Upgrading rear diff

Engine, Transmission and related drivetrain.
vetteguy22
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Upgrading rear diff

Postby vetteguy22 » 27 Feb 2017 07:45

Hi guys,
I'm new to the Datsun world and am beginning a new project 510 4 door for my wife.
I have an opportunity to purchase a R200 diff from a 240 sx.
Would this be a good upgrade and what extras would I need to look at?
Thanks for any input,
Rob

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bertvorgon
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Re: Upgrading rear diff

Postby bertvorgon » 27 Feb 2017 08:23

That is a really big, HEAVY diff, and unless you are going to make some huge torque, I would suggest sticking with the R-180 diff. There are a bunch of us on here making upwards of 260 - 300 Hp to the rear wheels through a R180 with no issues.
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Re: Upgrading rear diff

Postby 510rob » 27 Feb 2017 08:52

Regardless of the overkill-ness (which is likely true, unless your wife is Michele Mouton?), the R-200 used in the 240SX is the short-snout type - it won't bolt in without extensive mods. The R-200 used in some of the 280ZX and 300ZX is a long-snout type.

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vetteguy22
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Re: Upgrading rear diff

Postby vetteguy22 » 27 Feb 2017 12:11

Thanks for the input guys.
The car will have approx 400 hp at the crank and will be used for auto cross, some road race along with street driving.
Just want to make sure that things are over built instead of breaking things.
Sounds like a diff from a 280 or 300zx is a better idea.
What years, etc. should I be looking for?
Did they make a posi unit?
Should I look for one from a turbo car?
Thanks,
Rob

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JordanTr
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Re: Upgrading rear diff

Postby JordanTr » 27 Feb 2017 12:38

Mid 87-89 300zx turbo has a factory 2 way lsd. Very rare but you could find. There are clip in stub axles with 4 bolt flanges than can be had from a 280zx.

After mid '86 model year, ring gear bolts were 12mm. This means that a late 86 turbo would yield a 3.545 with 12mm RGBs. 87-89 turbo is 3.7 LSD, 87-89 NA z31s are 3.9 open. One of the 80s 200sx turbo cars came with a 4.11 open R200. Also very rare.

You can take an s13 29 spline aftermarket LSD center and swap it into the post 86 long nose easily. Earlier units can take the same units as well but the M10 ring gear bolts should be sleeved to suit the M12 holes in the newer LSD units.
Jordan | '72 2 door KA project | '94 240sx RB26DETT | '97 Silvia RB25DET | '90 Audi 90 Quattro 20V (DD)

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TheHeretic
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Re: Upgrading rear diff

Postby TheHeretic » 27 Feb 2017 20:36

I would just purchase a used 2004-05 Subaru Sti R180 diff and call it a day. Easy to find and install and strong enough to handle the level of power you are going to be putting down. Might want to consider upgrading to CV axles at the same time though.
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vetteguy22
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Re: Upgrading rear diff

Postby vetteguy22 » 28 Feb 2017 21:17

Thanks for the input Ryan.
Like I said, these are new to me. Is the Subaru R180 a posi diff?
What's the difference between the Datsun R180 and the Subaru unit?
There is nothing wrong with the unit in the car now but I just want to make it as bullet proof as possible.
Is it possible to make the original 1970 diff a posi without to much hassle?
Thanks again,
Rob

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funwithmonkeys
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Re: Upgrading rear diff

Postby funwithmonkeys » 01 Mar 2017 18:47

You can turn the stock open diff to a LSD or you can just find a Subaru R160 with an LSD. The are the same except for the pinion flange and axle stubs. I have a Subaru LSD with 4.44 gears. The axle stubs from your stock diff will bolt straight in and I just had to shave down 2 sides of the pinion flange so it would slide into the rear crossmember without having to remove the crossmember. I think the LSD R160 with 4.44 was in a Forester. I'm not too sure of the year but it is not hard to find out.
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okayfine
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Re: Upgrading rear diff

Postby okayfine » 01 Mar 2017 19:02

vetteguy22 wrote:Like I said, these are new to me. Is the Subaru R180 a posi diff?


Sube R180s are posi, but the type of LSD varies with the years. Some prefer the clutch-pack versions, some like the Torsen. A couple good threads here talking about the differences.

vetteguy22 wrote:What's the difference between the Datsun R180 and the Subaru unit?


Datsun units are rare, and old. Subaru's units are newer, more available, parts are easier to find, and you have choice of LSD types.

vetteguy22 wrote:Is it possible to make the original 1970 diff a posi without to much hassle?


DQ Volume 10 Issue 1 - Tech How-To: R160 Differential Rebuild, Part I -- R160 differentials dont often need service or a rebuild, but when they do, where do you go to find that information? In Part I, Derek Garnier shows how to disassemble your R160 and R160 LSD and also reviews the steps necessary to convert to 4.11 gears.

DQ Volume 10 Issue 3 - Tech How-To: R160 Differential Rebuild, Part II -- In Part I, we finished with a fully disassembled, cleaned, and painted differential housing along with a fully disassembled and cleaned (and possibly machined) center section. It’s now time to inspect our parts, order bearings and seals, reassemble, and adjust the differential.
Because when you spend a silly amount of money on a silly, trivial thing that will help you not one jot, you are demonstrating that you have a soul and a heart and that you are the sort of person who has no time for Which? magazine. – Jeremy Clarkson

vetteguy22
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Re: Upgrading rear diff

Postby vetteguy22 » 01 Mar 2017 20:54

Thanks guys,
That's some really helpful info.
I really appreciate it.
Rob

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okayfine
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Re: Upgrading rear diff

Postby okayfine » 03 Mar 2017 07:46

DQ Volume 12 Issue 4 - Tech How-To: Installing an '06 Subaru STI-R R180LSD — Beta Motorsports 27T stubs create new possibilities. Accessorize your new differential with a Perrin large-capacity diff cover.
Because when you spend a silly amount of money on a silly, trivial thing that will help you not one jot, you are demonstrating that you have a soul and a heart and that you are the sort of person who has no time for Which? magazine. – Jeremy Clarkson

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PoorMtnKid
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Re: Upgrading rear diff

Postby PoorMtnKid » 03 Mar 2017 11:35

I second going with the R180 out of the Subaru with the Beta Motorsports stub axles ( Sold by Futofab.com now right ? )
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Dave Patten
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Re: Upgrading rear diff

Postby Dave Patten » 10 Mar 2017 13:48

PoorMtnKid wrote:I second going with the R180 out of the Subaru with the Beta Motorsports stub axles ( Sold by Futofab.com now right ? )


Yup, STi conversion stub axles are in stock at FutoFab, $550/set.
http://www.futofab.com/index.php?option=com_content&view=category&layout=blog&id=38&Itemid=122

FutoFab has made some upgrades from the design Beta Motorsports / Wolf Creek Racing sold.

We now make our STi Conversion stub axles out of forgings, not cut from billets as was done in the past. Also, only the shaft is heat treated for surface hardening. If the entire stub axle is heat treated (as done in the past) the flange becomes brittle. The heat treating penetrates to a depth of roughly .250". The flanges are so thin that the heat treatment fully pentrates the material making it brittle. On the shaft the core of the shaft remains untreated which gives the axle some added flex to absorb the shock loading driveline parts are subjected to.

Our forged STi conversion stub axles are easily identifed by their round flanges.
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