Jwconeil

I debate this partially. Your car is still accelerating from momentum. Technically you just lose additional exceleration. The car does not actually stop moving during shifts. Maybe I’m crazy, but in my head I’m right.

isfvss

YOU were angry with RR RACING the people that are the best in the ISF IS business come on.

isfvss

Was your gearbox slipping or traction,. The ISF doesn't need a lower first gear, but thanks for the ride.

1sFTW

Yeah, customer service is customer service. If I’m going to be spending thousands of dollars, I want things to go my way. Didn’t get that with RR, VR had the same products, for cheaper, with better customer service.

1sFTW

I forgot that the final drive ratio only effected first gear. Thanks for the comment

Jwconeil

Thanks for the work you shared with us. You saved me a lot of time and money. After seeing your results, I’ll stick with my stock torsion unit.

lobuxracer

iTrader: (2)

What is torsion about a Torsen?

Jwconeil

My diff is different. It works off rubber bands and wizardry.

lobuxracer

iTrader: (2)

For all practical purposes, this is correct. Once you get to the meat of the powerband in first gear, there are enough gears to keep you in the meat of the powerband from there out to 6th pretty easily. What that means is, it isn't possible to get more power to the rear wheels. As I mentioned previously, I got in a huge debate with a good friend about this when I initially considered the idea of putting in lower final drive gears. He said, "It won't make much difference at all." I called him out and he answered with some pretty clear mathematics showing the only thing changing from a power perspective was the time it took to get to the meat of the powerband in first gear. After that, there's no measurable difference in acceleration because you're putting all the available power through the drivetrain. Gearing can't change power. It only changes the balance between rotation and force. If you want force, you lose rotation. If you want rotation you lose force. Very similar to volts and amps in electricity.

Traction problems on even pretty decent tires are common in first gear with the OEM final drive ratio. Adding force and sacrificing rotation will only make managing traction more difficult, so in the end, without considerably more traction there won't be much payout from changing the gearing. Believe me, I spent a whole lot of time debating this and even thought really hard about a smallish change in final drive when I put the Giken spool in my diff because everything was apart anyway and it would have been relatively simple to do. It just didn't make sense mathematically.

I am glad you were able to bear this out empirically, and at a relatively small cost. Had I swapped ratios on the Giken install, it would have been a huge PITA to go back.

tas02

iTrader: (2)

You also significantly reduced the top speed your F will achieve.

lobuxracer

iTrader: (2)

Still seems to be some doubt about something. Here's the document and a quick quote from it:
In our case, because the number of gears is rapidly approaching a CVT, final drive gearing means less and less except for how long it takes to get to peak power in 1st gear. Also, drag races are mostly won in the first 16" of travel, so getting the most possible traction to apply the most possible power in that critical segment is the difference between a win and a loss. Translated this means a very low final drive with the stickiest possible tires wins in ET racing because you get to peak power as quickly as traction allows.

1sFTW

Actually, voltage and current are directly proportional and inversely proportional to resistance. I have anecdotal evidence of shorter gears not equating to faster times (for this car). I know gearing doesn't change power, but drag racers modify gearing for acceleration, which is what I was shooting for. I was hoping for a gain down low and no change up top (to a point), but I have proved otherwise. I never had traction issues on a/s tires on OEM gearing at the track, this is a fact, I have plenty of times cut 1.9s on pilot sport a/s 3 plus. My fastest 60 was 1.95 on all seasons. Now with the R888Rs and the GS gears, I have cut 1.87s in the 60. Last Friday I went 12.48 @113, (113 is my usual trap speed). The car really does feel quicker but not faster.

1sFTW

Never have I ever cared about top speed. I’ve only been to 120 because I keep going past the line at the quarter. I refuse to drive like a maniac on the street going 100+. 100% of my driving is in the city unless I go on a trip which is not often. Even on highway im cruising at 75-80. Do I accelerate quickly to say 60? Yeah. I will never try to max out the speed on my car or even care to. So irrelevant for me.

mahcah

iTrader: (3)

I can agree with this here. And I dislike it if people ask me “how fast can this thing go”. Tells me you probably don’t know much about cars.

lobuxracer

iTrader: (2)

Read the PDF. Volts and amps are power. Resistance only plays if you calculate power using current squared times resistance. Power is defined as I*E. If power is constant when one goes up the other goes down. Same with gearing. Power doesn't change, and your trap speed attests to this. If we had a three or four speed gearbox, yes, lower final drive would make a much bigger difference.