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4.08 to 4.36 gear change Q's

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  • 4.08 to 4.36 gear change Q's

    Anyone on here with experience on the change here? Im struggling with keeping my current turbo setup or going to a t28 setup. this is mostly an issue for autox which is all i really do with the car. The issue is basically coming out of a sharp corner in second gear say 30mph and the lag associated. Im making 200ftlbs at 1500rpm and making 300+ftlbs at arouind 3500rpm. given that the car still lags coming out of a corner and my thoughts are that the 4.36 should really help with that and on off throttle acceleration without having to change my turbo, mani, dump etc. I think the 4.6 might be overkill but Im all ears for any one with experience with the swaps or ideas otherwise

  • #2
    What turbo do you have?

    I went from a 4.08 to a 4.36 with no other changes. Car felt good, a little stronger in each gear, but not a huge change. IMO, if you feel the car is dead on its face coming out of a tight corner, ~8% shorter gears are not going to cure that. It will make the car pull a hair harder and come on boost in a faster period of time, but it will not change the behavior of the car drastically.

    The 4.6 will turn things up a notch, but you're talking a few percent more. It all adds up, but it's not going to make your car a rocket down low.

    So that said, 4.36 is a no-brainer mod for our cars. Does not make the gearing too short, and makes 3rd gear more liveable on track. In autox I imagine it would help you quite a bit in 2nd. Any amount of power and a 4.6 would make balancing the throttle tough in 2nd IMO.
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    • #3
      How tall of tires? I do know that some people like the 4.6 with the 275/17's.
      30mph should be around 3500rpm with the 4.6 and do 65mph in 2nd, 25.4 inch tire.
      That may not be enough speed for you.

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      • #4
        I feel bad for you guys on the small lots.... usually at regional events I'm hitting the rev limiter on 2 to 3 sections of the course (72-ish mph), as we were only pushing 13psi at the last event. National Tours and ProSolos seem to have similar speeds (at least around here), so I wouldn't go shorter on gearing unless I upped the rev limiter (7200 atm).

        That said, isn't 30mph like mid 2nd gear? You should be making decent power there unless you're waiting for the turbo to spool. On laggier cars I transition to the throttle right off the brake and try to maintain steady throttle out so I can have the turbo spinning early. I haven't really learned to left foot brake effectively in a full size car (go figure I can do it all day in a kart), but I'd imagine it'd help.

        Anyways, the GT2871r turbo helps with slow digs, so in general I'd recommend it (at least with a KA-T) over a final drive swap. I'd like to try the 3071r, but kind of waiting to see if someone releases a smaller VGT turbo.

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        • #5
          turbo is a gt32 .60/.63, tires are 275/40s. I run them on a 10 inch wheel and I may soon try 255s to see how they fair on the 10" wheel. Def I agree with the thought of having to fight the throttle a little more with the 4.6 set making over 300hp. Thats why Im favoring the 4.36 set. Should give better accelleration down low without compromising too much in the higher gears Im pretty sure that I have to give this a shot before jumping the gun and having to retune and put together a whole ew setup

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          • #6
            GT32 - was never too hot on that turbo. I'm guessing you have a KA? Seems like it was popular with the KA-T guys a while back.

            I think tossing on a GT3071R would give you a big amount of response, but hard to say if it's worth it from a cost standpoint. You really shouldn't have to retune. In fact, I'm not sure what the retune would even involve except maybe a small small tweak to the timing due to a GT3071R possibly having a little better flowing turbine wheel(guessing here). I wouldn't go with a T28 - it's got a pretty fast response, but it will not do 300 rwhp happily, and the power is a bit lumpy(strong midrange, dies off up top at higher power levels over ~240 rwhp).

            The 275/40-17 is also hurting you pretty badly. I hated how the car accelerated with those on there. I went from that to a 235/40-17 and it was night and day. 255/40-17 isn't a huge change, but it seems like going to a small tire really fits these cars better with inertia and gearing. 285/30-18 is where it's at if you want a really wide tire.
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            • #7
              yeah Im workin towards an 18" wheel setup, hopefully sometime next year. thanks for the input

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              • #8
                Where are people getting their final drive R&P? I know you can get them off the internet for ~$400+, but has any one gotten their from a r200 or c200 differential from a truck? From what I understand there are a few pathfinders that might be common in junkyards.

                I know I can get a 2000'ish xterra front carrier and get it from there, but a junkyard pathfinder R&P would be like $70 vs $200+ for the xterra.

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                • #9
                  I got mine from a local JDM importer(it was an A31 Cefiro VLSD) - JHot Imports. They sell on ebay mostly.

                  They advertise them as "4.40 gearing" - since they just do an input to output shaft rough check without opening the diff.

                  Cost was ~$180 since I picked it up, and I threw the VLSD in my 4.08 case and sold it for $150 locally - so not a bad upgrade, and really didn't take too long.
                  '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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