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R180 Differential

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  • R180 Differential

    Hey everyone. Today I bought a Tomei Tech Trax lsd off craigslist, guy I picked it up from had it in his s13 over in Japan. First thing I notice is that it's longer than the standard r200 by .75 inches, so I think no big deal it's the same length as j30 diffs, when I get a one piece ds I'll get an abs one and it will be fine. The pumpkin also looked a little different, but since the guy had it in an s13 I went ahead and bought it anyway, I figured worse comes to worse I'll swap the guts into my pumpkin. I get back to my place with it and take the rear cover off, turns out I can't just swap the internals over. The ring gear is held on with 8 bolts vs the 10 inside the stock diff, and the output shafts are different. After measuring I notice the whole width from output shaft to output shaft is 1" shorter than the stock diff. I called the guy up and asked him what the diff was really from, apparently he wasn't lying and NA SR's came with this diff from the factory, the reason he used it was because it has a 4.36 final drive. Did some digging, found out that the s13 rear subframe has two sets of diff bolt holes because the r180 was indeed stock on the s13 at one point. So at this point I'm left with some options, and I'd like to hear other's opinions.

    1. Sell the diff and continue looking for an r200 compatible 2-way.
    2. Bolt the diff in as-is.
    3. Make axle spacers to account for the width difference.

    I've been looking for a 2-way for a while and I got this for a steal, so while selling it wouldn't be the end of the world I don't really feel like continuing my search.

    Option 2 isn't going to happen, but this diff was factory in some s13s...there weren't any differences in axles though, were there? Are there people out there running this diff that don't realize it?

    My car is pretty low, and I've heard of people blowing out axles due to the CV joints being stretched. I've already drawn up spacers in Solidworks, I just need to get the material and machine them.

    Basically is it worth the time and effort to run this diff? I'm a little concerned about the taller final drive, but I guess my car sees more track time than anything else these days so it wouldn't be too bad. Is the r160 as bulletproof as the r200?

    Here are some pictures of the differences.

  • #2
    So it will bolt in but you have to use axle spacers correct ? Why not give it a shot if thats the case.
    SM 63 KA-t 470hp 480tq G30-660 A2W IC


    • #3
      What's the weight difference between the R180 and R200?

      I don't see the R180 being a reliability problem below about 400 rwhp or so. The R200 is way overkill for 99.999% of the S chassis out there.
      '18 Chevrolet Volt - Electric fun hatch for DD duty!

      DefSport Koni Sleeve and Spring Perch Buy!!!


      • #4
        Originally posted by Scores240 View Post
        So it will bolt in but you have to use axle spacers correct ? Why not give it a shot if thats the case.
        Technically it should bolt in without the spacers, I wouldn't feel comfortable without them though. I'll measure from the mounting points to the output flanges, it's possible that this diff is centered on the subframe and I could use the longer axle on both sides.

        Def, it's definitely lighter than the r200. The main thing I'm bummed about is the different ring gear. If I upgrade transmissions in the future I won't be able to change the final drive unless I find an 8 bolt ring gear.


        • #5
          Some more info in case anyone researches this in the future. Stock gearing in this diff is 4.36. '77 and later r180's used a 115mm ring gear, so for s chassis it's going to be all 115mm but some Z cars might be different. '83 and '84 automatic Maxima sedans had r180's with 3.36 gearing, and it seems like Xterra's had a range of gearing from high 3's to low 5's.

          I'll update with more info when I install it. It might turn out that one axle lines up perfectly and the other is off by the full amount, it all depends on where the diff sits in the subframe. You can see in this picture the 6 holes where the diff mounts, the r180 is perfectly centered whereas the r200 uses the wider bolt holes.


          • #6
            The r180 came out of the silvia Q (the na version) and you are correct the axles are different. Also the later r180's you mention have a K stamped on them fyi.


            • #7
              Update: Installed the diff this afternoon, ran into some issues. My driver's side axle started clicking so in preparation for installing this diff I bought a passenger side axle since it's longer.

              Turns out the passenger axle is too long, I can't line up the diff with the subframe because the axle pushes it to the right. I put the stock axle back in to see how much longer of an axle I need, looks like I need an axle about 3/4" longer than stock. I've found conflicting information about the length of s14 axles, I'm wondering if I can get an s14 driver's side will it be longer than the stock s13 driver's side? Here's a picture of the diff with the stock axle in.


              • #8
                Where do you live? I have r180 axles if you are interested. Shipping might be high though as I am in Vancouver (canada).


                • #9
                  I'm in NC. I'm using a new stock axle, haven't had any problems so far. First track day with this diff is in a few days, hopefully it doesn't give me any trouble.


                  • #10
                    you have one of the first s13 diffs, that were residual leftover from the s12 chassis. essential early 1988 production cars I have a early 1989 production s13 and mine has the r200 diff. you might want to look into s12 axles. also to note. subaru uses r180 diffs as well. so you might want to search around if they use 8-bolt ring and pinions.