Differentials and gearing.

[Rookieca18det]

Ive recently been bitten with the suspension and gearing bug and find them fascinating (more gearing than suspension), and wondered if anyone would care to point me in the right direction to learn a bit more. I am currently searching nico for a thread I saw a while back that was interesting I think it was done by float...not sure.

Any who just kind of want to be a bit better informed on the subject as I feel I am a complete novice (I MEAN COMPLETE) when it comes to the relation of speed+diff+gearing+smooth delivery or better yet more usable power. Now I understand diffs, well that is to say I understand the different types i.e. 1.5 way, helical, vlsd yadda yadda yadda. But, when it comes to final drive ratios and gearing ratios my brain barely scratches the surface of the content. Im sorry to rant on like this, but I think properly setup gearing will give me a more enjoyable street/track (more street) car overall. Anyway if you have any and all info please send it my way. Sorry if this a absolute newbie question to sum.

-richard

[c-rad]

Your usable options for the R200 diff are 3.91, 4.08, 4.36 and 4.63. They can all be ordered on the courtesyparts.com website. A word of caution though-- with the CA's relatively high 5th gear and the combination of a 4.36 or 4.63 ring and pinion, highway driving would be atrocious! You'd be cruising above 5k rpms in 5th at 70mph with the 4.63, lol.

[biosehnsucht]

ca stock is 4.363 - this leads to gearout at around 150mph, if you have the power to reach it.

ca on a 4.08 US rear end gives gear out more like 180, which is totally useless.

[dattodude]

MY CA18det is in a 700kg Datto. I run standard weight flywheel and 3.45:1 diff and stock CA18 gearbox. I really like driving it like that. Having a light car, I can afford to work the motor a little harder. I can use 1st gear when going around hairpins. With 3.9 gears, I never used 1st gear. I used to drive around using 2nd and 4th. Gotta love torque. :-)

With a heavier car, like an S13, you'd be wanting to raise the ratio to 4.1 or lighten the flywheel a little. This will be an interesting topic I'm sure.

Chris.

[Rookieca18det]

so if i could somehow get my hands on a stock ca ring and pinion it would be well worth it... Im currently looking into getting a 1.5 way or maybe an s15 helical, I kind of remember float doing somewhat of a write up on his diff combo but couldnt find it last night. Only thing I really came across was a couple of threads on a tomei 2 way he lucked into. So would I be correct in thinking that if I could get my hands on a ca 4.363 and use it in a s15 diff I would have very good gearing for my street car. Im really trying to avoid the 5k rpm while doing 70. Thanks for all the info so far keep adding and I'll keep searching. Infact I remember a thread about different transmission options for the ca and the differnt gearing of each car...I may aswell look that up as well.

[XTCshri2222]

IS it possible to use Nissan truck R200 gears? I came across a 5.14 R200 gear, i'm building mine for show and drag so i was wondering would it work, it's a R200 ring pinion set.

[Kouks]

ca stock is 4.363 - this leads to gearout at around 150mph, if you have the power to reach it.

ca on a 4.08 US rear end gives gear out more like 180, which is totally useless.

In GT4, the 88 silvia with the ca18det, goes like 146, and tops out at like 7200rpm, installing the Full customize transmission and keeping the gearing EXACTLY the same, cept for ka rear end gear(4.083), it then tops out at 158mph in 5th gear(as obviously i dont use the 6th gear cuz we dont have one, but the calculations are spot on.

[float_6969]

I'm currently running a KA box with a CA diff with an S15 helical diff. The only gearing difference between the KA and CA box is 5th gear. I'm also on a 12lb flywheel (stock is 25lb-ish). As far as in town is concerned, first is the only gear that can give me problems. It tends to buck and only likes to be used when accelerating. I generally just use 1st to get moving from a stop and then get into 2nd pretty quickly. Also, with my 205 series tires, and 14psi on an S15 T28, it'll light up both tires all day long. All of the other gears are fine for daily driving.

As for highway speeds, I'm not looking forward to putting the CA box back in. I'm already turning about 3700-3800 rpms in 5th at 70mph, and putting the shorter 5th geared CA box in is probabally going to put me over 4K at 70mph.

[Rookieca18det]

Thanks for all the input guys and thanks for chiming in float. Well, I will more than likely be staying with the stock CA gearbox but I will probably need to get another one as my second and fourth gear are grinding every now and then. Then again I might just take it to a transmission shop and have them inspect it and see how bad the damage is and if it is just cheeper to replace the syncros or just buy a used transmission. Looks like it is time to do some more reading. Thanks all

-richard

[driftin8ez]

using the stock ca box and the gear set from a j30 r200v diff would seem like a good match. It makes the gears a little taller on my ka transmission which is good to keep the turbo spooled longer it would also lower the rpms when ridding in 5th gear on the highway. Anyone do any calculations on that combo. This is all theory from me.

[Kouks]

I can do it for you, whats the j30's FD? 3.92?

Combo: Ca18det CA transmission J30 FD

Here it is: Assuming 7500rpm redline.MAx Speed

2nd: 72mph3rd:104mph4th:135mph5th:164mph

5th gear at 70mph was steady at 3300rpm
Modified by Kouks at 5:04 PM 7/7/2006

[driftin8ez]

could you do it with the ca transmission and j30 final drive? Thats what i was wondering. However it looks like the ka transmission would be good for gas mileage.

[Kouks]

Float, I did CA transmission with ca FD and 70 should be at 3600rpms in 5.

If you are at that now with a KA transmission, dont understand, GT is calculating 3300rpms in 5th at 70mph.

Are you on stock size tires?

[Kouks]

Redone above for Ca transmission.

[driftin8ez]

I can do it for you, whats the j30's FD? 3.92?

Combo: Ca18det CA transmission J30 FD

Here it is: Assuming 7500rpm redline.MAx Speed

2nd: 72mph3rd:104mph4th:135mph5th:164mph

5th gear at 70mph was steady at 3300rpm

Modified by Kouks at 5:04 PM 7/7/2006

this is what i was looking for. Looks like a good combo to me. Anyone else have any comments on that?

[Vetal]

Your usable options for the R200 diff are 3.91, 4.08, 4.36 and 4.63. They can all be ordered on the courtesyparts.com website.

Can you please give me more precise link? I'm thinking about trying 4.36 or 4.63 for drag purposes

[Vetal]

Wow, found them:http://www.courtesyparts.com/nms/s13/s13_4.htmlThey're $482

[tyrannix]

Did you ever get your 4.36+HLSD pumpkin installed Ryan? I don't remember.

Btw, as I traded my flywheel for the giken twin plate to go on teh ca20, i'm waiting on a new jun 5.xkg flywheel from raretrick, so I'm going to use the KA transmission with my s13 as well to get the better 5th gear ratio.

CJ

[tyrannix]

Wow, found them:http://www.courtesyparts.com/nms/s13/s13_4.htmlThey're $482

i got a new set used for less then that, but only because i forgot to grab the pumpkin from my silvia

you have to factor in rebuilding the pumpkin too (what i had to do) i paid $160 for somone else to do it for me, as i dont have the tools. thats the only thing on my car that i havnt done myself (including rebuilding the engine, minus teh machine work)

so youre looking at a total price of around $800 to get those gears into a pumpkin

if you want 4.36 gears, your best bet really is to get the whole pumpkin from a CA silvia shipped to you (even if its $300 for shipping, it will probably be less than rebuilding)

BUT, theres also the little reassurance knowing that you have basically a whole brand new pumpkin, and wont have to worry about it (but that doesnt count for much. who has had a problem with their pumpkin ****ting with a CA?

just things to think about

CJ

[float_6969]

Did you ever get your 4.36+HLSD pumpkin installed Ryan? I don't remember....

Yup, I drive on it everyday...

[asher4857]

sorry guys.. i dont quite understand this..

as far as i know, im running the stock CA box and stock KA diff.. its not an SE so it isnt a lsd..

right now 65 is about 3K in 5th gear.. anumeric on here hits about 80 at 3k.. what would I need to do in order to get this effect.. my main concern right now is gas milage as i wont be tracking all that often

[tyrannix]

all you need is an LSD if you want then (dont touch the gears), besides that you could just leave it alone

CJ

[asher4857]

what do you mean just leave it alone.. im asking because its not what i want.. lol.. if my friend can cruise at lower then 3K, i would like to be able to get the same effect if possible..

[anumeric]

CJ how long have you been waiting for your JUN flywheel from Raretrick? I was planning on ordering one from them as well "quite possibly next week" and was wondering how long the expected wait would be.

thanks in advance Wei

Oh yeah sorry for the thread jack.

[tyrannix]

what do you mean just leave it alone.. im asking because its not what i want.. lol.. if my friend can cruise at lower then 3K, i would like to be able to get the same effect if possible..

if you have a CA transmission (didnt reread whole thread) then swap it for a KA transmission, 1-4 gear will be the same but 5th will be lower, giving you lower cruise revs

most of the time, people wanting to swap gears want to accelerate faster (higher diff ratio)

having a lower ratio means lower revs, swapyour transmission (cheaper by far than mussing with diffs)

youll just need teh bellhousing from your CA transmission, and bolt it to the KA transmission

CJ how long have you been waiting for your JUN flywheel from Raretrick? I was planning on ordering one from them as well "quite possibly next week" and was wondering how long the expected wait would be.

thanks in advance Wei

Oh yeah sorry for the thread jack.

last i heard from them was jul 11:CJ,

I do have the order fror the JUN CA18 Flywheel.I am looking to place an order to Japan very soon, no eta yet.

Thank youDrew- Show quoted text -

[rotorific]

Hey guys i got a 4.36 lsd up for grabs BUT you will not be able to use the LSD and there is no backcover. Reason is someone did not seat the axles correctly and the snap rings just kept spinning in the LSD. So i bought it from work expecting to use the gearing but I found out that a 4.36 with a CA transmission is not a likeable combo. So basically you would get the ring and pinion and the housing.
Modified by rotorific at 4:27 AM 7/30/2006

[asher4857]

cj, does it matter that when i had my KAE and ka transmission, my 5th gear was virtually the same as it is now with my CA and CA transmission?

i guess, would the CA and KA combo be different the KA and KA combo

[tyrannix]

Hey guys i got a 4.36 lsd up for grabs BUT you will not be able to use the LSD and there is no backcover. Reason is someone did not seat the axles correctly and the snap rings just kept spinning in the LSD. So i bought it from work expecting to use the gearing but I found out that a 4.36 with a CA transmission is not a likeable combo. So basically you would get the ring and pinion and the housing. Modified by rotorific at 4:27 AM 7/30/2006

the 4.36 ratio is what CA silvias had stock, and they have a higher ratio 5th speed gear (read more accel, less top end). Whats not to like (except 5 gear cruising burning up all your fuel)

cj, does it matter that when i had my KAE and ka transmission, my 5th gear was virtually the same as it is now with my CA and CA transmission?

i guess, would the CA and KA combo be different the KA and KA combo

the CA trany has a higher 5th gear

if you use your KA transmission with the USDM rear, youll get better mileage (because of the ower ratio) in 5th

but i probably wouldnt race with that diff

[rotorific]

exactly tyrannix.... I dont mind 3k at 75 mph but it would probally be near 4k with that 4.36. I couldnt even imagine it.

[float_6969]

Right now I'm running a KA box with the CA diff gears and it's not that bad on the highway. I can tune my standalone to get as good of gasmilage as I'd like, so that may not be a fair comparision, but I don't anticipate the different 5th gear in the CA box to effect the mileage that much. I should know more later when I get the rebuilt CA box back in the car.