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Discussion Starter · #1 ·
I installed a lsd rearend from an '88 300zxt(viscous type) in my 83 n/a 280zx 2+2. today. It took about 6 hours & went very well. I 1st took off the rear wheels & brakes, then I took the half shafts out, then the drive line after draining the tranny (manual 5 speed) & open differential. The old 3.9 rear end came out easily-I used my floor jack to lower it. I changed the drive shaft attachments & also the rear attaching stuff that is bolted onto the rear diff. housing. Then I did the reverse of the above.

The car is noticebly "zippier"- the lsd is a 3.7 vs the original 3.9. My engine RPM power/torque range seems to be 500-750 RPMs lower than before & it seem quite a bit quicker off the line. haven't been on the freeway yet. Beings as I mostly drive around town-alot-I'm real pleased so far. My next project is to put a rebuilt turbo engine & related parts into the car. the engine is in an 81 ZXT coupe I picked up for a couple hundred bucks-It's just sitting in my driveway yelling at me to hurry up and get to it!
 

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Discussion Starter · #2 ·
<b>Are you sure it's viscous</b>

Doug are you sure it is a viscous type, did you use silicon fluid . The 88 is the right year did the 300 have all white mags and white pearl paint . I have heard that you can not do this swap because the halfshafts do not lock into the snap rings. Please write back with more details there is an 88 SE burned up right next door to me . Then I'll switch from clutch to viscous and let you guys know the difference .
 

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RE: Are you sure it's viscous

I've had a viscous rear before and the snap rings wouldn't snap because the standard halfshafts wouldn't fit all the way into the rear. maybe you used the halfshafts from the 88 car? Even though I thought they were too long, they may work in a zx due to the wider rear end than a earlier Z. Though it's too late for you to tell without taking the rear or at least the cover off, here's how I identify the types of rears externally.

look into the holes where the halfshafts fit. If you can see all the way through to the other side unobstructed then it is a clutch type LSD. If you can see all the way through to the other side, but there is what looks like a washer/thrust button in the center, then it is a viscous LSD. Viscous LSD's also have a sticker by the filler saying so, but it may be gone, of course. A standard rear has the rod that holds the spider gears blocking your view. It has also been my experience, somewhat limited, that all LSD rears (both types) have aluminum finned rear covers. I have not seen otherwise, but someone on the Z mailing list (Ross C?) said that all LSD rears have finned covers, but not all finned covers are LSD's.

I'd be interested to know how the viscous rear was made to work since I had to sell one I had at a sight loss since I couldn't get it to work in my 240.
greg
71 240z
 

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Discussion Starter · #4 ·
RE: Are the lcutch types a direct bolt in 83t?

I would like to replace my rear with an LSD rear. I would like to have a numerically lower gear than I have now. Stock is supposed to be 3.54. My cars first and second gears wind out way too quick for my liking. Third and on is fine.
 

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RE: Are the lcutch types a direct bolt in 83t?

Opie83zxt wrote:
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I would like to replace my rear with an LSD rear. I would like to have a numerically lower gear than I have now. Stock is supposed to be 3.54. My cars first and second gears wind out way too quick for my liking. Third and on is fine.


Yes they bolt in fairly easy, but only available in 3.7 and 3.9 ratios. They also have a oddball bolt size that prevents swapping in standard gear sets. I'd like to do more research on this as I want a gear better suited to a turbo car myself.
greg
71 240z
 

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Discussion Starter · #6 ·
RE: Are you sure it's viscous

In response to Clint's & Greg's posts-

I got the differential through a local wrecking yard, but it came out of another state so I never saw anything of the 300zx it came out of. The guy at the local Nissan Dealership's parts dept. told me only turbo's had the lsd. He also told me that according to the pictures on his micrfiche of both the viscous & clutch lsd's out of '88 300zx's, the clutch type would have a bunch of springs(7?) around the center portion of where the half shafts go into and the viscous would not (looking at the innards after removing the rear cover plate). Mine didn't have any springs, just a pretty good sized cylinder thingy that had another cylinder inside of it. Going on that information I figured it was a viscous lsd.

I used the half shafts from my 280zx & they went in about like they did in the stock differential-a couple of tries and they went right in all the way no problem.

I could look all the way through the lsd when looking into where the half shafts go- I don't think there was any washer/thrust button in the center. The rear case cover does have fins and was longer to the rear on the bottom portion, allowing for more of a fluid capacity. There was plenty of room on my car for this-I wonder if that would be the case on a coupe.

I used mobil 1 synthetic gear lube-75-?weight.
thanks for your replies!
 

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Discussion Starter · #7 ·
<b>RE: Are you sure it's viscous</b>

You have a clutch type limited slip, the viscous is a rare find . The viscous must use silicone fluid to heat up and provided locking between wheel . There are no visable springs in the clutch LSD just the carrier which blocks the view of all the clutches .
 
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