johnc Posted June 29, 2012 Share Posted June 29, 2012 Am I missing something obvious where the z31 diff is better at something than the aftermarket units? My experience is limited to factory units on other cars I've messed with, never aftermarket diffs, so I very well might be missing something silly. A new 2 way KAAZ unit is about $950. A new 1.5 way Cusco unit is about $1,200. Those are the cheapest new aftermarket units for the R200, other then the OBX. That price is just for the differential and does not include the ring and pinion and housing which you get with most of the used Z31 R200 LSD purchases. Quote Link to comment Share on other sites More sharing options...
letitsnow Posted June 29, 2012 Author Share Posted June 29, 2012 Thanks, I wasn't sure if there was another reason besides cost. I don't want the ring and pinion that comes with the z31 diff, I have a spare 3.54 R200 that I would rather put the carrier in, I feel 3.70 is a poor choice for this engine setup. Quote Link to comment Share on other sites More sharing options...
kaito Posted June 29, 2012 Share Posted June 29, 2012 Ive been reading up on the z31 clsd swap and it really looks like you would have to have custom length halfshafts made unless you want to chance messing up the diff. I looked into the 280zxt cvs, the z31 n/a units which apparently are just 280zxt units, as well as the 87.5-89 units that seem to be the stronger of them all. If you got a good deal on the unit with cvs and dont have a lowered s30 you can probably get away with the mods you have to do to fit them. As for the cv adapters, you can make them yourself if you have a welder and alittle know-how. Good luck though. Quote Link to comment Share on other sites More sharing options...
letitsnow Posted June 29, 2012 Author Share Posted June 29, 2012 I was planning on keeping the stock axles for now. Quote Link to comment Share on other sites More sharing options...
KROz Posted June 30, 2012 Share Posted June 30, 2012 I bought a Tomei CLSD for like 850 shipped. I haven't installed it yet but it smells wonderful! That's another option for you. Quote Link to comment Share on other sites More sharing options...
2802NR Posted July 2, 2012 Share Posted July 2, 2012 I was attempting a final install of my OBX today, till I had minor binding on one side of the ring gear and backlash on the other. Put a dial indicator on it, in a few different planes, the machined surface that the ring gear sits on appears to be running out at an angle with about .009 sweep. Once I get a bearing separator we plan on pulling the side bearings, chucking it in my friends lathe. Then we can zero it in and make sure that's the problem before a fix 'er finish pass is cut. I was a big fan of the OBX, bought a spring washer & bolt kit, reversed the direction of it, (mine was backwards) got the ring gear bolt spacers, I'm pretty damn confident that it was assembled clean and correct, followed the FSM, all that. Once I chuck it up I'll know for sure but I'm loosing hope for this thing and I haven't even laid two black strips of rubber yet. Sure, I don't have $1200 for a quaffie either but at that price I doubt a unit like mine would have ever made it past the machinist work bench, let alone the quality control guy. Updates in a week I hope Quote Link to comment Share on other sites More sharing options...
letitsnow Posted July 2, 2012 Author Share Posted July 2, 2012 I finally found a z31 diff that I feel is fairly priced for the miles, so I'm buying it. I was afraid of runout issues with the OBX and in the end couldn't talk myself into rolling the dice. Now I need to find a mustache bar, r200 output shafts, and figure out what to do with the driveshaft. My 280z was unlucky enough to come with an r180 because it was an automatic. Quote Link to comment Share on other sites More sharing options...
roger280zx Posted July 2, 2012 Share Posted July 2, 2012 Ive been reading up on the z31 clsd swap and it really looks like you would have to have custom length halfshafts made unless you want to chance messing up the diff. I looked into the 280zxt cvs, the z31 n/a units which apparently are just 280zxt units, as well as the 87.5-89 units that seem to be the stronger of them all. If you got a good deal on the unit with cvs and dont have a lowered s30 you can probably get away with the mods you have to do to fit them. As for the cv adapters, you can make them yourself if you have a welder and alittle know-how. Good luck though. -You're so right, there has never been a successful zxt lsd swap into an s30 with out one-off axles. Good observation. Can we get back on topic and have some real world experiece with the obx, please. I also read internet threads both for and against obx reliability and functionality they all seem to point out the importance of setup. Questions like "condition of diff prior install" and "previos experience setting up/tuning with obx diffs" I feel are some of the important ones. The Honda croud loves these things, and they also have an expensive factory JDM option, but tons of guys run obx's because they are cheap, plentiful, and the set-ups well documented. I'd love to be able to say the same for the r200, unfortunatly at this point I can not. Quote Link to comment Share on other sites More sharing options...
2802NR Posted July 8, 2012 Share Posted July 8, 2012 Got the OBX in the lathe today. Chucked on one side with a steady rest on the other, as zeroed in as it would get (the case half's weren't concentric either, about .002 thou out) and sure enough, about .0085-.0090 runout. Spent most of the afternoon shaving down the ring gear mating surface, that stuff gets pretty work hardened from the grinding process when manufactured. Anyone have any idea what material the case on these are cast out of? The chips kinda resembled magnesium the way they kept burning. Anyway, got it nice and straight, Bolted the ring gear back on, set it in the case, got it down too .002, most likely still the case halfs playing a big roll in this runout but it's barely within the FSM tolerance. The backlash represents this number also, measured anywhere between .0050 and .0071 at many points around the ring gear. The wipe pattern looks good, right in the center of the gear, where they ran for many years. I'm gonna go ahead and run this diff as it sits and see what happens. its barely within spec so it should be good enough for a street car. If any problems arise this group will be the first to know. Quote Link to comment Share on other sites More sharing options...
letitsnow Posted July 9, 2012 Author Share Posted July 9, 2012 There are two different things going on here: adding clutches to a 300ZXT diff, and shimming. Adding clutches will allow the CLSD to hold down more power and also make it more aggressive. Shimming makes the breakaway torque tighter. Adding the clutches is a very good idea. Shimming is probably not necessary for most people and will make the diff more likely to chatter. I know I started this thread regarding picking out an LSD, but now that I bought a z31 diff, I have a few questions about adding clutches and shimming. I don't have the diff in hand yet, and I'll probably put it in as is for now and add clutches/shim over the winter. From what I read in the FAQ, when adding clutches we add them outside of the 2 plates, my question is on the outside wear surfaces of the clutches we add. One of the 'new' wear surfaces is the spring plate, and the other is the center piece. Are there any issues with the clutch wearing on the spring, such as uneven wear or spring wear? What about on the center piece, could the clutch wear that out?(I'm assuming that the center turns with the plates) Quote Link to comment Share on other sites More sharing options...
kaito Posted July 9, 2012 Share Posted July 9, 2012 Mine feels pretty good BUT I just installed it and it clunks. I havent investigated the cause yet but I feel it is due to improper lash. I set it up according to the fsm and it felt tight before it was run but now there is a lot of slack in the driveline, If I shift my car into gear with the clutch pedal depressed it will clunk. (enter sadface here) Other than the clunk though, it acts very good, two wheel burnouts, normal low speed turning, but it seems to induce a bit of understeer when engaging. It is a MUCH more mild engagement than my welded diff. BTW I hated that welded diff. All in all it is worth the money if you are willing to put in the extra effort that money didnt and pull it out and reinspect if things arent quite right. Quote Link to comment Share on other sites More sharing options...
2802NR Posted July 22, 2012 Share Posted July 22, 2012 Happy to report my diff is operating flawlessly. After a couple hundred miles and a full day of track abuse, all is well inside the rear end. I also wanted to note that my u-joint stub axles don't rub at all when I lift the throttle thanks to the removal of the dust shields and a little clearance work on the case, no internal spacer is needed. Quote Link to comment Share on other sites More sharing options...
GOTHALOSISM Posted July 27, 2012 Share Posted July 27, 2012 Makes me want to upgrade to an OBX now. If I do I'll have to find a shop to do it for me though since I have no access to machining tools. Quote Link to comment Share on other sites More sharing options...
letitsnow Posted July 27, 2012 Author Share Posted July 27, 2012 Most diff/tranny places won't be able to correct machining flaws if you get a bad one. Quote Link to comment Share on other sites More sharing options...
GOTHALOSISM Posted July 27, 2012 Share Posted July 27, 2012 I do have a friend that has acess to a waterjet and cnc machine if needed. Quote Link to comment Share on other sites More sharing options...
2802NR Posted July 30, 2012 Share Posted July 30, 2012 If I had bought it from OBX I would have sent it back but I thought I was getting a screaming deal buying a new in box one for $25 less. the things we do to save money. . . I must say as far as on track use goes, all the work and money into my LSD was well worth it. Throttle induced slip angle is a beautiful thing. Pushin a little too hard towards that curbing?? giver moar GASS!! Quote Link to comment Share on other sites More sharing options...
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