How to spot an R200

[dohc]

Hi All,

I'm pretty sure that this question has been asked before but I really can't find it, and I've searched through a good back log of threads!

How can I tell if a diff is an R200 or an R180?

I'm sitting looking at my parts car, a 1975 260z 2+2 and I seem to remember someone telling me that they all came with 3.90 R200's. Can anyone verify this??

Cheers,

Ross.

[Z Kid]

I too was told that all Aussie spec 260's 2+2 came out with an R200 rear diff, but i'm still not sure what the hell is lying on my shed floor taking up space.

[Mike]

Courtesy of Carl Beck:

About the R200 Differentials:

The R200 has a 200mm ring gear hence the designation (likewise the R180 has a 180mm ring gear). Nissan used this same differential although modified over time, in the Z Cars from 1975 through 1996. However some changes made to them during that period were minor and others of a more major nature.

The R200 of the first and second generation Z Cars (280Z/280ZX) were for the most part the same and are therefore interchangeable on a direct bolt in basis.

The R200 of the third generation Z's (84-89 300ZX) are also basically the same, but do have major differences that must be addressed, prior to retro fitting them to the earlier generations of Z Cars. The side output shafts (stub axles) have to be swapped with those of an R200 from the first or second generation cars.

What Is Different Among / Between The R200's ?

Ring Gear Bolts:

The 84 to 89 R200's used a ring gear bolted to the carrier with 12mm bolts vs. the 75-83 R200's which used 10mm bolts for that purpose. Thus the ring and pinion sets are not interchangeable between the two.

Stub Axles with Bolt on Flanges, CV Joints and Driveshaft Flanges:

Some of the R200's use stub axles (stub axles come out the side of the differential carrier) with bolt on flanges, which attach to the halfshafts (which Nissan calls driveshafts - side) that use universal joints. Some R200's use stub axles that are attached to CV Joints. You can pop the stub axles out of the differential carrier in each of these and swap them.

About Swapping-out The R180 In The 240Z - For An R200 LSD From A 300ZX.

You need the same mounting hardware described above. Plus you have to change the flanges and/or drive shaft input yoke.

The R200's used in the 84-89 300ZX Turbo were equipped with Clutch Type Limited Slip Differential Units. These rear end's are set up to run with CV joints. So to install one in your 240Z you have to remove the CV joint type stub axle and replace it with the stub axles with flanges that will match the flanges on your half shafts (what Nissan calls a "drive shaft -side" - we usually refer to as "half shafts"). This is a pull out/snap in operation.

The input flange is another story however. You either have to change your drive shaft yoke to match the input shaft on the differential, or you have to change the input shaft on the differential to match the yoke on your stock drive shaft. Most people suggest that this is a job for a professional rear end shop. Because the internal parts to the rear end have to be removed and then reinstalled. (not something you want to mess up on).

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What Gear Ratio Is In This Differential?

You do NOT have to count the teeth. Just turn the ring gear until you see two numbers separated by a slash ( / ) or colon ( : ). Simply divide the larger number by the smaller number and (tah dah!) you will have your final drive ratio.

If you can't remove the rear cover - then you have to turn the wheels and count the driveshaft turns to determine the rear gear ratio. Use this method.

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R200 - 3.9 gear sets: FYI, THE 3.9 (R200 ONLY) RATIO WAS OEM IN THE 2+2 M/T (FROM 8/79) AND 2-SEATER M/T 'J' MODEL (FROM 8/79). YOU CAN VERIFY A 'J' MODEL BY LOOKING AT THE MODEL ID #. AFTER THE "S130" THERE WILL BE THE LETTER "J". THE 280ZX MODELS EQUIPPED WITH AN R180 DIFF HAD EITHER 3.364 OR 3.545 GEARING. See Rear End Ratio Chart

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Speedo Gears:

3.3?? : Yellow

3.545 : Black

3.7 : Blue

3.9 : White

The following rear gear ratios were only available from Nissan Competition Dept. - not OE in any models sold in the US

4.11 : Red

4.375 : Purple?

[Rogersz]

I'm pretty sure all Aussie 260z's are R200's ,I have an aussie Nissan workshop manual and it only list's the R200. My car is an early 260Z 4/74 and it is a R200.

Cheers Roger

[sjcurtis]

I checked out a mates 260Z sport on the weekend and have posted it for sale on this site and it is 2/74 Australian complied vehicle with an open center R200, it has not been played with, it looks genuine factory on a very low Kilometre car. I believe the 4.1:1 ratio R200 open center came to Australia as the standard front diff in the 720series diesel 4X4. Another thing I heard on the week end was if you have an R200 open center diff and you replace it with an R200 LSD version then the two half shafts have to change positions for the installation IE: left to right side and right side to left.

steve :classic:

[spooge-au]

you can tell the difference between the R180 and R200 because I think the R180 has some hexagon thing on the side with 5 bolts in it or something along the lines the R200 doesn't, I am trying to find the article, I have just purchased a 260z 2 seater and own a 2 seater 260z also I will check if there is any difference in the morning

Check out the size difference between a R200 (left) and R180

http://www.zhome.com/rnt/L28conversion/Diff.jpg (not the picture i was after but best I could do)

Get the R-200 differential out of a junkyard '81-83 NON-turbo ZX . This will have a 3.90 ratio ('81-83 turbos had a 3.54) compared to the 3.36 in the 240 and 3.54 in the '75-78s. Some 280ZXs had a R180 rear like the 240Z, make sure you don't get one of those by mistake. Since the entire 280Z rear end will tranplant into a 240, offer them $100 for the whole rear-end and see if they bite. Talk about a wolf in wolf's clothing. Grab these parts:

[sjcurtis]

Ijust grabed my 82 print of the s30 body manual, looking at the PD section of the manual it states that manual cars have 3.7 R200 and autos have 3.545 R200 diffs. I have attached the schematic of the R200 take note of the extra size, strengthening ribs on the fwd section, and the large rear raised attach pad for the rear mount bracket R180 does not have this feature, also from the rear the R200 housing normally appears oval when compared to the R180.

Steve

[Pennyman]

The input flange is another story however. You either have to change your drive shaft yoke to match the input shaft on the differential, or you have to change the input shaft on the differential to match the yoke on your stock drive shaft.

So would it be easier to get an aftermarket LSD pumpkin from a 240sx (ready available now) and swap that into your R200 case (you'd just have to make spacers to fill the gap from the 12mm bolts to the 10mm)? Would the ouput shafts from the old R200 work on the new Pumpkin? (I.E. number of splines and length of shafts). I'm kinda tired of looking for a Z31 LSD and there are many aftermarket 240sx LSD's around...Help?

[Walter Moore]

"LSD pumpkin"?

Didn't they have those at Woodstock?

I wasn't there, but I saw the movie. ;-)

[Mr Camouflage]

Hi All,

I'm pretty sure that this question has been asked before but I really can't find it, and I've searched through a good back log of threads!

How can I tell if a diff is an R200 or an R180?

Ross.

An R200 is a whole lot bigger and rounder than a R180. The R180 has a farily flat rear plate and the R200 is much rounder

R200 Left R180 Right

R200:

[Pennyman]

"LSD pumpkin"?

You know what I mean. One of these:

Anyway, so again a question: Any idea whether the halfshafts out of an old R200 will fit into the input slots on an LSD unit like this one? (if the LSD is for a 240sx with the "short-nose" version of the R200)