Sorry if I'm not explaining my question well.

What I am asking is if I put 4 of the standard strut mount insulators in and ignore their 260/280z-only rear insulator spacer (or any other donut/etc spacer) in there, will the rear wheel gap (good call on that metric) be greater than, less than, or equal to the wheel gap in the front?

It will be about 0.7" less than it should be.  MSA/Zstore designed the spacer to give 280Z owners an option to get their proper ride height with a new insulator.

 

Sorry for the ranting.  I've been watching World Cup soccer.  We got van Gaal'ed.  p.s. I don't know what the wheel gaps are on a 280Z so can't really say what they'll be with four 240Z insulators.  But they will be 0.7" lower in the back than a factory stock 280Z.  According to MSA.

Edited December 5, 20222 yr by Zed Head

It sounds like you are assuming that the front ride height is the same for all the years, and I'm pretty sure that is not the case. And you are also making the assumption that the center line of the bumpers was the same for all the years? I'm not sure if this is the case, but I'm not comfortable making that assumption without data.

And to make that point... Here's a pic showing how they changed the front spring perch location between the 240 and 260. So in theory, not all the front ends are at the same height from the factory :

That pic came from this thread. Some good pics and info:
https://www.classiczcars.com/forums/topic/60161-lowering-bottom-spring-perch/

And forget 77 and 78... According to the FSM's the rear bumper was lowered compared to the previous 280's. The front seems to be the same as the rest of the 280's but the rear is different.

41 minutes ago, Captain Obvious said:

It sounds like you are assuming that the front ride height is the same for all the years, and I'm pretty sure that is not the case. And you are also making the assumption that the center line of the bumpers was the same for all the years? I'm not sure if this is the case, but I'm not comfortable making that assumption without data.

And to make that point... Here's a pic showing how they changed the front spring perch location between the 240 and 260. So in theory, not all the front ends are at the same height from the factory :

That pic came from this thread. Some good pics and info:
https://www.classiczcars.com/forums/topic/60161-lowering-bottom-spring-perch/

And forget 77 and 78... According to the FSM's the rear bumper was lowered compared to the previous 280's. The front seems to be the same as the rest of the 280's but the rear is different.

Any idea without the spacer, would the vehicle sit level with the ground or would the rear sag compared to the front?

One thing you haven’t mentioned which I’m familiar with. Did you happen to remove the factory bumpers and replacing them with the 240 series bumpers? Just asking. When I removed mine the car’s ride height went up over 2 inches.

Edited December 5, 20222 yr by Yarb

10 hours ago, Yarb said:

One thing you haven’t mentioned which I’m familiar with. Did you happen to remove the factory bumpers and replacing them with the 240 series bumpers? Just asking. When I removed mine the car’s ride height went up over 2 inches.

I haven't actually.  That said, I have the considerably lighter (23 lbs) 77/78 bumpers so I don't think it would change the ride height as much as it would have with the 74-76 ones which were ~90 lbs each.

My car is a 78 as well

11 minutes ago, Yarb said:

My car is a 78 as well

Oh, so the spacer would be necessary for the car's rear not to sag then it seems?

I didn’t gi that route I installed BC coil overs where I could dial the height in.

3 hours ago, chaseincats said:

Oh, so the spacer would be necessary for the car's rear not to sag then it seems?

No offense but you seem to be going round and round with "sag" and rake.  If you explained what you were trying to do and what you've changed so far you might get better advice.  These cars are old and in many cases the springs themselves have "sagged" from when they left the factory.  So one person might get rake and another might get sag after replacing parts.

The MSA "spacer" is just a way for people to replace their old 280Z insulators with new 240Z insulators.  But even the rubber in the insulators has parts that sag.  There is actually a small rubber piece inside the insulator that's called a spacer, that compresses over time, causing "sag"..  So, another point of confusion.

http://www.carpartsmanual.com/datsun/Z-1969-1978/axle/rear-suspension/13

2 hours ago, Zed Head said:

No offense but you seem to be going round and round with "sag" and rake.  If you explained what you were trying to do and what you've changed so far you might get better advice.  These cars are old and in many cases the springs themselves have "sagged" from when they left the factory.  So one person might get rake and another might get sag after replacing parts.

The MSA "spacer" is just a way for people to replace their old 280Z insulators with new 240Z insulators.  But even the rubber in the insulators has parts that sag.  There is actually a small rubber piece inside the insulator that's called a spacer, that compresses over time, causing "sag"..  So, another point of confusion.

http://www.carpartsmanual.com/datsun/Z-1969-1978/axle/rear-suspension/13

I've been asking in a variety of ways if the spacer is needed to have the gap between the body and tire identical on the front or rear.  I haven't received a yes or no yet.

If your tire spaces are currently even, I don't see how it couldn't help but change is you remove 1/2" from the height of the rear strut