mditt8671 Posted February 6, 2013 Share Posted February 6, 2013 OK I've been reading all night about the STI R180 differential swap. I'm rebuilding the SBC in my 1971 240Z to make up to 400hp. I initially thought I definitely needed to swap my stock R180 with an R200, but the Subaru option is very tempting due to the simplicity of the swap as well as using a more modern and more available differential. Also, my research has led me to the CLSD diff, and the R200 isn't all that easy to find, especially in the 3.54 ratio. What I wasn't able to find was how much stronger the STI R180 would be versus the R180 that came stock on the 240Z, and how much better the R200 CLSD would be compared to the STI R180. Any insight would be appreciated! Quote Link to comment Share on other sites More sharing options...
raven12 Posted February 6, 2013 Share Posted February 6, 2013 Watching. I am a bit curious on the STI r180 vs the r200. Quote Link to comment Share on other sites More sharing options...
RebekahsZ Posted February 6, 2013 Share Posted February 6, 2013 When you say "stronger"..... I don't know of anyone who has broken a ring gear, pinion, or case on any of these diffs. The weakest part of the diffs is the spider gears and the cross shafts. That's what breaks. Read the FAQs at the top of the forums page and pursue one of the diffs that has four spider gears instead of just two. I have had all of the diffs you mentioned. And I haven't broken any. But I feel most confident with my R200 CLSD. I just met a guy who is spraying a 260z into the 9s on an open 2-spider gear R200 but he has an auto trans which is infinitely more gentle on the diff and axles. I have seen lots of guys at the track with open R180s and rusty greasless 40-year-old stock axles-but i dont see them out there often. You can probably get away with anything for a while. I think your killers of any diff are one wheel tire spin and wheel hop. We drag racers are going in a straight line trying not to spin. Those of us who hammer the car often are most likely to break just from repeated exposure. Quality parts, prep, inspection,quality hardware and frequent use of a torque wrench are your best bet everytime. Quote Link to comment Share on other sites More sharing options...
mditt8671 Posted February 6, 2013 Author Share Posted February 6, 2013 OK I did more reading and it seems that though I wouldn't likely break the STI diff, I would still be somewhat limited with the weaker 240Z hardware surrounding it. I don't foresee myself doing much drag racing, if at all, but I'd rather not risk weak spots in my build if I can help it. It appears that for about the same $$ as the STI diff and the betamotorsports adapters (about $1k), I could go with a cheaper open diff R200 in the ratio I want, put in an OBX center and buy all the required parts to install in my Z. Am I on the right track? I'm very new at this but I'm soaking in as much as I can here. Quote Link to comment Share on other sites More sharing options...
BluDestiny Posted February 6, 2013 Share Posted February 6, 2013 You'd probably be better off just welding the R200 because the obx lsd's have geven other people problems. Also a 3.54 r200 are quite easy to find. Turbo 280zx's had them. Quote Link to comment Share on other sites More sharing options...
mditt8671 Posted February 6, 2013 Author Share Posted February 6, 2013 Although my car isn't going to be a daily driver per se, it will see a LOT more street time than any other type of driving (probably 95%), so I don't think a welded diff would make sense for me. Quote Link to comment Share on other sites More sharing options...
johnc Posted February 6, 2013 Share Posted February 6, 2013 The single best thing you can do for the handling of you car is to install a LSD of some kind, so you're on the right track. Either the OBX diff or finding a used CLSD for your R200 are the cheapest options available. If you go thorugh the OBX unit per the thread in the Driveline FAQ you should be OK. Quote Link to comment Share on other sites More sharing options...
mditt8671 Posted February 6, 2013 Author Share Posted February 6, 2013 Thanks John, From what I've read, there should be no problem buying a longnose open diff R200 and replacing the center with the OBX, correct? Quote Link to comment Share on other sites More sharing options...
johnc Posted February 6, 2013 Share Posted February 6, 2013 ....there should be no problem.... That's funny! "Bolt-on" means you need a $5,000 lathe and $10,000 mill to bolt it on. Of course your'e gong to encounter a problem. Accept it. 1 Quote Link to comment Share on other sites More sharing options...
mditt8671 Posted February 6, 2013 Author Share Posted February 6, 2013 Ha, I know I'm always going to run into something and there will be issues. I accepted that well before I even got this Z in my garage. I don't have a lathe or a mill, just basic tools and a welder so I hope it's not THAT bad. Just trying to reaffirm my shopping list so I don't end up with a bunch of expensive paperweights. Quote Link to comment Share on other sites More sharing options...
galderdi Posted February 7, 2013 Share Posted February 7, 2013 I have had the STI R180 diff in my car with the input adaptors for 3 years now with no issues. I would recommend that option for anyone with any zed except those with significantly high Horse Power and torque combinations (Eg 300HP plus). I orginally tried an R200 but its amazing how noticable the extra weight is. I also tried a Detroit locker which was OK but I didn't like the idea of having to replace the diff oil every 3 months. So the STI diff went in. Plus now that I have it set up if the diff does ever give up I can easily replace it and reuse the other hardware. The subi diffs benefit from an extra 30 years of evolution/learning and suffer less because they have 30 years less wear. Quote Link to comment Share on other sites More sharing options...
RebekahsZ Posted February 7, 2013 Share Posted February 7, 2013 (edited) Ditto on the Subi diff. I had one and loved it. johnc's adapters are awesome and you can get a "new" diff in your car straight away. I didn't break mine. I did a season of dragging with the L24 and drag radials on it, then did 1 night at the drags with my LS2 spinning a bunch on street tires. It was fine and wasn't whining or anything. I really just swapped it to an R200 in order to get set up with the Z31 axles. And I really only swapped to them from Wolf Creek axles in order to simplify my hardware. I have no idea how many miles the old R200s have on them, but so far it hasn't mattered. The Z31 axles have 4 bolts per side. That is 4 less than stock axles and 16 less than wolf creek (per side)! I just didn't want to have to keep all that hardware inspected and torqued. Plus 8 of the bolts were hidden from view in the Wolf Creek system, so they couldn't be inspected without tearing the whole thing down. I see more reports of broken axles than broken diffs. After a day at the drags, with stock axles, my 4 stub axle nuts (near the hub) ALWAYS needed retorquing. wfritts911 lost an axle to loose hardware and so did mnoel. wfritts on a stock axle and mnoel on a Wolf Creek. Plus it doesn't help that all the the different axle bolts require a crow's foot on your torque wrench, rather than a socket, so I'm always afraid I'm gonna slip off and goof the nut or bolt head all up. If anybody has another way to torque Z31 axles I'd love a tip for it. If you would consider an R200 VLSD-I have one I would part with (axles included) because it needs a good cleaning and a competent inspection. PM me if interested. Edited February 7, 2013 by RebekahsZ Quote Link to comment Share on other sites More sharing options...
mditt8671 Posted February 9, 2013 Author Share Posted February 9, 2013 I guess what I'm worried about, is what exactly IS considered high horsepower?? My plans were to modify my SBC according to this guide. With the part numbers supplied, etc., it's pretty much a recipe to get up around 350hp or so. I am guessing that the Subaru diff probably wouldn't be ideal for that much horsepower? I'm not going to be drag racing it much at all, maybe a few times to see how it does, but I'm also not building this car to baby it either. Quote Link to comment Share on other sites More sharing options...
BluDestiny Posted February 9, 2013 Share Posted February 9, 2013 Its not a matter of hp, its a matter of shock to the system, how you drive your car, and what you use your car for. I know guys that run 400-500hp Z's and have had a welded diff in their car for years, I've also heard of people going to the track for the first time and blowing out their diff and axles after a few goes. Quote Link to comment Share on other sites More sharing options...
RebekahsZ Posted February 10, 2013 Share Posted February 10, 2013 Try not to torture yourself about the diff. Get the motor done, then sweat the details. Worst thing that can happen is to break. Quote Link to comment Share on other sites More sharing options...
galderdi Posted February 10, 2013 Share Posted February 10, 2013 Yeah ditto on both those last two points. If you are already set to go with an R180 then continue on that path and see how you go. From what you are saying I suspect you'll be fine. Quote Link to comment Share on other sites More sharing options...
mditt8671 Posted February 11, 2013 Author Share Posted February 11, 2013 I get what you're saying... but it's hard for me to leave it alone, because I know I'm going to be building up the engine while it's out. It has a Muncie 4 speed in it now and I really want to find a T56 to put in it as well... I am going over it and fixing up all the rust, everywhere, new floor pans, etc etc... I just want to do it once, RIGHT, when it's disassembled like this. I'm in no real rush to get it done, I'm really enjoying learning about stuff I had NO CLUE about a year or two ago and am just enjoying the whole process. I'm of the "Buy once, cry once" mentality. Quote Link to comment Share on other sites More sharing options...
galderdi Posted February 11, 2013 Share Posted February 11, 2013 Sure, thats sensible. But look at it this way. The diffs can be converted in a couple of hours (assuming you have all the components) with no need to touch the engine or gearbox. So there is nothing lost by sticking with what ever you currently have. I still think the STI R180 is the way to go. Quote Link to comment Share on other sites More sharing options...
mditt8671 Posted February 11, 2013 Author Share Posted February 11, 2013 I see. I thought it would be a little more involved than that, so maybe I will hold off on that and keep my eyes open for a good deal... if I find one, I'll jump on it. If not, I'll run the R180 for a bit and just keep looking for the right opportunity. So you think a 350-400 hp engine should be OK with the STI R180 then? I guess I'll be watching for the next round of adapters... Quote Link to comment Share on other sites More sharing options...
RebekahsZ Posted February 11, 2013 Share Posted February 11, 2013 You know, I never get past 4th gear on the track. I use 3rd on the 1/8 and 4th on the 1/4. Only use 2nd at autocross. Summer is coming-get that thing on the road! If you are worried about doing it once-that is a pipe dream. You are gonna break stuff and you are gonna want to make changes over the years. If I were you, I would not let the car go into the spring still on jackstands. Drive it! I build everything with the thought in mind: "I'm gonna have to take this apart again." 1 Quote Link to comment Share on other sites More sharing options...
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