vega Posted February 24, 2012 Share Posted February 24, 2012 The car is a 1978 datsun l28 5 spd (factory r200 3.545 diff) I have been building a 327 with a 6500 rpm redline. I am finding that a higher differential ratio is needed. Through some research I am going to go with a a Obx diff, I will deal with the issues. the problems I am having are as such. 1. from my understanding this can change the final ratio (I am looking for a 4:1 or higher)is this true? 2. how do I know I am getting the right unit for my diff? is this a longnose/short nose? 3. what gear ratio options to do I really have here? (keeping the stub axles btw) Is there something else that I may be missing? All in all I want to stay with a r200 diff that I have I just want to change the pinion out for a 4:1 or higher (I could live with a 3.9:1 but no less). All help would be greatly appreciated. Quote Link to comment Share on other sites More sharing options...
getoffmyinternet Posted February 24, 2012 Share Posted February 24, 2012 It sounds like you need to learn a little more about how differentials work and those questions will answer themselves. The final ratio has nothing to do with the differential center, or the stub axles. If you buy an aftermarket center, it probably isn't going to come any ratio at all, you can either reuse your old gears or buy a set in any flavor you want. Whether the diff is compatible with your stubs or vice versa depends on which stubs you have, ie. how many teeth. Quote Link to comment Share on other sites More sharing options...
vega Posted February 24, 2012 Author Share Posted February 24, 2012 are there gear sets i can buy somewhere? i did not know what the obx unit was. I am a lead mechanic by day- i know how diffs work.... i read that the units affect the axles hence the question. I didn't know if it was the entire setup or what. more or less as previously stated i am looking for a a 3.9 gear and up. Quote Link to comment Share on other sites More sharing options...
feifongwong3 Posted February 24, 2012 Share Posted February 24, 2012 Basically, you'll have to either source another r200 with 3.90 gearing or change your existing pinion set to the 3.90 set. Quote Link to comment Share on other sites More sharing options...
cheesepocket Posted February 24, 2012 Share Posted February 24, 2012 Here's a good source for chasing down the ratio you want, at least within the Datsun/Nissan factory availalbility: http://www.zhome.com/ZCMnL/tech/GearRatios.html Quote Link to comment Share on other sites More sharing options...
vega Posted February 25, 2012 Author Share Posted February 25, 2012 Basically, you'll have to either source another r200 with 3.90 gearing or change your existing pinion set to the 3.90 set. where can one purchase a 3.9 set? Quote Link to comment Share on other sites More sharing options...
vega Posted February 25, 2012 Author Share Posted February 25, 2012 Here's a good source for chasing down the ratio you want, at least within the Datsun/Nissan factory availalbility: http://www.zhome.com/ZCMnL/tech/GearRatios.html I was there already - i did google this you guys. I did do some searching. Just for future reference. Quote Link to comment Share on other sites More sharing options...
NewZed Posted February 25, 2012 Share Posted February 25, 2012 This might help - http://forums.hybridz.org/index.php/topic/54124-step-by-step-installing-an-lsd-into-your-open-diff/ It's in FAQ - Powertrain instead of Drivetrain for some reason. Hard to locate. Worth reading. Quote Link to comment Share on other sites More sharing options...
getoffmyinternet Posted February 25, 2012 Share Posted February 25, 2012 You sounded like you read up on the obx issues so I assumed you knew what an obx was to begin with. It's the china brand helical diffy center. IIRC a compatible center is very easy to find, because they are interchangeable with silvia r200s which are also 29 spline. It's probably harder to find a gear set that fits by itself. Easier to buy a whole diff and leech it, not many people are taking these out and even less are selling new ones that are compatible. That site is nice but it still doesn't tell you the spline counts. I'm pissed that the old wiki on the subject is no more and I didn't print it out or anything because it had every possible rear end and the spline counts for each. Sad day for me, but again if you're just swapping the gears it doesn't matter what the spline count on the victim is. Quote Link to comment Share on other sites More sharing options...
getoffmyinternet Posted February 25, 2012 Share Posted February 25, 2012 This might help - http://forums.hybrid...your-open-diff/ It's in FAQ - Powertrain instead of Drivetrain for some reason. Hard to locate. Worth reading. Lol, that's gonna piss him off. Dude didn't ask how to swap the centers... Quote Link to comment Share on other sites More sharing options...
NewZed Posted February 25, 2012 Share Posted February 25, 2012 (edited) Lol, that's gonna piss him off. Dude didn't ask how to swap the centers... Actually, his question was more about how to get a specific ratio. That would require a certain ring and pinion gear set, to be bolted on to his OBX. So the link is right in line with what he was asking, and he should be happy to check it out. What's up with people using the word "center" to describe the differential? Even though the whole assembly is often called the differential, if you're going to go deeper, isn't the "center" that you're talking about typically called the differential (see the OBX page). How did "center" get in here? A little more research seems to show that "carrier" might be a more common word. Edited February 25, 2012 by NewZed Quote Link to comment Share on other sites More sharing options...
getoffmyinternet Posted February 25, 2012 Share Posted February 25, 2012 Carrier, center, differential, whatever. I wish I could slap everyone that calls the housing a pumpkin, but that's just me. Obviously we're talking about the actual differential here, but I thought it would be confusing since he seemed to be talking about it as a whole including the housing. Quote Link to comment Share on other sites More sharing options...
vega Posted February 25, 2012 Author Share Posted February 25, 2012 (edited) Carrier, center, differential, whatever. I wish I could slap everyone that calls the housing a pumpkin, but that's just me. Obviously we're talking about the actual differential here, but I thought it would be confusing since he seemed to be talking about it as a whole including the housing. I am very surprised that with the popularity of the car that a gear set has yet to be made aftermarket like gm and ford etc. we all know that it is technically called a carrier, i am just waiting to slap the guy that calls a crank shaft an arm.... Edited February 25, 2012 by vega Quote Link to comment Share on other sites More sharing options...
vega Posted February 25, 2012 Author Share Posted February 25, 2012 http://image.truckinweb.com/f/26921920+w750+st0/1001tr_05+genuine_gear_ring_and_pinion_gear_set+parts.jpg Quote Link to comment Share on other sites More sharing options...
vega Posted February 25, 2012 Author Share Posted February 25, 2012 http://www.rhdjapan.com/kameari-r200-final-gear-set-s30-z31-r30-r31-58311 1500 huh .... Quote Link to comment Share on other sites More sharing options...
feifongwong3 Posted February 25, 2012 Share Posted February 25, 2012 Probably better off finding a manual trans s130. They seem to have 3.90 gears and you'd come out tons cheaper if you get the carrier, halfshafts, and companion flanges from a junkyard car. Quote Link to comment Share on other sites More sharing options...
vega Posted February 25, 2012 Author Share Posted February 25, 2012 http://www.thenismoshop.com/Nissan-Factory-OEM-Final-Drive-Gear-Sets--Ring-and-Pinion--S-Chassis_p_68.html this is for the later s series Quote Link to comment Share on other sites More sharing options...
vega Posted February 25, 2012 Author Share Posted February 25, 2012 http://www.thenismoshop.com/Nissan-Final-Drive-Gear-Sets-Ring-and-Pinion--350z-G35_p_69.html for a 350z - Can anything (aside the obvious 1500 dollar unit) be made to work with the older unit? this is where my knowledge on ring and pinions end. as far as that I don't know what can or can't be done as for swapping out ring and pinion from year to year to housing to housing. Quote Link to comment Share on other sites More sharing options...
vega Posted February 25, 2012 Author Share Posted February 25, 2012 http://www.pirate4x4.com/forum/showthread.php?t=655774 Quote Link to comment Share on other sites More sharing options...
vega Posted February 25, 2012 Author Share Posted February 25, 2012 https://www.4x4parts.com/nissan/advanced_search_result.php?keywords=gear&osCsid=0663f5b54717075070f43f272a8f849e&x=0&y=0 Quote Link to comment Share on other sites More sharing options...
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