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| Engine, Exhaust, Transmission Discuss the FR-S | 86 | BRZ engine, exhaust and drivetrain. |
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#1 |
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Has anyone been using close ratio gears?
I have 4.67 FD, upgrading to 4.88 this week (just arrived). I did some local autocross and 4.88 will probably be too much (I run 95% on 2nd, downshift to 1st twice and to 3rd twice during one lap), so will these gears help me? N/A MT |
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#2 |
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The MT box already has close ratio gears.
If you're talking about FD only, you need to get the terminology correct. https://docs.google.com/spreadsheets...it?usp=sharing |
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#3 |
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Have a look at some online gearing calculators, you can enter your gear ratios, max rpms, and final drive ratio to come up with a mph/kph conversion for each setup. Here's one for example: http://www.apexgarage.com/tech/gear_ratios.shtml This one is not graphing, but there are some out on the web that do comparative graphic overlays. You can then compare this info to any data collected on track and it can help you determine if you can save a shift or two along the way.
Edit: What are the chances...nice link! |
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| The Following User Says Thank You to matthewdesigns For This Useful Post: | GT86_PRAGUE (09-08-2015) |
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#4 | |
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OP it would counteract some of your FD change and probably mean you'll be changing gears more often. Depending on the course, the cars setup and your driving it may or may not be quicker.
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| The Following User Says Thank You to Turdinator For This Useful Post: | GT86_PRAGUE (09-08-2015) |
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#5 | |
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So close gears (like Cusco) will help me with 1st (specially after 4.88 upgrade), 4.88 will help me with 3rd and it may or may not screw up 2nd (depending on track). Right? CUSCO 1st: 2.946, 2nd: 2.011 REVOLUTION 1st: 2.907, 2nd: 1.988 OEM 1st: 3.626, 2nd: 2.189 According to ratios, 1st and 2nd will become longer, right? Edit: Where is the engineer when you need him? ![]() If I did the math right after 4.88 upgrade 1st should be +- same length as OEM (0.46% or 1.54% for Revo longer) but revving 18.29% faster 2nd should be 10.16% (9.11% for Revo) shorter and 18.29% faster 3rd should be same but 18.29% faster Compared to current 4.67 setup I will gain: 1st: 14.36% (15.44% for Revo) longer gear, 4.39% faster 2st: 3.74% (4.79% for Revo) longer and 4.39% faster 3st: only 4.39% faster Last edited by GT86_PRAGUE; 09-08-2015 at 04:25 AM. |
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| The Following User Says Thank You to GT86_PRAGUE For This Useful Post: | Turdinator (09-08-2015) |
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#6 | |
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Cusco makes one, so do Revolution or Autofactory (probably just rebranded stuff). Last edited by GT86_PRAGUE; 09-08-2015 at 03:05 AM. |
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#7 | |
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Edit: I am more concerned about rpm than speed, because I dont want to hit rev limiter. I think I am between 4k and 5k most of the time, but again, no logs or time to observe. Last edited by GT86_PRAGUE; 09-08-2015 at 07:41 AM. |
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#8 |
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I sometimes wonder what is the reasoning for such short stock OE 1st gear.
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#9 | |
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And if you're worried about RPM, then put in the RPM that you DON'T want to be at and it will tell you the speed. |
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#10 | |
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I have 215/45R17, 4.67 FD. I dont have any data from track and track is different every run (cones on windy airport strip). |
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#11 | |
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#12 | |
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Anyway, for my purposes I dont need anything NASA approved, I just wanted to know if the Close Gear set (lets say Cusco) will/should help me or not. It is not cheap and nobody has it. After 4.88 upgrade, I would have even shorter gears (I will be shifting more), so this Cusco set should fix gear length more to original setup while maintaining faster revving (more torque). Right? |
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#13 | |
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What differential did you switch to? Or did you keep the MFactory?
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#14 | |
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I am very happy with current setup, I only thing guys set it up more to 1.0 than 1.5, because there is zero kick/slide on downshift while braking. This is the only thing I will change with 4.88. |
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