Subaru R180 diff in Nissan case

Engine, Transmission and related drivetrain.
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iceman510
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Subaru R180 diff in Nissan case

Post by iceman510 » 12 Jun 2019 06:51

Hey all, I hope someone out there has done this and can chime in. I acquired an R180 Subaru CLSD unit bare, and I am looking to put it in my Nissan 720 truck housing with the 4.38 ring and pinion. It is the K housing, so I am thinking this should fit. This installation shouldn't really be any different than doing an aftermarket diff installation basically, right?

I have compared and measured the two, and within my capability and tool accuracy of measuring I see about a 0.5 mm difference in the ring gear mounting surface to bearing outer case dimensions (measured both directions). I am thinking this should be within the scope of adjusting with the side case shims.

I plan to use the matching ring and pinion from the truck. Any advice on pitfalls for recommendations appreciated. Photos below. Thanks in advance.
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Subie clutch diff
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iceman510
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Re: Subaru R180 diff in Nissan case

Post by iceman510 » 12 Jun 2019 06:56

Hmmm, dropped two pictures for some reason.
The attachment datsun _subi diff small.jpg is no longer available
The attachment datsun _subi diff small.jpg is no longer available
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funwithmonkeys
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Re: Subaru R180 diff in Nissan case

Post by funwithmonkeys » 12 Jun 2019 11:53

I found out the hard way that there are 2 different ring gear sizes. The older Nissan ones are 110mm ID and the newer ones are 115mm ID.
If no one from the future comes back to stop you from doing it then how bad of a decision can it really be?

iceman510
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Re: Subaru R180 diff in Nissan case

Post by iceman510 » 12 Jun 2019 12:32

I didn't check that yet, but I need to to make sure. Truck unit is a considered the newer type I believe, so it should match.

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JordanTr
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Re: Subaru R180 diff in Nissan case

Post by JordanTr » 13 Jun 2019 08:37

funwithmonkeys wrote:
12 Jun 2019 11:53
I found out the hard way that there are 2 different ring gear sizes. The older Nissan ones are 110mm ID and the newer ones are 115mm ID.
Do the bolt PCDs line up still? Could always do some machining to make it work if that’s the only issue.
Jordan | '72 2 door KA project | '94 240sx RB26DETT | '97 Silvia RB25DET | '90 Audi 90 Quattro 20V (DD)

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funwithmonkeys
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Re: Subaru R180 diff in Nissan case

Post by funwithmonkeys » 13 Jun 2019 08:40

From what I understand the bolt pattern is the same. I just got the Cusco LSD to fit the 110mm ring gear.
If no one from the future comes back to stop you from doing it then how bad of a decision can it really be?

iceman510
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Re: Subaru R180 diff in Nissan case

Post by iceman510 » 16 Jun 2019 19:53

Did some exploration on this today. The ring gear inner diameter is 115 mm, so no problem fitting the CLSD unit. After removing it I could also establish the distance from mounting flange to bearing is identical on the two units.

One issue to adapt is the bolt size. The Subaru LSD flange has 11mm bolt holes, and the Datsun ring gear uses 10mm bolts. They are also a bit short since the flange is thicker. I will likely mod the bolt holes to use the Subaru LSD bolts mentioned in some other posts here (8002 11140).

One other issue, the Datsun diff has the metal locking straps that fold up across two bolts. These will likely not fit because the contour and shape of the surface is different. Is loctite sufficient to hold these, or should I modify the lock tabs somehow to work? Sorry, I will have to get a picture of those.

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JordanTr
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Re: Subaru R180 diff in Nissan case

Post by JordanTr » 16 Jun 2019 20:05

If you clean/degrease the threads, a Loctite product would suffice. Red 272 @ ~2900psi shear strength or 680 retaining compound @ ~3700psi shear strength would be good options to consider.
Jordan | '72 2 door KA project | '94 240sx RB26DETT | '97 Silvia RB25DET | '90 Audi 90 Quattro 20V (DD)

iceman510
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Re: Subaru R180 diff in Nissan case

Post by iceman510 » 17 Jun 2019 10:10

Researching further today and talking to some people in the business, it is suggested that the ring gear will be hard enough material that it may be difficult or near impossible to drill and tap those holes larger. I know Kurt mentioned having that done in the original FAQ written about this many years ago (or maybe it was someone else, there are so many versions of that doc around).

The Nismo bolts are NLA. :( Subaru bolts are easy to get, but maybe not usable. Interestingly enough, those show on the ordering site as only 20 mm long. I will have to check my notes again tonight, but I think the original 10mm were almost the same. I suspect I may be going the sleeving holes route.

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Byron510
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Re: Subaru R180 diff in Nissan case

Post by Byron510 » 23 Jun 2019 20:07

Keep us posted- certainly interested in what you find out in the end.
Tanks for taking the time to post.

Byron
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because the opposite never works.

iceman510
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Re: Subaru R180 diff in Nissan case

Post by iceman510 » 24 Jun 2019 05:36

I found and ordered spacers (set of 10 from ebay) that are designed to sleeve bolts on some Dana ring gear applications. They are here:

https://www.yukongear.com/productdetail ... rodID=8508

These initially appear a bit pricey at over $5 a piece, but the set of 10 were just over $30. Need 8, so not a terrible deal. Guy at the local diff shop told me they use compression fitting ferrules and pound them in to fit. Thought this might be better.

Anyway, the OD of said 7/16" was just about 11.2mm. They tapped into the holes in the Subaru diff unit with a nice snug fit. The ID of said 3/8" was too small for the Nissan bolt of 9.95 mm diameter, so I filed the ID with a round file until the bolt fit through snugly. Looks like this will work. I only completed one so far.

Bolt engagement into the ring gear will be a very minimal bit shorter than original. I don't remember exactly now (wrote it down in the garage), but it is less then half a thread, I think about 0.5mm with the thread pitch of 1.25mm.

Looking like this will work if the diff unit will fit and be properly adjustable for backlash and side preload. Will see when I get there. I may have a low-mile R180 CLSD (3.90) for sale if this works out.

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