Over Thinking R200 internal swap?

[Geno750]

After surgery to my foot I've had way too much free time on my hands to read/research but not turn a wrench, so forgive any ignorance on my part with a few of these questions.

 

First assumption - all 1976 280Z's have R200 longnose rear ends.

 

Second assumption - All VLSD R200's from a 180SX are 29 spline. But does this really matter in the long run? (see below).

 

I'm trying to do this correctly the first time. My big question is if I go with the T3 back plates to use later model hubs, can I simply swap to whatever R200 diff I want, use the correct input shafts for that diff in my 76's long nose and be good to go with the T3 axles?

 

I've tried to search for this answer but the information is somewhat convoluted at best. Worst case, this thread will document my trials and tribulations of attempting this swap my self.

 

Next question, and somewhat related. Is there a strength advantage (long or short nose, I have both) to how the diff is mounted to the car? My Z has a 1JZGTE and will exceed 450ft/lb of torque once the fuel system is upgraded to use E85. I'd prefer to install whichever diff will be held in more securely.

[Xnke]

The longnose R200 is fine...I'm sure you've seen the wheelstanding R200-diffed car photo here multiple times.

 

For the money, the OBX helical is the way to go. The VLSD's out there all have high milage and are generally starting to wear out at best, or are worn out nearly-open diffs at worst. It's a direct fit, only need to check your gear mesh and possibly shim it side-to-side to get the lash set properly. It's not a hard job.

 

That said, the VLSDs MUST use the stub axles that came with the diff, as the axle lengths are different. One stub is short and one is much longer. Generally these axles will be too long to fit under the back of a Z car, by several inches. You will have to dissasemble the axles, swap the center bars around, and figure out which center bars will be the proper length.

 

All the information you will need is contained in the Drivetrain forum here.

[Geno750]

Yeah. I'm lucky/unlucky and know the exact miles on my 180SX diff. I wadded up the 180SX the diff came from, car had just over 47k miles.

 

The VLSD will simply hold me over until I find a deal on a 1.5way.

 

If using the vlsd from my shortnose in the longnose will let me use the 180SX stub axles then great, I won't buy a shortnose mount (unless there's an advantage to be had here.), I'll just buy the t3 axles.

[Xnke]

You can do that, but you will need to get companion flanges to fit your outer stub axles, and the center bars to go between the CV joints. the 180SX axles will be too long to fit.

[Geno750]

You can do that, but you will need to get companion flanges to fit your outer stub axles, and the center bars to go between the CV joints. the 180SX axles will be too long to fit.

I'll go with T3 back plates, use a 240sx hub and t3 shortened axles. 29spline parts should last longer and from what I've seen, T3's solution is by far cheaper while offering what seems like a better option.

[Xnke]

I'm not seeing anything on the T3 website in their product list that would indicate they have the shortened center bars, companion flanges, adaptors....

 

Enlighten us?

 

EDIT:

 

Must be thinking this package...

 

https://technotoytuning.com/nissan/280z/complete-r200-r230-rear-end-conversion-z-car

 

At $2780, that's only ~5.8 times the cost of buying the OBX helical diff that many of us run with the stock Z-car axles, or 300ZXT conversions. Doesn't seem like good value if all you're doing is fitting a limited slip differential.

Edited December 26, 2015 by Xnke

[Geno750]

I'm only interested in their axles and the backing plates. I have all of the other components from my other car. Including new wheel bearings and Z32 rear brake assembly's.

[seattlejester]

The short nose in those cars are going to have a different crown gear if I remember correctly. You would have to swap the crown gear out of the long nose R200 onto the short nose, the problem then becomes the hole diameter mismatch on the center vs the crown gear. You can either drill out the crown gear to run the larger bolts, or you can shim the center down to the smaller diameter bolt size. You can restore some lost wear by shimming the center, but that will eventually wear out as well. 

 

You would also have to purchase the suspension upright since you would essentially be removing the whole upright from the 280z. That would mean not only the backing plate, but the strut/coilover as well. At that point I really would be tempted to just convert to the short nose given the cost. Usually people either cobble together a solution keeping the factory upright, or ditch it altogether for another solution, what you are proposing is to ditch the upright, but to keep the differential. Kind of only a half benefit.