Rear diff swap from 4.10 to 4.30
 

So I imagine most of you know that in the 2017-2020 models they went to a 4.30 rear diff from the 4.10. I was very close to swapping the diff in my '13 before I sold it, and now the 22+ has the 4.10 again. Since the drivetrain itself is relatively unchanged, I imagine the 17-20 diff should be a direct swap. Now, everyone seems happy with the new one in all the reviews so far, but I think that extra punch would be just that much better. since you have to shift to 3rd for 0-60 anyway, I'm guessing they did it for emissions, but who knows. I think I may try to swap the diff pretty quickly.

Rear diff swap from 4.10 to 4.30
 

So I imagine most of you know that in the 2017-2020 models they went to a 4.30 rear diff from the 4.10. I was very close to swapping the diff in my '13 before I sold it, and now the 22+ has the 4.10 again. Since the drivetrain itself is relatively unchanged, I imagine the 17-20 diff should be a direct swap. Now, everyone seems happy with the new one in all the reviews so far, but I think that extra punch would be just that much better. since you have to shift to 3rd for 0-60 anyway, I'm guessing they did it for emissions, but who knows. I think I may try to swap the diff pretty quickly.

They probably did it because the new engine makes peak torque at 3700rpm and the old engine makes it never.

ehh That peak torque being soo much sooner is a bit of a buzz word. On the 1st gen the initial torque peak at about 3700rpm was JUST BARELY lower then the peak torque at like 6600rpm.

Excellent idea.

Not worth the effort...
FWIW my '17 (4.3) vs. my bud's '13 (4.1) at the track (road courses) turned pretty much identical times, and hit similar speeds on the straights. He got a '17 this year, still same times vs. his old car.

Compare acceleration times from '13 and '17 BRZ (non Brembo) and the '17 has a 0.1 second advantage 0-30, while 30-40, 40-50, 50-60 etc. acceleration times remain identical. '17 one tenth quicker in the quarter at the same speed.

4.1 to 4.3 is just about no difference at all in the real world.

https://drive.google.com/file/d/0B78...YU3YzZ0JB/view
https://drive.google.com/file/d/0B78...uaXRfRl9j/view

weight: '13 = 2764 lb., '17 = 2777 lb.

0-30mph: '13 = 2.3s, '17 = 2.2s
30-40mph: '13 = 1.0s, '17 = 1.0s
40-50mph: '13 = 1.4s, '17 = 1.4s
50-60mph: '13 = 1.6s, '17 = 1.6s
60-70mph: '13 = 1.9s, '17 = 1.9s
70-80mph: '13 = 2.2s, '17 = 2.3s
80-90mph: '13 = 2.8s, '17 = 2.7s
90-100mph: '13 = 3.2s, '17 = 3.2s

30-100mph: '13 = 14.1s, '17 = 14.1s

1/4-mile: '13 = 14.9 @ 95mph, '17 = 14.8 @ 95mph

Lol okay.


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I'll repeat my reply from the twin thread here:
Not worth the effort...
FWIW my '17 (4.3) vs. my bud's '13 (4.1) at the track (road courses) turned pretty much identical times, and hit similar speeds on the straights. He got a '17 this year, still same times vs. his old car.

Compare acceleration times from '13 and '17 BRZ (non Brembo) and the '17 has a 0.1 second advantage 0-30, while 30-40, 40-50, 50-60 etc. acceleration times remain identical. '17 one tenth quicker in the quarter at the same speed.

4.1 to 4.3 is just about no difference at all in the real world.

https://drive.google.com/file/d/0B78...YU3YzZ0JB/view
https://drive.google.com/file/d/0B78...uaXRfRl9j/view

weight: '13 = 2764 lb., '17 = 2777 lb.

0-30mph: '13 = 2.3s, '17 = 2.2s
30-40mph: '13 = 1.0s, '17 = 1.0s
40-50mph: '13 = 1.4s, '17 = 1.4s
50-60mph: '13 = 1.6s, '17 = 1.6s
60-70mph: '13 = 1.9s, '17 = 1.9s
70-80mph: '13 = 2.2s, '17 = 2.3s
80-90mph: '13 = 2.8s, '17 = 2.7s
90-100mph: '13 = 3.2s, '17 = 3.2s

30-100mph: '13 = 14.1s, '17 = 14.1s

1/4-mile: '13 = 14.9 @ 95mph, '17 = 14.8 @ 95mph

?? What did I say that was wrong? Why are you being such a tool?

Thank man, that's an awesome break down, I appreciate it. Didn't realize it would be so pointless. People I talked to seemed to suggest it was a solid upgrade on the 13-16's

On street I didn’t notice much difference.

On my tracks, it made a huge difference. Saves about 4 shifts per lap. With the 4.1 I was in between gears a lot. I went back to a 4.1 because I thought e85 would overcome the difference but it’s not enough. Im going 4.44 next and raising the rev limit.


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I think changing the diff in such a small increment is more worthy for the FEEL of the car than it is for real world numbers. But I can't say much about the comparison of feel when it comes to these two (I've only owned a 17+) other than the fact that many who got the 17+ after owning a 13-16 stated that it "felt" quicker.

Ah, but there are places where instead of getting an "extra 300rpm" you'll either have to be more on the rev-limiter, or have to upshift. It's going to be very course-specific, and overall as likely to hurt you as help.

:shrug:

I guess they just stayed home and made these numbers up:
https://drive.google.com/file/d/0B78...uXfT1q4d2rUvGA
https://drive.google.com/file/d/0B78...e7fBsneVQecZXQ

It is worth noting that the '17 was much quicker when intentionally lugging it, i.e. 5-60 (no launch) and top-gear 30-50 and 50-70 pulls. But who does that?

It would give you an extra 300 rpm on the autocross course.

In second gear? Not buying it.

Hes not wrong, it peaks or nearly peaks at around 3700ish, then dips and comes back at 5k before peaking at 6600rpm.

But everyone seems to be incapable of driving a low torque car like every non-turbo econobox in existence, so they only feel the lack of power due to the torque dip.