NM 521

[Oilspot]

Just a thought DP

 

 What size tire are you running? 

[wayno]

I have a friend that used an early 620 5 speed in his SD22 powered diesel 720 truck, it did not work out well, it was like he was in 4th gear while in 5th gear and he had to ring that engine out just to do 60mph, you need a 720 5 speed to be sure you get one with a decent over drive gear.

 

In my opinion the L16 will not likely turn 3.88 gears in 5th gear, it just does not have the HP at them rpms to keep it moving up a hill, you will have to down shift a lot and you will be almost floored a lot, and if your floored that much all the time and you do not have hardened valve seats your valves will sink into the head, also 4.11 gears are very hard to find anymore, and if you can find a set in a wrecking yard, they are very expensive.

 

I would save up and find an L20b/5spd and put that in your 521 if your actually going to keep it, you will be much happier, you would be even happier if you built a LZ23 out of a car Z22 block, punch it out to 89mm to except new stock Z24 pistons, find a 219/V912 head and put some dual SUs on it, it will pull hard all the way to 90mph+, you can use a truck Z22 engine, but they are different, they have lower compression as I did it and am unhappy, I likely would not be unhappy if that engine was in my 520, but it is in my work truck right now and I am UNHAPPY!

 

The L16 is a high rpm engine, I have changed out the gears for other people, and they usually sell the vehicle because it does not meet their expectations, it just does not have the power they wanted and it never will unless they have a race engine in the truck, and who drives a truck like that on the public roads revving it to 6000rpms+, it is a waste of money to spend that kind of money on an engine and drive it normally.

 

 

Edited January 30, 2022 by wayno

[datzenmike]

All 720 diesels used the wide ratio 5 speed with an 18.7% over drive.

 

Most 620s used the mid ratio with the 13.6% OD.

[Oilspot]

7 hours ago, wayno said:

I have a friend that used an early 620 5 speed in his SD22 powered diesel 720 truck, it did not work out well, it was like he was in 4th gear while in 5th gear and he had to ring that engine out just to do 60mph, you need a 720 5 speed to be sure you get one with a decent over drive gear.

 

In my opinion the L16 will not likely turn 3.88 gears in 5th gear, it just does not have the HP at them rpms to keep it moving up a hill, you will have to down shift a lot and you will be almost floored a lot, and if your floored that much all the time and you do not have hardened valve seats your valves will sink into the head, also 4.11 gears are very hard to find anymore, and if you can find a set in a wrecking yard, they are very expensive.

 

I would save up and find an L20b/5spd and put that in your 521 if your actually going to keep it, you will be much happier, you would be even happier if you built a LZ23 out of a car Z22 block, punch it out to 89mm to except new stock Z24 pistons, find a 219/V912 head and put some dual SUs on it, it will pull hard all the way to 90mph+, you can use a truck Z22 engine, but they are different, they have lower compression as I did it and am unhappy, I likely would not be unhappy if that engine was in my 520, but it is in my work truck right now and I am UNHAPPY!

 

The L16 is a high rpm engine, I have changed out the gears for other people, and they usually sell the vehicle because it does not meet their expectations, it just does not have the power they wanted and it never will unless they have a race engine in the truck, and who drives a truck like that on the public roads revving it to 6000rpms+, it is a waste of money to spend that kind of money on an engine and drive it normally.

 

 

When  I drive my truck, I'm constantly feeling like I should shift! It's not, with the stock muffler, even loud. I can just feel the engine winding and it makes me feel like I'm beating on it!  I've got a close ratio, high reving,  6 speed  ,07' civic that took me a while to feel comfortable with cruising at higher rpms also (but I'm fine with now). 

I didn't know jack shit about Datsuns or the L16 motor a few months ago so this has been a learning experience. I've just gotta get it outta my head that this little motor is redlining at 4200rpms!!!

 

Hearing about people making changes and selling their trucks because of frustration makes me appreciate how happy my little turd of truck makes me when I'm cruising around.  She pulls good in traffic, keeps up on the hwy when needed, and gets thumbs ups consistently around town. 

 

I really appreciate all the feedback! 

Edited January 30, 2022 by Oilspot

[datzenmike]

Vehicles today probably have 60 pounds of sound deadner and carpet in them. The 521 had a thin vinyl floor mat. Add sound deadner to the floor and up under the dash as far as you can and behind the seats, try to do the insides of the doors and carpet the floor at least. Maybe a liner for the hood. Datsun trucks are a tin can and an engine. I cut a 720 carpet and underlay for my 620 and it was marvelously quiet in comparison. 

 

Trust the builder, Nissan. Trucks ran for generations like this without ill effect and the seemingly high RPMs is normal. Rather than change it, just change your perception of it. 

[thisismatt]

L motors always sound like a box of rocks. 

[datsunfreak]

On 1/30/2022 at 6:17 AM, Oilspot said:

I didn't know jack shit about Datsuns or the L16 motor a few months ago so this has been a learning experience. I've just gotta get it outta my head that this little motor is redlining at 4200rpms!!!

 

21 hours ago, datzenmike said:

Rather than change it, just change your perception of it. 

 

The crux of what I have been trying to say. 😁

 

And to say one more time, they are pretty loud at 3800-4300, but mine always seemed to get a little quieter above 4300. It was weird, but I've had it happen on 3 different L16 cars. When I started this journey, I felt like you did. Mostly coming from the Chevy world where 4k rpm seemed like you were trying to blow it up on purpose. It took awhile to get over the mindset that I wasn't hurting the engine by spinning it up to 4500rpm. 

 

When I was but a youngster, my first Datsun was a '79 210, A14/4spd. I liked it, but it was really slow. I let my brother drive it one time and noticed it seemed much faster with him behind the wheel. Next time I drove with him in the passenger seat, he kept telling me I wasn't revving it high enough to get the most out of it, and he was right. 

[datzenmike]

I've noticed that as a passenger the ass dyno seems to register more output. Perhaps because the driver is holding onto the steering wheel for support or the passenger isn't busy actually driving the car Anyway it always felt faster as a passenger.

 

As to the engine getting quieter with a specific RPM, could be exhaust resonances cancelling each other out in the pipe and muffler. I find my L20B has a noise peak at 2,500-3,000

[Stoffregen Motorsports]

To truly enjoy older vehicles, you need to remember that they are old, and not apply your modern expectations to them. In retrospect, I don't recall any real frustration with how my daily Datsuns drove. I only remember the good things. Manage your expectations and your experiences will be good ones.

 

Also keep in mind that if you do get tired of the low HP of the L16, you can always stuff an L20B in there or mod the L16 for more power.

 

You have options.

 

Side interlude - yesterday my dad asked me why I keep buying these old Jeeps when I apparently detest their build quality. I replied that the fact that they suck so bad is exactly why I buy them. Because there is a LOT of room for improvement, they can brought up to par very easily. Keep that mindset with the Datsun. There are sooooo many possibilities with an old Datsun.

[datsunfreak]

2 hours ago, datzenmike said:

As to the engine getting quieter with a specific RPM, could be exhaust resonances cancelling each other out in the pipe and muffler.

 

Could be. I always run a 2" exhaust on an L-series. 👍

 

But it seemed like it was the valvetrain that was quieting down...

[datzenmike]

The clearances don't change just the frequency. Or the sound is drowned out by something else.

[d.p]

On 1/29/2022 at 4:17 PM, Oilspot said:

Whats the final drive on the 5 speed you've got. The stock 4 speed is 1:1, I'm gonna guess the 5th in your box is pretty close to that. 

what trans did you put in there?

 

 

No fucking idea, it came in the truck when I bought it and I have been too lazy to go outside and spin the drive shaft and count how many times the tire spins to find out.  I put what I believe was a 79 280zx trans in it (at least that is what was sharpie'd on the outside of it).  I bought it from an estate so the guy selling it didn't even know what it was but I think @datzenmikeconfirmed what it was. 

 

This be it:

 

 

On 1/29/2022 at 6:30 PM, datzenmike said:

All 4 and 5 speeds are 1:1 in 4th.

 

There is one more year of zx 5 speed, and that is the mid ratio of '79. It has a 13.6% OD (about half the other two) and this amounts to a 544 RPM drop, a lot less noticeable. This transmission is also used in the late 280z, 620, 720, 810 and Maxima.

 

 

 

That is what I believe I have and like I said my RPMs are not that low at 70MPH, so we can do all the calculations but real world doesn't align with them,.

 

On 1/29/2022 at 7:11 PM, Oilspot said:

Just a thought DP

 

 What size tire are you running? 

 

195/50/15 the only tire size anyone should run with 15s/ 

 

[datzenmike]

That is an L 5 speed made before '80 and it is from an EFI car. Can only be a mid range from an 810, 280z or the first year zx. 

 

Perception is iffy like guessing your RPMs by the sound of it. Do you have a tach? Take to an even number like 3k and shift to 5th. With a 13.5% OD it should drop about 400 RPMs. First to second is 37%, second to third is 37% and third to forth is 23% so a mere 13.5% isn't a big deal.

[Oilspot]

DP.   (Doing quotes on my phones is a pain in the ass!). 

From what I understand a 195/70r14 is pretty close to stock tire circumference at 77.7". 

A 195/50r15 rolls out at 71.2".

 

You re-geared your truck at the tire!

 

 

 

Edited January 31, 2022 by Oilspot

[wayno]

51 minutes ago, datzenmike said:

That is an L 5 speed made before '80 and it is from an EFI car. Can only be a mid range from an 810, 280z or the first year zx. 

 

Perception is iffy like guessing your RPMs by the sound of it. Do you have a tach? Take to an even number like 3k and shift to 5th. With a 13.5% OD it should drop about 400 RPMs. First to second is 37%, second to third is 37% and third to forth is 23% so a mere 13.5% isn't a big deal.

 

What makes you say this transmission came out of a car and not a 620 truck?

 

I will not use anything that has them gussets on the side bolt tail shaft housing holding the cases together, I suppose they would work in my work truck but they do not work for my diesel trucks.

 

Is anyone else on here having issues with this site?, right now when I click on a thread it goes to page one every time even though I click on where it says posted 2 hours ago, anyone else having this issue?

[datzenmike]

24 minutes ago, wayno said:

 

What makes you say this transmission came out of a car and not a 620 truck?

 

I will not use anything that has them gussets on the side bolt tail shaft housing holding the cases together, I suppose they would work in my work truck but they do not work for my diesel trucks.

 

Is anyone else on here having issues with this site?, right now when I click on a thread it goes to page one every time even though I click on where it says posted 2 hours ago, anyone else having this issue?

 

Easy. Cars 5 speeds are all 6 cylinder and EFI equipped 280z/zx and 810/Maxima. They have no use for emissions switches like top gear and neutral, only a reverse light switch. The 620 has neutral/top gear switches to turn the emissions equipment on off.

[wayno]

I did not know all that, it is good to know, car transmissions only have one switch.

Is the front bearing cover aluminum or steel?

 

7 hours ago, datzenmike said:

 

Easy. Cars 5 speeds are all 6 cylinder and EFI equipped 280z/zx and 810/Maxima. They have no use for emissions switches like top gear and neutral, only a reverse light switch. The 620 has neutral/top gear switches to turn the emissions equipment on off.

 

[datsunfreak]

Also, in my personal experience, that double rib over the starter means early 290ZX. 

 

FYI, the DQ Newsletter did a transmission spotters guide to tell you what everything is, Mike kindly linked to it here:

 

 

[datzenmike]

I looked through my 71B transmission pictures (about 1,000 related) and could not find one that didn't have those ribs. I have shorty 5 speeds and some 4 speeds and even the 71C and they have the ribs. May have been added in late '70s, just means I can't find a earlier 4 or 5 speed picture. The 5 speed in my 710 has an '85 S12 5 speed with an L series front case but the original CA case was without ribs just like the dogleg. I'll watch for this every time I look at them.  

[d.p]

On 1/31/2022 at 4:46 PM, Oilspot said:

DP.   (Doing quotes on my phones is a pain in the ass!). 

From what I understand a 195/70r14 is pretty close to stock tire circumference at 77.7". 

A 195/50r15 rolls out at 71.2".

 

You re-geared your truck at the tire!

 

 

 

well seeing as I’m not going to change the tires I guess I’ll just live with it.  I mean at the end of the day I guess it doesn’t matter all that much but I would be happy if I could get the cursing RPMs down without having to drive slower. 

[thisismatt]

So change your rear end fffs

[Oilspot]

24 minutes ago, d.p said:

well seeing as I’m not going to change the tires I guess I’ll just live with it.  I mean at the end of the day I guess it doesn’t matter all that much but I would be happy if I could get the cursing RPMs down without having to drive slower. 

4x4 guys change diff gears all the time to compensate for gearing changes at the tire, and that's 2 diffs at a time.

 

Are aftermarket r&P's available for the 521 rear end? Or are the only options used oem units?

 

 

 

 

Edited February 2, 2022 by Oilspot

[mainer311]

No aftermarket support, but the diffs in these trucks are pretty common across all 70’s datsun vehicles. Common practice is to find a 3rd member from a different vehicle and swap it in. I know the diffs in my roadster and 521 are basically the same except for the ratios.

Edited February 2, 2022 by mainer311

[datzenmike]

Only trucks differentials will work. The Roadster, 510, 610, 810/Maxima wagons (all cars) are H-190 but the 23 side gear splines* won't take a 29 spline truck axle. For gears lower than a 4:10 you would have to look at the 720 truck or the D21 Hardbody. 

 

*You can dismantle the H-190 differential and swap your side gears in to convert it to work with truck 29 spline axles.

[d.p]

What would be the best diff for a 521 and getting the RPMS down on the freeway?  I’m running out bolt on shit to do on this fucker.