KA swap trans choices: B, C, or S13/S14?, Which is best? Options

[NateMorris]

i keep seeing on here that you can use the b tranny and stock driveshaft if you swap the ka bellhousing on it. if thats the case, then will the ka motor line up with the stock b trans in you use stock s13 motor mounts?

[Jay]

i keep seeing on here that you can use the b tranny and stock driveshaft if you swap the ka bellhousing on it. if thats the case, then will the ka motor line up with the stock b trans in you use stock s13 motor mounts?

It's not as simple as you think to do a bellhousing swap on a B trans. The input shaft bearing sizes are very different from the KA C trans Bellhousing to the B Trans bellhousing. Thus requiring a bearing that, to my understanding, isn't the easiest to find.

But, if you did decide to that route. It would be the KA motor mounts, stock driveshaft, and stock transmission crossmember yes.
,
It's better to go with the KA trans. The B Trans is weak, and there have been several on here that used them with KA's only for them to blow chunks shortly thereafter.

This post has been edited by Jay: Feb 1 2010, 03:54 AM

[NateMorris]

ok thanks, good to know. i figured there had to be a catch or everyone would be doing it.

[Wolf Dilworth]

It's better to go with the KA trans. The B Trans is weak, and there have been several on here that used them with KA's only for them to blow chunks shortly thereafter.

Yes make the jump to ludicrous speed with the FS5W71-C tranny. Those old -B's are just plain door stops.

Peace, Wolf

[Arro]

Or if you're lucky enough to find a Mark II 5-speed S12, use that trans. It's the S12 "C" trans which is as far as I know the same thing as the S13/S14 KA trans, only shorter so you don't have to change a bunch of crap (namely the interior). And you can run the lifter-plate style short throw shifters from the S13/S14.

[NateMorris]

yeah thats mainly why i wanted to use the b trans is because i dont want to cut up my interior. and also to save a little $ on a driveshaft.

[Arro]

Then use the S21 "C" trans, found in any 5-speed Mark II S12 (some 1986, all '87 and '88). Mark I "B" trans on the right, Mark II "C" trans on the left:



You can identify it by the shifter plate:



You will still need to change the front half of the driveshaft. Make sure you just grab the driveshaft with the trans, and just swap the whole shaft for ease.

If you run the S12 "C" trans, you can use this kind of S13/S14 short-throw shifter kit:



Works like a charm. Lets you keep your interior stock. Stronger than B trans. A bellhousing swap for KA or SR is easier with the S12 "C" trans. Need I say more?

[NateMorris]

Yeah but finding a s12 with a c trans in VA is goona be very tough. it's hard enough finding a s12 in general around here.

[Jay]

Yeah but finding a s12 with a c trans in VA is goona be very tough. it's hard enough finding a s12 in general around here.

You can use the KA trans without cutting up the interior bits too. just the tunnel. Relocating the center console 3 inches back is easy, just drilling a couple holes and tightening some screws.

Either way, easy peasy

[heatw]

You can use the KA trans without cutting up the interior bits too. just the tunnel. Relocating the center console 3 inches back is easy, just drilling a couple holes and tightening some screws.

Either way, easy peasy

ka truck tranny is the same length as the s12 one and it's alredy ka.. theres got to be rwd ka24 d21's around to loot from

[Arro]

I remember us talking about the truck trans, it's too short, and would locate the shifter where the S12's radio is So no, that won't work. Gotta be either an S12 trans or an S13/S14 trans.

The one nice thing about the S13/S14 trans is the relocated shifter is a bit further back which is IMO actually more comfortable.

[NateMorris]

yeah i'm sure i'll figure something out. most likely i'll get stuck with a s13/14 trans. i didn't think about shifting the whole console back. good idea.

ka truck tranny is the same length as the s12 one and it's alredy ka.. theres got to be rwd ka24 d21's around to loot from

i have a d21 pickup that i just replaced the trans in and compared the old d21 trans with my s12 trans and the shifter is located closer to the bellhousing than the s12 trans, like arro said. any more forward than the b trans would be quite rediculous..

[Redneck]

Wow no shortage of B tranny hate going on in here. Is the B tranny as strong as the C tranny? No. Does the B tranny shift as nice as the C tranny? No. Is an average condition B tranny more then sufficient enough for an n/a ka swap? Yes. I plan on upgrading to the C tranny down the road, mostly for shorter and smoother shifting, but the B tranny with the bellhousing swap has been more then adequate for my stock kade. As long as the B tranny is in decent shape and not beat to shit it will be fine.

This post has been edited by Redneck: Feb 2 2010, 02:15 AM

[Arro]

B tranny is "ok". C trans is far better, which you point out. But I think some of these guys want to make sure that if they swap to a manual trans, it's the best choice from the get-go.

[Wolf Dilworth]

If you run the S12 "C" trans, you can use this kind of S13/S14 short-throw shifter kit:

Hey Arro

Where is the lifter-plate thingy? The extended nose picker alone is only half the equation. Is there a way to make the small cover (shown) fit the 71-C's? I was so cheap I made my own lifter-plate and turned an extension for the nose picker. The extension will replace the stock ball which I have to cut off then counter-bore a hole for the extension and weld-in. Still need to finish that part of the job, I think I will also add a few degrees of rake to the rear so the shifter does not have to hit the radio. :o)

Peace, Wolf

[Arro]

I'm not sure what you're asking, but I *think* you are talking about the square piece in that photo... it lifts up the pivot point for the replacement shift arm. The replacement shift arm gets its shorter throw from raising the pivot point, lengthening the lower section of the arm below the pivot, and shortening the topmost section. I thought you knew this already, so maybe I'm misunderstanding the question...?

All that's pictured there is what you'd need on an S12 "C" trans or on an S13/S14 trans. The pictured kit is actually sold as an S13/S14 "240SX" short throw shifter kit", but like I said we have successfully equipped it onto the S12 "C" trans and it works like a dream. I don't remember the specific long number names of the transmissions, so I usually refer to them by year and model found in.

[Wolf Dilworth]

I'm not sure what you're asking, but I *think* you are talking about the square piece in that photo... it lifts up the pivot point for the replacement shift arm. The replacement shift arm gets its shorter throw from raising the pivot point, lengthening the lower section of the arm below the pivot, and shortening the topmost section. I thought you knew this already, so maybe I'm misunderstanding the question...?

All that's pictured there is what you'd need on an S12 "C" trans or on an S13/S14 trans. The pictured kit is actually sold as an S13/S14 "240SX" short throw shifter kit", but like I said we have successfully equipped it onto the S12 "C" trans and it works like a dream. I don't remember the specific long number names of the transmissions, so I usually refer to them by year and model found in.

Yes Bro

I fully understand the geometry of the postulation presented under the current confirmation of things related to, reduced travel, ratio selections, per se... :o)

However, I do not see where the plate (yes the square piece) goes on a 71-C unless there is some machining required. Most of these "kits" provide a new cover-plate with the pivot raised and are direct bolt-ons. I elected to make a spacer that goes between the OE cover-plate and the tail housing, to raise the cover a half inch (thickness of the aluminum plate I had at the time). I am guessing that the plastic bits in the photo are doing the raising, but I do not see how the square plate will attach to the cover-plate.

Peace, Wolf

[Arro]

LOL yeah I figured you understood but you never know right? Ahhhh yeah I understand your question now, the square metal plate goes over the existing plate. Just like you made for yourself.

The kind you're talking about where you replace your entire plate are not gonna work. I have one of those on my S13 trans (and as it is one of the bolt holes is off, stupid chinese parts), but the S12 plate is slightly different.

"...the geometry of the postulation presented under the current confirmation of things related to..."

LOL Wolf were you wearing your pocket protector when you wrote that?

[Wolf Dilworth]

LOL yeah I figured you understood but you never know right? Ahhhh yeah I understand your question now, the square metal plate goes over the existing plate. Just like you made for yourself.

The kind you're talking about where you replace your entire plate are not gonna work. I have one of those on my S13 trans (and as it is one of the bolt holes is off, stupid chinese parts), but the S12 plate is slightly different.

"...the geometry of the postulation presented under the current confirmation of things related to..."

LOL Wolf were you wearing your pocket protector when you wrote that?

I still don't see how the little plate will work. The adapter that I made goes under the OE plate raising the whole plate half an inch. Does this square plate go inside or on top of the cover? Have pix of this mod?


Peace, Wolf

[Arro]

it goes OVER the stock plate's round section...