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KA24de Transmission -- 240sx vs. Frontier


klam07

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Hi all,

 

Got a question regarding which transmission to use for a KA24DE swap in a 620 (King cab if it matters).

I currently have a ka24de ready with a 240sx trans on it, as well as a Frontier (D22) trans separately.

 

From what I've read, gearing wise they're the same up til 5th gear, where the Frontier trans is more aggressively geared (?).

The main difference then comes from the lengths. 240sx trans' are something like 33.25 ~ 33.5", while the D22 is ~28.5".

Given that the stock L-series trans is 31.5", I don't think theres any way around having to either shorten or extend the driveshaft for the swap.

 

My question is, would the longer or shorter trans work better in the tunnel and with the OEM console/boot placement?

My goal is to modify the body as little as possible and have the most comfortable shifting position. I don't know if I'll be using a 'dual bend' shifter or a regular 240sx 'short' shifter yet.

 

Any input for those who have done this swap and used either transmission?

 

Thanks in advance for any and all help!

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This is just a guess but the 71C transmissions seem to have the shifter just slightly more forward then the older 71Bs. The D21 Hardbody is already shorter than the 620 transmission and will move the shifter even farther forward than where it is now. You have bucket seats so using a 240sx transmission, it won't hurt if is should move the shifter slightly back from present position. In addition I think shortening a drive shaft is probably easier/cheaper than lengthening it.

 

I haven't measured these directly but thought they were closer to 34" and 30"??? I stand the transmission up on a couple of 2x4s, put a straight edge across the case where the drive shaft enters and measure vertically down from the straight edge to the front case where it meets the engine. This avoids a longer slope distance

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Oh, I didn't consider the shifter placement on each. Maybe I'll measure from front of trans to shifter, since I think maybe someone had numbers on here for the 71B...

I'd like to somehow fit a nice bench in the KC but its more probable that I'll end up sticking with buckets to keep the console.

In any case it sounds like the 240sx Trans should work better and would be cheaper/simpler for the drive shaft modification.


I was going off what I read here on the forum for the 240sx trans length. My measurements were a bit approximated and ended up closer to ~34". But that wasn't exactly a straight measurement, as its still mounted to the engine and has part of the output shaft/flange (?) part, so I can't get a flat measurement.

The Frontier trans measurement I got from your method, measuring from edge of case and putting a piece of 2x4 across the end to reach the tape.

 

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If you keep your buckets, it won't matter... but the 240 KA trans does move the shifter back a few inches. In my standard cab with the redeye mounts it still fit through the stock shifter hole, but was far enough back that I needed to get a short shifter to keep it from interfering with the bench seat. 

 

48548136701_0919cff44a_z.jpg20190815_185841 by devon M, on Flickr

 

I thought the shifter might be backwards... but it seemed to be too far forward when flipped around... the long shift knob didnt help either... Picked up a cheap short shifter from ebay and it is all good 

 

Edited by demo243
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Interesting, thanks for the picture - really puts it in perspective.

I wonder if something like a single bend shifter would put that at a better angle for you in 2nd/4th n reverse. Or if that even exists for nissans..

 

The fact that it fits through the stock opening has me sold. Im not sure if mine is a short shifter or not.. looks to be, but my only other comparison is a long hardbody/d21 shifter arm that is something like a dual bend.

 

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On 12/6/2019 at 11:14 PM, klam07 said:

Interesting, thanks for the picture - really puts it in perspective.

I wonder if something like a single bend shifter would put that at a better angle for you in 2nd/4th n reverse. Or if that even exists for nissans..

 

The fact that it fits through the stock opening has me sold. Im not sure if mine is a short shifter or not.. looks to be, but my only other comparison is a long hardbody/d21 shifter arm that is something like a dual bend.

 

I think the stock truck trans shifters are bent to clear the seats better and be more vertical.

 

I used an OEM boot and the OEM metal shift hole cover, just shifted it further back with some new screw holes

 

I looked to see if I have any other good photos of the shifter but I dont... and the truck is under snow right...

 

For a driveshaft I didnt have a good donor so I went with a full new fresh one - one piece - was like $350ish.  The new flanges are a bit thicker the  the old datsun flange so I had to pick up some new 12.9 shouldered metric bolts and trim em down to clear.

 

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7 hours ago, demo243 said:

 

 

Right on - I imagine the truck KA24 shifters would work on the ka24de trans? The other shifter I've got is from a d21 pickup, so ka24e. Wonder if it would feel as 'tight' though.

For the drive shaft, would you have used the existing 620, or a donor 240sx - then shorten? Because I also have both. But I believe its the 620 thats meant to be used yea?

 

Also, on an unrelated note. What radiator did you end up going with for your swap?

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36 minutes ago, klam07 said:

 

Right on - I imagine the truck KA24 shifters would work on the ka24de trans? The other shifter I've got is from a d21 pickup, so ka24e. Wonder if it would feel as 'tight' though.

For the drive shaft, would you have used the existing 620, or a donor 240sx - then shorten? Because I also have both. But I believe its the 620 thats meant to be used yea?

 

Also, on an unrelated note. What radiator did you end up going with for your swap?

 

If I had the stock 620 driveshaft and it was all in good shape, I may have considered using it.... but for the cost of having that shortened and worrying about the carrier bearing... I probably would have gone custom one piece like I did... just simplifies things and is nice to know its got fresh joints.

I used a big AFCO on my 510, unfortunately I can't tell you about the 620. The engine, trans, rad... overall swap... came with the truck so I didn't order the radiator. It works... but not my favorite. 

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  • 1 year later...

What happened with your transmission adventure?

 

Is the Frontier transmission usable? Where does the shifter location fall between the two?

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Posted (edited)
On 3/24/2021 at 3:49 PM, Bleach said:

What happened with your transmission adventure?

 

Is the Frontier transmission usable? Where does the shifter location fall between the two?

 

Since this post I ended up picking up a different full ka24de swap from a 93 240sx and selling the first engine with the frontier trans. So unfortunately I'll never know.. I still have yet to do the swap, since lockdown its been difficult to get all my parts assembled so I had to leave the truck running.

 

In my mind, shortening the driveshaft would be easier and cheaper than extending it for the Frontier trans. That and I sit pretty far back so the 240sx placement might be better for me in the kingcab.. maybe. The truck gearing would have been nice though for cruising

Edited by klam07
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S13/S14 (I don't have the KA engine D21 ratios but I believe they would be the same as the S14)

1st: 3.321
2nd: 1.902
3rd: 1.308
4th: 1.000
5th: 0.759.... 24% OD

 

D21 2wd Z24

1st: 3.321

2nd: 1.902

3rd: 1.308

4th: 1.000

5th: 0.838.... 16.2% OD

 

D21 2wd VG30E

1st: 3.580

2nd: 2.077

3rd: 1.360

4th: 1.000

5th: 0.760.... 24% OD

 

All 4th gears are 1 or the same on any 4 or 5 speed, there is no gearing at all.

Fifth is a highway cruise gear. Too high and you have to down shift on windy days or on every low hill specially on a lower torque L20B engine. 24% OD it too much. Half that would get more use.

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@datzenmike I dont know which model Frontier trans I had.. seems like a good chance it also had a 0.838 5th according to this though (https://zilvia.net/f/showthread.php?t=89509) .
I'd prefer to downshift on a hill than being forced to cruise the highway at like 3500rpm+, but oh well! It'll be a summer putter, not a miled out grocery getter for me so the s13 trans will have to do haha.

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 Throw in what ever transmission you like. Then put a 3.889 or 3.70 differential in it.

 

Stock tire and 0.838 5th at 3,500 you'll be going 79.5 MPH with a 3.70 ratio differential.

 

Keep in mind that as speed doubles wind resistance increases 4 times!!! A small speed increase gobbles up a large amount of power. The engine has limits and has to rev up to make power. If you reduce the engine speeds too much you'll slow down when put into 5th or have to lower your speed.

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Posted (edited)

@datzenmike From a quick search, seems like my 79 has a 4.11 diff, and s13s were ~4.08 - kind of comparable, so I can probably expect it to jive well and have similar rpm ranges to a stock s13 yea? And to get to about 110km/h or 68mph...

 

- s13 trans with 3.70 diff on stock tires does ~68mph at 2700rpm

- s13 trans with 4.11 diff on stock tires does ~68mph at 3000rpm

 

If I did this right.. its less of an RPM difference than I thought. Gas mileage is probably minimal but performance is probably noticeable.. doesnt seem worth the effort. And 3000rpm to cruise the highway is much lower than I thought it'd be. I don't have a tach atm but doing 110km/h on the highway feels like a mission for the l20b.. but maybe thats a symptom of other things.

I guess Ill know when the swap actually gets finished if I need/want to swap diffs but its good to be able to put actual numbers to each combo - helps me put the 'real world' benefits in perspective.

 

Edited by klam07
used the wrong numbas
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The 240SX has a much taller 5th so I would suggest keeping your diff low like it is.

Most people are running tire sizes slightly smaller than stock for the 620 truck.

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18 hours ago, Bleach said:

The 240SX has a much taller 5th so I would suggest keeping your diff low like it is.

Most people are running tire sizes slightly smaller than stock for the 620 truck.

I always get mixed up with the jargon when it comes to diffs and trans. Short, long, tall, low.. lol.

My current wheels are 195/60/15, I'd stay pretty similar in the future with 15's or 16's. A truck needs a bit of meat

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