My 1971 521

[d.p]

9 hours ago, wayno said:

 

OK Mike, this is what was said in Oilspot's thread about D.P's tire size.

 

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!

 

So Mike, with 195/50r15 tires what gear ratio would a 3.7 gearset be with a 71.2 round tire be compared to a stock size tire?

Would it be close to a 3.89 ratio?

It’s took cold for me to do anything with the truck right now (below freezing). But if that rear end and my 15” tires would essentially be the same as 3.90 with stock tires I am in.
 

How much you want for that 3.70? 

[datzenmike]

Stock 77.7" circumference is 24.75" diameter with 4.375

Your 71.2" circumference is 22.67" diameter but feels like 4.776

 

If you put a 4.111 differential in this will feel like a 4.448

If you put a 3.889 differential in this will feel like 4.250

If you put a 3.70 differential in this will feel like a 4.039

 

If you put a 3.545 differential in it will feel like 3.87 .... we have a winner.

 

 

A quick look shows '83 model year through '84 Reg cab, King Cab and Long Box 2wd 720s with the Z24 engine only, came with 3.545 geared differential. Check the bottom right on engine tag for HF35 for the 3.545

 

The same 3.545 ratio gear set was also used on the '90-'2000 D21/D22 Hardbody KA24E 2wd 5 speed. I think the Hardbody also has engine tags in the same location.

 

The 3.545* H-190 was used in the '80-'84 Maxima wagon

*needs truck side gears swapped in

 

 

 

[d.p]

Am I going to notice a difference between waynos 3.70 and 3.45? Probably raise to get waynos and be done with it. 

[wayno]

I am certainly not going to send a 3.5 gearset across the country for a 521 unless it has an SD25 diesel in it or another engine that has a shitload of torque, but what do I know, I sent a 3.5 gearset to a guy with a 320, but it had a LD20 diesel engine in it, he was very happy.

 

Anyone that goes from 4.37 gears to 3.7 gears is going to feel and hear a significant difference, that is like deleting first gear completely and likely a lot of second gear also, I suspect with some effort someone on here could figure out what gear it would feel like you were starting out in comparing what you have now and what would 1st feel like with 3.7 and 3.5 gears, basically I am asking what gear will it feel like he is starting out in with 3.7 gears and for fun 3.5 gears with the 4.37 gears he has now, either of them close to 3rd gear in his transmission he has now?

Edited February 5, 2022 by wayno

[d.p]

@wayno how’s this for an engine? Built L20b and dual Mikunis. 
 

 

[thisismatt]

Just swap in a Toyota 8" and you have way more options for gear sets and limited slips

Edited February 5, 2022 by thisismatt

[wayno]

My engine is made to get 6000lbs+ of weight rolling and keep it moving on the freeway, yours is made to go fast.

 

 

1 hour ago, d.p said:

@wayno how’s this for an engine? Built L20b and dual Mikunis. 
 

 

 

This is my engine, it is a hell of a lot dirtier, but it is a work truck, all my engine compartments are way too busy.

 

 

 

 

 

Edited February 5, 2022 by wayno

[d.p]

So you going to sell me that rear end then? 

[thisismatt]

15 minutes ago, d.p said:

So you going to sell me that rear end then? 

 

No salvage yards around you?

[mainer311]

10 minutes ago, thisismatt said:

 

No salvage yards around you?

We’re on the east coast. Most people don’t even know what a Datsun is.

[thisismatt]

1 minute ago, mainer311 said:

We’re on the east coast. Most people don’t even know what a Datsun is.

That's fine, you're looking for a Nissan 😛

[datzenmike]

2 hours ago, wayno said:

I am certainly not going to send a 3.5 gearset across the country for a 521 unless it has an SD25 diesel in it or another engine that has a shitload of torque, but what do I know, I sent a 3.5 gearset to a guy with a 320, but it had a LD20 diesel engine in it, he was very happy.

 

Anyone that goes from 4.37 gears to 3.7 gears is going to feel and hear a significant difference, that is like deleting first gear completely and likely a lot of second gear also, I suspect with some effort someone on here could figure out what gear it would feel like you were starting out in comparing what you have now and what would 1st feel like with 3.7 and 3.5 gears, basically I am asking what gear will it feel like he is starting out in with 3.7 gears and for fun 3.5 gears with the 4.37 gears he has now, either of them close to 3rd gear in his transmission he has now?

 

Wayno, DP's smaller tires make the 4.375 more like 4.776.

 

5 hours ago, datzenmike said:

Stock 77.7" circumference is 24.75" diameter with 4.375

Your 71.2" circumference is 22.67" diameter but feels like 4.776

 

If you put a 4.111 differential in this will feel like a 4.448

If you put a 3.889 differential in this will feel like 4.250

If you put a 3.70 differential in this will feel like a 4.039

If you put a 3.545 differential in it will feel like 3.87 .... we have a winner.

 

 

A 3.545 will be equivalent to a 3.889 with those smaller tires. A 3.70 will feel like a 4.039 and is also a good option.

[wayno]

1 hour ago, d.p said:

So you going to sell me that rear end then? 

 

I will sell you the 3.7 gearset, but I still think you should know what it will feel like when starting out in first.

If someone can figure out what 1st gear will feel like in your truck right now with 3.7 gears I would be a lot happier about selling them to you, I suspect it will be like somewhere between 2nd and 3rd gear if not 3rd gear, I can get my 521 diesel moving in 2nd or 3rd gear as I have done it, but I suspect my clutch would not last very long.

I will want a $100.00 plus shipping for it, and I chose too publicly say what I want for it, as maybe someone else will sell you one for cheaper.

[wayno]

OK, it appears that Mike has answered the question, a set of 3.545 gears will be sluggish off the line/starting out and only get worse with weight, the 3.70 gears will be like having close to 4.1 and that seems more reasonable to me, I am unsure of the rpm drop from 4.37 gears on the freeway, maybe Mike can tell you the RPM drop for both the 3.545 and 3.7 gears from the 4.37 gears you have now.

 

I have both the 3.7 and the 3.545 sets of gears, both are tight, meaning the pinion flange has maybe a 1/16" play in it(lash?), I do not knowingly sell wore out parts, but both need to be cleaned as they both have dust on them from sanding on the U320, I had them in plastic bags, but floating dust gets into everything.

 

 

24 minutes ago, datzenmike said:

 

Wayno, DP's smaller tires make the 4.375 more like 4.776.

 

 

A 3.545 will be equivalent to a 3.889 with those smaller tires. A 3.70 will feel like a 4.039 and is also a good option.

 

Edited February 5, 2022 by wayno

[datzenmike]

3.545 gears will be the same as 3.889 gears because of the smaller tires.

 

IF you are experiencing 3,890 RPMs say at 60 MPH going from a 4.375 down to a 3.545 will lower the RPMs by about 738 to 3,152 RPMs. Or 23.4% lower

 

 

 

 

[mainer311]

@wayno Are you not using these rear ends anymore? If you’re looking to offload them, I’d be interested in whatever Drew doesn’t want. I’m running the same size tire he is, but I have the stock 4 speed trans.

[d.p]

3 hours ago, thisismatt said:

 

No salvage yards around you?

yeah not no Datsun. I always look on car-part and will buy if the junkyards ship but hit or miss if they do.   I got my windshield and my hubs from some junkyards in AZ and VA.  

[d.p]

2 hours ago, wayno said:

 

I will sell you the 3.7 gearset, but I still think you should know what it will feel like when starting out in first.

If someone can figure out what 1st gear will feel like in your truck right now with 3.7 gears I would be a lot happier about selling them to you, I suspect it will be like somewhere between 2nd and 3rd gear if not 3rd gear, I can get my 521 diesel moving in 2nd or 3rd gear as I have done it, but I suspect my clutch would not last very long.

I will want a $100.00 plus shipping for it, and I chose too publicly say what I want for it, as maybe someone else will sell you one for cheaper.

Thanks @wayno message me with what you want for it. 

[thisismatt]

12 minutes ago, d.p said:

yeah not no Datsun. I always look on car-part and will buy if the junkyards ship but hit or miss if they do.   I got my windshield and my hubs from some junkyards in AZ and VA.  

 

https://www.facebook.com/marketplace/item/2587379804891743/?ref=search&referral_code=marketplace_search&referral_story_type=post&tracking=browse_serp%3Aab8de128-5e7d-45f5-8437-d42185eee76e

 

 

[d.p]

59 minutes ago, thisismatt said:

 

https://www.facebook.com/marketplace/item/2587379804891743/?ref=search&referral_code=marketplace_search&referral_story_type=post&tracking=browse_serp%3Aab8de128-5e7d-45f5-8437-d42185eee76e

 

 

 

[wayno]

3 hours ago, mainer311 said:

@wayno Are you not using these rear ends anymore? If you’re looking to offload them, I’d be interested in whatever Drew doesn’t want. I’m running the same size tire he is, but I have the stock 4 speed trans.

 

I used to save all good drop out assemblies, at one point I had more than 10 of them, I scapped a couple because they got wet and rusted.

All I have left is the 3.89 with some rust on the ring gear which will not be sold, the 3.70, the 3.545 that was in the 521 kingcab at one point, and the 3.545 LSD that was in the 521 kingcab until I found the 3.3 gears for it, the LSD was dangerous in the 521 kingcab turbodiesel when it was wet outside, more than once the backend started coming around when I gave it the pedal to make a left turn at an intersection, or on an uphill turn like an entrance to a freeway where I was trying to speed up to match freeways speeds or just trying to keep up with the vehicle in front of me, it did not do that with the regular 3.545 gears it would just spin out going straight.

 

I will sell the one that d.p does not buy, but keep in mind it is not 2004 anymore, I have no idea what shipping will cost, certainly not $60.00 like it was 8 years ago, these are heavy steel drop outs, they are not alloy.

[thisismatt]

Last time I bought a pumpkin (toyota 8"), the guy shipped it to me in a 5 gallon bucket.  An 8" is bigger than an H190, but I'm not sure about the snout length.  The 8" fit in the bucket with the bottom & lid bulging from the length.  Anyways, just an idea for a quick and liquid-tight option.

[wayno]

I will post one more time about gear ratios, I have used every ratio in one of my many Datsuns trucks over the years except the 4.1 ratio, I have used or am using 4.88, 4.625, 4.37, 3.89, 3.70, 3.545, and 3.30 I believe, when you change your gear ratio from say 4.37 to 3.70 it is harder to get the vehicle moving, but it is also harder to keep it moving on the freeway, with 4.37 gears you might just go right up the hill, but with 3.70 gears you might have to down shift to keep it moving at freeway speeds, I can almost guarantee that going from 4.37 to 3.545 you are going to have to down shift, maybe even in a head wind on level ground as the engine does not have enough HP to keep it moving at the lower RPMs, these trucks/engines are not Chevy small blocks with 300HP, you are only going to so much out of a L20b, and an L16 can barely move the 521 down the freeway at 70mph, I could barely keep my Datsun Roadster with the R16 going 70mph up a mountain pass road, these engines were made to rev, that is where they shine and create the most HP, when you gear them for lower RPMs they will not do near as well, and having a 5spd just compounds the issue.

[wayno]

22 minutes ago, thisismatt said:

Last time I bought a pumpkin (toyota 8"), the guy shipped it to me in a 5 gallon bucket.  An 8" is bigger than an H190, but I'm not sure about the snout length.  The 8" fit in the bucket with the bottom & lid bulging from the length.  Anyways, just an idea for a quick and liquid-tight option.

 

I actually rolled one up in cardboard and a delivery guy told me they did not like round packages as they roll around in the back of the truck, they want something with at least one big flat side.

I used a 5 gallon bucket once to keep oil from getting everywhere, the bottom of the bucket cracked open from the weight, these drop outs have been sitting on my extra roofing material packages, there is no oil in them anymore, I bag them anyway.

 

[d.p]

On 2/5/2022 at 4:31 PM, datzenmike said:

3.545 gears will be the same as 3.889 gears because of the smaller tires.

 

IF you are experiencing 3,890 RPMs say at 60 MPH going from a 4.375 down to a 3.545 will lower the RPMs by about 738 to 3,152 RPMs. Or 23.4% lower

 

 

 

 

 

Wait so do I want Waynos 3.5 or 3.70 gears?  Looks like I would be better off with the 3.5S?