Limited-Slip Differential

[red_dog007]

I could have sworn that I have seen a Limited-Slip for the 240z or the Z series just in general.

So, is there a limited-slip differential for my Z? Or did I read it wrong and the R180 and R200 are already limited-slip differentials? Or there aren't any at all?

[jmortensen]

I wrote up a pretty detailed post about this over at your favorite place if you can stomach it: http://forums.hybridz.org/showthread.php?t=114798

There are R180 LSD's available from Nissan, a 2 pinion (crappy) and a 4 pinion (much better) from Nissan. There are also aftermarket LSDs available from KAAZ, Cusco, OBX, Quaife and others I'm sure. The only R diffs that came in Nissan's with LSD's were the 87-89 300ZXTs and some later shortnose R200's from Z32s and 240SXs so far as I know.

[Zs-ondabrain]

So tell me this. In all your dealings with the LSD, can you tell by looking at the 2 pics below, what diff this is.

I was told it's an LSD 3:90 or something like that. It needs a rebuild kit but I'd like to know what it is before I buy a kit for it.

any help would be greatly appreciated,

Dave.

[mrcheeze36]

It looks like an R200 to me Dave, however you need to check the stamp on the ring gear to be sure if its a 3.9 or not. I believe 3.9 usually appears as "39:10" (basically 39/10 = 3.9...not sure if there are other ways it is stamped though)

[jmortensen]

Yep, as Eric says look for the ring and pinion gear count, divide it out and that tells the gear ratio. I'm don't have any part numbers committed to memory, so that doesn't help me. It is an R200, and it is definitely an LSD. You can tell if it is the more or less aggressive version by looking at the ramps and the cross pin shaft (which is point more or less right at the camera in the photo). If it looks like this it is the less aggressive diff with the big spacer:

http://album.hybridz.org/data/500/90952way1.jpg

This is the better one with more clutches and the more aggressive ramps:

http://album.hybridz.org/data/500/R200_NISMO_ramps1.JPG

[jmortensen]

Dave, if you're rebuilding the LSD you might want to take a look at these threads:

http://forums.hybridz.org/showthread.php?t=92629

http://forums.hybridz.org/showthread.php?t=117818

If you're rebuilding the whole diff I'd say good luck. I think the outer pinion bearing is NLA and it is a Nissan specific bearing I'm pretty sure. I'd transplant the LSD into another diff.

Here's a thread on that procedure: http://forums.hybridz.org/showthread.php?t=119990

[Zs-ondabrain]

Thank you SOO much guys!!!

I have an 3:90 R-200 with ZX turbo CV's in the 240Z right now. So what you're saying is that I can pull the Gears out and throw the LSD into the R-200 body that is already in my car?

If so, I'm all over it. I'll read up on all the links you guys suggested and go from there.

Thanksd again,

Dave.

[Pir0San]

I just read through your writeup Jon, and I'd have to say you did a great job. My question is this: has anyone done a writeup on how to install the r200 differential into the 240Z? I've tried to look it up, but had little success.

I did see the part list on your writeup, and I understand what I need, but what really confuses me is the prospect of the halfshafts. I was thinking about going for the 84-89 300zxt r200 swap, but I don't quite understand what I'd have to get in order to make the halfshafts/cv shafts work. I guess it's just not clicking quite yet .

I want to get something with a higher gear ratio for more acceleration, so I was thinking a 3.90 differential, hence the 300zxt differential. Or would it just be easier to swap to a non-lsd 3.90 r200 from a 280zx?

Oh, one last thing. How would 3.90's perform on a f4w71b 4 speed in top gear on the freeway? Would I be revving much higher than I do now with my stock 3.54 (I think that's what it came stock with).

Thanks!

[jmortensen]

Thanks for the compliment. I just got fed up of answering the same question over and over and over and over.

The stub axles will stay, so what you are doing is connecting the diff to the stock stub axles.

You can do this two ways:

1. Use the output stub shafts from a 280Z. These plug into the sides of the diff and then you can use any just about any halfshafts out of a 240Z, 260Z, or 280Z.

2. Use the CVs from the 300ZXT (not the NA CV shafts, only the turbo) along with an adapter from Modern Motorsports. This adapter replaces the companion flange on the stub axle -- the inboard side only. You can send yours to Ross and he'll weld on the adapter, or you can buy his new billet adapters.

As to gear ratio, this page should help you. Plug in all the pertinent info and then you can figure out what your rpms will be at cruising speed on the freeway. http://www.geocities.com/z_design_studio/

There really isn't a "right" answer to gearing, but my personal preference is for a closer ratio transmission like the ZX trans along with a lower rear gear like 3.90s or 4.11s. This works well with NA cars and especially those with larger than stock cams or induction. I ran mine for years with a ZX trans and a 3.70 rear gear, it was OK, but it would have been better with the lower gears, and I never did utilize the rpm limited top speed of 178mph with my 3.70s...

[Zs-ondabrain]

Seaking only from what I know and have experienced. Here's what I have....

79' 280ZX 5-speed

83 ZX turbo R-200 and CV's from the turbo as well. (it's a 3:90)

I don't know where he (JZM) got them but I ended up witha rare pair of companion flanges that slid right onto my stub axles. But I also recall JZM giving me a set of stub axles from another car that allowed the companion flanges to slide right on.

Anyways, I also have 225/50R 16's and When I'm doing 60 MPH The tach is only at 2300 RPM's. And I think it's only 400 rpm's for every 10 MPH

2700 RPM at 70 MPH

3100 RPM at 80 MPH

3500 RPM at 90 MPH and so on....

The CV's fit tight on the right? side but there's just enough slack that there is not a problem. The only problem is when I jack up the rear of the car, My rear sway bar rests on the bottom side of the CV boots. So as long as I don't turn the wheels too much when it's in the air, I'm fine.

Hope the numbers help.

JON,

Thanks again for all your help. Every one is their own expert and I as well as other are very greatful that you've shared your expertease with us. I do the best I can for every one here and so do others. I think that's what makes this such a great site. I learn something new every visit.

Thanks again Jon and every one who donates their time here,

Dave.

[jmortensen]

OOPS!!! I totally forgot about the 280ZXT CV axles. I think that info is on the first link to Hybrid Z, but for those who would rather read it here there are actually two ways to install those.

1. Buy the companion flange adapter from www.modernmotorsports.com.

2. You can use the 280ZXT companion flange with the 240Z (but not 280Z) stub axles. More info there on www.alteredz.com.

Sorry for the error.

[mrcheeze36]

Hi Dave,

Jon provided a lot of great threads...here's one more thread to add to the list (Power Brute LSD install).

Precision Gear LSD install by Mike C