3:31 gears in a 2015 PP?

NightmareMoon said:

Because the gearing needs to match the track. FS guys whine because the courses often go to 65+mph and we redline at 59 in 2nd.

The ESP guys are probably running smaller diameter tires (18" wheels?), and they also have more hp, so they'll hit their redline even faster. They'd need to go down to at least 3.55 just to correct for tire diameters, and 3.31 if they want any additional top speed in 2nd.

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Yes and the 3.73 aren't particularly good at anything. Unless you go to a higher redline.

Probably be a pretty good choice for the 2018 with the taller gearing in the modified MT82 and higher redline.

Grintch said:

Yes and the 3.73 aren't particularly good at anything. Unless you go to a higher redline.

Probably be a pretty good choice for the 2018 with the taller gearing in the modified MT82 and higher redline.

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So based on this theory 3.73 should be pretty good with a GT350 IM rev limit of 7800? Would the 4.09 be too short? Manual car

Right, the rev limit going up from 7000->7800 more than makes up for the 373 gears when it comes to top speed, although depending on your application or track, you might want both 3.55 gears AND a 7800 rpm redline.

fwiw, 2 out of the last 3 years i've had to shift in lincoln @ nats in both ESP and CAM prep (on 25.9" 335s). also could never put the power down when i did run 3.73s (for the first half of 2015), even on A7. i run 3.55s to 8250 to avoid the speed loss you suffer (vs. 3.73) through transitions when you can't shift and bounce off the rev limiter. you will never have enough gear on big, fast courses with the MT82/3.73 combo, regardless of what you rev to. MT82-D4, different story of course.

edit: never considered running the 3.31 with the amount of torque the 5.0 (doesn't) make down low. i had them in my '13 GT, too much of a compromise.

I love my 3.31s and have even thought about stepping down to 3.15s(similar gearing to a gt350 when using mt82). The 3.73s I couldn't stand with an mt82.

Scott Wilson said:

I love my 3.31s and have even thought about stepping down to 3.15s(similar gearing to a gt350 when using mt82). The 3.73s I couldn't stand with an mt82.

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3.73 too short for the MT82? 3.55 seems pretty long for the street but would be good on track.

spiller said:

3.73 too short for the MT82? 3.55 seems pretty long for the street but would be good on track.

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I had 3.55s too. They were ok but ultimately I went back to my stock 3.31s. There are a lot of junk yard diffs on eBay.

Scott Wilson said:

I had 3.55s too. They were ok but ultimately I went back to my stock 3.31s. There are a lot of junk yard diffs on eBay.

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What was your reason for the swap? Is your car FI?

Scott Wilson said:

I love my 3.31s and have even thought about stepping down to 3.15s(similar gearing to a gt350 when using mt82). The 3.73s I couldn't stand with an mt82.

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i make max power at 7700; i'd rarely get over 7000 in 2nd with 3.31s on a typical course, and i know from experience that my car *loves* to be high in the revs! i assume your goals are different than mine

all this said, i'm going F/I this winter, and just dropped my case today to swap in 3.31s :lol:

I'm still NA. But my car is mostly for autox and grand touring. Most autox courses I never leave 2nd and I'm running it up to 7500rpms.

I know with my Ecoboost I had the best gear was a 3.15. Even with how much power I had. Big reason was I was shifting much earlier around 6k. It funny how the 5.0 is a higher reving beast over the 4cyl.

I missed a lot of the conversation, but as stated already, gear ratios are course and "use" specific. On Mid Ohio, my gear ratios are bang on. Our local autocross courses aren't as fast as national level courses either.

Competition Orange said:

I missed a lot of the conversation, but as stated already, gear ratios are course and "use" specific. On Mid Ohio, my gear ratios are bang on. Our local autocross courses aren't as fast as national level courses either.

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I will say that I enjoy being able to stay in second autocrossing and never need to shift. That said, I don't go to nationals and most of courses I run on don't get me past 6000-6500 rpm. I could easily afford shorter gears considering I can rev to 7400 with my tune, and it'd be more fun in daily use too. Mostly I want the diff. The torsen definitely feels better to drive than the clutch pack.

Vegas5OH said:

I just swapped out my PP 3.73 rear end with a 3.31 rear. Way more usable gearing for my tvs car but for na stick with the 3.73

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Were you able to find a steal housing 3.31?

whatsup62 said:

Go 3.31 then when you boost it you will be all set up....

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You guys who are FI and have switched from 3.73's to 3.31's. Did you just switch out the gears or entire pumpkins? I just picked up a new 3.31 take-off pumpkin to replace the 3.73's, and now second guessing myself. I'll be doing occasional drag strip runs, so should I have just put 3.31 gears in my existing differential, so that I still have use of the torsen diff, or will the LSD be fine in the 3.31 pumpkin?