Transmission options for J series pickup

[reinCARnate]

I can't remember now, but I believe that the transmission was changed when they went to the L series engine. My L521 pickup had the J series engine, however, the engine was busted when I bought it.

 

So...I'm wondering if it is worth it to upgrade to a different transmission if I'm going to change out the motor anyway. I'm definitely not a purist who runs everything stock. So wondering if the J transmission is a good design, reliable and worth keeping or if I should take this opportunity to ditch that drivetrain altogether and go with another.

 

The other consideration is parts. I have been unable to find a clutch kit for the J series transmission. But I found one for the L series.

 

Just curious to hear what my options are. I guess the options are kind of limitless but I'm hoping to find one that doesn't require cutting the body and it would be especially nice if the L series trans fit into the existing mounts. But that would be asking too much.

 

Also, does anyone know the rated torque on these stock transmissions?

[datsunaholic]

This all depends on what you are planning to replace the engine with. If it's another J-series, you're stuck with the transmission you have as they didn't come with anything else, unless you went with an even OLDER transmission from an early 520. Any other ENGINE will require using a transmission that fits that engine.

 

Actually, The L521 (J13) and PL521 (L16) transmissions were both the same model- F4W63. But the front case was different, due to the different bolt pattern. The rear mount was identical, but the PL521 used a flanged output. If you were going to an L-series engine, the DIRECT replacement transmission would be the 4-speed from a 68-73 510 or a 73 620 pickup, as they are the same length and share the same mount location as the 521 transmission but unlike the PL521 they don't have the bolt-on flange. If you instead opt for a 5-speed, that will require a modified rear mount no matter what you do, but since you also need motor mounts it's just another thing to fabricate.

[reinCARnate]

Now why did they have to go and change the front case design? Thanks for the info. That helps.

 

So, does it follow, if they are the same model trans, that the clutch kit is the same for both as well?

 

As to what engine I'm using, I haven't settled on anything. I'm trying to weigh the pros and cons of the options. It seems that it's much easier to find parts for the L16 drivetrains (much more common?) and if that would fit just as well, then maybe that is the way to go. I see your point about mount fab though. Are J series engines hard to come by these days?

[datsunaholic]

No, the clutches aren't the same. The clutches have nothing to do with the kind of transmission used- in fact you'll find different clutches used with identical transmissions.

 

Parts availability for J-series engines depends on several things, but the J-series was used in Mexico much longer than in the US. Plus J-series share some minor parts (gaskets) with MGB engines.