Whats the right LSD Diff and ratio for me?

[twoforty z]

Hi all,

Before you say it, I've read almost every diff related post I could find but I'm still scratching my head.

 

I have a 240z with an RB20DET (basically stock, 150kw atw) and RB gearbox and I'm not sure what diff ratio I currently have but 2nd gear just keeps going, and going. No joke I can pull away from a standing start in 2nd and get to about 110km/h. Great party trick but not overly practical.

 

So I want to change my diff so I'll have more acceleration and a LSD. The car is mainly street driven but I would like to do a few track days and 1/4 mile passes in the future. I've budgeted around $1500-2000 and was thinking the "easiest" option would be the 4.44 ratio (I believe the R32 came with a 4.363 ratio) LSD R180 from the GC8 Subaru STi with side axles from Wolf Creek Racing.

 

So.....have I budgeted enough? Should I stick with R180's or go R200 diffs? is 4.44 the right ratio for me? Does it matter what sort of LSD it is as its a street car? why do some people say the R180 Subaru swap isn't so easy?

 

Thanks

[dat2kman]

Grab a r200 out f a dr30 skyline  they'll be 4.375 and lsd, grab a set of halfshafts from a 260z 2+2 with the two ( slightly different lemgths) push in stub flanges.

Mark one shaft/flange as LEFT etc.

Bolt the lot in.

If you have r180 now, grab the moustache bar off the 260.

Lowest cost and easiest option.

[twoforty z]

so what would you think I should expect to pay for a DR30 R200? they seem to vary in price a bit

[d3c0y]

You've been reading my posts aww 

 

 

Why do some people say the R180 Subaru swap isn't so easy? Because they are a bit mechanically retarded, it bolts in.

Both these diff swaps are the same difficulty because you do the same things.

 

 

The big question is how much power do you think you will end up with as the R180 will have a limit around about 260rwkw i believe. It's more about torque but an RB20 won't be breaking any records there.

 

 

I think you are on the money for the ratios. The STi diff will have a better clutch setup than the R200 (correct me if i am wrong there Jason) and is obviously a bit lighter (approx 5kg from memory).

 

 

Money wise it all depends what you can get the correct R180 + the side axles for. Both diffs should get an R/T style mount at the front. Those diffs can be anywhere from $200 - $600 + $500 for the side axles.

 

 

 

 

 

 

[funzies]

I have a 240z with an RB20DET (basically stock, 150kw atw) and RB gearbox and I'm not sure what diff ratio I currently have but 2nd gear just keeps going, and going. No joke I can pull away from a standing start in 2nd and get to about 110km/h. Great party trick but not overly practical.

 

I have exactly the same thing with my rb20 Z, but many other things to fix before I bother with a LSD diff

[dat2kman]

TIR31 on here sometimes comes up with the odd DR30 diff to sell.

The Subi STI diff is an option, but they sell for bit more than the 200-500.

Have seen DR's go from 800-1300

They are a bit heavier, and stronger.

 

As long as you are not silly on takeoffs, the r180's are fine.

Roundabouts vs ferriswheels, r180 goes straight in, but need the special flange outputs.

R200 needs the moustache and 260Z type click in outputs

Both then use your existing halfshafts.

Check ebay/gumtree, or see what pops up on various forums,

[twoforty z]

So....

The R180 is easier to find, but its weaker

The R200 is harder to find, but stronger.

 

Both can be found with the right ratio (around 4.4) and both are "roughly" the same price to install.

 

"Legally" I'm not allowed to make any performance mods to my Rb20 so it will probably never have more than 200rwkw (which for a 980kg car is plenty in my opinion) so I'm thinking of going down the R180 Subaru path

 

 

[d3c0y]

There is more to it than that. The R180 is nearly 20 years newer and if you get that ratio will have a 4 plate clutch in it. It's also lighter.

[twoforty z]

Well given both diffs are hard to find, i decided to buy which ever one I found first.

So I just bought a R200 2 way LSD 4.375 from a Dr30 for $900

Now to find the required 260z parts ☺