posi rear end???

[benrob]

has any one put a  posi rear end in there 521. if so what rear end works? can you just change the gears in the stock rear end  to make it posi?  any help is much appreciated 

[datzenmike]

Read this first... http://www.houseofthud.com/differentials.htm#wacky%20demo%201 this should answer question #2

 

Now go to the SEARCH ... top right of page just under the 510 car logo and type in "truck lsd" start reading. This will likely answer question #1

[XXL]

Read this first... http://www.houseofthud.com/differentials.htm#wacky%20demo%201 this should answer question #2

 

Now go to the SEARCH ... top right of page just under the 510 car logo and type in "truck lsd" start reading. This will likely answer question #1

 

I agree... search FIRST.  In this case, though, "truck lsd" only brings up your post above (and now, probably this one) ;)

[datzenmike]

truck lsd gives.....

 

http://community.ratsun.net/topic/42811-truck-h190-lsd-section/

 

http://community.ratsun.net/topic/34706-precision-gear-power-brute-lsd-for-your-h190-truck/

 

http://community.ratsun.net/topic/56078-lsd-for-720/

 

http://community.ratsun.net/topic/751-rear-ends-for-our-lsd-ventures/

 

... at least, and does not include trying various other key words like 'lsd in datsun trucks' or 'truck posi'. Be creative.

 

Try 'Lincoln Locker' for info on the good and mostly bad of a welded rear end.

 

 

 

.

[XXL]

truck lsd gives.....

 

http://community.ratsun.net/topic/42811-truck-h190-lsd-section/

 

http://community.ratsun.net/topic/34706-precision-gear-power-brute-lsd-for-your-h190-truck/

 

http://community.ratsun.net/topic/56078-lsd-for-720/

 

http://community.ratsun.net/topic/751-rear-ends-for-our-lsd-ventures/

 

... at least

 

 

 

.

 

 

We must be using different search functions.  In the "Search" box in the top right corner, below the 510, when I type "truck lsd" (I actually just copied and pasted it from your previous post), I get ONLY this thread, with the 3 (now 4) posts in it.  Just an FYI, in case there's something wrong with the Search functionality.  See attached PDF of the results page I just got...

 

http://myattitudesucks.com/fark/search.pdf

 

I'm using Google Chrome 28.0.1500, which is current version, if that matters.

[datzenmike]

That's why I often try using several variations of the words.

[mrbigtanker]

So has any one put a LsD in a 521. lol

[Ranman72]

^^^^^ 

LOL 

NO

[erichwaslike]

i have a nsd in my 521.... its a no slip differential... its welded... and the only bad side is the lil bit of chirping(i like it) i never noticed bad tire wear, and if you break down or run out of gas you better hope you only gotta push it straight, they dont turn well without power....

[benrob]

Ya ive been thinking about that and that might b the root I wana go worst comes to worst I have another truck that I can pull yhe rear end out of and put it back to stock

[benrob]

Anthother question I have is , is my stock rear end holding back power because of the gearing it has . I feel like it should b quicker than it is ?

[datsunaholic]

"Holding back power"?

 

Well, the rear end was geared as a compromise.  Allowed normal US Freeway Speeds (for the time, which was around 70MPH) but also allowed the truck to haul a full load without burning out clutches with only a 1.6L engine.   Hence the choice of 4.38 gears.  The same gear ratio used with L20B (though the power at the wheels was similar due to increasing emissions equipment, hence the larger engines).  Sure, you could put different gears in it- there aren't much to choose from, though, but earlier 520 and L521 (1969) trucks with the J13 had 4.88 gears so they exist.  That's certainly get you through the gears faster... and increase the freeway RPMs.  At 60 MPH it translates into about a 410 RPM difference.  As in more.

 

But remember, if this truck is stock, you're LUCKY to be pushing 70 HP to the wheels.  They are NOT quick.  Weren't meant to be.  They were meant to haul bedloads of stuff from point A to point B, with half the fuel consumption of their US Full-size brethren.

[benrob]

Ya sory forgot to mention that it has a sr20 in it. But yes its the stock 521 rear end

[datzenmike]

Ya ive been thinking about that and that might b the root I wana go worst comes to worst I have another truck that I can pull yhe rear end out of and put it back to stock

.

Lincoln Locker? I don't agree with them. All rear ends should be somewhat 'open' at times. A welded rear end is good for driving in a straight line. On corners they introduce understeer. On all corners, the outside wheel has to travel further than the inside one but they are locked together. One or both are slipping to some extent and on dry pavement not so bad, but on wet, snow, ice or dirt covered roads the back end will want to come loose into oversteer. Yes lots of people do it and are lucky get away with it.

 

With a true LSD if it breaks loose you let off the gas and the clutches uncouple and the wheels are free to spin the correct speed and traction is restored. On a welded diff once traction is lost you are in for a ride. Just saying that if you go this route, know what you are getting into.

[benrob]

Ya I think untill I can get the money for lsd I might try it , like I said I have another rear end if I dnt end up liking it.

[datsunaholic]

OK.  SR20.  Close to twice the horsepower, So yeah, I can pretty much guarantee it's not geared optimally, BUT it comes down to what you "feel".  "Quick" is a function of how fast it accelerates in each gear.  If you're overpowering the gearing, you feel you can't accelerate fast enough because you're actually accelerating too fast, meaning you have to shift too soon.  Whereas in underpowered for the gearing, it feels as if it bogs on acceleration, slow to accelerate. 

 

Likely you have too MUCH horespower for the gearing- you can't use what you have, because you're already shifting gears.

 

You could definitely change the gear ratios, lots of '80s 720s came with gears in the 3.6 and 3.8 range (ones with Z22 and Z24 engines, non 4X4).  That will make you shift LATER, and will drop overall RPMs.   But it will let you use the power you have. 

 

But if you feel the engine is bogging, particularly in 4th or 5th (or whatever top gear you have), then it's more a matter of having to match your RPMs with your intended cruising speed.  Up or down, though I can't believe an SR20 would be underpowered for a truck that light.

 

However... an SR20 has a higher RPM for both the max RPM and Max Torque curves.  The SR20 max HP is in the 6000-6400 range depending on version, whereas the L16 had max HP at 5600 RPM.  Same thing with torque- the SR maxes out somewhere between 4000-4800, whereas the L16 was at 3600.  So it could be possible that going the other way would make it peppier, and I suspect you have an overdrive transmission so you wouldn't be spinning the thing to the grave going to a 4.88 rear.  But that could be the wrong way to go, if you aren't using the power you have.