So it’s 99.9% certain that I’ll be the proud owner of one of these badboys sometime this or next week, so I wanted to ask about the gearing. I’m aware that the tranny on the CA, RB20, SR and KA are the “same” with different bellhousings, but then I heard about different gearing on the CA. Now the two options I’m considering, one has a full CA tranny, the other has just a CA bellhousing and I need to stuff my KA tranny in there, so I wanted to get stuff fairly cleared up before I purch-ass a motor 
What is the gearing on the CA, KA, SR, etc… if anyone knows… and I searched… oh I searched.
one thing i know for sure is CA18DET cars have a different rear final drive gear
got numbaz?
i never had a chance to take apart the ca tranny i had ive only taken apart ka tranny but i never counted the teeth on the gears to calculate the ratio’s
but like avery said the final drive is for sure, but its probably better for drag racing or circut racing than the 4.5:1 that i think the ka has final drive.
it was roughly about 3500rpm for 120kmph where as ka is around 3000rpm for 120kmph.
even that though is not bad, gas mileage on a proper running ca is great so its nothing to pull your pants down for.
the ca tranny will have less km than any ka tranny so i would take the ca tranny if its not much more.
I’m not positive that they’d be the same, but my old Pulsar had a CA16DE and at 120 km/h it was at 4,000 RPM. When I got the 240, it was 3,000 RPM.
Of course the redline is higher on the CA too though. But it does rev high on the highway.
CA18DET from a 88-90 Silvia K’s
1st - 3.321/3.027
2nd - 1.902/2.057
3rd - 1.308/1.000
4th - 1.000/0.694
5th - 0.838/-
reverse - 3.382/2.272
final drive - 4.363/4.363
VS
SR20DET from 90-93 Silvia K’s
1st - 3.321/2.785
2nd - 1.902/1.545
3rd - 1.308/1.000
4th - 1.000/0.694
5th - 0.759/-
Reverse - 3.382/2.272
Final Drive - 4.083/3.916
what the heck kinda gear ratio’s are these?
must be the diameter of the gears? what units is it measured in?
ratio is to 1
lol, on the right is auto dude
So if the only different thing in the manuals is the final drive, that’d be related to the diff, not the tranny itself and it wouldn’t matter whether it’s CA or KA, am I right?
No you’d be wrong since the CA and SR tranny have, as per the information supplied above, different ovderdrive (ie 5th) gear ratios.
Otherwise you are right!
believe it or not… but Nissan sells the CA 5th gear 0.838 as a “Nismo” upgraded 5th gear for a SR tranny etc
There’s so many numbers floating around on the internet it gets confusing because no one knows where they are getting them from.
The USDM cars’ diff ratio is 4.08:1
I think there’s 3 different gearsets, North America, Europe and Japan
But the differences are pretty tiny. I’ve swapped a ton of bellhousings to a ton of different Nissan trannies and they all work. The only problem I have run into is older stuff (pre '86). Nissan switched to a larger diameter countershaft bearing for 87 (actually 86.5). Something is different with the 97s, but beyond the ABS sensor, I can’t really see what it is.
Yes the ratio is to one.
Each gear multiples torque.
So if you have a 400 flywheel torque motor,
in first gear which is 3.32:1, 1328 lb-ft is being applied to the driveshaft.
Mutliply that again by the final gear (in the diff in RWD, in the transfer case in FWD)
Which is 4.08 (USDM) you get
5,418 lb-ft hitting the tires in 1st gear
That’s why they run Dyno tests in 4th gear, which has a ratio of 1:1 - ie no multiplication.
This is also why a manual car will be faster than an auto
Just as an example, think 155 hp for the KADE.
3.321 vs 3.027 in 1st gear
514hp vs 469hp in 1st gear
2097hp vs 1913hp to the tires
The manual is leaving the line with more than 200 extra hp even though both cars make the same power.
Gear ratios are fun.
I have always wondered this, and since you brought it up… I might as well ask ya…
What about about the final drive ratio and tire diameter. Do those affect dyno readings as well? Do you have to compensate for either?
Dyno calculates it I think.
I honestly don’t know the inner workings (never asked) but I’d assume either you have to input tire size/diff ratio or the dyno has some kind of auto configuration.
Not ALL cars have a 1:1 in 4th.
My Charger has to be dynoed in 3rd (well, there is no 4th either LOL, but)
I’ll be sure to ask next time.
But there was a certain company/magazine that were seriously nailed for running all their project cars/customer cars in 3rd gear just to make their numbers seem that much higher.
I have yet another question now… How difficult is it to swap a bellhousing? And what about clutches, I’ve heard a lot about them supposedly fitting, but when I read through here, the KA clutch wouldn’t fit on Jessy’s CA when he was doing his swap. What I’m curious about is, will it fit if I use a KA tranny in a CA bellhousing, or is it the actually bellhousing that is a problem for the clutch fitting?
problem with the clutch fitting is the bolt holes on the CA flywheel will not perfectly match up with the KA pressure plate (was the convo Jesse and I had on MSN last year when him and Chris tried it)
I did read on I believe like CA18DET.org or some shit “cant remember” but they did state that a KA clutch unit would bolt up to a CA flywheel but Jesse did try that and it did not work so Im not sure if its a certian year Flywheel needed or a what not etc etc…
Allrighty, sorry to bother you guys with that, but it turns out that the CA clutch is included :thumright: so I will have a brand new ACT for KA for sale.
It’s the pressure plate that won’t bolt up.
You’d be in trouble if you bolted the clutch to the flywheel
I ran a KA clutch in my CA with no problems. I also used a KA pressure plate. The 97+ KAs have a problem lining up, so it might have been a later KA pressure plate. You just have to enlarge one of the dowel holes a bit IIRC.
The only thing that determines whether or not a clutch will fit is spline count and diameter. And Nissan tends to use the same centers on just about everything.
MSSC can reman factory clutches and pressure plates to serious clamping power for a nominal fee.
Swapping the bellhousing is pretty straight forward but you have to be careful.
You have to undo the 8 (I think) bolts that hold the two halves together.
DO NOT undo the two bolts that go into the adapter/sandwich plate (the piece in between the bellhousing and tailshaft) those hold the spring/ball in for your shift alignment. They stay put.
Then you have to undo the aluminum plate with the clutch pivot on it.
Bang that free with a dead blow mallet.
Underneath there, you have to undo a snap-ring that keeps the countershaft bearing in place. Try and not bend it.
That part is the biggest pain in the butt.
Once everything is undone, some careful drifts with a hammer or shaking, prying and cursing will separate the two halves.
I think I have a link to some pics I took when I had to do this for the Tadpole.
http://www.sequence-garage.com/forums/index.php?showtopic=584
There’s nothing really there, but you can at least see what I’m talking about.