Which transmission is this?

[Tieny]

I've been trying to figure out where this tranny came from for the longest time. It has three sensors on it (Neutral, OD, and Reverse). So I'm thinking its an s14 tranny, BUT... there is no hole on top of the bell housing for the CrankShaft Position Sensor. Is this an s14 or s13 tranny? Also this it labeled TA-71B #2.

[jr_ss]

How about a picture? You describe what could be hundreds of transmissions. Try again.

[Tieny]

Hundreds? Probably more like two or three... If ya'll really knew about these transmissions, all the information I gave to identify it should be right there to figure it out.

From what I searched and found so far:
S13 transmissions usually have 4 sensors on it. (Neutral, OD, TOP, and Reverse)
S14 transmission usually have 3 sensors on it. (Neutral, OD, and Reverse)

One difference is that the S14 trannys have the hole on top of the bellhousing for the crank position sensor. This is the reason you can't use an S13 tranny in an S14 chassis without throwing a code unless you drill that hole in.

So yeah this thing I'm trying to figure out: I have 3 sensors on mine (probably came from an S14 right?) But I don't have the crank position hole slot (wait, it can't be from an S14 then...?) Hmm.. maybe someone swapped the bellhousing (nope can't be.. its definitely a KA housing and the sensor that's different is on the same front half as the housing)
Maybe there was an older type S14 that didn't the bellhousing crank position? Or maybe from a later model type S13 that started transition? The model number should tell exactly where it came from (TA-71B #2), but seems there's nothing on google about the #2 type...

[tuzzio]

The time it would've taken to post a picture is the same amount of time it would've taken to not be a dick. That attitude won't last long around the zilvia vultures.

You're asking for help. Provide the information asked for.

Try again.

[Tieny]

Hey wasn't trying to be a dick. Jeez I even reworded that so many times without trying to sound like a dick too... =/

Can't upload photos, its been giving me errors even though the image is like a 50kb jpeg..

[tuzzio]

www.imgur.com

[jedi03]

lol many transmissions look similar to description@ but you try googling the numbers

[Kingtal0n]

you can get two different 5-speeds in the same year

some have reverse synchros, some not,
some have different 5th gear ratios
some have updated shift fork hardware
silvia trans is similar to but many differences from KA trans including synchro rings

The only really important thing that makes any difference is the gear ratio of 5th, and the fork if you can get the good ones, or install a good 5th fork (they break and lead to infamous 5th grind)
The s13 trans have shorter ratios, the S14 trans has a better cruise ratio, so we always want the identify and use the better overdrive for economy

spin output shaft vs input shaft and try to identify the ratio of 5th

[duballstar37]

Originally Posted by Kingtal0n

you can get two different 5-speeds in the same year

some have reverse synchros, some not,
some have different 5th gear ratios
some have updated shift fork hardware
silvia trans is similar to but many differences from KA trans including synchro rings

The only really important thing that makes any difference is the gear ratio of 5th, and the fork if you can get the good ones, or install a good 5th fork (they break and lead to infamous 5th grind)
The s13 trans have shorter ratios, the S14 trans has a better cruise ratio, so we always want the identify and use the better overdrive for economy

spin output shaft vs input shaft and try to identify the ratio of 5th

Can you please elaborate on the difference in gear ratios between S13 and S14 transmissions? I swapped a S14 KA trans onto my S13 SR (swapped the bellhousing) and the gearing felt identical.

[jr_ss]

Originally Posted by duballstar37

Can you please elaborate on the difference in gear ratios between S13 and S14 transmissions? I swapped a S14 KA trans onto my S13 SR (swapped the bellhousing) and the gearing felt identical.

All USDM transmissions have the .759 ratio for 5th or overdrive. The transmissions that back the Sr20de and DET come with varying 5th gears. Depending on what motor you have, some are .759(S13) and some are .838(S14/15).

[Tieny]

Originally Posted by duballstar37

Can you please elaborate on the difference in gear ratios between S13 and S14 transmissions? I swapped a S14 KA trans onto my S13 SR (swapped the bellhousing) and the gearing felt identical.

Gears 1-4 are identical between the KA and SR trans. The SR trans will have a slight higher gear ratio (0.838) than the KA trans (0.759) with a few exceptions in some Silvia models that also have an SR at 0.759. At highway cruising speed with the SR (0.838) you'll probably sit at a higher rpm compared with a KA (I wanna say probably about 300-500 rpms higher?)

If transmission is benched, one way to check is by marking a tooth on the output shaft. Put it in 5th gear and spin the input shaft one revolution. If the mark is now 7-8 teeth away from the original position it has a 5th gear ratio 0.759. If 4-5 teeth away, 0.838.

Originally Posted by Kingtal0n

you can get two different 5-speeds in the same year

some have reverse synchros, some not,
some have different 5th gear ratios
some have updated shift fork hardware
silvia trans is similar to but many differences from KA trans including synchro rings

The only really important thing that makes any difference is the gear ratio of 5th, and the fork if you can get the good ones, or install a good 5th fork (they break and lead to infamous 5th grind)
The s13 trans have shorter ratios, the S14 trans has a better cruise ratio, so we always want the identify and use the better overdrive for economy

spin output shaft vs input shaft and try to identify the ratio of 5th

While rebuilding my trans I found (at least on my model trans) that the only thing that actually engages 5th gear is a small retaining clip on the 5th fork rod. This clip is forced against the fork which engages the hub. It was somewhat warped, loose, and was free to spin. Once this clip breaks off it ends up getting incomplete 5th gear engagements.

My trans has a 0.759 gear and does not have a reverse synchro. After searching for a long while I haven't found any full rebuild tutorials anywhere on the net for a 240 transmission. I'm thinking of possibly making a video of a full teardown disassembly and rebuild.