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  • Sr20ve-t z32 q45

    Is anyone else running a be setup with z32 trans and q45 diff? I have my setup in and running. 2nd gear at 60mph has me at 5200 rpm...

  • #2
    Sounds like way too long gearing. I'm thinking Z33 box and 4.08s.
    '18 Chevrolet Volt - Electric fun hatch for DD duty!


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    • #3
      Ha yeah I wish I had the cash sitting around for that. Can 240 gears be put in a q45 diff I've looked some and it has me questioning bolt sizes

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      • #4
        depending on what you're doing, that could be nice gearing....
        coming off a corner at 55mph in 2nd is nice.
        Originally posted by SoSideways
        I don't care what color they are as long as they are LONG AND HARD.
        '04 G35 Sedan 6MT- The DD
        '96 240SX- The Track Toy

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        • #5
          The problem is the drop between gears is high on the lower gears. So it's better to use 3-5 than 2-4 even if the top speed in a say 2nd and 3rd are the same.
          '18 Chevrolet Volt - Electric fun hatch for DD duty!


          DefSport Koni Sleeve and Spring Perch Buy!!!
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          • #6
            depending on how much power you make at speed, that could be a proper decision.. There's a HUGE gap between 4th and 5th on the 240SX and 300ZX transmissions and sucks balls for top speed of an NA engine. Hardbody 5th gear would be much better for a lower power engine, or shifting to a taller rear end and using 2nd gear for corner exit assuming you have room to get off the corner before shifting.

            coming out of a corner at 6000rpm with a 6700 redline is useless. conversely, shifting into 5th gear at TWS's S/F line and gaining ZERO speed is useless. Given our combination of gears and diff ratios, a low-power KA is better off with a taller diff and using 2-3-4 than a shorter diff and using 3-4-5.

            For an SR with more power and might be able to us a .75 OD 5th gear and still accelerate, that's a completely different ball of wax.


            My RX7 has a close ratio gearbox and I can run to ~72mph in 2nd gear. I use gears 2-3-4 at MSRHouston, but I'm at 8700rpm in 5th with the same rear end at TWS. so I use 2-3-4 at MSRH and 3-4-5 at TWS. Works great.
            In my 240, I only use 3-4 at MSRH and 3-4-5 at TWS but 5th gear suuuuucks.
            Originally posted by SoSideways
            I don't care what color they are as long as they are LONG AND HARD.
            '04 G35 Sedan 6MT- The DD
            '96 240SX- The Track Toy

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            • #7
              Originally posted by Matt93SE View Post
              depending on how much power you make at speed, that could be a proper decision.. There's a HUGE gap between 4th and 5th on the 240SX and 300ZX transmissions and sucks balls for top speed of an NA engine. Hardbody 5th gear would be much better for a lower power engine, or shifting to a taller rear end and using 2nd gear for corner exit assuming you have room to get off the corner before shifting.

              coming out of a corner at 6000rpm with a 6700 redline is useless. conversely, shifting into 5th gear at TWS's S/F line and gaining ZERO speed is useless. Given our combination of gears and diff ratios, a low-power KA is better off with a taller diff and using 2-3-4 than a shorter diff and using 3-4-5.

              For an SR with more power and might be able to us a .75 OD 5th gear and still accelerate, that's a completely different ball of wax.


              My RX7 has a close ratio gearbox and I can run to ~72mph in 2nd gear. I use gears 2-3-4 at MSRHouston, but I'm at 8700rpm in 5th with the same rear end at TWS. so I use 2-3-4 at MSRH and 3-4-5 at TWS. Works great.
              In my 240, I only use 3-4 at MSRH and 3-4-5 at TWS but 5th gear suuuuucks.

              1st: 3.321
              2nd: 1.902
              3rd: 1.308
              4th: 1.000
              5th: 0.759


              3rd to 4th and 4th to 5th is basically the same. 2nd to 3rd is quite a bit bigger drop (~31% vs. ~24/25%). Granted it's less noticeable at low speed, and you're unlikely to shift into an "aero wall" like you describe.

              But overall the gear drop is about the same across the box except 2nd to 3rd. I agree 4th to 5th sucks on anything but a 4.63. I just have enough oomph with the 7163 to pull out of that hole and accelerate about 12-14 mph on the front straight vs. the T25 which would basically be stuck at 122-123 mph the whole way down the straight. With a higher rear end than the 4.63 you can't pull in 5th with aero on an S-chassis unless you're making some mondo power, and even then acceleration will be very muted.
              '18 Chevrolet Volt - Electric fun hatch for DD duty!


              DefSport Koni Sleeve and Spring Perch Buy!!!
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              • #8
                ... or you could run a hardbody 5th gear which is .85 I think.
                Rob did the swap and many of the Prod racers I know do it as well.
                You could then run a 4.3 and use 3,4,5 at both MSRH and TWS. Not sure about other tracks tho, simple because I haven't been there. Or you could run a 3.9 and use 2nd to dig out of the tight corners, especially if your redline is higher than 7k.
                Originally posted by SoSideways
                I don't care what color they are as long as they are LONG AND HARD.
                '04 G35 Sedan 6MT- The DD
                '96 240SX- The Track Toy

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                • #9
                  Yeah 5th gear will have me will over 140mph. I was in 3rd not even over 5500 and was at 100mph

                  Just from a quick calculator I'll be topping out 2nd in the 90's and third at almost 140...

                  Street tune is being called at 500whp and my road coarse will be 350-400whp
                  Last edited by BEXE; 05-17-2016, 09:13 PM.

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                  • #10
                    ^^3rd at 140?? That's comical. Take it to the salt flats...

                    5th does suck horribly, especially running on a stockish KA. It 'feels' like it sucks so much that I ended up taking my engine up to 6500-6600rpm in 4th at the end of the back straight at Watkins Glen to avoid shifting in 5th at the top of the esses since it felt faster. It turns out though that 2 of the 4 drivers on my team were shifting into 5th instead and were going 3-4 mph faster according to data. I had a faster lap times by significant margins interestingly enough. Could've cut the time down a bit more knowing that bit of info. So regardless of how much 5th sucks, it accelerates more than keeping it 4th with a powerband that falls off the face of the earth if you're in a situation where you're right at the cusp of 4th and 5th.
                    Core4 Motorsports
                    CLICK HERE for Wilwood FSL6R Radial Bracket & Rear Wilwood BBK GROUP BUY
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                    • #11
                      hmm.. I had the opposite happen, at least looking at end-of-straight speed. I never compared straight lap times tho.

                      But at TWS, I have played around with different shift points to 5th gear. my highest speeds at end of the straight were when I'd run 4th gear to redline and then shift to 5th. Once I shift to 5th, I gain very little speed at all so I'm better off wheezing in 4th vs. going to 5th and bogging..
                      Originally posted by SoSideways
                      I don't care what color they are as long as they are LONG AND HARD.
                      '04 G35 Sedan 6MT- The DD
                      '96 240SX- The Track Toy

                      Comment


                      • #12
                        Originally posted by Matt93SE View Post
                        hmm.. I had the opposite happen, at least looking at end-of-straight speed. I never compared straight lap times tho.

                        But at TWS, I have played around with different shift points to 5th gear. my highest speeds at end of the straight were when I'd run 4th gear to redline and then shift to 5th. Once I shift to 5th, I gain very little speed at all so I'm better off wheezing in 4th vs. going to 5th and bogging..
                        I'm speaking strictly end of straight speed also. Lap times between the other drivers can't be compared with mine because they have less experience and time behind the wheel (7 to 8 seconds difference over a 2:20-2:30 lap).

                        What I should say is that my speed through turn 1 before the esses and back straight was higher yet their end of straight top speed was higher because they shifted into 5th. I didn't shift into 5th because it felt slow as balls, and because I felt like I could enter the next turn much smoother without having to worry about the shift.

                        Mind you, this was with an S13 engine that we had found on Craigslist the weekend of the race because ours spun a rod bearing on practice day. It was completely unknown and felt more doggish everywhere compared to our original engine.
                        Core4 Motorsports
                        CLICK HERE for Wilwood FSL6R Radial Bracket & Rear Wilwood BBK GROUP BUY
                        S14 VQ AER Endurance Racing Team

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                        • #13
                          Originally posted by Matt93SE View Post
                          ... or you could run a hardbody 5th gear which is .85 I think.
                          Rob did the swap and many of the Prod racers I know do it as well.
                          You could then run a 4.3 and use 3,4,5 at both MSRH and TWS. Not sure about other tracks tho, simple because I haven't been there. Or you could run a 3.9 and use 2nd to dig out of the tight corners, especially if your redline is higher than 7k.
                          Hardbody 5th is either 0.82 or 0.83 I think.

                          But I bring up the ratios and the drops because a Z32 box is basically the same ratios, and has all the disadvantages.

                          The Z33 box only drops down to a 0.80 6th from a 1 5th, so it's not too bad if you do get into it, although not optimal if you have something like a 4.08 rear end. It's not going to pull worth a crap with a 180+ mph gear in it regardless of the drop down to it.
                          '18 Chevrolet Volt - Electric fun hatch for DD duty!


                          DefSport Koni Sleeve and Spring Perch Buy!!!
                          http://www.nissanroadracing.com/showthread.php?t=5902

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                          • #14
                            Originally posted by Def View Post
                            Hardbody 5th is either 0.82 or 0.83 I think.

                            But I bring up the ratios and the drops because a Z32 box is basically the same ratios, and has all the disadvantages.

                            The Z33 box only drops down to a 0.80 6th from a 1 5th, so it's not too bad if you do get into it, although not optimal if you have something like a 4.08 rear end. It's not going to pull worth a crap with a 180+ mph gear in it regardless of the drop down to it.
                            Here's some vid of an S14 VQ35DE with Z33 box and 4.08 rear at the The Ridge in Washington. https://youtu.be/6iRZxmYaDY8 Seems to be accelerating decently in 6th. That combo with 25" tire package is gear limited at 160ish at 7k rpm.
                            Core4 Motorsports
                            CLICK HERE for Wilwood FSL6R Radial Bracket & Rear Wilwood BBK GROUP BUY
                            S14 VQ AER Endurance Racing Team

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                            • #15
                              Originally posted by Def View Post
                              Hardbody 5th is either 0.82 or 0.83 I think.

                              But I bring up the ratios and the drops because a Z32 box is basically the same ratios, and has all the disadvantages.

                              The Z33 box only drops down to a 0.80 6th from a 1 5th, so it's not too bad if you do get into it, although not optimal if you have something like a 4.08 rear end. It's not going to pull worth a crap with a 180+ mph gear in it regardless of the drop down to it.
                              Agreed. however, you also have two useless gears in the Z33 box. 1st and 2nd do nothing for a road race car. so now you're in 3-4-5-6. maybe that's better than 3-4-5 or 2-3-4, but I've never really been impressed with the smoothness of the shifts in my G35. it's an early model (2004) with a factory clutch, so it might be the white collar accountant squishy marcel in the clutch disc... (I did notice that my 240SX shifted much quicker when I went to a non-marcel puck type disc.)..

                              But I've never been able to shift quickly in the G and it's annoying when the RPM drops faster than the transmission during shifts so I'm always bucking the car around like a 16yr old driving a stick for the first time.
                              Originally posted by SoSideways
                              I don't care what color they are as long as they are LONG AND HARD.
                              '04 G35 Sedan 6MT- The DD
                              '96 240SX- The Track Toy

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