how can i determine if the rear differential is positraction or lsd

Asked by Jan 15, 2008 at 05:24 PM about the 1978 Nissan 280ZX

Question type: Car Customization

I currentky own a 78 280z and would like to source a 1988 300zx positraction rear differential for it but i would like to know how to determine if the differential i'm considering is posi or lsd

10 Answers


easy way is to jack the car up, turn a wheel and look at the other one. If it turns the same way, (I beleive) you have posi, if the wheel turns the other way you have a floating diff. hope this helps


Yes, you can also check the axle code on the door information sticker with the tire info, or have a dealer decode your VIN for you at no charge.


dont look too hard for a posi diff from an 88 300zx because they only came with a clutch type lsd, and no an lsd will spin both tires the same way, an open one wheel wonder diff will spin them opposite


Nissan was very good about identifying what was contained in the differential by indicating so on the differential housing. The 1988 differential was coded R200 (200mm ring gear). If it had a factory LSD then it would be stamped on the housing. If so then the LSD was a clutch type LSD. I believe the Z31's also had a LSD badge on the rear if the car came with an LSD. There was never a locking-type factory differential on any of the Z-cars. For added info the Z32 300ZX's had an R200 with open diff in N/A trim and the Twin Turbos had the R230 with a viscous-type LSD.

2 people found this helpful.

FYI posi and lsd are the same thing. posi is what dodge called a limited stip in the 60's


Great answers by everyone else, another quick way to check... if the diffrential has a finned cover it has the clutch type LSD. Years: 1987-1989 300zx Turbo - Clutch type LSD 1988 300zx Shiro Edition - Viscous type LSD


just get in ur car and take a corner on the gas and see if u chirp of slide if it does this it's posi


Hi: Don't know if you can help me or not, but I thought perhaps you might be able to. I have a 93 300zx NT. I love the car except on the highway, at 80mph my tach is at about 3800rpm (Not only that - but my 1st gear is a complete waste of a gear 0-5mph isn't good for much.) Do you know is this normal (seems high) - and is it possible to change the differential and lower it to say 2600? I am not at all concerned with racing this car - I just enjoy driving it. Lowering the rpm's would make it quieter and more fuel efficient. If not. do you have any ideas as to where or who to ask? Any help is greatly appreciated. THank you, Dan Simon

1 people found this helpful.

Z31 Turbos manufactured 4/87 and later have clutch-type LSD's. The special edition 1988 Shiro has a viscous type limited slip. All other Z31's have open differentials. Typically you can identify a LSD externally by it's finned cover. See uploaded picture.

3 people found this helpful.

lsd has fins, just look, if no fins, no lsd

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