3.9 vs 4.1 wrx 5 speed gearbox
I have a blobeye wrx and one of the worst pieces of the car for me is a gearbox. It is a stock wrx 5 speed with 3.9fd. Its only advantage is quite long 5fth gear which is useful on motorway etc. Apart from that, all of the gears seem to be too long, in my opinion this gearbox is killing the car's performance. I especially don't like the second gear which is incredibely long. In my previous car, audi s3 I could drive on second gear in most of very slow dricing situations (like bump stops, 90 degrees turns, etc.). In a scooby in all of these situations I have to go to the 1st. And this is very annoying, since 1st gear is much harder to shift to.
I think that sti gearbox (or legacy spec B) would be ideal for me (ratios-wise) but it is too costly, so I am considering other options. As far as I know, gearbox on newer WRXes, starting from a hawkeye, have shorter final drives - 4.1. Is the difference noticeable? Does car feel faster on this gearbox? And is second gear more usable in very slow speeds? |
Never had to use 1st on normal driving with my WRX. Cheaper to just adjust your driving I would have thought. Is the problem that the car bogs down at low revs? Are you running stock power?
|
Yes, the RPMS just get too low, 1200-1500RPM, and I have to shift down.
I mean slowing down to 10mph or even less, which I do very often, since I drive mostly in a city. In my S3 I could do that on 2nd gear. The first gear was nearly only for starting. The car is nearly stock WRX blobeye (PPP). |
I believe that from 2006/7 the WRX final drive is actually longer, to take advantge of the extra torque of the 2.5l. It goes from 3.90 for pre 2006 to 3.7 for post 2007.
Only 2.5RS and Automatics hav 4.11 FD. Maybe and Impreza is not the right car for City driving? |
I may be wrong, but I am pretty sure that after 2006 Wrx got gearbox with 4.11 fd. There are however misleading info in the Internet. If you take a look at american forums or websites they say it is 3.7 fd. And they are right, but only for american market. All other imprezas got shorter fd. And it is probably one of the reasons why these later gearboxes can handle higher tourque numbers.
|
IF these calcs are correct, it won't make any noticeable difference swapping to a 4.11 FD
stock WRX rpm 1st 2nd 3rd 4th 5th 1000 5.521 9.795 13.960 19.619 25.840 1250 6.901 12.243 17.451 24.524 32.300 1500 8.282 14.692 20.941 29.429 38.760 1750 9.662 17.140 24.431 34.334 45.220 2000 11.042 19.589 27.921 39.239 51.680 2250 12.423 22.038 31.411 44.144 58.140 2500 13.803 24.486 34.901 49.048 64.600 2750 15.183 26.935 38.391 53.953 71.060 3000 16.563 29.384 41.881 58.858 77.520 3250 17.944 31.832 45.372 63.763 83.980 3500 19.324 34.281 48.862 68.668 90.441 3750 20.704 36.730 52.352 73.573 96.901 4000 22.085 39.178 55.842 78.477 103.361 4250 23.465 41.627 59.332 83.382 109.821 4500 24.845 44.076 62.822 88.287 116.281 4750 26.225 46.524 66.312 93.192 122.741 5000 27.606 48.973 69.802 98.097 129.201 5250 28.986 51.421 73.293 103.002 135.661 5500 30.366 53.870 76.783 107.907 142.121 5750 31.747 56.319 80.273 112.811 148.581 6000 33.127 58.767 83.763 117.716 155.041 6250 34.507 61.216 87.253 122.621 161.501 6500 35.887 63.665 90.743 127.526 167.961 6750 37.268 66.113 94.233 132.431 174.421 7000 38.648 68.562 97.723 137.336 180.881 WRX w/ 4.111 rpm 1st 2nd 3rd 4th 5th 1000 5.238 9.292 13.244 18.612 24.514 1250 6.547 11.615 16.555 23.265 30.642 1500 7.857 13.938 19.866 27.919 36.771 1750 9.166 16.261 23.177 32.572 42.899 2000 10.476 18.584 26.488 37.225 49.028 2250 11.785 20.907 29.799 41.878 55.156 2500 13.094 23.230 33.110 46.531 61.285 2750 14.404 25.553 36.421 51.184 67.413 3000 15.713 27.876 39.732 55.837 73.542 3250 17.023 30.199 43.043 60.490 79.670 3500 18.332 32.521 46.354 65.143 85.799 3750 19.642 34.844 49.665 69.796 91.927 4000 20.951 37.167 52.976 74.450 98.056 4250 22.261 39.490 56.287 79.103 104.184 4500 23.570 41.813 59.598 83.756 110.312 4750 24.879 44.136 62.909 88.409 116.441 5000 26.189 46.459 66.220 93.062 122.569 5250 27.498 48.782 69.531 97.715 128.698 5500 28.808 51.105 72.842 102.368 134.826 5750 30.117 53.428 76.153 107.021 140.955 6000 31.427 55.751 79.464 111.674 147.083 6250 32.736 58.074 82.775 116.327 153.212 6500 34.045 60.397 86.086 120.981 159.340 6750 35.355 62.720 89.397 125.634 165.469 7000 36.664 65.043 92.708 130.287 171.597 |
And what are all these numbers? :)
|
double post
|
Rpm / gear /speed
1500rpm in 2nd is 14.7mph. Swap to a 4.11 fd and it drops to 13.9mph. Is that going to make any noticeable difference when driving? |
All times are GMT +1. The time now is 07:24 PM. |
© 2024 MH Sub I, LLC dba Internet Brands