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Looking to get a rear LSD Diff, what ratio/config for my 510?


B^2

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I'm in the market for a new rear differential for my 1970 510. Currently running an L20B with dual mikuni 40's. No immediate plans to upgrade the engine. Current diff is clunking so I'm in the market for a lsd diff and thinking 4.11 gears. I know lsd 4.11 diffs are rare so I'm wondering if I'm better off getting a 3.7 LSD and swapping the core into a 4.11 diff?

Also I see a lot of diffs on ebay but it's not quite clear what it would take to fit it up to my 510: https://www.ebay.com/itm/234135521644?epid=1130916661&hash=item368390896c%3Ag%3AL5cAAOSwp45hFZOI&fbclid=IwAR36v95Znsab9mXTR_LW-ojFUjcj0bi3PpZ45pPwzyMcY0Iz2_1PAcpiW9c


Should I be looking at a ratio other then 4.11?  Plan is to covert to cv axle kit.

 

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I've always liked the clutch type because they are easy to work on, easy to modify and have predictable handling. If you want to make them stiffer, you simply disassemble the unit and flip the concave discs upside down and put it back together. You can also shim it with shim stock, or even get thicker shims (NISMO/Datsun Comp offered thick shims back in the day? but good luck finding those.

 

Gear ratio? For the bay area, with all those hills, I would stick with the 4.11, unless you've got a lot of HP which can push a higher gear ratio.

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  • 2 weeks later...

All Datsun R160's (510) & R180's (Z car) had a BOLT IN stub axle.  All 84-89 Subbie's had a similar BOLT IN stub axle, but you will need to use your existing 510 stub axles.  Datsun Competition offered an R160 4.11 clutch type LSD diff, sold over the parts counter, never offered in a production car.  That said, they are kinda rare, hard to find.  The 84-89 Subbie turbo R160 clutch type LSD units bolt straight in to the 510, again, using your existing 510 stub axles.  Pretty sure Subbie only offered 3.7 & 3.9 in LSD, never the 4.11 in LSD.  The early Subbie LSD's are getting hard to find.  If you find the same 84-89 generation Subbie R160 4.11 OPEN (very common in non-turbo AUTOMATICS), you can swap the 3.7/3.9 LSD carrier unit into the 4.11 diff.  This way, you do not necessarily need to shim for proper lash.  If you do it the other way, swap a 4.11 ring & pinion into the 3.7/3.9 LSD diff, you MUST properly shim for lash, otherwise you risk premature wear by not having the lash set up!  Around 1990, Subbie switched to the SNAP RING style stub axles, thus you would need to purchase the custom made 510 style stub axles with the snap ring. 

 

The 70-83 240Z 260Z 280Z 280ZX R180 open diff's all bolt right in to the 510.  You would use the Z car stub axles, not the 510.

 

The 75-83 280Z 280ZX R200 open diff's are overkill for a 510 & much heavier than the R160 or R180 diff's, unless you are running a big power turbo swap and always running your 510 really hard.  We run the R180's in our full blown vintage race 240Z's............again, we think the R200's are overkill & they are much heavier.  I don't think in the 6++ years of balls to the wall vintage racing, we have ever blown up an R180........they are stout!

 

The current common diff swap is to use the later Subbie R180 viscous or Torsen LSD diff's, but you must purchase the custom 510 style stub axles with the snap ring.  I don't think the later Subbie R180's ever offered a 4.11 ratio...................I think you are limited to only two ratio's...........??  Unless you are hard on your car, doing hole shots & burnouts, the stock 510 u-joint axles should hold up just fine.  Always a good idea to replace the u-joints & have the axles balanced, but not imperative.  We DO run CV axles in our vintage race 240Z's & most guys running any combo of turbo engines in their 510's are typically running CV axles. 

 

Pretty sure I got that all correct!

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On 9/7/2021 at 3:03 PM, yenpit said:

All Datsun R160's (510) & R180's (Z car) had a BOLT IN stub axle.  All 84-89 Subbie's had a similar BOLT IN stub axle, but you will need to use your existing 510 stub axles.  Datsun Competition offered an R160 4.11 clutch type LSD diff, sold over the parts counter, never offered in a production car.  That said, they are kinda rare, hard to find.  The 84-89 Subbie turbo R160 clutch type LSD units bolt straight in to the 510, again, using your existing 510 stub axles.  Pretty sure Subbie only offered 3.7 & 3.9 in LSD, never the 4.11 in LSD.  The early Subbie LSD's are getting hard to find.  If you find the same 84-89 generation Subbie R160 4.11 OPEN (very common in non-turbo AUTOMATICS), you can swap the 3.7/3.9 LSD carrier unit into the 4.11 diff.  This way, you do not necessarily need to shim for proper lash.  If you do it the other way, swap a 4.11 ring & pinion into the 3.7/3.9 LSD diff, you MUST properly shim for lash, otherwise you risk premature wear by not having the lash set up!  Around 1990, Subbie switched to the SNAP RING style stub axles, thus you would need to purchase the custom made 510 style stub axles with the snap ring. 

 

The 70-83 240Z 260Z 280Z 280ZX R180 open diff's all bolt right in to the 510.  You would use the Z car stub axles, not the 510.

 

The 75-83 280Z 280ZX R200 open diff's are overkill for a 510 & much heavier than the R160 or R180 diff's, unless you are running a big power turbo swap and always running your 510 really hard.  We run the R180's in our full blown vintage race 240Z's............again, we think the R200's are overkill & they are much heavier.  I don't think in the 6++ years of balls to the wall vintage racing, we have ever blown up an R180........they are stout!

 

The current common diff swap is to use the later Subbie R180 viscous or Torsen LSD diff's, but you must purchase the custom 510 style stub axles with the snap ring.  I don't think the later Subbie R180's ever offered a 4.11 ratio...................I think you are limited to only two ratio's...........??  Unless you are hard on your car, doing hole shots & burnouts, the stock 510 u-joint axles should hold up just fine.  Always a good idea to replace the u-joints & have the axles balanced, but not imperative.  We DO run CV axles in our vintage race 240Z's & most guys running any combo of turbo engines in their 510's are typically running CV axles. 

 

Pretty sure I got that all correct!

 

 

So if I wanted to get this diff: https://www.ebay.com/itm/234177237749?hash=item36860d12f5:g:uyQAAOSwcEdhN-xg  , I would just need to get the 510 style stub axles with the snap ring?  Seems to me that it's probably easier to get newer stub axles rather then getting two rear diffs and swapping the LSD carrier unit into the 4.11 open diff?  Just trying to understand the pros and cons and where to actually find parts so I buy what I need and not parts I can't end up using.

 

Is there any advantages to running CV axles over stock 510 u-joints when I just have an L20B?  Down the road I may decide to build or swap an engine but right now I'm not pushing any crazy HP.

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10 minutes ago, B^2 said:

 

 

So if I wanted to get this diff: https://www.ebay.com/itm/234177237749?hash=item36860d12f5:g:uyQAAOSwcEdhN-xg  , I would just need to get the 510 style stub axles with the snap ring?  Seems to me that it's probably easier to get newer stub axles rather then getting two rear diffs and swapping the LSD carrier unit into the 4.11 open diff?  Just trying to understand the pros and cons and where to actually find parts so I buy what I need and not parts I can't end up using.

 

Is there any advantages to running CV axles over stock 510 u-joints when I just have an L20B?  Down the road I may decide to build or swap an engine but right now I'm not pushing any crazy HP.

 

Subbie DID make a 4.11!!  That's a no brainer to me.............yes, those later Subbie R180's are easily had & I think the custom stub axles are available from a couple different sources!  And the fact they do make the 4.11 is killer!  The earlier Subbie R160's are really getting hard to find.  I'm in CO where they sold lots of Subbie's throughout the 80's & I haven't found an LSD in at least 3-4 years in the junkyards..............

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14 minutes ago, B^2 said:

Is there any advantages to running CV axles over stock 510 u-joints when I just have an L20B?  Down the road I may decide to build or swap an engine but right now I'm not pushing any crazy HP.

 

I bet u-joint axles would hold up just fine with an L20B AND some "spirited" driving.  Yes, you can simply upgrade later!

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The early clsd’s are super hard to find. Second hand they are about $600 and in a 3.7. 
 

i had to buy a 510 to get my first one and just got really lucky on a Craigslist post on the second. Been looking for years and years. Second hand they come up often enough but ya gotta pay!

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Is there a difference between the r180 subaru diff I posted and an STI R180 diff?  I want to get the datsunrestomod cv axle kit and I'm trying to confirm it will work with that diff.  I don't know how to check if that diff is a clip in style differential or requires the stub axles to be bolted in.

Edited by B^2
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I believe the Legacy/Forester/Impreza (including WRX) diffs are all R160s, not 180s.  The STI is the only one that had 180s.

 

As far as I know. all the newer Subarus use the clip-in/snap ring axles, no bolt-in stub shafts.  I have a 3.9 CLSD R180 here that I will be using with the Restomod full CV axle kit (no separate stubs), and a R160 4:11 VLSD that I will use the Restomod clip-in stub shafts to adapt to stock half shafts.  That's the reason to use stub shafts, to adapt to stock axles, but they are still all snap ring type. 

 

The stock Datsun stub shafts from R160 or R180 diffs are slightly too short to modify for snap rings.  The Datsun Restomods stubs I have are made from Subaru inner plug-in axle cups from the original full CV axles.

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47 minutes ago, iceman510 said:

I believe the Legacy/Forester/Impreza (including WRX) diffs are all R160s, not 180s.  The STI is the only one that had 180s.

 

As far as I know. all the newer Subarus use the clip-in/snap ring axles, no bolt-in stub shafts.  I have a 3.9 CLSD R180 here that I will be using with the Restomod full CV axle kit (no separate stubs), and a R160 4:11 VLSD that I will use the Restomod clip-in stub shafts to adapt to stock half shafts.  That's the reason to use stub shafts, to adapt to stock axles, but they are still all snap ring type. 

 

The stock Datsun stub shafts from R160 or R180 diffs are slightly too short to modify for snap rings.  The Datsun Restomods stubs I have are made from Subaru inner plug-in axle cups from the original full CV axles.

 

Do you know what ratios the STI R180's came in?  I'm fairly convinced I want to go 4.11 LSD if possible.  It seems like I can get an R160 diff and get stub axles but not the full cv axle conversion, or I can try and find an R180 diff in order to get the full Datsun Restomod kit but it's unclear whether the R180 ever came in 4.11

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I don't have the full data at my fingertips, but the 2000's era R180 Subie diffs are generally either 3.90 or 3.54.  they change depending on the front differential ratio used (some 1:1, some 1.1:1)  There are also multiple types, for certain clutch and Torsen.  I don't know of any 4.11 or higher R180s.  

 

You can do a CV conversion with shafts from other sources than Datsun Restomods, but most use stub axles and adapters (Futofab, Ermish, Driveshaft shop) not the OE type axle assembly with integral shafts like Restomods made (makes?).  Looks like Futofab has both options.  http://www.futofab.com/index.php?option=com_content&view=category&layout=blog&id=38&Itemid=122

 

More info:  http://www.futofab.com/index.php?option=com_content&view=article&id=173:subaru-wrx-sti-conversion-stub-axles&catid=38:datsun-drivetrain&Itemid=122

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Yes, there are advantages for CVs vs Ujoint axles. Vibrations caused by lowered suspension can be annoying in a 510, especially if the rear crossmember is not slotted o modified to allow camber and toe adjustments.

 

Also, with some of the Subaru diffs, swapping out the 510 inner gears and adding the nut from the Datsun R160 makes it a simple bolt in job. But this requires tearing down the LSD unit to get inside. Not difficult, but there is a learning curve there.

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