datsun 521 rear differential gears?

[datsunaholic]

What were the 521 options?

 

A PL521 (70-72) was 4.375.

A L521 (68-69) was 4.889.

 

 

620 rears were normally 4.375 as well. There were exceptions- 73-74 Automatics were 4.625. '79 Manual transmissions were 4.111. '73 Heavy-duty may have had 4.88s.

 

"Running out of 5th on the freeway" is next to impossible. With a 5-speed and any rear end, even a 4.88, you'd be pretty much doing 100MPH by the time you hit 5600 RPM. With a common 4.375 you'd be over 110MPH @ 5600 RPM. More likely you're running out of horsepower, and changing gear ratios won't help.

 

Every year I go cross state. I've run for hours at 80MPH with a 4-speed, stock rear end 620 King Cab. That included climbing mountain passes, but more telling is I ran up the inclines out of Vantage doing 80. The only mod I have is a Weber. It pulls it just fine.

[what]

If anybody is interested I have the center section out of a 720 2wd with 3.89 gear ratio. Send me a p.m. if interested. $100.00. No shipping. Its to heavy.

[Jayden71]

A PL521 (70-72) was 4.375.

A L521 (68-69) was 4.889.

 

 

620 rears were normally 4.375 as well. There were exceptions- 73-74 Automatics were 4.625. '79 Manual transmissions were 4.111. '73 Heavy-duty may have had 4.88s.

 

"Running out of 5th on the freeway" is next to impossible. With a 5-speed and any rear end, even a 4.88, you'd be pretty much doing 100MPH by the time you hit 5600 RPM. With a common 4.375 you'd be over 110MPH @ 5600 RPM. More likely you're running out of horsepower, and changing gear ratios won't help.

 

Every year I go cross state. I've run for hours at 80MPH with a 4-speed, stock rear end 620 King Cab. That included climbing mountain passes, but more telling is I ran up the inclines out of Vantage doing 80. The only mod I have is a Weber. It pulls it just fine.

 

I have dogleg in my 521 with 488s, I am now turning approx 3700rpm at 65mph. I'm running 215/70/R14s.

 

I am in love with it :thumbup:

[minitrucker80]

^{I have a 71 521 rearend in my 720....will the 3rd member out of a hardbody work in it..both are h190 rearends}

[]2eDeYe]

Yes, they should swap.

[green180]

I pulled the gears out of an 83 720 5 speed and ended up with 37:10 gears, hopefully my little l16 won't be too slow with 3.7 gears, were 3.7 gears supposed to be in 5 speeds, and would the speedo gear just swap over

[wayno]

I pulled the gears out of an 83 720 5 speed and ended up with 37:10 gears, hopefully my little l16 won't be too slow with 3.7 gears, were 3.7 gears supposed to be in 5 speeds, and would the speedo gear just swap over

 

You will likely not be able to haul loads with them gears, the L16 is not known for having torque.

[datzenmike]

I pulled the gears out of an 83 720 5 speed and ended up with 37:10 gears, hopefully my little l16 won't be too slow with 3.7 gears, were 3.7 gears supposed to be in 5 speeds, and would the speedo gear just swap over

No, speedo gear won't swap over. Your 521 should have a 189 tooth mated to a 4.375 ratio diff. To go down to 3.7 ratio you need to slow the speedo down about 18%. A 16 tooth pinion is almost perfect. You could try a speedometer pinion (this is just the plastic gear, about $20) from a 510 32703-22000. Also found in 610/710 and early 620s. If looking the gears are Yellow plastic.

[Calbuzzard67]

So what is the diff ratio on the 720 ?

[Calbuzzard67]

So what is the diff ratio on the 720 ?

I found my answer in another post

[Blazed22s]

So I have read through this post, and tried to do a little bit of research in other places, but I still have a question. The only way to lower the gear ratio in my 1971 521 truck is to get a whole center section out of another truck? No one sells a gear set that I can buy either online or a parts store? 

 

I put a chevy 4.3L v6 and 5speed in my truck out of an 1991 s10. I'd like to get a lower gear ratio, something closer to what the stock s10 had. I pretty much have no 1st gear at the moment, revs out super quick. I really dont have time to go junk yard shopping around here. Finding any kind of Nissan truck, much less a datsun truck in a yard is near impossible. I'm just wondering if that will be my only option (other than spending bookoo bucks on a whole new custom rear end).

[wayno]

Just find a Nissan 720 with an H190 with 390/370/350/330 gears and put it in your truck, the thing about doing it this way is there is nothing to set up, you just remove your center pumpkin/gearset, and put the one out of the 720 with an H190 in your 521, fill it with gear lube and your good to go, it takes less than 2 hours.

What gearing did the S10 have?

So I have read through this post, and tried to do a little bit of research in other places, but I still have a question. The only way to lower the gear ratio in my 1971 521 truck is to get a whole center section out of another truck? No one sells a gear set that I can buy either online or a parts store? 

 

I put a chevy 4.3L v6 and 5speed in my truck out of an 1991 s10. I'd like to get a lower gear ratio, something closer to what the stock s10 had. I pretty much have no 1st gear at the moment, revs out super quick. I really dont have time to go junk yard shopping around here. Finding any kind of Nissan truck, much less a datsun truck in a yard is near impossible. I'm just wondering if that will be my only option (other than spending bookoo bucks on a whole new custom rear end).

[Blazed22s]

Not sure what the s10 had, but i do believe that it didnt go through first gear in 1.2 seconds. If i could find a 720 in a yard around here, it wouldn't be that bad of task. But finding a donor truck is the problem.

[wayno]

I understand, maybe someone closer to you has a pumpkin/gearset, and it likely will be cheaper than what they are getting for parts around here at the wrecking yards, I have what you want, but by the time it got to you, it would be close to if not at $200.00 shipped.

Perhaps you can contact members that are close to you and ask if any of them have better gearing, there are a few members in your area sort of.

Not sure what the s10 had, but i do believe that it didnt go through first gear in 1.2 seconds. If i could find a 720 in a yard around here, it wouldn't be that bad of task. But finding a donor truck is the problem.

[datzenmike]

There were several cars with the H-190. The '78-'84 810/Maxima wagon and the '82-'83 S110 200sx and the '84 S12 200sx all had the H-190 but different axle splines. Easy enough to slip your truck side gears into them.

[]2eDeYe]

You can also find them in 2wd hardbodys and frontiers up to a certain year, not sure what the cutoff year is.  The h190 is pretty easy to identify though, the late model axles (non H190) have a removable plate on the back of the diff.