6-Speed transmission?

Post by **Mikie** » Mon Oct 13, 2003 12:35 pm

I LOOOOVE my CA, I just dont like to traveling long distances at 5-6000 rpm.

I have heard that there might be a six speed transmission out there for my CA. Any truth to this? Opinions, etc? I don't know much about transmission internals, or if my some remote chance there was a bolt up 6 speed that I could switch to, I just want to be able to accelerate quickly in 1st through 3rd, maybe 4th, and have a higher top speed without the engine working harder. Suggestions?

Website · Post by **s86d** » Mon Oct 13, 2003 12:35 pm

sadly your best bet is to probably get a z32 tt diff the gearing is more towards highway.

Post by **themadscientist** » Mon Oct 13, 2003 12:35 pm

there is a six speed for the SR but not the CA.

Post by **Mikie** » Mon Oct 13, 2003 12:35 pm

maybe the internals would transfer over from a 6 speed?

...or could I add in like a really big 5th gear or something?

Post by **drumma022** » Mon Oct 13, 2003 12:35 pm

Last I checked the miata 6-speed has a very similar setup as the S15. Since the transmission is a 3 piece instead of 2 piece, you would have to involve some welding in order to make it fit.

Post by **boost_boy** » Mon Oct 13, 2003 12:35 pm

I owuld seriously question the durability of the 6-speed trannies, unless this is your everyday putt-putt with just above stock power. A CA's gearing is long enough IMHO. How fast are you trying to go? If your 5th gear has you at like 5-6k rpm, something is wrong with your car. The average CA powered vehicle at 5-6k rpm is doing in the ballpark of 125-140mph (depending on vehicle set-up). Do anyone else agree?

Post by **Trigger** » Mon Oct 13, 2003 12:35 pm

i would like to agree but i still dont know what 5th gear...or 1st gear feels like in my ca

Post by **drumma022** » Mon Oct 13, 2003 12:35 pm

Boostbiy-- I agree, since I was running 115 MPH at redline on 3rd gear. I had a speadsheet on what the speed was in 5th at various RPMs, but It is lost somewhere on the computer. Even if you could do 180 in 5th at 8000 RPM, that is an easy 90 at 4000 RPM. I dont mind driving around at that RPM, especially since that is when boost starts building! hehe

Post by **drumma022** » Mon Oct 13, 2003 12:35 pm

If I did my mathe correctly and the website i used for the formulas and values are correct, here are the speeds at various RPMs in 5th gear on the SR20/CA18.1000 21.475668952000 42.951337893000 64.427006844000 85.902675785000 107.37834476000 128.85401377000 150.32968268000 171.80535169000 193.2810205

Post by **Mikie** » Mon Oct 13, 2003 12:35 pm

well...my speedo doesn't actaully read correctly soooo...

It just seems to be kind of wound up going 70-80. I would kind of like to be around 3000 rpm at these speeds.

Post by **Mikie** » Mon Oct 13, 2003 12:35 pm

or maybe I am just going faster than I think:D

Thanks for the calculations though, what site was that from?

Post by **alfred183** » Mon Oct 13, 2003 12:35 pm

Maybe it's because we're using the CA speed sensor...and not the KA one like we should...but our speedo is pretty much wrong throughout the whole range. I rolled next to my friend at what I thought was 55 and he said we were doing like 70....SO, when when you're going in 5th gear at 4k, you're probably doing 85 like what was said above. The good thing is that when your car starts going 'ding dong ding dong' at 55mph, you're doing like 70mph

Post by **quest** » Mon Oct 13, 2003 12:35 pm

I'd just get a 3.7 or 3.9 LSD to bring down your revs in 5th. I think thats why uk guys go after s14 rearends. Once upgrading, your powerband should be wide enough so you won't need to spend more time rowing thru gears. Turbos luv load. 6spd is a move in the wrong direction imo.

Post by **drumma022** » Mon Oct 13, 2003 12:35 pm

If you use the KA transmission, it will put you at about 71 mph at about 3000 rpm. Keep in mind, I am using ~24" for the wheel diameter figure.

Post by **r34 gtr** » Mon Oct 13, 2003 12:35 pm

good lord...thats why i was passing everyone on my way to get the car dyno'd. speedo said 80, but i was at 4200-4400 in 5th the whole way. lucky i didnt meet a cop.

- tim

Post by **float_6969** » Mon Oct 13, 2003 12:35 pm

Change your speed sensor. At least change the gear on the speed sensor. Otherwise your speedo and mileage will be all screwed up. And just to remind everyone, if you have a SOHC gauge cluster, you have to swap that to a DOHC cluster.

Post by **CA19DET** » Mon Oct 13, 2003 12:35 pm

i think i read somewhere that nissan sells longer 5th gears for the KA and they might work on the CA, i really need to find out where i saw this, other than that you could always get a custom g-box built for bling bling...

Post by **boost_boy** » Mon Oct 13, 2003 12:35 pm

Gears longer than stock won't be necessary if you don't have the power to row through them. And besides, anyone trying to go 200+mph in their S13-14? Go for it, but this discussion on the stock CA transmission needing to be longer is crazy. Those gears are long enough for anyone on this forum with a car exceeding 300whp, 300whp and less than 250whp. In my FWD application, I'm doing a confirmed 121mph in 3rd gear at 7400rpm (dyno proven), at 6600rpm in 4th gear I'm going 130mph and in 5th gear at 5300rpm I'm at 126mph. The point I'm making is that the stock CA transmission provides enough gearing for both street and strip. And just to help clear the air on my results my car has been calibrated to +/- 2mph accuracy which is definately proven to be a -2mph reading.

Post by **float_6969** » Mon Oct 13, 2003 12:35 pm

I think you just need to adjust the the motor. It's a small displacement motor, it's going to have to run at higher RPMS to get into the power band. If you're really concerned about it, your easiest fix is going to be to get a Z32 TT rear-end. But that is going to mess with your gearing through all of the gears. But it will also help the gas mileage too and really help that top speed.

Post by **CA18Fastback** » Mon Oct 13, 2003 12:35 pm

if you really want longer gearing get an SR gearbox. MY CA18 has a CA bellhousing with an SR20 gearbox. You could swap the gearboxes and find a set of longer gears for an SR. just an idea.

-Ian

Post by **boost_boy** » Mon Oct 13, 2003 12:35 pm

Quote »if you really want longer gearing get an SR gearbox.[/quote] Are the gears of the SR longer than that of the CA? I mean in a comparison between the FWD trannies, the CA (by far) has the longer gears and the sweet final drive as well as being a few times more durable. I've driven SR powered 240's as well as CA18 powered 240's and from the way they felt, the characteristics were the same as the comparison between the FWD. The reason why I see people attaching a RWD CA bellhousing to a RWD SR20 gearbox is because they want the shorter gears. CA gears are taller than SR gears! And if I'm to be corrected, please bring the technical literature with you because this I got to see.

Post by **Trigger** » Mon Oct 13, 2003 12:35 pm

hmm i thought that the CA,SR and KA all used the same gear box just different bellhousings....if this is true then wouldn't the gears be the same?

Post by **Xero** » Mon Oct 13, 2003 12:35 pm

gears are different, KA gears are more geared towards torque, and are taller, CA would be shortest of the 3, and SR is in the middle,

Post by **CA19DET** » Mon Oct 13, 2003 12:35 pm

i heard that it was impossible to swap a SR box on a CA bellhousing and make it work, i would like to see photos of this, and are you using the SR or CA clutch?? i would imagine it is the CA cause the SR clutch cant fit under the CA bell.... did you get the g-box like this or did you piece it together yourself??

just curious?

Post by **boost_boy** » Mon Oct 13, 2003 12:35 pm

Quote »And if I'm to be corrected, please bring the technical literature with you because this I got to see.[/quote] Quote »i heard that it was impossible to swap a SR box on a CA bellhousing and make it work, i would like to see photos of this, and are you using the SR or CA clutch?? i would imagine it is the CA cause the SR clutch cant fit under the CA bell.... did you get the g-box like this or did you piece it together yourself??[/quote] Quote »just curious?[/quote] That's the point I'm trying to make as well. My firend with kick-azz KA pwered 240 producing better than 470whp went crazy when he got behind the wheel of a 240 with CA18DET. Although it had considerably less power than his KA24DE(T), he couldn't help but babble on about the how much longer the CA18DET's gears are compared to his KA24's gearing. Like I say, I've built and driven all of them and the SR's gearing just don't seem to be as long as the CA's. Maybe it's just the ability of the CA18 to rev which makes since for the manufacturer to design gearing to accomodate the engine ability. Whereas the SR isn't the most rev friendly of motors, but still can rev; kinda like the FWD trannies as they are perfect for the performance of the motors, but are butt-weak when it come to durability.

Post by **paul_s13** » Mon Oct 13, 2003 12:35 pm

A friendof mine has an SR box on his CA and he never noticed much difference, you will need the longer geared manual S14 diff to to make a big difference. To fit the SR box you change the bellhousing and sandwich plate and thats more or less it.

Post by **drumma022** » Mon Oct 13, 2003 12:35 pm

To fit an of the 240sx/Silvia trannies (except for the S15) I thought you have to keep the CA bellhousing, and swap out the plate and tail-shaft that houses the gears?? If I wanted a more friendly 5th gear, I would swap to the KA transmission, which has identicle gearing as the RWD CA18 except for 5th. But since my motor only makes like 50hp at 3000 rpm, I still prefer the stock gearing!

6-Speed transmission?

6-Speed transmission?

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