What diff do I have? What diff should I get?

Collapse
X
Collapse
 
  • Page of 1
  • Time
  • Show
Clear All
new posts
Previous template Next
  • Raven Tooth
    Advanced Member
    • Feb 2010
    • 130
    #1

    What diff do I have? What diff should I get?

    I have a 1989 325i. I think I have an open 3.73. (how do I tell?) I def want at least an LSD of the same ratio. Would you recommend swapping for a 3.93 or a 4.10? Will I feel a big difference?

    I would love to get more acceleration from the car, but I don't know what it will be like to have crazy revs on the highway. I frequently cruise at 80-90, don't often go beyond that but would like to be able to hit 110 or 120.
    Tags: None
    • jlevie
      R3V OG
      • Nov 2006
      • 13530
      #2
      The car could have an open or limited slip differental. There should be a metal tag on the right side of the differential cover that will tell what differential you have. An S on the tag means that it is a limited slip.
      The car makes it possible, but the driver makes it happen.
      Jim Levie, Huntsville, AL

        Comment

        • Raven Tooth
          Advanced Member
          • Feb 2010
          • 130
          #3
          I'm sure it's an open diff, just don't know the ratio (I spun the wheels while it was on a lift). Sounds like all I need to do is check under the car

          http://www.r3vlimited.com/board/showthread.php?t=190044


          But assuming I do have the open 3.73, what are thoughts on changing the ratio or not?

            Comment

            • jlevie
              R3V OG
              • Nov 2006
              • 13530
              #4
              A higher ratio will yield better acceleration but you'll pay for it with increased rpm at speed. There's no perfect answer. If you do a lot of highway driving, I'd say to stay with the 3.73 as it is a good compromise between performance and engine speed.
              The car makes it possible, but the driver makes it happen.
              Jim Levie, Huntsville, AL

                Comment

                • The Humjet
                  E30 Addict
                  • Jun 2010
                  • 528
                  #5
                  Your ratio should also be on the tag so if its a LSD 3.73 then it will say S3.73

                    Comment

                    • Raven Tooth
                      Advanced Member
                      • Feb 2010
                      • 130
                      #6
                      yeah, I know it's not an LSD, it was just a question of ratio, but I will check next time I'm under the car. Is it really so bad to have a 4.10 and be on the highway? Why would that be bad?

                        Comment

                        • BrownBeanE30
                          E30 Modder
                          • Nov 2010
                          • 965
                          #7
                          its not really bad your just gonna be at a higher rpm that is all and your top speed will decrease a lil
                          Originally posted by InuFaye
                          silver is old man color car. you need dat BRO-SECA BLUE.
                          Originally posted by blunttech
                          so true.. never let them know where you live..I almost ended up in jail when I was raping young women on craigslist
                          Originally posted by george graves
                          An S5x is like the girl you want to marry - an m30 is the girl you don't bring home to mom.

                            Comment

                            • StereoInstaller1
                              GAS
                              • Jul 2004
                              • 22679
                              #8
                              I have a 3.73 and am willing to sacrifice a little acceleration for lower cruising RPMs.

                              I will be doing a 3.46 in my next E30. A 4.10 on the roads around here would piss me off in a hurry.

                              Closing SOON!
                              "LAST CHANCE FOR G.A.S." DEAL IS ON NOW

                              Luke AT germanaudiospecialties DOT com or text 425-761-6450, or for quickest answers, call me at the shop 360-669-0398

                              Thanks for 10 years of fun!

                                Comment

                                • boostownsme
                                  Member
                                  • Apr 2011
                                  • 43
                                  #9
                                  Put it back on the lift, have one person hold the opposite wheel steady. Then with a dot or reference point on your tire and driveshaft see how many revolutions of the driveshaft you get per one wheel revolution

                                    Comment

                                    Previous template Next
                                    Working...