My understanding is that Nissan improved some front strut suspension angles with the introduction of the Z31. For whatever reason, has anyone fitted Z31 struts to their ZX?

 

Not that I'm aware of.

I would rather go full coil-over than mess with trying to retro-fit Z31 struts into a 280ZX.

 

Yes, I've heard of this, talked with a guy who did it and saw pics on Hybridz.org

The Z31 strut bolts right in and attaches to the 280ZX ball joint. This will move your hub forward about 1 inch which is not 'good' or really bad except that the front wheel looks like the rear. (forward in the wheel well) Someone said it increases caster which doesn't hurt...
It also adds some positive camber. This is corrected either by lowering the front of the car or by buying camber plates. Most of us are lowering the front anyway so this does away with the problems of too much negative camber. Bump steer spacers should still be used to keep the lower control arm angle correct.
The bennefits are 5-lugs (if you want that for wheel options) and larger brake rotors. Early Z31 struts can also be used to maintain 4-lug.
There were 3 different brake setups in the Z31 I believe

84-86 (non-turbo the same as turbo except for Turbo being 5-lug)
87-89 non-turbo, thicker rotors
87-89 Turbo, even larger brakes, and calipers

Once 87-89 hubs are installed, the theory is that the 4-piston Z32 (1990-96) calipers bolt right on. BAM!

There is a Z31 forum that has some FAQs on this subject. I went over it when considering the swap but I ended up finding some nice (and rare) 4-lug wheels so now I'm just going to do minor improvements on the factory 280ZX brakes.

I have 1987 non-turbo brakes for sale if you're interested.

Also, 1987-89 Z31 rear brakes have vented rotors from the factory where all earlier Z's used solid rotors. These of course would only be used if you're doing a front and rear 5-lug swap.

 

Is there a matching bolt-in mod for the rear hubs so that it's 5-lug all around? Also, would the tension rods, control arms, and steering components need to be swapped to the Z31's, or do those 280ZX parts bolt right up to the Z31 strut without modification?

 

The control arm and tension rods bolt together. (stock 280ZX) 280 ball joint goes on top of that and bolts to the Z31 strut assembly.

For the rear, you disasemble your 280 hub, drill out the plate to five lug, then insert new studs and slap on the rotor. A custom caliper bracket will need to be made for the rear caliper.
More details on drilling the holes and stud inserting can be found:

http://zcar.netdojo.com/5lug.htm

http://www.z31.com/brake.mods.shtml

On Hybridz look under the Brakes/Wheels section. Search for 5-lug 280ZX

 

Thanks for that, sounds like a worthwhile mod.

 

From The Z-Series Datsuns by Ray Hutton, on front suspension changes made to the Z31 over the ZX.

At the front, castor was increased from 5 to 7 degrees and both trail and scrub radii decreased. Anti-dive characteristics were also increased.