z31'84-86 turbo flywheel size

[z31 maniac]

Is the z31 84-86 turbo flywheel the same size as the z32 na flywheel measured from one side of the ring gear to the other side (diameter)?
It had always been said the 84-86 is 240 mm and the z32 na is also 240 mm. But that is the size of the clutch contact area of both flywheels I believe diameter wise.
Please can someone verify this?

[flatfoot]

Correct me if I'm wrong but doesn't the Z31 have 6 bolts from the flywheel to the crank and the Z32 have 8 bolts??

[Z_Karma]

Yeah, Z31 is 6, Z32 is 8

http://www.z31.com/transmission.shtml

The non-turbo and the 84-86 turbo came with a 240mm flywheel. The 87-89 turbo came with a 250mm flywheel. This isn't the overall diameter of the flywheel, it is the diameter of the clutch surface area. The overall diameter of the flywheel is the same.

As for OD (outer diameter) supposedly the z32 ring gear is larger and won't work with the z31 starter location unless the holes are slotted outward to allow adjustment.

[z31 maniac]

Would it be possible to slot the starter outwards? Has it been done before? Do you know? There is very little material on the brace and bell housing to nudge the starter outwards. I believe the Z32na flywheel is approximately 12mm or so larger than the Z31 84-86 flywheel. To fabricate new bolt holes 12mm outwards would i think be quite dodgey as the starter when engaged spins with quite some force. Has it been done before? That would require some precision work..

[shromy]

Would it be possible to slot the starter outwards? Has it been done before? Do you know? There is very little material on the brace and bell housing to nudge the starter outwards. I believe the Z32na flywheel is approximately 12mm or so larger than the Z31 84-86 flywheel. To fabricate new bolt holes 12mm outwards would i think be quite dodgey as the starter when engaged spins with quite some force. Has it been done before? That would require some precision work..

The better question may be why would you want to

[Z_Karma]

Go for it. Slot them out and make up little crescent shims in the void behind them so it can't wander back.

But first, understand and measure the tolerances of a stock starter pinion engaging a flywheel and try to duplicate those tolerances.

[z31 maniac]

Excellent piece of engineering afterthought. I think I may fabricate a flat ring similar to the shape of the brace holding the starter, offsetting it in the process to nudge it outwards in order to engage the larger flywheel. The only snag shall be the little bulge where the starter pinion goes. The starter pinion may scrap the bellhousing since the starter is now about 12mm outwards.. Like you said, Z_Karma, tolorences of the pinion engaging the flywheel must be observed with great precision, otherwise the flywheel ring gear or the pinion maybe chewed up instantly.
Thank you Z_Karma. You have been very helpful and an extremely optimistic Z car enthusiast..

[Z_Karma]

I'm optimistic only when it isn't me doing it

But it's been asked before and the guy doing it never responded back if he completed it or not, iirc.

If it were me, i'd physically verify the OD of a Z32 vs the OD of the Z31 with some big calipers i have at work and triple check the 12mm number before slotting anything.
Is it 12mm total or 6mm per side, circumference or diameter. things like that...

Also, thinking about it more, i would look into shimming the starter bracket the required distance rather than slotting the holes in it if it is just slotting it laterally relative to the motor.
That would also brace the starter outward without allowing it to wander inward.