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521 5spd swap


Haug521

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Ok so im new to the forum, and just purchased a 1971 521, and its in pretty decent shape. Runs and drives pertty good, but lots of little things need repair or replaced. Pics coming soon. I am trying to find out what a good 5spd transmission would work to swap into my truck. I am limited on shop space (like none) but, I feel I could do a swap if it were fairly sraight forward. I've looked at some of the roadster 5spds, and some from the 620 and 720. I would like to keep the fab. down to a min. oh, and I'm keeping the L16, fer now... any ideas, advice direction?

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Welcome to Ratsun B)

The transmission with the least amount of fabrication would likely be a dogleg, it will bolt to your engine, you will need to keep your throw out bearing collar, you will have to modify the tranny mount, and you will have to put a soft plug in your transmission yoke. The other two options will take a lot more knowledge of transmissions, and fabrication.

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The Roadster transmission was used on the U20 motor and won't fit the L16. The Roadster morphed into the 240z around 1970 and only came with a 4 speed. Outside N America the Roadster 5 speed was used in the 240z because of a special L bell housing that would convert it for use on any L series motor. These can be found but pricy and as it was used mostly in racing applications worn out or destroyed, making then somewhat rare. It's also a long tranny so your driveshaft would need shortening and the mount modified.

 

For the same amount of work a 620,280z or zx or Maxima 5 speed could be used. Lots of gearing and overdrive options and not at all rare.

 

The FS5W63A dogleg is the same length as your 521 4 speed so the driveshaft need not be shortened. You would have to mod the rear mount to suit and as Wayno sid the front spline on your drive shaft will need a $0.50 plug in the end. The dogleg is strong enough for an L16 but only came in one car and and only in one model of another. These have been and still are somewhat in demand by 510 owners for easy 5 speed swaps, so kind of rare.

 

For a bit more work you can get a later, 2wd 720 truck short 5 speed and remove the front case and swap on one from a 620/280z/zx/Maxima that will convert it for use on an L series engine. It will fit the 521 without shortening the driveshaft. The rear mount will need modding but the speedometer drive is on the same side as the 4 speed..

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Hey, thanks for the info everybody! Now I can start somewhere, and do some searching. Yes, pictures are coming...soon. I'll take some good ones on my little road trip to Walla Walla this weekend. I 'll have 'em up by monday. It does have some body damage from the previous owner(had it in gear and shut the engine off, and let the clutch out before the stopped running...right into his roomates car). But, it drives down the highway straight as anrrow...brakes are awfull(are all 521 this way?)! I want to keep the L16 at least for a little while, it seems to run really well (valves need adjusted, and leaks oil pretty bad). I just want one more gear on the highway. Oh yeah, I bought this thing for $1600, and it has the rear bumperets and a washer bag...that works!

 

anybody else on here close to spokane?

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As far as I know, you cannot use a 280Z/ZX transmission bell/case on an L block without it being tilted, or is this something I didn't know about?

I have no idea on the maxima case.

It is good to know the 620 5 spd. case will work with the 85/86 720 shortshaft though.

 

The 620 ('74 and up), 280z and zx and the Maxima all have L series engines and the 71B transmissions are interchangeable. There were 5 speeds after '77. There is little difference between 4 and 5 speed front cases too, often just the position of the reverse lamp switch. Often a 4 speed case can be used on a 5 speed..

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The 620 ('74 and up), 280z and zx and the Maxima all have L series engines and the 71B transmissions are interchangeable. There were 5 speeds after '77. There is little difference between 4 and 5 speed front cases too, often just the position of the reverse lamp switch. Often a 4 speed case can be used on a 5 speed..

 

 

This I did not know, if I had known that a 280z and zx transmission was compatible, it might have made life a little easier.

What year did they change/become not compatible?

I have used a 1980 datsun 720 4X4 4 speed case to make one of them shortshaft 5 speeds, but I had no idea about Z car trannys being the same, so they are basicly the same as 620 5 speeds, did they change in 1980 like the 720 transmissions?

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All L series transmissions will fit L series motors like the L16/18 20B four cylinders and the L24/L26 and L28 six cylinders.

 

It's the Z series transmissions on Z series motors, like the Z20/22/24, that are tilted differently than the L. Swapping an L cront case onto a Z series tranny will convert it for use on an L series.

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All L series transmissions will fit L series motors like the L16/18 20B four cylinders and the L24/L26 and L28 six cylinders.

 

It's the Z series transmissions on Z series motors, like the Z20/22/24, that are tilted differently than the L. Swapping an L cront case onto a Z series tranny will convert it for use on an L series.

 

 

So your saying that anything with an "L" in front of it is compatible with the 85/86 shortshaft transmission, and if that case is put on a 71B transmission, it will bolt to a L16/18/20b, and any of the Z blocks to make a LZ hybrid.

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So your saying that anything with an "L" in front of it is compatible with the 85/86 shortshaft transmission, and if that case is put on a 71B transmission, it will bolt to a L16/18/20b, and any of the Z blocks to make a LZ hybrid.

 

yes

 

just drive the 4 speed.

ck the oil every now and then

 

As always Hainz the voice of reason. Yes the 521 is fine by itself with the stock 4 speed. Good power and carrying, top end speed and reasonable mileage. It's debatable if a 5 speed would be worth the bother for any improvements. Certainly it would only be in 5th at highway speeds and be milage related.

 

If the 4 seed is toast and you like doing thigs like this... and if 5 speeds or parts are available then the way is clear.

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I was going to use the oppertunity of swaping for a 5spd, to reseal the engine too. Just pull them both at the same time and get it done. Pretty sure most of my oil leaks are from the rear main anyway so...

Pictures are comming today btw. I might throw in some of my 240Z also(this was my first car, bought it when I was 15). The 240z is where I really want to put my efforts. Its very complete but needs a bunch of work!

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welcome friend. i got my 521 with a dogleg from a '78 510 wagon(according to the PO) if you go that way make sure to plug the yoke like datzenmike said cause the PO of mine didnt do that and there was gear oil everywhere and would have to refill ofen which is a pain. and hurry up with the pics already, we get restless. :D

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I swapped in a ZX 5 speed out of an 83 Z car into my 71 521 a few years back.

Took me about a week working on it a few hours a day.

Youll need to use the truck clutch slave, throwout bearing, clutch fork & trans mount (shortened about an inch).

I welded up the slip yoke that came out of the 521 4 speed & shortened the front driveshaft several inches.

Had to also cut trans tunnel a little (shifter is farther back) Btw i ran bucket seats..a bench seat wont work unless it has a cutout in the middle.

I noticed the rpms on the freeway dropped way down with the ZX trans which i liked.

Like Hainz said..if your 4 speed works leave it as is & cruise it.

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