limited slip diffs?

[seattle smitty]

Couldn't determine this with a search.  Was/is there a limited-slip option that could be applied to my early ('81) 720?

Also, in reading the '81 owners manual, I see that besides the standard pickup, the long box, and the King Cab (mine), there were one or two "Heavy-Duty" versions in that year.  Was that a matter only of springs and shocks, or was there more to it?  I'm going over to work on my truck today and will look for model designation letters/numbers.  This poor little neglected machine is eventually going to be my shop truck,  with flatbed and side-boxes.  And semi-massive-looking homemade bumpers, lah di dah!!

A comment on converting to a DGEV Weber:  I'd be curious to see how Redline, or whomever makes it, did their adapter plate.  I made mine, and found it to be a bit of a chore. FWIW, I have the primary side pointed left (driver side) and secondary to the right.  I had to make it with two separate plates, one screwed to the 720 intake manifold, one screwed to the underside of the carb, the both screwed together around their edges.  Doing this while providing clearance for the various DGEV throttle shaft gizmos that hang down below the carburetor's base was a little tricky.  I could have done the adapter with a single plate had I welded some material to the manifold, maybe, but it came out okay.  Funny, the last time I adapted one of these Webers, it was to an '86 Dodge Colt Vista, and it seems like it was a lot simpler operation, with only a single adapter plate needed.

Dang, I gotta get this vehicle fixed and in-service, it or my Vista.  Right now I'm making do, barely, with a '90 Geo Metro.  Purchased cheap but what a heap!  Hardly any traction, Chinese wiring, too new, and thus too complicated with a bleeping computer running everything via the too-small-guage wiring system,    .   .   .   If I had it to do over again, I'd get a Yugo, as the superior machine!!!

(EDIT) --  Oops, don't know right from left.  Carb is set with choke, and primary side, to the, uh, let's see, the right side, passenger side (U.S.)  .    .    .    .

Edited October 31, 2018 by seattle smitty

[wayno]

There are very few LSDs out there for the H190 rearend in the 720, they did make them but I believe they were special order.

I found one in a 1993 Nissan D21(hardbody) with 3.5 gears at the wrecking yard, I could hardly believe that I found one, I had been looking at every 720 and Hardbody truck with an H190 for years and I didn't really believe it was one, but I could not leave that yard without finding out, I truly believed that when I dropped it out it was going to be a welded up gearset, when I seen it I still didn't believe it was an H190 LSD until I installed it into the 620 axle housing across the row, H190 LSDs are very rare.

In my opinion unless you are going off road or dragging your truck down the drag strip having an LSD in your 720 is a waste of time and it can cause issues, I put that LSD I found in my 1969 Datsun 521 kingcab turbodiesel I made, when it is raining outside and I am making a left turn at an intersection I have to be very careful as if I give it too much pedal the back of the truck breaks lose and starts coming around on me, this has happened a bunch of times to me, especially since turbocharging the engine.

[datzenmike]

It was available '88 through '93 in the Hardbody 4 cylinder trucks. 38420-G7020 and $1,417 to buy from the dealer 20 years ago, a lot cheaper as an option. They are great for going straight ahead when traction is bad under one or both tires. The rest of the time it's a liability.  

[seattle smitty]

Wayno, I experienced what you described with a '79 Econoline 150 "Trailer Special" van, 351, C-6, and a 9" with Traction Lock.  Great for pulling a boat out of the water, but it wanted to swap ends on snow. But I attributed that to all the weight of a cast iron V-8 and dual batteries in the front, and not much load in back. My interest in limited slip for the 720 comes from years ago when I did some welding for a little logging crew out in the woods (different vehicle), and had to be towed up the "road" and into camp with a dozer.  But I suppose that stuff is long behind me.  So I'll settle for putting a loop for a come-along under my new bumper, when I get to that point.  Thanks, fellas.

Edited October 31, 2018 by seattle smitty

[Spiff]

I know it's an old thread but here's what I know:

 

H190 LSD's are rare, and expensive if you do find one.

C200 LSD's are also rare, at least for you guys, here in scandinavia most 720's sold where 4x4 with a c200 lsd rear end. We got lucky, you got screwed. However most 720's are scrapped now due to salt+winter=rust so finding a rear axle is increasingly difficult over here as well. 

BUT! Internally the c200 is the same as the independent rear suspension R200 diff found throughout most of Nissans RWD cars from 280z's to 240sx's. And since aftermarket lsd's and even factory lsd's are available for these diffs it means you can buy one and put it in your C200 axle. It means you can even swap gear ratios. The only issue would be the 10 vs 12 mm ring gear bolts that have to be adressed, either drilling out the carrier holes if using an older carrier with newer crown wheel or using spacers if using an older ring gear with a newer carrier. Not even an issue if you are using a complete setu mind you.

[G-Duax]

Not all R200 LSDs are the same.

They come with different spline counts for the axles.

I have personally handled 29, 30, and 31 spline LSDs.

 

Oh, and H190s are not so rare as one might think.

They were used in solid axle cars up until 2008.

But to use them in the truck, you have to add a spacer in the center for the axles to but up against.

 

Which might be the case on using the R200 in a truck C200.

You put an LSD out of a car, into a truck, there most likely be nothing in the LSD to hold the truck axles up tight against the outer axle bearings.

 

Not to mention the C200 ring gear flange is spaced differently than the R200.

Edited December 6, 2018 by G-Duax
Additional info showing that this will not work.

[metalmonkey47]

26 minutes ago, G-Duax said:

Not all R200 LSDs are the same.

They come with different spline counts for the axles.

 

Which might be the case on using the R200 in a truck C200.

You put an LSD out of a car, into a truck, there most likely be nothing in the LSD to hold the truck axles up tight against the outer axle bearings.

 

Not to mention the C200 ring gear flange is spaced differently than the R200.

This is VERY IMPORTANT. Even now, Nissan still uses the R200 in the 350Z, 370Z, G37, G35, FX35, etc. They are very different than the R200's that the Datsuns got, totally different ring gear offset and bolt pattern. Many people confuse them with the older R200 from the Z32 NA which was very different. 

The new Infiniti Q's use an R190.

IIRC, the R200 has a 200mm ring gear, that's where the name comes from.

[Spiff]

34 minutes ago, G-Duax said:

Not all R200 LSDs are the same.

They come with different spline counts for the axles.

I have personally handled 29, 30, and 31 spline LSDs. True. But most aftermarket that cater to the older cars with open diffs are 29 spline, 30 and 31 are newer and vlsd for the most I believe and also have different lenght axles?

 

Oh, and H190s are not so rare as one might think. No but h190's with lsd's are. Aren't they?

 

Not to mention the C200 ring gear flange is spaced differently than the R200.  When I compared my C200 clsd to my R200 open carrier they where both physically the same dimensions and spacing though?

 

[datrod]

I think I might have one here at my shop. I thought it was for a wagon but the wagon axle is to small. So I'm thinking it might be for a truck.

 

[G-Duax]

"True. But most aftermarket that cater to the older cars with open diffs are 29 spline, 30 and 31 are newer and vlsd for the most I believe and also have different lenght axles? "

No......

 

"No but h190's with lsd's are. Aren't they? "

I was speaking of LSDs.... A lot of Nissan Taxi cabs used H190s, and did in fact have an LSD in them. I've got one in my truck.

 

"When I compared my C200 clsd to my R200 open carrier they where both physically the same dimensions and spacing though? "

Not that I have ever seen, and I have imported both from Japan.

 

 

[datzenmike]

51 minutes ago, datrod said:

I think I might have one here at my shop. I thought it was for a wagon but the wagon axle is to small. So I'm thinking it might be for a truck.

 

 

H-190

Early truck H-190 differentials were 13 spline.

Cars (like the 510/610/810/Maxima goons) are 23 spline (with the exception of the '82-'84 200sx which are 29 spline) and trucks (520/521/620/720, D21) are 29.

[G-Duax]

The Cedric, Gloria wagons, and Taxis up to 08 are also 29 spline (Japan market).

My LSD is from a late taxi.