6inline Posted April 14, 2014 Share Posted April 14, 2014 I'm building a N/A L28 for my 72 240z. My actual need is not much horsepower, something around 200-230hp. Just something to have fun. I should tell you that I may not be a burnout guy but I enjoy a lot donuts and drift. I do lapping on weekend and the car will be almost a dayli as well. So some say you need a R200 others say you don't if not turbo etc etc.. The sure thing is I will go lsd sooner or later. For now I'm staying with the original 4 speed but I might change my mind. I've read a lot about diff ratio to, 3.9 seems to be the most popular. (if I need to change) Quote Link to comment Share on other sites More sharing options...
duragg Posted April 14, 2014 Share Posted April 14, 2014 What you want is LSD. For me that came in the form of an R200 so I ran with it. R180 is lighter by a fair bit. I think either can take a lot of abuse. 3.90 is fine. You need to keep your eyes on tire diameter. There is an online calculator to help figure all that out. Quote Link to comment Share on other sites More sharing options...
helghast7 Posted April 14, 2014 Share Posted April 14, 2014 The same question I've been pondering. Long nose r200's are getting harder to find and long nose r180's with lsd off of older sti's are becoming more easily attained. My only personal dilemma is I'm intending on running an RB25 and top off around 450-500hp, nobodys been able to confirm nor deny if the sti diffs can handle that kind of power reliably and I'm not in the business of doing things twice if it can be helped. Quote Link to comment Share on other sites More sharing options...
NewZed Posted April 14, 2014 Share Posted April 14, 2014 The axles seem to be the weak link. There are more stories of broken axles than broken diffs around the Z interweb world. If you're going to drift with over-inflated slippery tires then the diff's probably not a concern, except that you'll want LSD. If you're going to drag race, then the hooking is the diff killer. The road racers like the LSD for drive out of the corners. It comes down to what you're planning to do with it. A horsepower number is just a number. To the OP, don't forget that your 72 4 speed has a 3.592 first gear and no 5th. The 3.9 was typically used with a 3.062 1st and a 5th. 1 Quote Link to comment Share on other sites More sharing options...
joker81 Posted April 14, 2014 Share Posted April 14, 2014 They also sell LSD conversion units that fit into the R180....That might be a very good option to consider. The unit is around $350 if I remember correctly... Quote Link to comment Share on other sites More sharing options...
seattlejester Posted April 14, 2014 Share Posted April 14, 2014 My friend used to work at a subaru performance shop, so I've actually asked around about hp/torque limitations of the subaru r180. The consensus was that even the 6xx hp cars were running the stock differential, but the power was of course being split to all 4 wheels. The shop owner seemed to think that it wasn't a part that needed upgrading in subaru applications other then maybe a cooler/finned cover for most builds. There was actually some talk about taking the R200 from our Z cars for those who were thinking of drag racing or running a lot of rear bias on the forums, but who knows if that was just bench racing. The roadkill rotsun is pushing over 350hp and 400tq if memory serves through it's wrx differential. Some of the local 510 guys say they put 300-400 daily through theirs. I also think the halfshafts/stub axles are the weak points. With the stub axles breaking being a lot more of a concern then the half shaft. A broken halfshaft may be bad, but a broken stub axle will mean you loose a wheel. Keep in mind converting to a subaru diff is still a pricey task, either conversion stubs or running a custom cv axle conversion. If drifting is going to be an activity you are more limited in your differential choices, I've been told the viscous units will over heat and not lock the wheels as efficiently with longer sessions, so at that point an aggressive clutch style or a welded diff would be preferable. Living with either is going to be a chirping nightmare. Quote Link to comment Share on other sites More sharing options...
johnc Posted April 14, 2014 Share Posted April 14, 2014 If the diff has an LSD and the tires are spinning, then the diff is not working hard. A R180 in a road race application is limited to around 300 ft. lbs. of torque. And at that level you need an oil cooler. I know of a number of road racing STis running under 400hp who cooked their R180s. That's with real sticky race slicks in a 3,100 lb. car. Again, spinning tires means the diff isn't working hard. Quote Link to comment Share on other sites More sharing options...
6inline Posted April 14, 2014 Author Share Posted April 14, 2014 Well you answer my question, r180 should be fine if I do not dumb the cluch to often.. Joker81, you're point is interesting. I will look for that. Do you have any suggestion? Quote Link to comment Share on other sites More sharing options...
helghast7 Posted April 15, 2014 Share Posted April 15, 2014 What John said is exactly what I was worried about, guess I'll stick with an r200. Quote Link to comment Share on other sites More sharing options...
roger280zx Posted May 5, 2014 Share Posted May 5, 2014 Subaru r160's are readily available in 3.54, 3.9, 4.44 and lsd is not that hard to find. They are stronger than an American Z car r180, significantly lighter than a 200 and more efficient. Many 510 guys road race them over 300 lb.ft. and I've seen Subaru guys drag race them with 400-450 whp and 3300 lbs. A few Subaru guys have problems with them at those levels, but they tend to have the extra 10% in the center diff. Quote Link to comment Share on other sites More sharing options...
johnc Posted May 5, 2014 Share Posted May 5, 2014 How can a ring gear 20mm smaller in OD be stronger? Assuming same number of spider gears and an open diff... Quote Link to comment Share on other sites More sharing options...
FlawleZ Posted May 5, 2014 Share Posted May 5, 2014 (edited) For what its worth, back when I was running the R200 open diff in my Z31 was making 480 lbs tq and I ran it for 4+ years street and track use without issue. My Z31 weighs 2800 lbs (still full interior) and this was always with Mickey Thompson MT Streets out back. I now run the R200 LSD just to help with traction. Edited May 5, 2014 by FlawleZ Quote Link to comment Share on other sites More sharing options...
JMortensen Posted May 5, 2014 Share Posted May 5, 2014 For what its worth, back when I was running the R200 open diff in my Z31 was making 480 lbs tq and I ran it for 4+ years street and track use without issue. My Z31 weighs 2800 lbs (still full interior) and this was always with Mickey Thompson MT Streets out back. I now run the R200 LSD just to help with traction. The Z31 open is a 4 pinion and stronger than the 2 pinion used in the S30 and S130 R200s Quote Link to comment Share on other sites More sharing options...
roger280zx Posted May 6, 2014 Share Posted May 6, 2014 I'll take a 4 pinion r160 over a 2 pinion r180. Though I've had no problems with my own 2 pinion r180 (3.36) as the old dried up 225/45's let loose too soon. I haven't tried too hard with the 330's as I have enough other stuff to fix. Quote Link to comment Share on other sites More sharing options...
logr Posted May 6, 2014 Share Posted May 6, 2014 Another question might be, Where am I going with the build? I have just under 300 whp and wtq. I had a Suby r160 from a rally car. It was some sort of helical but not the regular version. Last weekend I broke the stub shaft coming out of the diff(stock 240Z). While fixing that I saw the carrier inside was cracked too. What to do? An old STI diff is cheapest but we all know an STI is made for racing, so it hasn't had an easy life for the first 10 years before we get it, and they have 4 wheel drive. What if we want to go cv's in the future. The options for this diff use extra adapters on both ends(seems like that would put extra force on the stubs) and are known to have issues with keeping bolts tight. LSD's are another issue entirely if you go with an R200. No real answers from goggling but lots of wrong information. I have been searching for the answer to "Will a short nose lsd work in a long nose and then what about axles?". I see lots of info on shortening and regrooving and it might work but no definitive answers, from what I found. I personally tried a long nose R200 open diff with short nose open diff axles.They go in and the keeper groove is perfect. I also tried Z31 axles just to make sure and they work perfectly too. I can see no reason that any short nose lsd made for the short nose open diff(240SX) won't work perfectly with 280Z stubs or Z31 axles. I ordered an OS Giken yesterday, the 046 one. I have put these in numerous cars and they are great. I also ordered the flanges and axles from Checkered Flag Joe. I have the Z31 axles. The r160 held up until I went to 245/40/17 Z2's and a sticky track. Hit 2nd a bit hard at 13# and it was all over. I only use it for daily driver fun, an occasional track day and autox, mostly autox. I would like a 4.11 but not sure if any came in r200 longs. I found one place that said 85-88 200SX's came with a 4.11 R200 long but have not been able to verify. Anybody know? I am going with a 3.9 for now. Hope this helps. I should have mine done in with in a week or so. A vlsd only partly hooks up and on hard corners with reasonable power, they can spin an inside tire easily. A helical does the same if you take enough weight off it. Quote Link to comment Share on other sites More sharing options...
helghast7 Posted May 6, 2014 Share Posted May 6, 2014 (edited) Yea I was just going to go with a modified obx and z31 axles, just seems like the simplest thing to do for my r200, especially since I have the axles already. Edited May 6, 2014 by helghast7 Quote Link to comment Share on other sites More sharing options...
JMortensen Posted May 6, 2014 Share Posted May 6, 2014 I would like a 4.11 but not sure if any came in r200 longs. I found one place that said 85-88 200SX's came with a 4.11 R200 long but have not been able to verify. Anybody know? I am going with a 3.9 for now. I have a 4.11 R200 out of a 200SX. I think it might have come in the turbo version, not sure. It's rare, but not as rare as the 3.36 R200. You can find one if you keep your eye out. Quote Link to comment Share on other sites More sharing options...
RebekahsZ Posted May 6, 2014 Share Posted May 6, 2014 If OP is still subscribed, sound off so I know whether to chime in. Quote Link to comment Share on other sites More sharing options...
logr Posted May 6, 2014 Share Posted May 6, 2014 I'm interested in what you have to say. Quote Link to comment Share on other sites More sharing options...
seattlejester Posted May 6, 2014 Share Posted May 6, 2014 (edited) Yes correct R200 from late 200sx turbo is an open 4.11, I have one myself as well. Edit: wrong thread...my bad Edited May 7, 2014 by seattlejester Quote Link to comment Share on other sites More sharing options...
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