahahahahahah f--- this community its like am making my life with you guys
                          And am making my life with you guy too. ;)

                          Comment

                          • joonsup
                            Mod Crazy
                            • Mar 2009
                            • 776

                            #14
                            Originally posted by nando
                            a 4.10 is about 3000rpm at 60mph, not 3500-3700. 80mph is about 3750.

                            on my 3.73 lsd i'm hitting 3000rpm at around 80mph in my 5 speed stock transmission

                            Comment

                            • nando
                              Moderator
                              • Nov 2003
                              • 34827

                              #15
                              I'm telling you - there is no way a 4.10 will do 4000rpm at 60mph. Not unless you're running rubber band tires on 13" wheels.

                              I get 2800rpm at 60mph with 205/55-15 tires (23.9" diameter) and a 4.10 with the .81 G260 5th gear. with my 235s it just a hair lower.

                              and a 3.73 with stock diameter tires is 3400 at 80, not 3000. people exaggerate a lot.. 4000rpm with stock diameter tires and a 4.10 is over 85mph, not 80mph as many claim.
                              Last edited by nando; 05-11-2011, 07:57 AM.
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