My current setup is an S4C B16 Tranny with the JDM 4.785 Final Drive with LSD on a B16A3.

I want a bit more from the transmission setup, I was considering going with the MFactory 4.928 FD but recently I've been more interested in the 3rd/4th gear close gear set. I think I'll get better gains from it as opposed to what I'll see by going to the 4.928 FD. My question is,

Will a 4.785 final drive (with ITR 1st / 2nd gears), be too much combined with the MFactory 1.6 and 1.3 3rd and 4th gears? I plan to keep the GSR fifth gear that I have in the tranny now, so that I don't "over-rev" during freeway driving which I do quite often.

The other question, is a lightweight flywheel pretty much a necessary addition at this point? I left the OEM one in when I did the FD swap but now am considering it since I'm pulling the trans again. I mean, I really don't want to compromise driveability since I already have a bit of "bucking" with the 4.875 FD. Are brands like TODA worth the $500 price tag since they can't be re-surfaced?

Thanks

 

You can't talk about gearing without talking about the engine's powerband / torque curve and what the car's intended use is.

Since you have an NA 1.6L though... I'll go ahead and say shorten up the gearing as much as possible... you won't be over-doing it. :p

 

The intended use is to have fun with the gearing. I honestly don't want to touch the motor (it's been stock for a while now). So it's just a daily driven, stock 1.6L. I know the gearing might be a bit "much" for daily, but the long fifth should keep it within acceptable daily use imo.

 

the gearing will be fine for a daily, I find tight gears actually make getting through traffic and crap easier. If I were you I would put in a longer first gear, I have an Mfactory 3.07 first gear and the fact that 1st and 2nd are actually close together now makes a huge difference in how the car feels.

Also, the lightweight flywheel isn't going to make a HUGE difference in how fast the car more in the feel, however the engine will be more responsive and letting out the clutch will require a little more precision but you will get the hang of it quickly.

 

thanks - your opinion is helpful. So with a transmission setup like that, do you recommend the lighter flywheel or at that point is it hardly worth it considering every thing else you have done?

 

i would say it would not hurt to have one but then again you will be in higher rpm either way.

 

If you do that, your 4th-5th shift is going to suck.

From the tinkering that I've done, My preference is close ratio gears
With a taller final drive.

I'd go with the taller 1st gear, the 3-4-5 and even consider the 4.05 final drive. But I definitely wouldn't use the close ratio gears with a 4.786 or a 4.928 final. You can make your gears so short that your 2nd gear becomes your 1st gear, 3rd becomes 2nd, and etc. Then you end up having a 5th gear that's not long enough to cruise in, and a 1st gear that's too short to be of any use.

 

Well I guess that's why I was going to use the 3.07 1st gear and the GSR (0.787) 5th. That way, the two "end" gears would be still be useful, but the 2nd / 3rd / 4th would be nice and short / close. Opinions?

 

This is my exact thoughts!
My next transmission will be close gears with a 4.05 final drive (My only concern is the length of 1st gear with this setup as I do plan to use the 3.07 1st as well).

Presently I have the JDM 96 spec Transmission w/98 spec 4.785 and MFactory 3.07 1st gear (JDM 96 Spec R)
The distance between 1st and 2nd is simply AWESOME and I can still accelerate in 5th.

I had a ACT Prolite 8.8lb flywheel until a couple weeks ago, it was great as well. Downside is going up steep hills or carrying a lot of passengers.

I say get the flywheel and the 1st gear. If you had the stock 4.4 FD, I would say get the 3rd and 4th gears.

 

The over all gear ratio would be
4.05 * 3.07 = 12.4335

D-series have a first gear of 3.25,
12.4335/3.25 = 3.83

So a 1988 dx with a 3.722 final drive and a 3.25 first gear ends up having a taller 1st gear than with your setup, and it has less tq.

lots of d-series came with 3.88 final drives in 1988-1991
some even came with 3.72 and 3.25 final drives, and those engines have less power.

 

I understand that shorter gears and shorter final drive is too much as you were saying earlier, that 2nd becomes 1st, etc. but can you explain in practical terms why it'd be beneficial to use a taller final drive with shorter gears as opposed to taller gears with a shorter final drive?

 

The short gears and the tall final drive give an better overall closeness without sacrificing speed.

 

Right, but on a daily driven car you won't really see speeds in excess of 90mph (if that) so if sacrificing speed isn't of concern, then technically speaking - short gearing and short final drive might actually be of benefit.

 

Spend some time with a gear calculator and make your decision
http://www.fatboyraceworks.com/gears/

 

need someone like aquafina or honda bull to chime in they have alot of knowledge with trannys

 

Oh I have, it's been very helpful. I guess I just want to understand Bense's comment of why you'd go with a 4.05 fd and short gears. I mean, it sounds counter-productive to me. Why you go below the stock fd (make it much longer) and then shorter gears, it sounds like you'd be back to OEM gearing (4.4 with regular gears).

 

http://bensebuilt.livejournal.com/2006/09/05/

 

thanks, that helped to answer alot!

 

Be careful how you phrase "short gears". Just because they are short does not make them beneficial. The closer ratios are what helps keep the engine in its powerband upon shifts when you want to be using it.

Think about this:

Say we have an engine that we shift at 8000 rpm. And the tire diameter of the tires fitted to the chassis is 22". And let's say that the engine is our typical Honda 1.8L or 2.0L VTEC engine, making peak torque (160 wtq) at around 6200 rpm, and holding that pretty flat. Generally, we'll want the engine to stay above 5000 rpm on shifts, as that will be the 'meat' of the powerband.

With this setup, we have two transmissions to choose from: a B16 S4C transmission, and a custom transmission that has longer gears than the B16 transmission, but with a higher numberical final drive. So we have a short geared, taller final drive trans (B16) and a long geared, shorter final drive trans (custom).

B16 Transmission
Gear Ratios / Max MPH / RPM Drop / Peak Torque To Ground
1 - 3.230 / 36.9 mph / 0000 rpm / 2274 ft-lb
2 - 2.105 / 56.5 mph / 5213 rpm / 1482 ft-lb
3 - 1.458 / 81.6 mph / 5541 rpm / 1026 ft-lb
4 - 1.107 / 107.5 mph / 6074 rpm / 779 ft-lb
5 - 0.848 / 140.4 mph / 6128 rpm / 597 ft-lb
F - 4.400

Custom Transmission
Gear Ratios / Max MPH / RPM Drop / Peak Torque To Ground
1 - 2.850 / 39.5 mph / 0000 rpm / 2122 ft-lb
2 - 1.900 / 59.2 mph / 5333 rpm / 1415 ft-lb
3 - 1.360 / 82.7 mph / 5726 rpm / 1012 ft-lb
4 - 1.045 / 107.7 mph / 6147 rpm / 778 ft-lb
5 - 0.802 / 140.3 mph / 6139 rpm / 597 ft-lb
F - 4.655

So, you have two transmission that offer the same top speed but will allow two different ways of getting there. The custom transmission, despite longer gear ratios, is actually closer together and the rpm drop shows this. However, the custom transmission puts less torque to the ground in the first two gears (keep in mind this is peak torque for simplicity, not overall or average torque) which may help reduce wheel spin if this car is FWD. That's how you can have longer gears, which are actually closer together, and it may be beneficial over its counterpart.

Obviously, gearing needs chosen based on how the car is going to be used. And there is no one-size-fits-all in any way, shape, or form.

 

Everything I've ever built from dirt bikes, sprint racing karts, radio control sprint racing hydroplanes - I've always favored "Short" gears.

The blistering acceleration works for me and also the control when winding through turns, etc.

Taller in first, then shorten up 2-3-4 to closer ratios should be a lot of fun to drive.

Short gears, light flywheels and even a good rumbling exhaust ain't for everyone - but if you like it, you like it and I like it!