joel n

We are running a 95 delsol with a 96 JDM ITR motor and trans. Trans has a Mfactory Helical LSD and Gear-X 4.7FD. On a real good lap, we hit the limiter in 4th on the back straight. Or if we are in the draft we hit alot. 6 times or so. 3-4 out of draft. We change between 225/50/15 tires to 225/45/15 tires. The 50s never get to the limiter, but the 45s do. I would like to go back to just 45 series and the car feels better in the corners. We bought Hoosier that were really good and cheap in 50 sidewall and a set of V710. thats why we have that sidewall.

Question is would you rather hit the limiter some or should i swap in the JDM ITR 98+ 4th gear. It would give us that little extra on the 45 series. But hurt us on the 50 series.

JDM ITR 98+ spec.
4th. 1.034

USDM ITR + JDM ITR '96 Spec
4th. 1.107

We just started running the Nitto NT-01 tires and i am blown away at how fast they are. Makes the toyo R888 look pretty bad.
R888 can do a 1:18.4 225/50/15
NT-01 can do 1:17.2 225/45/15
Hoosier R6 can do 1:16.0 225/50/15
Just for a idea on how tghe lap times sit with the current setup.

ALSO what Rear toe do you guys run?

Sccacivic1997

iTrader: (2)

1/16 rear toe in on my 2000 civic si

Xian

Curious but have you looked at the data to see if going to a shorter FD may be a better option? I'd be hesitant to swap out just 4th gear... my thinking is that eventually you're gonna start carrying more speed onto the front straight (via power, suspension, or tires) and end up with the same problem all over again. Depending on where a 4.9 would land you with regard to gearing/shift points on the rest of the track, that may be a better long term solution.

Zero toe. No reason to have the rear end scrub and impact straight line speed.

0parts@synchrotech

I would go to the 1.034 4th gear which is available in the USDM GSR(same gearset). This will allow you a little more time in the gear and utilize more usable power unless you are making power all the way to the limiter. Xian brings up a good point about carrying more speed and it being a negative byproduct. Something to definitely keep in mind Gearing is one of those things that is trial and error. It will be cheaper to buy two gears than to buy a final drive set. So I would go with that and see what results you gain. If you are not happy..work with a final drive set and see what is achieved at that point. Keep us posted!

joel n

I have thought about the 4.9FD but worry it will hurt more then help. Shifting to 5th is a killer. we have a small track, right now the max speed we see is 170KPH. Thats a good pass on the back-starightish. Small amount of rev limiter. We currently do not shift mid-turn, 1 spot is just after mid-turn but is a decent spot. So i was hoping to try the JDM 98+ 4th gear. It wont be untill winter, maybe do it for the 3 hour canfield race in late sept if time permets. There is another couple of guys here with a EG civic with a 98+ spec ITR swap, running a 4.9FD. They tracked it a bit last year, but tore it apart to do some needed service and unneeded upgrades. They wont be back on track this year i am guessing. I was hoping between them and us, we could sort out what works best. But they seem to be more concered with Putting cool parts on then building a reliable, functioning car. lol.

James, just wanted to thank you again for getting the trans parts to us so quickly, and giving some info for the trans work, and fluid. We dont have a lot of sources around here when it comes to racing hondas, and as we are the only honda racing right now, everything we learn is from something we did right or wrong.

I will try and get some video next race weekend to give a idea on the shift points and rev limiter we are hitting. Both the first and second race weekend we forgot to record the good races.

96dxB16

My trans (that is now for sale, lol) has the 4.9 FD. What I did for 5th gear was swap in a 92-93 GSR 5th gear which is a little shorter than the B16 5th gear. I loved it, pulled well in 5th gear that way.

Black R

OP, is raising the rev limiter an option for you?

If not, then the gsr 4th sounds like the cheap solution.

Another (possibly better) option would be an mfactory close gearset and 4.4 final drive, but that's more expensive.

joel n

I would rather bounce off the limiter then raise it a bit. I want the motor to last and keeping it in the factory set range should help that. Would like to rebuild this motor in 2 years.

We looked at the custom gears last year? But outside 4th gear the others are great. So I was hoping we could find a cheaper solution then a full custom set and the GSR-98+ ITR 4th seems like a great solution. Started looking for some today but as I stated before we are kinda along here. Lol. Might just call honda or James at syncro tech this winter.

Also I found a webpage before with the tooth counts for each gear in most of the popular transmissions. Can't seem to find it any more. Anybody have a link.

Need the tooth count for

SIR 2nd gear. Main and counter shaft.
I think it's the same for type r and GSR.

GSR/ 98+ ITR 4th gear. Main and counter shaft.

Black R

Ok I was just wondering - some of us have run upwards of 9200 rpm for years on stock itr motors, but you're right: rpm = ruins peoples motors.

I wasn't sure if your class enabled you to raise rev limiter or install aftermarket valve springs - IMO those are easier than pulling and rebuilding the tranny.

Is building a second tranny as a backup for higher speed tracks an option?

Or maybe something as simple as a backup 98spec itr tranny?

But the cheapest solution sounds like 4th gear swap.

joel n

I know lots of people have raise there limiter, but the moment we do,,, booom. lol.
The class is a joke. Must have been a legal IT class car, Cage can't incorporate the rear suspention, and the cage can't pass the firewall. DOT tires only. Outside of that, its open. We could build a LS/VTEC turbo/supercharged, custom dog box, fully lightened, areo monster. lol. Kinda whatever you wallet can handle. We are tring to get some better rules, and right now the 3 main cars are close.

We are going to have a spare box soon, its going to be just a mismash of a box. 4.4 FD, JDM ITR LSD, hoping it will have the same gear ratios as the ITR box, but might not. And it will be just a bunch of used parts from the stock we have and what we take out of the ITR box tomorrow. It will also be the first trans ill build by myself. should be fun. Might toss it in on a lapping day and make sure it works.

The 4th gear swap looks to be the way to go, cost wise and setup wise.

maxogsr

I say it's all about compromise... what will work on a track, won't on an other... to be on par at each track, you'll need a tranny set up for each track... And I'll say even at the same track... you'll gain at some corner and loose at other... Me and a friend of mine have tried so many set up and at the end, the clock dosen't change that much...

If you are always on the same track, then I would go with the gsr 4th gear... Don't go 4.9... it's too short with the itr gearing. you'll end up shifting 5th gear at 160km/h and you'll be slow cause the usdm 5th gear is too long...unless you are going very short with the 3-4-5 close ratio gearing... But you'll end up with a top speed of 200-210km/h... You'll hit the rev limiter at some big track i.e Mosport...

Here's your best friend! http://www.teammfactory.com/gear-calculator

I spend so much time using my dataloging and this gear calculator tool! It's pretty much accurate!

Better rubber is always the easiest way to go faster... if you are aloud in your class...

joel n

Thanks, that is very useful, But it doesn't match the GPS data. GSP shows we are going 170KPH, on the rev limiter. 8800 or 8900. stock 96 Type R motor and ecu. The calculator shows 186KPH. Ive gone over all the gears ratios, FD and rev limiter. Still not making sence.
4.7FD, plus stock 96 type R gears. 225/45/15 NT01 tires.

I dont remember the name of the GSP data logger we use, but it seems to work really good for everyone else.

And we are maxed out for tire. Only thing that will change is going from a 225/50/15 Hoosier R6 to a 225/45/15 Hoosier R6. We really only use the NT01s for the 1 hour race and the odd sprint. I am guessing we will be hard on the limiter with the Hoosiers in the 45 series. But we have enough hoosier and khumo to finish this year off with running the 50 series sidewall.

Xian

Hoosier makes a 245/40 and 245/50 in 15"... maybe use one of those for additional rubber at either roughly the same diameter as the 225/45 or ~1" larger.

96dxB16

This is why I swapped out my 5th gear for the slightly shorter 92-93 GSR 5th. Loved having my 4.9, especially at thunderhill. Made 5th gear useful.

maxogsr

True and it's new from this year... But I think it's gonna be available only in A7-R7...

245/50 would give you 24.5 of diameter and this should almost be like if you would put a 4.4fd... But you'll need at least 9'' wide rims...

As for the GPS, I know what you mean about the difference between the gps speed vs cluster but with a bit of math, you can get close to the real number...

I'm preety much in the same ship with my new set up this year at my local track... I used to run a specR with a usdm tranny but with a 4.785 in it on 225 45/15... Now with my new set up k20a I'm flirting with the redline all the time...As soon has I will get used to the set up, I'll carry more speed and will have to shift for a second in a upper gear... I'm considering 17x9 on 245 40/17 next year...

joel n

We looked at the 245 tires from Hoosier just yesterday. They will fit a 8inch rim, but a 9 would best. Meaning we need to buy new wheels. $$$$. and not sure on clearance. The 225/50 on a TRM wheel, 15X8 with a 20 offset lots of roll and hammer and a 3/8 spacer just rubs on the front. just shines the rubber. rear has no spacer lots of roll/hammer and rubs just enough to shine the rubber.

maxogsr
245/50 would give you 24.5 of diameter and this should almost be like if you would put a 4.4fd... But you'll need at least 9'' wide rims...

The car had a 4.4FD in it before and it really hurts at AMP. keeps the car falling out of VTEC and the next lower gear is close to the limiter. Could run a 4.4FD with custom ratios, but back into the money.

I will look into the Hoosiers again. see what the 245/40/15 R6 will be like. its only .1 of a inch larger.

Xian

I'm not sure about the 245/40 but I'm pretty sure that the 245/50 15 has been around since at least last year (a friend of mine runs them on his ITS Mustang). I agree that a wider wheel would be nice but not a "need" so much with the construction on the Hoosiers (aforementioned Mustang guy runs them on the class max width of 7"). If you're not limited by rules though there's no reason not to snap up any of the cheap 15x8 or 15x9 wheel options out there.

I've kicked around the idea of going to 17's in order to fit more (street) tire under the front of the car. Ultimately I don't think that I'll have the power to make it work better than the slightly narrower 225/45 15 options. With a K though...

Edit:
Posted at the same time as the OP.

I don't see any reason to run 245's at the rear... just fit them up front. If the class rules are the wild, wild west then roll the front fenders or trim them as much as is necessary. The TRM wheels are super cheap and you'd only need them for the front...

joel n

Yes this is for 2014.

I need to look at the speed difference between the 2 4th gear options. looking at it pretty hard right now. Will most likely be a winter upgrade.