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Datsun L series auto trans pix


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#41 datzenmike

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Posted 14 January 2010 - 07:22 PM

Datzenmike, can the lock up torque converter be used in an older transmission (3N71B or L4N71B) that did not originally have a lockup torque converter?


Unfortunately the locking torque converter tranny is also different inside the transmission itself. You can't just swap on the one part. BUT you could get a lock up tranny from a 720 truck and because the front bell is removable, you could swap the L series bell onto it. Voila'. Oh yeah the torque converter is larger and the flex plate is also different shape to fit this. So you would need those parts too. This is a picture of a locking and a regular flex plate from the engine side:

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The L4N71B is a 4 speed transmission and was never equipped with a locking converter.




How does the L4N71B do coupled to a stock L20B?

What gearing would you suggest for my 520 with an L20B & 3N71B?

What gearing would you suggest for my 520 with an L20B & L4N71B?



Well that is a very tall overdrive ratio but at least it is an automatic and a certain amount of slip is built in.

For an empty truck I think 4.375 is fine with the 3N71B automatic and even with one converted over to locking converter. The RPM drop is only a couple of hundred at 40-50 MPH I think. Don't forget both trannys have the same first three gear ratios but the L4N71B has about a 30% RPM drop in 4th. This means a 3000 RPM cruise on the highway at 60? in third, would drop down near 2000 RPMs in 4th. Will an L20B have the power at 2,000 RPMs to push the truck through the wind at 60 MPH? Don't know. At least on hills or windy days the 4th gear can be switched off manually.
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#42 Charlie69

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Posted 06 April 2010 - 07:39 PM

Thank you Mike as always you are very helpful with your knowledge and pictures.

#43 Daeron

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Posted 27 September 2010 - 06:35 PM

I have a question regarding a few variants of the L3N71B gearboxes..

We have a total of five of them, and all have the longer tail sections. My question pertains to the castings on that tail section; on the driver side (same side as the 3N71B/JAPAN casting is) I found four different casting codes: 1A, 3A, 1B, and 2B.

The 1A we know for certain came out of a 72 240Z. One with the 1B casting has a tag on it from a previous owner (no knowledge of how accurate the tag info is) that says "'81 200SX." There is a second box with this tailshaft casting on it. The 3A casting has a mark on it (looks like shoe polish almost?) that reads wither 5, 6, or 810. (I was presuming 510 while looking at it but had to admit it could have been any of the three.)

Now, we've got a gentleman who is interested in a 260 short block/head/flattop collection of separate parts, as well as the transmission from the Z. Unfortunately, the TC from the Z-car was thrown away, but the 3A gearbox has one in it.

Do any of you guys have any information that can help me with these different castings? Are the tail sections essentially the same as long as they are "long?" I would presume this torque converter works for the Z, but I am not certain the guy will need it; he has a running AT right now, this would be a spare (or, possibly, five spares?)



Interestingly enough, this Jatco gearbox is also used broadly in Subarus of the 80s and into the 90s; Subarus 4EAT is a 4N71B with some interesting modification done to fold it in half, and the 3AT was a locking 3N71B as well. This gearbox has been around the block ALOT.
I have a warehouse full of random assorted Datsun parts that NEED to get gone; most posts I make will be trying to get rid of this stuff to you guys for just enough money to reward the effort of keeping the parts out of the dumpster.
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Please keep that in mind when I post asking for pictures; I cannot ID most of this stuff and I am mostly into Z-s and roadsters, this is largely 510/210/some pickup stuff. Thanks!!

#44 datzenmike

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Posted 27 September 2010 - 07:33 PM

Post the numbers on the tag on the right (pass) side, I can try to ID the trany from that. The 1A 3A and such are like just casting revisions. Some small change that doesn't affect it's use.

The PL 510 auto had a short tail so if it was a 510 it may have been from a later HL510.

The '81 200sx would have the Z series bolt pattern and won't bolt properly to the L series.
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#45 Daeron

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Posted 27 September 2010 - 11:18 PM

That casting was the only one I noticed (although I must confess, after noticing the model number and that stamping i did sort of stop looking.) so is this another cast-in mark I an looking for on the passenger side?

I'm going to need to make an L-series and a Z-series bell housing pattern to ID the two anyhow; we've got these four autos plus eight, nine, ten or more unidentified manual gearboxes. (monkey motion and non, some of those roadster) It wouldn't be too hard to find some signboards left behind by a failed primary candidate and make up a couple of round bits with holes in the right spots and an outline, would it?

I should have looked harder at the tail housings, but some of these gearboxes were pretty buried and simply getting to this one mark on all of them was something of a feat! I am about 85% certain it was the same length tail on that box; when I first saw the shortened one my mind balked.
I have a warehouse full of random assorted Datsun parts that NEED to get gone; most posts I make will be trying to get rid of this stuff to you guys for just enough money to reward the effort of keeping the parts out of the dumpster.
Posted Image
Please keep that in mind when I post asking for pictures; I cannot ID most of this stuff and I am mostly into Z-s and roadsters, this is largely 510/210/some pickup stuff. Thanks!!

#46 Charlie69

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Posted 28 September 2010 - 09:19 AM

Here is one Quick510 is selling hope this helps

http://community.rat...ady-to-install/

#47 qwik510

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Posted 28 September 2010 - 12:31 PM

Here is one Quick510 is selling hope this helps

http://community.rat...ady-to-install/



Thanks for the bump Charlie. The trans I am selling is nice.

Also, I've determined, I'm not a hoarder, I'm a collector.
As I'm sure a lot of the old school datsun guys are.



Enjoy the Ride!


David



1972 Datsun 510(Pete Brock's 510)
1977 Datsun 620 King Cab (Barn Find)

#48 Charlie69

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Posted 17 January 2011 - 02:22 AM

Datzenmike or anyone else that might know the answer to this question please reply.

I pulled the speedodrive pinion out of a 1980 720 king cab L20B with what I thought was a 3N71B transmission. The tag on the inside of the passenger inner fender well does not list the rear differential ratio on the 1980 720. The black 1980 Drive pinion is made out of steel, the 1984 drive pinion is aluminum.

Violet or white or beige (unsure of color bad eyes) 21 teeth 1980 720 KC L20B L3N71B? HF?? Blue 18 teeth 1984 720 Z24 L3N71B HF38 (3.889}

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I am wondering what rear differential ratio would be for the violet 21 tooth gear would be?

Also would like to know if the 2 drive pinions are interchangeable due to the diameter difference of the gears?

#49 datzenmike

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Posted 17 January 2011 - 05:22 PM

Charlie, yes the pinions changed to aluminum ( I'm not sure when, around '80 ) but other than steel or aluminum they fit the same. I have asked others about this larger diameter and they assure me it works.

Ignore the ratios, probably for a car with smaller tires.
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.

All automatic 720s after Nov '82 with Z24 motor used a 3.70 ratio rear end and the blue 18 tooth pinion.
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#50 Charlie69

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Posted 17 January 2011 - 07:59 PM

Hi Mike, I have personally pulled 3 Blue cogs out of 84 85 automatic standard cab 720 trucks with the passenger side plates reading HF38. I thought HF38 translated to H190 3.889:1 Ratio

Here is a plate I pulled from the truck I got the blue cog from.

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Sent you a PM

Thank you Mike.

#51 datzenmike

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Posted 17 January 2011 - 08:15 PM

HF-38 IS 3.889 you are correct.

What can I say? I believe you. My info shows 17, 18, 19 and 20 tooth pinions used in the auto yet only one 3.70 rear ratio???? There were some optional tier sizes but not enough for that big a spread. Only 2wd gas engines got the automatic.

Well I found references to an auto using a 3.70 and a 3.889 so there are probably more. I haven't become perfect at reading the codes.

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The K in the MODEL # is for automatic
.
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#52 Charlie69

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Posted 17 January 2011 - 08:37 PM

HF-38 IS 3.889 you are correct.

What can I say? I believe you. My info shows 17, 18, 19 and 20 tooth pinions used in the auto yet only one 3.70 rear ratio???? There were some optional tier sizes but not enough for that big a spread. Only 2wd gas engines got the automatic.

Well I found references to an auto using a 3.70 and a 3.889 so there are probably more. I haven't become perfect at reading the codes.


Mike I am trying to compile good information for these trucks. FSM Trucks 1976 4.375:1, 1980 & 1985 does not state raio that I can find.

Your information has been right on and who knows if these rear ends/transmissions have been swapped out over the years on these odities that I am finding. I know over the years I have swapped lots of parts. I have been told that the early 520 had 5.13's & 4.875's. My 520 FSM only shows 4.875 ratio & I have not personally come across the 5.13's in any thing.

As I personally verify or any of you info collected I will update as much info as I can on the numbers I PM'd you.

#53 datzenmike

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Posted 17 January 2011 - 08:46 PM

The 720 trucks rear end ratios stretch from 3.364 through 4.625, incredible.
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#54 Charlie69

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Posted 18 January 2011 - 08:37 AM

The 720 trucks rear end ratios stretch from 3.364 through 4.625, incredible.


I need to go back to the JY and check the ratio on the rearend of the 1980 KC L20B L3N71B that I got the 21 tooth gear out of.

Mike you are like an encyclopedia when it comes to Datsuns.

#55 B210

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Posted 20 February 2011 - 10:07 PM

Would i be able to mate my 3 speed auto transmission to a honda b series motor?
is there a company that makes an adapter or some sort?

#56 HowlerMonkey

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Posted 23 April 2011 - 09:57 AM

The L4n71b from the 1983 and 1984 U.S. maxima (possibly the 1984 300zx as well) was 4 speed auto with lock-up convertor.

It is fully hydraulic shifted so it does not need the tranny controller that you would need if you used a E4n71b but it does have inputs for two simple switch circuits.

One is for kickdown and the other is to enable/disable OD.

They are available with two different torque convertors in the maxima which would be the 1983 diesel low stall speed and the standard gas engine stall speed.

I'm not sure if you can use the 300zx torque convertors (again two stall speed....non-turbo and turbo with higher stall) but it is posible that the only difference in dimensions is the flexplate between L engines and vg engines......still not sure.

The turbo transmissions will have more clutch frictions and steels in most, if not all clutch locations and some are seen with 4 planet gears rather than 3 in at least one of the gearsets.

If you have a high horsepower L engine, there are at least 4 good donor cars for the transmission.

1. the 1984 to 1989 300zx turbo (remember 1985 and later require electronic control unit)

2. the mitsubishi conquest/starion turbo (either tsi or esi)

3. the mid-80s rx7-turbos

4. some australian holdens or nissans with V8

Of course, you need to use the 1983 or 1984 nissan maxima bellhousing and most likely the flexplate and torque convertor but I would love to find out that the flex plate and bellhousing are the only thing different because that opens you up to many different stall speed convertors from the super high stall mazda rx7 to the super low stall speed Ld28 equipped 1983 maxima.

As far as 3n71b, the 280zx turbo 3n71b is sweet and has a pretty high stall speed convertor as well as a thicker output shaft.

The turbo car 3n71b have differences in the shafts inside the transmission with the turbo's sometimes having thicker output shafts as well as the short shaft between torque convertor and output shaft actually have a portion that slides within the other while the non-turbos don't have this.

Not sure if the 4n71b 4-speed has shafts mating or not.

280zx non turbo 3n71b have same output shaft diameter and outside diameter of the driveshaft yoke that slides in as the fs5w71b 5 speed manual but the 280zx turbo uses a larger diameter output shaft thickness while retaining the need for the same outside diameter of the yoke............outside diameter of this yoke is 35mm for both.

Some 4n71b have the same thicker output shaft as the turbo 3n71b but with a larger diameter yoke that slides in........outside diameter of this yoke was 38mm.

#57 darrel

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Posted 01 May 2011 - 09:48 PM

I used an '88 maxima auto shift handle with the switch and cut it down to fit. The OD is activated when there is no power going to the solenoid.

The lock up occurs after a certain number of revolutions the driveshaft spins, about 40mph. 3.9 rearend but am going back to the 3.54. With the 3.54 and 3 spd auto I got 19mpg on a trip west, with the 3.9 and 4 spd auto I got 24mpg on another trip west.



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#58 superharry

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Posted 04 May 2011 - 09:39 PM

I hope I got this right, from what I've heard here, I won't be able to put the 4spd. auto to a 1600 / 5bolt crank? I will ceck and measure, but if the old flex plate (3spd) is the same other than the holes for a 6 bolt crank, it should be good... anyone done this befor?!?!? help if you can, I really want a 4 spd auto!
Datsun, sure beats whatever's second!

#59 datzenmike

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Posted 05 May 2011 - 05:29 AM

The 3 speed flex platess are different from the 4 speed (besides the 5/6 bolt holes) The 4 speed has a huge fat doughnut torque converter and the flex plate has a bulge in it for clearance.
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#60 High5maxi!

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Posted 16 December 2011 - 12:18 PM

Can i use the first generation Maxima auto bellhousing to connect a 240sx 5 speed tranny to my L28?