trannys and ratios

[steve]

Here is some info on B series trannys and ratio calculations that may be of interest to you guys.

There are several B series transmission and differential ratios to choose from; The 94
or newer Integra LS, RS, GS, have the best Hydro tranny ratio for street use on a Mini;
especially if you are using 10" wheels. fifth gear is .714 to 1 and the diff is 4.27 to
one. Since 5th gear is overdriven, you must multiply it by the Diff ratio to get the
"Effective" final drive ratio. So, doing this with the LS tranny you get 3.04 to 1; the
highest Hydro tranny ratio available stock. However, this transmission does not come with LSD, (limited slip), I installed an LSD from another B series tranny but with a ratio of 4.40 to 1 instead of the desired 4.27. This calcs out to 3.14 to one effective final drive; Exactly the same as I had in my stock Mini, and a whole lot cheaper than buying an after market ring and pinion set for 1500$. Here are some calculations for this gear combination using 10" Yoko A032 tires that are 60.5" around.

Integra LS 5th gears of .714 with a GSR or early type-R 4.40 ring and pinion:

800 RPM in 1st gear (idle)....................................3.3 MPH (great for stop/go traffic)
9000 RPM in 1st gear (red line).............................37 MPH

60 MPH in 5th gear.............................................. .3288 RPM
65 MPH in 5th gear.............................................3 562 RPM
70 MPH in 5th gear.............................................3 837 RPM
you can achieve this by installing the LS 5th gears into a GSR or early R type tranny.
This results in close-ratios through 4th gear with a big drop into 5th). good for racing with the close ratio 1st through 4th, and the big drop into 5th will not be a problem when racing, because any speed past red line in 4th gear would be dangerously unstable in a Mini.

the other way to achieve a long effective final drive is by using the cheaper LS tranny with it's .714 5th and 4.26 diff ratios. (this tranny does not come with LSD). With this slightly longer combo, your speeds/rpm look like this:

800 RPM in 1st gear.............................................. ............... 3.7 MPH
9000 RPM in 1st gear(red line)............................................. 42 MPH

60 MPH in 5th gear.............................................. ............3184 RPM
65 MPH in 5th gear.............................................. ............3449 RPM
70 MPH in 5th gear.............................................. ............3715 RPM

Just for giggles, 9000 RPM in 5th gear ..............................170 MPH (suicide)

[pwr2wh8]

good info! can you post the calculations you used? i'd like to find and compare my setup to this one.

i currently have the s80 with a ls 5th gear for overdrive/cruising. as you mentioned, retaining the close ratio of gears 1-4 is great. however once i shift to 5th, there's a big drop, sometimes below vtec.

[steve]

Shon, The big drop into 5th should not be a problem. If you are not racing, the drop is of little consequence. If you are pushing it a little, You should be shifting at 7,000 RPM or more; thats going to be way over 100 MPH in 4th already, maybe 130; How much faster do you want to go in a Mini? You will never get into 5th except when cruising, unless you are short shifting, in which case you are not really trying to go fast anyway. If you are already in 5th when you decide to go for it, you should drop down a gear or two.

[boosted]

B-series Tranny Specs

Transmission Name Engine Counter Part 1st Gear 2nd Gear 3rd Gear 4th Gear 5th Gear Reverse Final Drive

S1/J1 JDM B16A X-Si 3.230 2.105 1.458 1.107 0.848 3.000 4.400

Y1; Y1 w/LSD JDM B16A SiR I 3.166 2.052 1.416 1.103 0.870 3.000 4.266

S4C/Y21 USDM B16A2, B16A3; JDM SiR2, JDM SiR2 w/LSD 3.230 2.105 1.458 1.107 0.848 3.000 4.400

Y80/S80 JDM B16B w/LSD; JDM B18C 96-spec R w/LSD 3.230 2.105 1.458 1.107 0.848 3.000 4.400

YS1 USDM B17A1; JDM B16A X-Si w/LSD 3.307 2.105 1.458 1.107 0.848 3.000 4.400

S1/YS1/A1 USDM B18A 3.166 1.857 1.259 0.935 0.742 3.000 4.400

Y80/S80 B18B 3.230 1.900 1.269 0.966 0.714 3.000 4.266

?? B18B (auto) 2.722 1.468 0.975 0.638 ---- 1.954 4.357

S80/Y80; S80 w/LSD, Y80 w/LSD JDM B18C SiR-G 3.230 1.900 1.360 1.034 0.787 3.000 4.400

S80 w/LSD JDM B18C Spec-R 3.230 2.105 1.458 1.034 0.787 3.000 4.785

Y80 USDM B18C1 3.230 1.900 1.360 1.034 0.787 3.000 4.400

S80 w/LSD USDM B18C5 3.230 2.105 1.458 1.107 0.848 3.000 4.400

S80 w/LSD EDM B18C Spec-R 3.230 2.105 1.458 1.034 0.787 3.000 4.785

[SixtyFo]

Good info. Since I'm trying for a B18C type R motor I would effectively be running sprint gearing with the mini's tiny wheels! From this it looks like a lsd box out of a SiR-G would be the way to go.

[250ptm]

The transmission I am using is from a JDM B16A which has an S80 LSD the ratios are:
1st 3.23, 2nd 1.9, 3rd 1.36, 4th 1.034 and 5th 0.787 fd is 4.4. This gives 17.07mph on 175/50/13 tire.
To my recollection the original S gearing with a 3.44 fd gave around 16.6 on 10 inch rims. Basically increasing the wheel size to a 13 inch rim does not increase the mph/1000 substantially(in my case) as the circumference of the 13 inch rim with the lower profile tire is basically the same as the original S wheel and tire dimension.

Here is a link to a site which will give you info on any wheel and tire combination as used with the various transmissions which are available. You can also play around with the ratios in each gear to see the effect it may have.

http://www.fatboyraceworks.com/gears/

[steve]

if you are doing any highway driving, you might consider the 4.26 integra LS, final drive ratio with the LS 5th gear set. you will be able to get the revs a little lower than the popular mini highway final drive gear of 3.14 used with the A series tranny. this is what I am putting into my re-done tranny now. I just bought the "Mfactory helical LSD" that takes the LS ring gear. This diff is equivalent or slightly better than the Quaife, and less money, (630$ shipped). They also have a 4.06 final drive set for 550$ for revs equivalent to many Honda VTEC cars on 15s. You can keep 1st thru 4th short for racing where you will probably never get into 5th, then use 5th for cruising/MPGs. 8)

[kusitolman]

I had a custom final drive made. If anyone is interested contact johnfrana at yahoo.com . he has a few others in stock now. both the smaller B16/ LS ring gear and the larger GSR/ ITR type in a couple ratios. his website doesnt show much, so just email. http://www.thefranagroup.com/johncfrana/finaldrivegears.html

[steve]

Thanks for the tip; Please let us know how loud those gears are when you get them in. 1200$ is not bad, cheaper than most, but still up there, compared to the shorter ratio gear sets out there, selling for 550 to 600$ range. I am checking with him to see if he has a volume price discount, though don't expect many will want the straight cuts at any price.