CA Guys, What gearing are you using?

[BACARDI_DWB]

Ok guys, What gear ratio's are you guys running? I am in the market for choosing gears and I have a few questions for you

What gear ratio are you running?What rear tire size are you running?What is your RPM at 60mph in 5th gear on a CA18DET transmission?

From what I have found NA 240's run 4.08's, I was looking at running 3.73's so I am able to load the RPM band and stay in each gear just a little longer. Short gears are not good for turbo'd cars because turbo's operate better under load. BUT I don't want to have a car that feels like a dog because of the low gearing. Thanks you guys for the help!!

[sjbsuperman1425]

What gear ratio are you running? - 4.08 What rear tire size are you running? - 185/65/15 (need bigger tires..)What is your RPM at 60mph in 5th gear on a CA18DET transmission? - 2900 - 3100rpm

I'm not sure on the speed and RPM though because I have the "JDM" cluster. My tire sizes and everything put together makes the cluster inaccurate.

[BACARDI_DWB]

I plan on running 205/50ZR16's on mine and they are only .4" smaller than what you are running and that would put me really low in the RPM Band on 3.73's. That would suck to be barely chugging along on the freeway. ( granted average speed on the freeway where i am is 70) But I want to be about 3000rpm at 60. that way I am not completely buzzing while at 75mph, but not dogging it at 60mph. Thanks, this really helps. Right now my gears have 3.27's in there, I think i may get the 4.10's and see how they are as a baseline. Its only $150 to get another set of gears to try out if those are too steep or to low.

Thanks!

[r34 gtr]

4.08 rear end

245/45/17 tahrrrs (tires)

Don't have a clue about rpm at 60. 3300? I know I sit right at 4000rpm at 70mph.

Granted my speedometer is waaay off.

[BACARDI_DWB]

ok I think i have it decided. looking at this link here:

http://www.csgnetwork.com/gearratcalc.html

with my RPM at 3000 with a tire diameter of 25" and a target mph at 60 I get 3.73's like i originally picked. BUT What I am thinking is that this calculator bases that my 5th gear would be a 1:1 ratio? or am I looking at this with to much thought? the CA's 5th gear ratio is .83 which would change the overall ratio.

I think i am trying to overthink this and I should just run the 4.10's right now and see if I am buzzing on the freeway.

[Ca_Silvia]

No idea on gears as i have a Cusco unit that came in the car from Japan

225/40/18

100kph ~60mph @ 3200rpm ish

[240meowth]

What gear ratio are you running? 4.36What rear tire size are you running? 205/55/15What is your RPM at 60mph in 5th gear on a CA18DET transmission? about 3000rpm, but my speedometer might be off.

[BACARDI_DWB]

I find it interesting that your tire diameter is 24" your gearing is steeper over stock, and you are only running 3k rpm's at 60mph. I think you are right, your speedo is off. sounds like you are running at 49mph at 3000rpm's

[240meowth]

I find it interesting that your tire diameter is 24" your gearing is steeper over stock, and you are only running 3k rpm's at 60mph. I think you are right, your speedo is off. sounds like you are running at 49mph at 3000rpm's

maybe you're right i'll verify after i get my car running again. hopefully soon

[float_6969]

What gear ratio are you running?4.363:1 (48/11)

What rear tire size are you running?Stock S14 tire, IDK the size off the top of my head.

What is your RPM at 60mph in 5th gear on a CA18DET transmission?IDK, the cluster is still calibrated for the 4.08 gears and so it reads wrong.

What is the weight of the 521? If it's light, I'd actually say to stay with the 4.08 gears. I like my 4.363's, but they suck on the highway, even with a KA 5th gear (it's taller than the CA's 5th gear) stuck in the transmission. For driving in town, autoX, drag, and road racing, they're awesome. That was in my stripped S13. I kinda regretted it at the time, but now that this driveline is in the S14 (heavier) I'm glad I kept it.

[BACARDI_DWB]

The truck will weigh about 2300 with me in it and fully loaded, so yeah kinda light

[BACARDI_DWB]

Wow, i was on crack or something yesterday. I woke up this morning and realized that I was overthinking it. those calculators base your speed off a 1:1 tranmission ratio. so here is my chart with the details24" dia. tires3000 rpm crusing speed in 5th gear (.838)

3.55 gears = 72mph3.73 gears = 68mph4.10 gears = 62mph

ok so I like the 4.10 gears for the cruising speed but a third gear rollon race from 60mph I would be pretty high up in the RPM's and shift quick, but with that gearing/tire size I would always be in boost on upshifts while under WOT. I like it

[sjbsuperman1425]

ok so I like the 4.10 gears for the cruising speed but a third gear rollon race from 60mph I would be pretty high up in the RPM's and shift quick, but with that gearing/tire size I would always be in boost on upshifts while under WOT. I like it

last year i raced a B18 Integra on a 3rd Gear Roll at 50-55mph and didn't even have to shift out of 3rd to win, just for reference

[BACARDI_DWB]

a third gear rollon would look like this from 60mph and 4:10 gears on 24" diam tires

RPM / 3rd Gear mph / 4th Gear mph

8000 / 106 / 1397000 / 93 / 1216000 / 79 / 1045000 / 66 / 874000 / 53 / 69

[dattodude]

MY datto is rolling on a 3.45 rear axle.Putting a 3.7 in when I get around to shortening the housing.

[float_6969]

Turbo motor's also tend to like taller gearing as well, and with a light chassis, it's really to your advantage to run taller gears. I think the stock gears, or taller would be fine. Are you running the Miata diff, or a Nissan diff?

[BACARDI_DWB]

Even better, I am running a ford 8.8 diff. Gearing is cheap for me. I think the 4.10s will work out. I know turbos like to have load on them( tall gears) but they run 4.08 stock so I will start there and see how it goes

[dash]

Quote »Turbo motor's also tend to like taller gearing as well, and with a light chassis, it's really to your advantage to run taller gears.[/quote]yep, you'd be surprised how many have't figured that out.... and wonder why their ETs sukEqually important to choose the "correct"/matching tire diameter for dragstrip use as well

8.8 is an unnecessarily heavy diff for such a light vehicle. I stick with the 90s toyota truck 7.5 or earlier chevy S10 for rear end sources in ca18 powered street corolla & starlet. Light, but strong enough to do the job. Relatively inexpensive LSD available.Close to stock corolla width, so may not require shortening depending on wheel offset used.

Check the gearing used in the 1/4 mile ET threads at http://datsun1200.com/modules/news/

[sjbsuperman1425]

i always get confused on the taller/shorter terminology..is it like this or do i have it backwards:

3.96 - Shorter4.08 - Stock4.36 - Taller

[BACARDI_DWB]

sjb, you have it backwards, 3.10's are tall4.55's are short

dash,

I understand that that is a very heavy diff for my truck but I have a few reasons for using it. I am building a IRS truck, the 8.8's have cheap gears and cheap to rebuild LSD units. I am also building a truck chasis and need the extra weight in the back to bring the weight closer to 50/50.

Also on top of that I have bolt in halfshafts that will work with the equipment that I am using (miata hubs and 8.8 diff) that are not one off.

Thanks for the attempt thou, if i wanted light I would of went with the miata diff, i just could not justify the cost of the LSD and it won't handle the power I want, and it was too light for what I wanted.

if you have any questions about my setup check out my build thread found in the CA setup.

Light Datsun Truck + Miata running gear + CA18DET = LOTS OF FUN

[mod_mastaz]

http://www.f-body.org/gears/

This calculator is much more accurate.From the CA18det FSM.1st: 3.3212nd: 1.9073rd: 1.3084th: 15th/OD: .838

Reverse: 3.382(for reference)

GL with your ratio search.