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MIKEYFTW

Frontier trans in ka24e swap

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I have had a 240sx ka24 trans in my 620 right now for about 4 years now.. 5th gear just gave out.. I can use a frontier trans and just get another driveshaft right?! Is that correct?

 

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I'm not positive... but I believe the bolt pattern on the blocks for the bell housing is the same, so in theory yes you could but why? You are going to have to buy both a trans and driveshaft. There has got to be plenty of the SR and 240sx KA transmission in the LA area. If you find an SR trans you can use it, just need to swap the bell housing from your KA trans over to it - behind the bell housing they are the same.

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240sx transmission is longer than the truck transmission so shifter will move forwards and drive shaft needs to be lengthened. Transmission mount may be in the same spot. dunnow.

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Thanks I just want to be able to use the original center console. I’m using it now with a modified  shift lever but I get a lot of hot air blowing in the car and it’s annoying. 

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37 minutes ago, MIKEYFTW said:

Thanks I just want to be able to use the original center console. I’m using it now with a modified  shift lever but I get a lot of hot air blowing in the car and it’s annoying. 

 

Do you have a boot on it? 

 

I am building a 620 with a 240sx KA right now --- I should say putting it back together... --- but it appears that the hole in the floor has not been cut larger and the stock metal cover will work. I just picked up a boot for it that is a little short... but hoping I can make it work. 

 

 

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Im keen to know as well how a frontier's trans fits relative to a 240sx, and original l-series.
Ive got a 79 KC with the l20 currently, and picked up a 240sx ka24de with what was said to be a frontier trans.

Planning to do the swap somewhere down the line but the trans has me confused (between the L's, napz, ka's, etc.).

 

What would fit and:

a) bolt up and work with the original cross/trans mount

b) not require modifications to the driveshaft (?)

c) have a not sloppy 5-speed setup?

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To satisfy a) and b) you will need an L series 71B 5 speed. None of the KA 5 speeds are the same length as the 71B, nor do they have the same bolt pattern orientation to an L series engine.

 

ivySUPf.jpg

 

The 240zx 71C is 35" long and 33 1/4" to shifter

 

I have another 71C 5 speed that is 32 3/4" long and presumably from a Hardbody. It doesn't have a case but the length pretty much IDs it.

 

The L series 71B is 31.5" long and 28 3/4" to shifter

 

 

 

To satisfy c) you need to replace the shifter bushings.

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22 minutes ago, datzenmike said:

To satisfy a) and b) you will need an L series 71B 5 speed. None of the KA 5 speeds are the same length as the 71B, nor do they have the same bolt pattern orientation to an L series engine.

 

ivySUPf.jpg

 

The 240zx 71C is 35" long and 33 1/4" to shifter

 

I have another 71C 5 speed that is 32 3/4" long and presumably from a Hardbody. It doesn't have a case but the length pretty much IDs it.

 

The L series 71B is 31.5" long and 28 3/4" to shifter

 

 

 

To satisfy c) you need to replace the shifter bushings.

 

so in theory, if you already have a factory 5 speed L20B, that trans will work with a 240sx ka24de engine?  and you wouldn't have to modify the drive shaft. what clutch/ pressure plate would you use?

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26 minutes ago, datzenmike said:

To satisfy a) and b) you will need an L series 71B 5 speed. None of the KA 5 speeds are the same length as the 71B, nor do they have the same bolt pattern orientation to an L series engine.

 

 

No way will an L series engine properly mount to a KA transmission. You would need to modify and swap the KA series front case onto the L series 71B 5 speed. The modifications are...

1/ The first/second shift rod is 14mm but the KA case hole is 16mm. The hole should be shimmed.

2/ Use the 71B front cover as the 71C counter bearing it covers is 62mm and the 71B is 56mm

 

Using a 71B on a KA is not a good idea. The 71C will handle about double the power a 71C can reliably take. Bearings are larger and gears wide to handle the extra power on the 71C. 

 

27 minutes ago, datzenmike said:

 

The 240zx 71C is 35" long and 33 1/4" to shifter

 

I have another 71C 5 speed that is 32 3/4" long and presumably from a Hardbody. It doesn't have a case but the length pretty much IDs it.

 

The L series 71B is 31.5" long and 28 3/4" to shifter

 

 

 

To satisfy c) you need to replace the shifter bushings.

 

There is a 35" - 31.5" = 3.5" difference in length here so no the driveshaft won't fit.

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12 hours ago, datzenmike said:

To satisfy a) and b) you will need an L series 71B 5 speed. None of the KA 5 speeds are the same length as the 71B, nor do they have the same bolt pattern orientation to an L series engine.

 

ivySUPf.jpg

 

The 240zx 71C is 35" long and 33 1/4" to shifter

 

I have another 71C 5 speed that is 32 3/4" long and presumably from a Hardbody. It doesn't have a case but the length pretty much IDs it.

 

The L series 71B is 31.5" long and 28 3/4" to shifter

 

 

 

To satisfy c) you need to replace the shifter bushings.

 

Thanks for the information, very helpful.

So I suppose its safe to assume ive got a 71B (some iteration of one), since Ive got 5 gears on my l20.

 

Had a quick read here about the 71-series trannys: 71-series info

 

So from what I gather:

• my 71b trans is ~31.5", the 'frontier' trans that I got is a 71C so likely longer (Ill grab a measurement to see if its 35" or somewhere in between).

• sounds like the 71C's are pretty standard between all the cars they came in according to that site.. but thats probably not the case yea? I assume there are differences in gearing and possibly physical lengths?

• shifter will be pushed back a few inches (?) If using a 71C mated to ka24

• not worth modifying/mating 71B to KA's.

• replace shifter bushings so I cant make circles while in gear. Feels like I could mis-shift currently if I wasnt paying attention

 

Sounds like in the end its just best to get a matching trans for the engine im swapping, and modify the drive shaft. Ie: use a frontier, d21, or 240sx trans with my ka24de and go from there.

 

Sorry for the long post! But thanks again

 

 

 

 

 

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The 71B was used on L, SD, CA, and Z  series while 71Cs were used on VG, CA, KA series. The earliest 71B was on the '71-'72 240z and '74 620 truck followed by the 5 speed (optional) in '77 in 280z and truck , '78 810 and the '80 720 and S110 200sx. The earliest 71C used here, was the '84 300zx (non turbo). Next was the '86.5 D21 Hardbody and the S12 car followed the next year on the new Pathfinder. Generally the C uses taller gears and larger over drives because of the larger displacement engines. I don't think there is a lot of difference between 240zx and Hardbody ratios and overdrives, just transmission lengths. 71 is the distance between main shafts and counter shafts and limits the maximum gear and bearing sizes. This was got around on the 71C by making the gears wider for added strength.

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